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Climate change response of vegetation across climatic zones in Italy
Abstract and Figures
Italy represents a good model region for assessing vegetation responses to changing climate across a broad climatic range, from Mediterranean warm-dry climate to alpine cold-humid climate. We reviewed results of studies analysing the response of natural vegetation to climate change in Italy, published until July 2016 in peer-reviewed journals. Evidence provided by these studies shows that climate warming is expected to overall enhance plant growth in Italy but the magnitude of growth stimulation will probably vary among climatic zones, with stronger effects in the cold regions of the alpine climatic zone. Drought, induced by reduced precipitation and/or increased evapotranspiration can override the positive effects of higher temperatures on plant growth not only in the Mediterranean warm-dry climatic zone but also in the less dry sub-Mediterranean climatic zone and even in the temperate one. Our review highlighted two major research gaps to which future research should be directed. First, there is poor knowledge of how species composition will change in response to changing climate and how this will affect ecosystem functioning in Mediterranean to temperate ecosystems. Second, there is poor knowledge of possible interactions between climate-induced vegetation changes and dynamic processes related to land-use changes.
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... Over the last decades, warming has been associated with variations in precipitation which in turn depends on the area (e.g. increases in the north-west and decreases in the south-east) and the seasonal pattern, with overall decreases in summer (Schmidli and Frei, 2005;Auer et al., 2007;Brunetti et al., 2009;Chelli et al., 2017). Future projections, even if affected by uncertainties depending on the global and regional circulation models considered, indicate the same trend: i.e. decreases in summer precipitation (especially in the southern Alps) and slight increases in winter by the end of the century (Gobiet et al., 2014). ...
... Temperatures showed an increasing trend while in summer the rainfall rate is decreasing (Toreti and Desiato, 2008;Lionello et al., 2014;Longobardi et al., 2016;Cramer et al., 2018;Caloiero et al., 2018;Cherif et al., 2020), and this was associated to an increased dry spell (Moberg and Jones, 2005). Chelli et al. (2017) highlighted that, although in the whole Italy changes in temperatures and precipitation occurred, the pattern of these changes was different in the northern and mountain zones with respect to the Mediterranean bioclimatic zone. According to Corti et al. (2009), in this region the decrease of precipitation in summer was higher than the other Italian areas, with a lower number of rainy days associated to a higher intensity of precipitation events and more severe drought periods. ...
... Giorgi and Lionello (2008), using an ensemble of 17 general circulation models (GCMs) projections, indicated that increase in temperature will be characterized by a strong seasonal trend where the highest increase will be centred on the summer season (Lionello and Scarascia, 2018), and this will be associated to a significant decrease in precipitation in summer from about 10-15% to 30% (Cramer et al., 2018), which however is not so rele-vant given the very low rainfall probability in summer months in this area. An increase of extreme weather events as storms, floods and heatwaves is also expected in the coastal areas of the Mediterranean climatic zone (Medri et al., 2013;Dono et al., 2016;Chelli et al., 2017;Zhang et al., 2019). ...
The ongoing climate change, which is threatening grassland agroecosystems throughout Europe, is also evident in the Italian grasslands. These systems, often located in marginal areas, are species-rich ecosystems characterized by variable, and often unreliable, grass and forage production and strongly dependent on interactions between climate, soil and agricultural management practices (e.g. land abandonment, lack of investments on innovation, stocking rates reduction, etc.), making them very sensitive and vulnerable to climate change. This review draws from the scientific literature the impacts of current and expected climatic changes on grassland and forage crop systems framed in three different bio-climatic zones of Italy, namely the Alpine, Continental and Mediterranean, and focussing on i) grassland biodiversity and vegetation and ii) forage production and quality. The main aims of this review are to i) revise the existing literature in the domain, highlighting different or common trends among different Italian biogeographical regions, ii) provide information on the main climatic impacts analysed and drivers involved in the studied evolutions, and iii) point out the knowledge gaps currently pending in order to hypothesize the future scenarios of research in this sector.
Even if this review has pointed out differences in approaches, adopted methodologies and purposes of conducted researches, some common trends can be highlighted, though located in three different environments. Expected warming and modification on rainfall pattern will produce deep changes in vegetation of grassland types, with reduction or the disappearance of cold tolerant species and a spread of xeric/termophilous ones and shrubby vegetation and with a general upward shift of vegetation types in mountain areas. Moreover, a general reduction of aboveground biomass is expected, as summer droughts is considered a main driver able to force grassland productivity. Finally, warming and rainfall reduction are considered the main factors able to reduce forage quality and palatability of grasslands, as a consequence of reduction of nitrogen content in the available biomass and of the higher spread of less unpalatable species and shrubs. The hypothesis is that the information gained from this review can provide insights on the current level of knowledge on the expected impacts of climate change on Italian grassland systems, and support the development of policy strategies for adaptation at national level.
... Alpine ecosystems, distributed over the limit of forests and beyond to the snow line, are among the ecosystems most sensitive to and threatened by climate change (e.g., raising temperatures and change in precipitation patterns) [1][2][3]. Alpine plant communities are mainly shaped by temperatures and hydrologic features, which in turn derive from the interaction of winter precipitation, wind exposure, landscape position [4], snowpack accumulation [5], snowmelt patterns [6], and summer soil moisture [7], overall influencing the duration of the vegetative period [8]. ...
... Considering the consistent and heterogeneous changes ongoing on alpine ecosystems, likely related with both the increase in temperatures [21,22] and the reduction in annual rainfalls [1,42,[48][49][50][51], the present work sets out to explore vegetation dynamics on alpine Mediterranean calcareous grasslands and swards in central Apennines (Italy). Through a re-visitation vegetation study (after 18 years), we explored the temporal changes in two alpine communities in the Maiella National Park (MNP) that are representative of the central Apennine's alpine belt: Apennine stripped grasslands, growing on steep slopes, and wind edge swards, both included in the 6170 EU Habitat "alpine and subalpine calcareous grasslands" [52,53]. ...
Global change threatens alpine biodiversity and its effects vary across habitat types and biogeographic regions. We explored vegetation changes over the last 20 years on two Mediterranean alpine calcareous grasslands in central Apennines (Italy): stripped grasslands (EUNIS code E4.436) with Sesleria juncifolia growing on steep slopes, and wind edge swards (EUNIS code E4.42) with Carex myosuroides. Based on a re-visitation of 25 vegetation plots of 4 × 4 m, we assessed changes in overall and endemic plant species cover and richness by nonparametric Kruskal-Wallis test. We explored changes in structure and ecology using growth forms and Landolt indicators for temperatures. We identified species' contribution to temporal changes using the similarity percentage procedure (SIMPER). The results evidenced a significant decline in all species cover and richness on both plant communities with a significant decline in alpine and endemic species and in hemicryptophytes with rosette and scapose ones on stripped grasslands, as well as a decline in subalpine and suffruticose chamaephytes species on wind edge swards. Such biodiversity loss, so far observed only in the warmest and Southern Mediterranean summits of Europe, is likely attributable to the combined effect of higher temperatures; the increase in the vegetative period; and the decrease in water availability, which is particularly severe in calcareous regions. Our study suggested the vulnerability of the analyzed alpine ecosystems to global change and the importance of monitoring activities to better understand vegetation trends and adaptation strategies in subalpine, alpine, and nival ecosystems.
... In fact, the air temperatures before snowmelt and after the meltdown (i.e., the May/June temperatures) are the main factor affecting plant growth in these ecosystems ( Jonas et al., 2008;Rammig et al., 2010;Carbognani et al., 2016). However, climate change probably interacted with land-use change, which can exacerbate the effects of climate warming on mountainous vegetation (Theurillat and Guisan, 2001), although such an issue is still largely unexplored ( Chelli et al., 2017). ...
... Ferretti et al. (2014), in a study including LTER forest sites in the Alps and Apennines, demonstrated that an increase in nitrogen deposition had a positive effect on tree growth (measured as basal area increment) and on aboveground net primary productivity (ANPP), thus promoting carbon sequestration. However, reduction in rainfall can override such positive effects ( Chelli et al., 2017). Long-term studies performed at a beech forest in the Apennines (LTER_EU_IT_031; Table 1) showed that carbon sequestration depends on both water availability (precipitation) and air temperature. ...
Mountain ecosystems are sensitive indicators of climate change. Long-term studies may be extremely useful in assessing the responses of high-elevation ecosystems to climate change and other anthropogenic drivers. Mountain research sites within the LTER (Long-Term Ecosystem Research) network are representative of various types of ecosystems and span a wide bioclimatic and elevational range. Here, we present a synthesis and a review of the main results from long-term ecological studies in mountain ecosystems at 20 LTER sites in Italy, Switzerland and Austria. We analyzed a set of key climate parameters, such as temperature and snow cover duration, in relation to vascular species composition, plant traits, abundance patterns, pedoclimate, nutrient dynamics in soils and water, phenology and composition of freshwater biota. The overall results highlight the rapid response of mountain ecosystems to climate change. As temperatures increased, vegetation cover in alpine and subalpine summits increased as well. Years with limited snow cover duration caused an increase in soil temperature and microbial biomass during the growing season. Effects on freshwater ecosystems were observed, in terms of increases in solutes, decreases in nitrates and changes in plankton phenology and benthos communities. This work highlights the importance of comparing and integrating long-term ecological data collected in different ecosystems, for a more comprehensive overview of the ecological effects of climate change. Nevertheless, there is a need for i) adopting co-located monitoring site networks to improve our ability to obtain sound results from cross-site analysis, ii) carrying out further studies, with fine spatial and temporal resolutions to improve understanding of responses to extreme events, and iii) increasing comparability and standardizing protocols across networks to clarify local from global patterns.
... According to Zilotto et al. (2004), the temperature of the air decreases at an average of 0.6 °C per 100 m height, thus causing a shortening of the vegetative activity by about 5 days and a decrease in forage production by about 5%. In the context of recent changes in annual rainfall and average annual air temperature (Figure 15.3b and c and Figure 15.4b and c), an analysis of vegetative cover estimates that plant cover has increased in Apennine mountain sites (Chelli et al. 2017). For example, a general tendency toward increased forest vegetative cover was also observed on Matese mountain at 1400-1600 m a.s.l. ...
... Indeed, in the case of the studied area, the increasing warming can affect ecosystems by increases in temperature, early snowmelt, and a prolonged growing season. These factors may have reduced climatic stresses on the plant communities studied by Chelli et al. (2017) and may have played a key role in the observed increase in plant cover. In fact, the air temperatures before snowmelt and after the meltdown (i.e., the May/June temperatures) are the main factor affecting plant growth in alpine ecosystems (Carbognani et al. 2014). ...
As a contribution to sustainable rural development in a multispecies herding system of internal areas of Centre-South Apennines, two studies have been carried out in Montenero Val Cocchiara (IS) and Frosolone/Macchiagodena (IS). The soil-vegetation systems of the selected sites in the Molise region of Southern Italy were studied in terms by pedo-geographical characterization. At the landscape level, a schematic transect representative of the distribution models of the main soil-vegetation units was reported for each site. Ongoing vegetation dynamics in areas affected by observed stresses and changes of land use are described in detail. Sustainable stocking rates are then determined using a spreadsheet model that simulates the nutritional needs of grazing species and their breeding techniques. Due to reduced stress, the natural vegetation colonizing abandoned agricultural fields and pastures is recovering well. The speed and spatial patterns of these processes of recovery are strongly influenced by differences in stresses due the soil conditions in degraded landscape. Within each pasture area, stress on plants, measured by stocking rate, is estimated up to the limit beyond which the production of the vegetation would be compromised in the long term. During some years, there were significant differences between estimated grazing pressure and the real grazing pressure, emphasizing the importance of preservation of resources of grass, trees and shrubs.
... Global change trends are undoubtedly producing effects on species diversity in different ecosystems (e.g. van Vuuren et al. 2006;Chelli et al. 2017;Rogora et al. 2018). In addition, there is growing consensus on the major impact of interannual climate variability (Grime et al. 2008;Cleland et al. 2013) and extreme weather events on plant communities (Jentsch et al. 2007), including seasonal effects e.g., extreme drought . ...
... However, the contemporary occurrence of both species replacement and species loss processes resulted from this research in the dry year calls for more detailed diachronic studies. Here, experimental approaches manipulating water availability (see Jentsch et al. 2007;Jentsch and Beierkuhnlein 2008;Chelli et al. 2017) could be key to assessing fine-scale mechanisms of community assembly. ...
Species pool conservation is critical for the stability of ecosystem processes. However, climate and land use changes will likely affect biodiversity, and managers of protected areas are under increasing pressure to monitor native species diversity changes by approaches that are scientifically sound and comparable over time. Here we describe a plant diversity monitoring system in use since 2002 in the "Montagna di Torricchio" Nature Reserve (LTER_EU_IT_033), a Central Apennines representative area of 317 ha, most of which is under strict protection. The aim of this paper was to assess changes in plant species richness over time and to deduce the patterns of species assemblage. The monitoring system was based on a probabilistic sampling design representative of the different physiognomic vegetation types occurring in the Reserve. A total of 34 plots (10×10m) were sampled in 2002, 2003 and 2015, and their species presence/absence and relative coverage were estimated. Repeated measure ANOVA was used to test for plot-level and ecosystem-based changes in species richness along the study period. Temporal nestedness and temporal turnover metrics were used to assess patterns of species' compositional changes. The results *Contributed equally as the first authors. A peer-reviewed open-access journal Stefano Chelli et al. / Nature Conservation 34: 145-161 (2019) 146 showed significantly different levels of species richness depending on the year, with the lowest value in 2003, probably linked to extreme drought events. Forest systems were comparatively stable, demonstrating the capacity to buffer interannual climate variability. Regarding compositional changes along the entire period (2002-2015), we found random patterns of both temporal nestedness and turnover, indicating stability in species composition. However, we also showed the contemporary occurrence of species loss and species replacement processes, considering the dry year 2003, a finding which should be further explored through fine-scale studies to unravel mechanisms of community assembly under drought. The use of a probabilistic sampling design representative of the different physiognomic vegetation types proved to be advantageous in monitoring the Nature Reserve vegetation and collecting reliable quantitative information. This data, in turn, provides the basis for improvements in management practices and proposed adaptation measures.
... In fact, the air temperatures before snowmelt and after the meltdown (i.e., the May/June temperatures) are the main factor affecting plant growth in these ecosystems ( Jonas et al., 2008;Rammig et al., 2010;Carbognani et al., 2016). However, climate change probably interacted with land-use change, which can exacerbate the effects of climate warming on mountainous vegetation (Theurillat and Guisan, 2001), although such an issue is still largely unexplored ( Chelli et al., 2017). ...
... Ferretti et al. (2014), in a study including LTER forest sites in the Alps and Apennines, demonstrated that an increase in nitrogen deposition had a positive effect on tree growth (measured as basal area increment) and on aboveground net primary productivity (ANPP), thus promoting carbon sequestration. However, reduction in rainfall can override such positive effects ( Chelli et al., 2017). Long-term studies performed at a beech forest in the Apennines (LTER_EU_IT_031; Table 1) showed that carbon sequestration depends on both water availability (precipitation) and air temperature. ...
Italy is among the European countries with the greatest plant diversity due to both a great environmental heterogeneity and a long history of man-environment interactions. Trait-based approaches to ecological studies have developed greatly over recent decades worldwide, although several issues concerning the relationships between plant functional traits and the environment still lack sufficient empirical evaluation. In order to draw insights on the association between plant functional traits and direct and indirect human and natural pressures on the environmental drivers, here we summarize the existing knowledge on this topic by reviewing the results of studies performed in Italy adopting a functional trait approach on vascular plants, briophytes and lichens. Although we recorded trait measurements for 1418 taxa, our review highlighted some major gaps in plant traits knowledge: Mediterranean ecosystems are poorly represented; traits related to belowground organs are still overlooked; traits measurements for bryophytes and lichens are lacking. Finally, intraspecific variation has been little studied at community level so far. We conclude highlighting the need of approaches evaluating trait-environment relationship at large spatial and temporal scales and the need of a more effective contribution to online databases to tie more firmly Italian researchers to international scientific networks on plant traits.
... The increase in the frequency and magnitude of climate extremes is a well-accepted feature of forecast alterations to the global climate (IPCC, 2007). How climate extremes affect species, communities and ecosystems has become critical to science and society (Jentsch et al., 2011;Smith, 2011;Lloret et al., 2012;Hoover et al., 2014;Chelli et al., 2017;De Boeck et al., 2017) but several effects on biodiversity, as the implications for ecological restoration, are still unknown (Harris et al., 2006). For example, it is acknowledged that restoration outcomes can be driven by biotic and abiotic factors (Stuble et al., 2017).We know that the effect of rainfall on species cover in serpentine grassland depends on the rate of disturbance, and that extreme climate events, such as el Niño cycles, contribute to the invasion of non-native species (Hobbs et al., 2007). ...
... The Mediterranean Basin is considered a climate change hotspot sensitive to global warming (Giorgi and Lionello, 2008). In Italy, during the last 55 years, extreme temperature indices showed a general warming trend for the entire peninsula (Toreti and Desiato, 2008;Chelli et al., 2017) and in future decades heavy rainfall and summer heat waves are expected (ISAC-CNR, 2009). In Tuscany, precipitation indices showed a negative trend (years 1955-2010) in the number of wet days, associated with an increase in the contribution of heavy rainfall events to total precipitation (Regione Toscana, 2012). ...
The impacts of climate extremes on species, communities and ecosystems have become critical concerns to science and society. Under a changing climate, how restoration outcomes are affected by extreme climate variables is a largely unknown topic. We analyzed the effects of experimental factors (grazing and sowing of native species), extreme climate events (intense precipitation and extreme temperatures indexes) and their combination on the restoration progress of a dry, calcareous grassland in Tuscany (Italy) with a 1 year before/15 years continuous annual monitoring after, control/impact (BACI) experiment. Grazing had a beneficial effect on the diversity of the grassland, while sowing had a limited impact. The climatic index that most affected the entire plant community composition was the number of very heavy precipitation days. The interaction of grazing and extreme climatic indexes had a significant detrimental effect on restoration outcomes, increasing the cover of synanthropic and cosmopolitan-subcosmopolitan generalist species and decreasing the cover of more valuable species such endemic species. In the richer grazed plots, species richness showedn a lower sensitivity to the average precipitation per wet day.: this results suggest that dealing with climate extremes, the richest communities might not be the more resistant. In grazed site restoration outcomes can be negatively influenced by the intensification of precipitation and temperature extremes. In a context of progressive tropicalization of the Mediterranean area, to assist managers setting achievable restoration goals, restoration practitioners should consider that climate extremes might interfere with the beneficial effects of restoration practices.
... In fact, the air temperatures before snowmelt and after the meltdown (i.e., the May/June temperatures) are the main factor affecting plant growth in these ecosystems ( Jonas et al., 2008;Rammig et al., 2010;Carbognani et al., 2016). However, climate change probably interacted with land-use change, which can exacerbate the effects of climate warming on mountainous vegetation ( Theurillat and Guisan, 2001), although such an issue is still largely unexplored ( Chelli et al., 2017). On European mountain summits, increasing atmospheric temperatures already have resulted in a measurable expansion of thermophilic species that increased their cover in situ and migrated from lower elevations into the alpine lifezone ( Grabherr et al., 1995;Gottfried et al., 2012;Jiménez-Alfaro et al., 2014). ...
... Ferretti et al. (2014), in a study including LTER forest sites in the Alps and Apennines, demonstrated that an increase in nitrogen deposition had a positive effect on tree growth (measured as basal area increment) and on aboveground net primary productivity (ANPP), thus promoting carbon sequestration. However, reduction in rainfall can override such positive effects ( Chelli et al., 2017). Long-term studies performed at a beech forest in the Apennines (LTER_EU_IT_031; Table 1) showed that carbon sequestration depends on both water availability (precipitation) and air temperature. ...
Mountain ecosystems are sensitive and reliable indicators of climate change. Long-term studies may be extremely useful in assessing the responses of high-elevation ecosystems to climate change and other anthropogenic drivers from a broad ecological perspective. Mountain research sites within the LTER (Long-Term Ecological Research) network are representative of various types of ecosystems and span a wide bioclimatic and elevational range.
Here, we present a synthesis and a review of the main results from ecological studies in mountain ecosystems at 20 LTER sites in Italy, Switzerland and Austria covering in most cases more than two decades of observations. We analyzed a set of key climate parameters, such as temperature and snow cover duration, in relation to vascular plant species composition, plant traits, abundance patterns, pedoclimate, nutrient dynamics in soils and water, phenology and composition of freshwater biota.
The overall results highlight the rapid response of mountain ecosystems to climate change, with site-specific characteristics and rates. As temperatures increased, vegetation cover in alpine and subalpine summits increased as well. Years with limited snow cover duration caused an increase in soil temperature and microbial biomass during the growing season. Effects on freshwater ecosystems were also observed, in terms of increases in solutes, decreases in nitrates and changes in plankton phenology and benthos communities. This work highlights the importance of comparing and integrating long-term ecological data collected in different ecosystems for a more comprehensive overview of the ecological effects of climate change. Nevertheless, there is a need for (i) adopting co-located monitoring site networks to improve our ability to obtain sound results from cross-site analysis, (ii) carrying out further studies, in particular short-term analyses with fine spatial and temporal resolutions to improve our understanding of responses to extreme events, and (iii) increasing comparability and standardizing protocols across networks to distinguish local patterns from global patterns.
... This strategy may be even more necessary as we consider the unpredictable effect of climate change on wheat in vulnerable areas such as Italy (Rogora et al., 2018;Spinoni et al., 2018). These areas are characterized by a large diversification of environments, constantly changing due to climate change, which is shaping biodiversity and ecosystem functioning (Chelli et al., 2017). For these reasons, selecting genotypes adapted to specific environmental conditions could be a winning strategy to face the challenges of global warming. ...
Grain yield plateau is a serious concern in many countries, including Italy. A specific‐adaptative strategy might apply to contrast this unfavourable condition. This study aimed to investigate the gain in grain yield and yield‐related traits of bread wheat in Italy over a 16‐year period. A historical dataset concerning 105 sites across Italy and observations on grain yield, heading date, plant height and thousand kernel weight was used. The target population of environments (TPEs) were defined using several environmental parameters. The results showed that while there was a general increase in thousand kernel weight over the 16 years, there was no significant improvement in grain yield and heading date. By contrast, plant height showed a slight decrease over the years. The study also identified five TPEs presenting different climate scenarios in Italy. The TPEs showed varying levels of performance for the traits of interest, with the Po valley (TPE4) showing the highest values for grain yield and thousand kernel weight. The study also identified the best‐performing genotypes for each TPE, providing valuable insights for future wheat breeding programmes in Italy.
... Woody plant encroachment has been documented in grassland, alpine, and sub-arctic ecosystems and linked to changes in precipitation and temperature that facilitate the establishment of tree and shrub species (Amagai et al., 2018;Fraser et al., 2014;Symstad & Leis, 2017;Wookey et al., 2009). Furthermore, changes in the geographical range of species, alterations in the dominant plant species in a community, or altitudinal shifts of plants to track temperature increases have also been recorded (Allen & Breshears, 1998;Chelli et al., 2017;Crimmins et al., 2011;Kelly & Goulden, 2008;Mueller et al., 2005). ...
The effects of climate change on vegetation composition and distribution are evident in different ecosystems around the world. Although some climate‐derived alterations on vegetation are expected to result in changes in lifeform fractional cover, disentangling the direct effects of climate change from different non‐climate factors, such as land‐use change, is challenging. By applying “Liebig's law of the minimum” in a geospatial context, we determined the climate‐limited potential for tree, shrub, herbaceous, and non‐vegetation fractional cover change for the conterminous United States and compared these potential rates to observed change rates for the period 1986 to 2018. We found that 10% of the land area of the conterminous United States appears to have climate limitations on the change in fractional cover, with a high proportion of these sites located in arid and semiarid ecosystems in the Southwest part of the country. The rates of change in lifeform fractional cover for the remaining area of the country are likely limited by non‐climate factors such as the disturbance regime, land management, land‐use history, soil conditions, and species interactions and adaptations.
... Our analysis show that, in the case of impacts of climate and soil conditions on shifts in public parks' vegetation, the influence of climate features on herb layer vegetation resilience may vary [93]. The direction of these changes can cause various transformations in the herb layer composition and structure. ...
Today, urban greenery is at the center of attention, especially in the context of climate change. Shaped in large part by natural factors, the herb layer of public parks is a part of urban greenery that is the most sensitive to climate and soil condition changes. In this paper, we present a study intended to answer how resilient is the species composition and herb layer structure against the soil and climate condition changes in parks. To this end, we analyzed Ellenberg and Zarzycki’s ecological index numbers for species recorded in different groups in terms of historical-geographical, life forms, prevalence within the flora of Poland, and relationships with different vegetation types (phytoassociation classes) in comparison to the conditions present in parks. It was found that a large part of various species groups showed an optima and ecological tolerance spectra that went beyond the park conditions, indicating that at least some park vegetation can be expected to show resilience to changing conditions. However, changes in temperature and humidity will alter the composition and structure of the park herb layer. The direction of changes in climate and soil conditions can be decisive for herb layer transformation directions. With rising temperatures, humidity can be crucial. Poor soil moisture conditions will promote an increased share of foreign, synanthropic species, while local natural and semi-natural species will disappear. When climate change that leads to a decrease in temperatures is concerned, it is temperature and not humidity that will be the key factor in the transformation of park herb layer species compositions. The herb layer of Krakow’s parks will have the least resilience to changes in conditions within local non-synanthropic species, rare species and geophytes and to some extent also forest and meadow species.
... For a cross-sectional data analysis of climate impacts like this, a dataset with high climate variability is needed. Italy covers multiple climatic zones, ranging from the warm and dry Mediterranean climate to the cold and humid alpine climate (Chelli et al., 2017). We distinguish four different irrigation options: no irrigation (rainfed farming) and surface, sprinkler, and drip irrigation (Sauer et al., 2010). ...
Farmers should increasingly adopt more water‐efficient irrigation technologies—such as drip irrigation—as a result of climate warming and aggravating water scarcity. We analyze how Italian farmers adapt to climate change by changing their irrigation technology mix. We apply a two‐stage econometric model to data from 5876 Italian farms. We find that farmers' initial reaction to increasing temperatures is reducing their surface‐irrigated fractions. When temperatures increase further, farmers switch toward more sprinkler irrigation. Our results show that farmers are not autonomously moving to drip irrigation in response to climate change, suggesting that government incentives are needed to encourage this transition.
... Italy is characterized by a heterogeneous distribution of climate, ranging from the Mediterranean warm-dry to the Alpine cold-humid climate (Chelli et al., 2017), physiography, vegetation cover and land use (Smiraglia et al., 2013). Moreover, Italy is one of the most geodynamically active areas on Earth, with a high seismicity in several areas, and it is the first European Country for number and magnitude of seismic events, with a maximum higher than 7.0 Mw and a return period of 20-25 years, but with numerous events with Mw 5-6 every 3-4 years. ...
Geomorphodiversity refers to the variety of landforms and morphological processes characterizing the landscape. The definition of an index to quantify geomorphodiversity is a relevant step for multiple fields of Earth sciences, since it is widely accepted that the variability of the geosphere deeply influences the diversity of the biosphere. Such an index should describe the number and type of landforms and geomorphological processes. We propose a quantitative land surface diversity index valid for Italy, considering multiple input quantities to describe geological constraints and geomorphological processes. Critical issues were the selection of moving window size for focal statistics operations, to calculate local diversity of slope, lithology, drainage density and terrain forms in individual raster maps. We compared the index with traditional geomorphological maps, in selected locations, in which information was available. Results show that a minimal set of heterogeneous data is a satisfactory approach to investigate the landscape diversity. Relating processing parameters and terrain spatial characteristics to the dataset resolution is a good choice to assess a reproducible land surface diversity index. Inclusion of drainage density allows the improvement of results in flat areas, in which other factors show trivial results. We argue that the index is relevant for land use management, assessment of ecodiversity, and it may help describing the interaction between abiotic and biotic compartments.
... Italy is characterized by a heterogeneous distribution of climate, ranging from the Mediterranean warm-dry to the Alpine cold-humid climate Chelli et al. (2017), physiography, vegetation cover and land use Smiraglia et al. (2013). ...
... Italy is heavily rich in biodiversity due to its wide range of biogeographic regions and climate and is an interesting region for studying and assessing vegetation and climate dynamics. However, there is a significant lack of knowledge between climate-induced vegetation and land cover changes throughout Italy (Chelli et al., 2017). The ecological regions or ecoregions have a relatively homogeneous ecological condition in which the evaluations and comparisons of biodiversity are meaningful within them (Painho et al., 1996). ...
Land cover and climate monitoring is a crucial task in agriculture, forestry, hazard management, and ecosystems assessment. In this paper, normalized difference vegetation index (NDVI), land surface temperature (LST), and land cover products by the moderate resolution imaging spectroradiometer (MODIS) as well as precipitation were utilized to monitor the spatiotemporal dynamics of vegetation and climate along with their correlation and coherency across Italy during 2000-2021. The analyses were performed on both pixel and ecoregion levels via the least-squares wavelet software (LSWAVE). It was found that relatively more areas in all ecoregions had positive NDVI gradients than negative for each month since 2000. It was estimated that the average NDVI has increased by ∼0.07 since 2000 for all ecoregions. Except the southern ecoregion which showed an insignificant daytime cooling, other ecoregions have been warming by less than 0.05 C/year since 2000. Furthermore, precipitation had an insignificant decreasing trend for almost all ecoregions over the past two decades. The annual coherency between NDVI and LST was found much stronger than the annual coherency between NDVI and precipitation. The annual cycles of NDVI and LST were out-of-phase for the southern ecoregion while the annual cycle of precipitation led the one in NDVI by about one month for this ecoregion, the only ecoregion showing the highest Pearson correlation (53%) and annual coherency (39%) between NDVI and precipitation. For other ecoregions, the annual cycles of NDVI and LST were approximately in-phase, i.e., less than a month phase delay.
... In fact, climate change is having more pronounced effects in high-elevation habitats than elsewhere (Giorgi and Lionello 2008;Lenoir and Svenning 2015), potentially causing biodiversity loss in plant communities (Losapio et al. 2021a). Research mainly focused on the negative effects of raising temperatures (Thuiller et al. 2005;Chelli et al. 2017) and nitrogen deposition (Bobbink et al. 2010) on plant species distribution, but also on the importance of plant-plant interactions for the diversity of alpine communities (Callaway et al. 2002) and their potential role in mediating species responses to climate change ). Here, we review and synthetize recent advances in alpine plant ecology with a focus on dry mountain ranges, mostly in Mediterranean-type climate, under a global change perspective. ...
The effects of global warming are stronger in high-elevation environments than elsewhere. Here, we review recent advances in alpine plant ecology with a focus on dry mountain ranges, mainly in Mediterranean-type climate, with a global change perspective. Raising temperatures and changes in precipitation influence both plant growth and reproduction, and therefore the spatial distribution of species. Research in high-elevation systems evidenced that plant–plant interactions involving cushion plants play a crucial role in the assembly of plant communities, influencing species richness, genetic and phylogenetic diversity, and species persistence. By buffering environmental extremes and ameliorating biophysical conditions, cushion plant species acting as ecosystem engineers are fundamental in the response of alpine ecosystems to global warming, mitigating negative impacts on different plant species with narrow niche and small distribution range.
... There was a shift in air temperature distribution towards warmer values in all seasons (especially for minimum temperature, while maximum temperature shows a more intense warming and a pronounced peak in summer) since the 1980s, with an acceleration in the 2000s [27], and it is projected to increase in the future [28]. In view of the expected increase in temperatures associated with a decrease in precipitation during the summer period, forage production is assumed to change in terms of quantity and quality [29,30]. Moreover, evolution of the distribution of species in herbaceous communities and changes in the botanical composition of semi-natural grasslands are highlighted [31]. ...
Future climate change is expected to significantly alter the growth of vegetation in grassland systems, in terms of length of the growing season, forage production, and climate-altering gas emissions. The main objective of this work was, therefore, to simulate the future impacts of foreseen climate change in the context of two pastoral systems in the central Italian Apennines and test different adaptation strategies to cope with these changes. The PaSim simulation model was, therefore, used for this purpose. After calibration by comparison with observed data of aboveground biomass (AGB) and leaf area index (LAI), simulations were able to produce various future outputs, such as length of growing season, AGB, and greenhouse gas (GHG) emissions, for two time windows (i.e., 2011–2040 and 2041–2070) using 14 global climate models (GCMs) for the generation of future climate data, according to RCP (Representative Concentration Pathways) 4.5 and 8.5 scenarios under business-as-usual management (BaU). As a result of increasing temperatures, the fertilizing effect of CO2, and a similar trend in water content between present and future, simulations showed a lengthening of the season (i.e., mean increase: +8.5 and 14 days under RCP4.5 and RCP8.5, respectively, for the period 2011–2040, +19 and 31.5 days under RCP4.5 and RCP8.5, respectively, for the period 2041–2070) and a rise in forage production (i.e., mean biomass peak increase of the two test sites under BaU: +53.7% and 62.75% for RCP4.5. and RCP8.5, respectively, in the 2011–2040 period, +115.3% and 176.9% in RCP4.5 and RCP8.5 in 2041–2070, respectively,). Subsequently, three different alternative management strategies were tested: a 20% rise in animal stocking rate (+20 GI), a 15% increase in grazing length (+15 GL), and a combination of these two management factors (+20 GI×15 GL). Simulation results on alternative management strategies suggest that the favorable conditions for forage production could support the increase in animal stocking rate and grazing length of alternative management strategies (i.e., +20 GI, +15 GL, +20 GI×15 GL). Under future projections, net ecosystem exchange (NEE) and nitrogen oxide (N2O) emissions decreased, whereas methane (CH4) rose. The simulated GHG future changes varied in magnitude according to the different adaptation strategies tested. The development and assessment of adaptation strategies for extensive pastures of the Central Apennines provide a basis for appropriate agricultural policy and optimal land management in response to the ongoing climate change.
... Global warming and the associated upward migration of vegetation has become a major threat to specialized Alpine plants, particular those that inhabit the alpine-nivale altitudinal zones (> 2600 m a.s.l.) [22,86]. Based on the GLORIA project data set, [22] concluded that for South Tyrol, with its highest peaks at almost 4000 m a.s.l., most plants can continue to invade higher elevations and, thus, the risk of extinction seems to be low. ...
Background: Worldwide mountain regions are recognized as hotspots of ethnopharmacologically relevant species diversity. In South Tyrol (Southern Alps, Italy), and due to the region’s high plant diversity and isolated population, a unique traditional botanical knowledge of medicinal plants has flourished, which traces its history back to prehistoric times. However, changes in rural life and culture may threaten this unique biodiversity and cultural heritage. Our study aims to collect and analyze information on native plants used in traditional folk medicine, focusing on the preservation of botanical and cultural diversity. Methods: Data were collected through a review of published material that documents traditionally used medicinal plants of South Tyrol in order to capture the total diversity of plants and their usage. We evaluated different parameters, comprising the ethnobotanicity index (EI), ethnophytonomic index (EPI), relative frequency of citation (RFC), red list status, and regional legislation with regard to the plant species. Results: A total of 276 species, including 3 mushrooms and 3 lichens, were identified. These belonged to 72 families, most frequently to the Asteraceae, Rosaceae, and Lamiaceae. The most frequently cited species were Hypericum perforatum L., Urtica dioica L., and Plantago lanceolata L. According to 12 ICPC-2 disease categories, the most frequently treated human health symptoms were from the digestive and respiratory systems as well as the skin. A total of 27 species were listed as endangered, of which 16 are not protected and two are now already extinct. Among the 59 predominantly alpine species, 11 species are restricted to the high altitudes of the Alps and may be threatened by global warming. Conclusions: Our research revealed that the ethnobotanical richness of South Tyrol is among the highest in Italy and throughout the Alps. Nevertheless, it is evident that biodiversity and traditional knowledge have been heavily eroded. Furthermore, we point out particularly sensitive species that should be reconsidered for stronger protections in legal regulations.
... Within the last decade, the Italian government has focused on implementing national climate change adaptation strategies, mainly due to the consequences derived from this issue [1,2]. In fact, over time, there has been an increase in temperatures and a succession of extreme weather events, such as heavy rainfall [3] followed by long periods of drought [4], with effects, for example, on vegetation [5] or landslide risk [6]. However, alongside environmental problems, climate change also seems to be affecting the country's economy, for example, due to the reduced attractiveness of Italy as a tourist destination [5]. ...
Climate Change, Natural Resources Depletion, COVID-19, and Wars are some of the
great challenges of our time. The consequences will affect psychological well-being and could have
a harmful impact on mental health. This study aimed to assess the level of preoccupation and
fears surrounding issues of the 21st-century and the implication for psychological well-being of the
general population from Central/Southern Italy among different age groups. A questionnaire that
included sociodemographic characteristics, topics formulated ad-hoc about preoccupation, fears,
habits, and willingness to change habits in the future related to the 21st-century challenges, and the
Depression Anxiety Stress Scales 21 (DASS-21) was administered online. A sample of 1831 participants
(61% F; mean age 47.71 17.30) was obtained. Results showed that young adults and older adults,
respectively, reported greater and less psychological well-being. Young adults reported higher scores
for preoccupation, changing habits, and willingness to change habits in the future, while older adults
reported the lowest scores except for changing habits, also controlling for gender. Results for this
variable, as well as correlations between the many variables described, rely on the specificity of
age, and 21st-century challenges. Moreover, the main fears related to the 21st-century concerns
were different based on both age and gender. In conclusion, the various stresses of the 21st-century
discussed in this study have a relationship with personal well-being, and it is important to consider
potential global mental health issues resulting from these stressors.
... Apulia was a peculiar case where sealed areas expanded drastically into rural areas, cropland intensified, and forest areas decreased substantially (see [88] and the report available at https://annuario.isprambiente.it/ada/downreport/html/7037, last accessed on 10 August 2022). Furthermore, as portrayed by the recent literature [89], some Southern Italian regions (namely, Sicily, Sardinia, and Apulia), among the areas most populated by high intercept-to-slope ratio values, are experiencing a considerable temperature increase and precipitation decrease [90][91][92], impacting the most typical cultivations (i.e., vineyards and olive groves, see [93,94]). ...
Taken as a classical issue in applied economics, the notion of ‘convergence’ is based on the concept of path dependence, i.e., from the previous trajectory undertaken by the system during its recent history. Going beyond social science, a ‘convergence’ perspective has been more recently adopted in environmental studies. Spatial convergence in non-linear processes, such as desertification risk, is a meaningful notion since desertification represents a (possibly unsustainable) development trajectory of socio-ecological systems towards land degradation on a regional or local scale. In this study, we test—in line with the classical convergence approach—long-term equilibrium conditions in the evolution of desertification processes in Italy, a European country with significant socioeconomic and environmental disparities. Assuming a path-dependent development of desertification risk in Italy, we provided a diachronic analysis of the Environmental Sensitive Area Index (ESAI), estimated at a disaggregated spatial resolution at three times (1960s, 1990s, and 2010s) in the recent history of Italy, using a spatially explicit approach based on geographically weighted regressions (GWRs). The results of local regressions show a significant path dependence in the first time interval (1960–1990). A less significant evidence for path-dependence was observed for the second period (1990–2010); in both cases, the models’ goodness-of-fit (global adjusted R²) was satisfactory. A strong polarization along the latitudinal gradient characterized the first observation period: Southern Italian land experienced worse conditions (e.g., climate aridity, urbanization) and the level of land vulnerability in Northern Italy remained quite stable, alimenting the traditional divergence in desertification risk characteristic of the country. The empirical analysis delineated a more complex picture for the second period. Convergence (leading to stability, or even improvement, of desertification risk) in some areas of Southern Italy, and a more evident divergence (leading to worse environmental conditions because of urban sprawl and crop intensification) in some of the land of Northern Italy, were observed, leading to an undesired spatial homogenization toward higher vulnerability levels. Finally, this work suggests the importance of spatially explicit approaches providing relevant information to design more effective policy strategies. In the case of land vulnerability to degradation in Italy, local regression models oriented toward a ‘convergence’ perspective, may be adopted to uncover the genesis of desertification hotspots at both the regional and local scale.
... In particular, with the support of observed rather than interpolated data, it makes possible to better define i) the similarity/dissimilarity within and between ecoregions in terms of climate mean and variability, ii) the effects of the different correlation between climatic variables on vegetation patterns, with a focus at the national/subnational scale, and iii) the vulnerability of sensitive ecosystems to local climate change trends, in accordance with the IUCN Red List criteria (Keith et al., 2015). Actually, the presented outcomes provide useful benchmarks to better focus monitoring programs as regards ecosystem responses (e.g., Chelli et al., 2017). It may be possible, for example, to determine according to which parameters the potential vulnerability to climate change of the Mediterranean ecosystems differs from that of the Temperate ones. ...
Motivated by real‐world data of monthly values of precipitation, minimum, and maximum temperature recorded at 360 monitoring stations covering the Italian territory for 60 years (12×60 months), in this work we propose a change‐point model for multiple multivariate time series, inspired by the hierarchical Dirichlet process. We assume that each station has its change‐point structure and, as main novelties, we allow unknown subsets of the parameters in the data likelihood to stay unchanged before and after a change‐point, that stations possibly share values of the same parameters and that the unknown number of weather regimes is estimated as a random quantity. Owing to the richness of the formalization, our proposal enables us to identify clusters of spatial units for each parameter, evaluate which parameters are more likely to change simultaneously, and distinguish between abrupt changes and smooth ones. The proposed model provides useful benchmarks to focus monitoring programs regarding ecosystem responses. Results are shown for the whole data, and a detailed description is given for three monitoring stations. Evidence of local behaviors includes highlighting differences in the potential vulnerability to climate change of the Mediterranean ecosystems from the Temperate ones and locating change trends distinguishing between continental plains and mountain ranges.
... Thus, understanding the strategies adopted by plants to face changes in the pattern of summer water supply is a key issue, with high economic, social, and environmental implications, especially in water-limited environments like the Mediterranean grasslands ). The inconsistencies of traits' response to drought highlighted in the former research, are probably due to various reasons, e.g., different scales of analysis (geographic/regional/local, community-or population-level), climatic gradient lengths or severity of drought treatments (Kreyling et al. 2008;Weißhuhn et al. 2011), different species ecological optimum (Albert et al. 2010), different strategies used to cope with drought stress even within the same growth form (Fort et al. 2013), analysis of inter-specific variation without accounting for intraspecific variability (Lepš et al. 2011;Pérez-Ramos et al. 2012;Kichenin et al. 2013), and overlapping of other factors that may override or confound climatic effects (Weißhuhn et al. 2011;Chelli et al. 2017). ...
Climate change models predict a strong reduction of average precipitation, especially of the summer rainfall, and an increase in intensity and frequency of drought events in the Mediterranean region. The research aim was to understand how four dominant grass species (Arrhenatherum elatius, Cynosurus cristatus, Elymus repens, and Lolium perenne) in sub-Mediterranean meadows (central Apennines, Italy) modulate their resource acquisition and conservation strategies to short-term variation of the pattern of summer water supply. During summer 2016, using a randomized block design, we tested the effect of three patterns of summer water supply, differing in water amount and watering frequency, on leaf area, leaf dry mass, specific leaf area (SLA), leaf senescence, and plant height. Our results showed that dominant grass species can modulate their strategies to variation of the pattern of summer water supply, but the response of leaf traits and plant height is mediated by the set of functional characteristics of the species. E. repens and A. elatius, with summer green leaves, lower SLA, later flowering period, and deeper roots, were less influenced by changes in water amount. C. cristatus and L. perenne, which display acquisitive strategies (persistent leaves, higher SLA values), earlier flowering, and shallower roots were more influenced by changes in the pattern of summer water supply. Our results suggest that a short-term decrease in water availability might affect primarily species with trait syndromes less adapted to face summer drought.
... This statement is supported by the dominant vegetation types at the highest elevation, which are strongly adapted to a lack of water in the summer, a feature that is accentuated by the carbonate lithology that amplifies the xeric adaptations of the mountain and high-mountain ecosystems of the Central Apennines (Chelli et al. 2017;Bricca et al. 2019;Stanisci et al. 2020). ...
The present work analyses the main weather patterns over the period 1981-2010 in the Central Apennines (Italy), drawing upon data from 23 monitoring stations spanning a wide elevation range (260-1750 m asl). Cluster analysis was used to identify homogeneous units and to verify the effectiveness of the bioclimatic classification by crossing the results derived from the application of hierarchical and non-hierarchical classification techniques. The results reveal a diversified picture of five clusters that depends on several factors as elevation, the geographic position within or outside the mountainous range, and the regional morphological traits. Although Mediterranean and Temperate climatic features coexist, the Mediterranean pattern in the southern areas and internal valleys better expresses the overall mixed characteristics of Central Italy. The use of a mixed methodology of hierarchic and partitioning methods of cluster analysis improves the bioclimatic classification, especially to quantify the level of humidity and the mediterraneity degree.
... Global warming and the associated upward migration of vegetation has become a major threat to specialized Alpine plants, particular those that inhabit the alpine-nivale altitudinal zones (> 2600 m a.s.l.) [22,86]. Based on the GLORIA project data set, [22] concluded that for South Tyrol, with its highest peaks at almost 4000 m a.s.l., most plants can continue to invade higher elevations and, thus, the risk of extinction seems to be low. ...
Background
Worldwide mountain regions are recognized as hotspots of ethnopharmacologically relevant species diversity. In South Tyrol (Southern Alps, Italy), and due to the region’s high plant diversity and isolated population, a unique traditional botanical knowledge of medicinal plants has flourished, which traces its history back to prehistoric times. However, changes in rural life and culture may threaten this unique biodiversity and cultural heritage. Our study aims to collect and analyze information on native plants used in traditional folk medicine, focusing on the preservation of botanical and cultural diversity.
Methods
Data were collected through a review of published material that documents traditionally used medicinal plants of South Tyrol in order to capture the total diversity of plants and their usage. We evaluated different parameters, comprising the ethnobotanicity index (EI), ethnophytonomic index (EPI), relative frequency of citation (RFC), red list status, and regional legislation with regard to the plant species.
Results
A total of 276 species, including 3 mushrooms and 3 lichens, were identified. These belonged to 72 families, most frequently to the Asteraceae, Rosaceae, and Lamiaceae. The most frequently cited species were Hypericum perforatum L., Urtica dioica L., and Plantago lanceolata L. According to 12 ICPC-2 disease categories, the most frequently treated human health symptoms were from the digestive and respiratory systems as well as the skin. A total of 27 species were listed as endangered, of which 16 are not protected and two are now already extinct. Among the 59 predominantly alpine species, 11 species are restricted to the high altitudes of the Alps and may be threatened by global warming.
Conclusions
Our research revealed that the ethnobotanical richness of South Tyrol is among the highest in Italy and throughout the Alps. Nevertheless, it is evident that biodiversity and traditional knowledge have been heavily eroded. Furthermore, we point out particularly sensitive species that should be reconsidered for stronger protections in legal regulations.
... Global warming and the associated upward migration of vegetation has become a major threat to specialized Alpine plants, particular those that inhabit the alpine-nivale altitudinal zones (> 2600 m a.s.l.) [22,86]. Based on the GLORIA project data set, [22] concluded that for South Tyrol, with its highest peaks at almost 4,000 m a.s.l., most plants can continue to invade higher elevations and, thus, the risk of extinction seems to be low. ...
Background: Worldwide mountain regions are recognized as hotspots of ethnopharmacologically relevant species diversity. In South Tyrol (Southern Alps, Italy), and due to the region’s high plant diversity and isolated population, a unique traditional botanical knowledge of medicinal plants has flourished, which traces its history back to prehistoric times. However, changes in rural life and culture may threaten this unique biodiversity and cultural heritage. Our study aims to collect and analyze information on native plants used in traditional folk medicine, focusing on the preservation of botanical and cultural diversity.
Methods: Data were collected through a review of published material that documents traditionally used medicinal plants of South Tyrol in order to capture the total diversity of plants and their usage. We evaluated different parameters, comprising the ethnobotanicity index (EI), ethnophytonomic index (EPI), relative frequency of citation (RFC), red list status, and regional legislation with regard to the plant species.
Results: A total of 276 species, including 3 mushrooms and 3 lichens, were identified. These belonged to 72 families, most frequently to the Asteraceae, Rosaceae, and Lamiaceae. The most frequently cited species were Hypericum perforatum L., Urtica dioica L., and Plantago lanceolata L. According to 12 ICPC-2 disease categories, the most frequently treated human health symptoms were from the digestive and respiratory systems as well as the skin. A total of 27 species were listed as endangered, of which 16 are not protected and two are now already extinct. Among the 59 predominantly alpine species, 11 species are restricted to the high altitudes of the Alps and may be threatened by global warming.
Conclusions: Our research revealed that the ethnobotanical richness of South Tyrol is among the highest in Italy and throughout the Alps. Nevertheless, it is evident that biodiversity and traditional knowledge have been heavily eroded. Furthermore, we point out particularly sensitive species that should be reconsidered for stronger protections in legal regulations.
... Le foreste italiane si stanno adattando alle nuove condizioni climatiche, modificando la composizione dei popolamenti (Chelli et al., 2017) e "muovendo" i loro areali di distribuzione sia in termini latitudinali che altitudinali (Pecchi et al., 2020). Conoscere queste dinamiche di adattamento acquisisce, quindi, un'importanza capitale nelle strategie di pianificazione forestale future per tutelare i servizi ecosistemici forniti nella loro globalità. ...
L’obiettivo del rapporto è quello di evidenziare quali sono gli scenari di cambiamento climatico attesi per l’Italia e quali rischi principali tali scenari potranno determinare in corrispondenza di diversi possibili livelli di riscaldamento globale, evidenziando alcune chiare priorità di intervento, anche in riferimento alla valutazione economica delle stesse e alle opportunità finanziarie.
... Climate change is influencing both species distribution and ecosystem functioning worldwide (Bellard et al., 2012;Moritz and Agudo, 2013;Burrows et al., 2014;Lenoir and Svenning, 2015;Alexander et al., 2018;Kotta et al., 2019). Temperature increases are particularly severe in alpine ecosystems (Thuiller et al., 2005;Chelli et al., 2017), where they lead to phenological and physiological changes (Körner, 2003;Wilson and Nilsson, 2009) that may cause important disruption in plant community composition and dynamics (Walther et al., 2005;Pauli et al., 2007). Plants respond by colonising suitable microhabitats (Scherrer and Körner 2011) or migrating upwards whenever possible (e.g., Pauli et al., 2007;Kullman, 2010;Du et al. 2018;Lenoir et al., 2008), sometimes using nurse plant species as stepping stones (Anthelme et al., 2014). ...
Climate change is more pronounced in high-elevation habitats than elsewhere, potentially causing disruptions in plant community structure and dynamics through changes in plant interactions. We tested the effect of warming and rainfall manipulations on growth and gas exchange of a cushion plant species, Arenaria tetraquetra, in the Sierra Nevada Mountains in SE Spain and assessed its consequences for plant interactions. Arenaria tetraquetra is a facilitator that often hosts a variety of beneficiary species within its canopy. Warming and drought could alter cushion growth patterns and canopy compaction, which in turn affect facilitation. We increased temperature using acrylic open-top chambers (OTC) and increased or decreased water availability with rainfall collectors. Our rainfall treatments did not have significant effects on cushion growth or facilitation. Three years of warming enhanced cushion photosynthesis and respiration, leading to larger cushions with thinner leaves, but did not change other cushion traits nor alter its facilitation effects. Some traits, however, readily responded to inter-annual climate variability. Global warming will change cushion plant physiology, as higher temperatures at times increase plant respiration above the level of carbon fixation. However, we did not find changes in interaction between benefactor and beneficiary species, perhaps due to the short-term nature of our experiment. Recorded physiological and morphological changes might be, however, signs of more pronounced, long-term consequences of warming on plant survival and community composition.
... The projected changes in air temperature for the three different cities shown in Figure 1 are in line with results from comparable studies for London [32], Luxembourg [33][34][35][36] and Rome [37,38]. For London, an increase in the long-term annual mean air temperature by 1.5 • C for the RCP4.5 and 2.5 • C for the RCP8.5 is projected. ...
Changes in the frequency and intensity of heat waves have shown substantial negative impacts on public health. At the same time, climate change towards increasing air temperatures throughout Europe will foster such extreme events, leading to the population being more exposed to them and societies becoming more vulnerable. Based on two climate change scenarios (Representative Concentration Pathway 4.5 and 8.5) we analysed the frequency and intensity of heat waves for three capital cities in Europe representing a North–South transect (London, Luxembourg, Rome). We used indices proposed by the Expert Team on Sector-Specific Climate Indices of the World Meteorological Organization to analyze the number of heat waves, the number of days that contribute to heat waves, the length of the longest heat waves, as well as the mean temperature during heat waves. The threshold for the definition of heat waves is calculated based on a reference period of 30 years for each of the three cities, allowing for a direct comparison of the projected changes between the cities. Changes in the projected air temperature between a reference period (1971–2000) and three future periods (2001–2030 near future, 2031–2060 middle future, and 2061–2090 far future) are statistically significant for all three cities and both emission scenarios. Considerable similarities could be identified for the different heat wave indices. This directly affects the risk of the exposed population and might also negatively influence food security and water supply.
... Forests are believed to provide a large set of ecosystem services in addition to wood and biomass production [1][2][3]. Climate change can reduce, or at least alter, quality and quantity of the ecosystem services that forests provide, thus affecting resilience and cultural identity of local communities [4][5][6]. It is, therefore, of primary importance to develop and use reliable and adequate climatic surfaces for the purpose [7][8][9]. ...
The European beech (Fagus sylvatica L.) is a widely distributed tree species across Europe, highly sensitive to climate change and global warming. This study illustrates results of a 5-year monitoring time period from eight sites of the ICP-Forests Level II (intensive monitoring network) along the Italian latitudinal gradient. The tree-level relationship between tree growth dynamics and environmental factors, including seasonal climate fluctuations were investigated by means of tree-level Generalized Additive Mixed Models (GAMMs). Model results revealed that climate was responsible for just a portion of the variability in beech growth dynamics. Even if climatic predictors were highly significant in almost all sites, the model explained nearly 30% of the total variance (with just a maximum value of 71.6%), leaving the remaining variance unexplained and likely connected with forest management trajectories applied to each site (e.g., aged coppice and fully grown high forest). Climate change scenarios were then applied to predict site-specific future responses. By applying climate change scenarios, it was predicted that central and northern Italy would face similar climatic conditions to those currently detected at southern latitudes. A special case study was represented by VEN1 plot (Veneto, Northern Italy) whose current and future climate regimes were grouped in a unique and separated cluster.
... In the Italian Peninsula, extensive surveys of dry grassland biodiversity patterns and their edaphic drivers at spatial grains ≤ 1 m 2 are lacking: the only paper we are aware of, that analyzed richness patterns and edaphic variables at fine scales (Maccherini 2006), was focused on a very small study area (cf. also Wellstein et al. 2014;Chelli et al. 2017). Nevertheless, the large areas of secondary grasslands in the Apennines chain (the mountain range forming the backbone of the Italian peninsula) are extremely interesting, because of considerable climatic and edaphic gradients (Primi et al. 2016), biogeographical position (e.g. ...
Secondary dry grasslands in Europe can host high levels of vascular plant richness at small spatial scales. However, in Southern Europe their biodiversity patterns are largely unexplored. In this work, we aim at: (i) estimating plant species richness patterns at very fine scales in montane dry grasslands, on limestone bedrock, in Abruzzo Lazio and Molise National Park (Central Apennines, Italy); (ii) assessing the most important physical and edaphic drivers of biodiversity patterns at multiple plot sizes. We used randomly placed nested-plot series where we measured alpha-diversity at three different plot sizes (1 m2, 0.1 m2 and 0.01 m2) and within-plot beta-diversity (as expressed by the slope of the species-area curve across plot sizes). Variable selection was performed by means of Random Forests. Relationships between selected variables and diversity measures were then assessed using Regression Trees, Linear and Generalized Linear Models. Overall, results pointed to topographically-controlled edaphic factors (soil pH and silt fraction) as the main drivers positively influencing alpha-diversity at all spatial scales, with a positive effect of rock cover and slope inclination at smaller spatial grains. Beta-diversity was positively influenced by rock cover. We suggest that high-pH, steep and/or rocky sites feature higher species richness because they lack competitive grass species. Our results are in agreement with previous works underlining the importance of less productive habitats for the conservation of secondary grassland biodiversity.
... By means of the increase in the occurrence of extreme heat and drought events, a substantial drying and warming of ecosystems in Mediterranean regions is expected (Gouveia et al., 2017;Paeth et al., 2017). Different patterns of these changes are expected for the various microclimates that characterize the Italian peninsula (Chelli et al., 2017). Increasing mean annual temperature and a reduction of precipitation (in particular snowfall) in summer and winter are expected in both the Alpine and in the mountainous temperate climatic zones (Gobiet et al., 2014). ...
In the Mediterranean region, ecosystems are severely affected by climate variability. The Italian Peninsula is a hot spot for biodiversity thanks to its heterogeneous landscape and the Mediterranean, Continental, and Alpine climates hosting a broad range of plant functional types along a limited latitudinal range from 40′ to 46′ N. In this study we applied a comparative approach integrating descriptive statistics, time series analysis, and multivariate techniques to answer the following questions: (i) do the climatic variables affect Gross Primary Productivity (GPP), Reco, Water Use Efficiency (WUE), and ET to a similar extent among different sites? (ii) Does a common response pattern exist among ecosystems along a latitudinal gradient in Italy? And, finally (iii) do these ecosystems respond synchronically to meteorological conditions or does a delayed response exist? Six sites along a latitudinal, altitudinal, and vegetational gradient from semi-arid (southern Italy), to a mountainous Mediterranean site (central Italy), and sub-humid wet Alpine sites (northern Italy) were considered. For each site, carbon and water fluxes, and meteorological data collected during two hydrologically-contrasting years (i.e., a dry and a wet year) were analyzed. Principal Component Analysis (PCA) was adopted to identify temporal and spatial variations in GPP, Ecosystem Respiration (Reco), WUE, and Evapotranspiration (ET). The model outlined differences among Mediterranean semi-arid, Mediterranean mountainous, and Alpine sites in response to contrasting precipitation regimes. GPP, Reco, WUE, and ET increased up to 16, 19, 25, and 28%, respectively in semi-arid Mediterranean sites and up to 15, 32, 15, and 11%, respectively in Alpine sites in the wet year compared to the dry year. Air temperature was revealed to be one of the most important variables affecting GPP, Reco, WUE, and ET in all the study sites. While relative air humidity was more important in southern Mediterranean sites, global radiation was more significant in northern Italy. Our work suggests that a realistic prediction of the main responses of Italian forests under climate change should also take in account delayed responses due to acclimation to abiotic stress or changing environmental conditions.
... In this study, we collected snowbed species after an above-average warm and dry winter (Colucci et al., 2017) to assess the effects of advanced snowmelt on seven representative snowbed plant species through the analysis of phenotypic variation of functional traits. The functional traits considered include both vegetative and reproductive traits that have been found to show plastic adjustment to environmental conditions (Nicotra et al., 2010;Wellstein et al., 2013;Jung et al., 2014;Liancourt et al., 2015;Chelli et al., 2017). These functional traits are related to important plant functions such as photosynthetic capacity, growth; and ultimately, competitive ability, reproduction and survival (Kudo et al., 1999;Baptist et al., 2010;Lluent et al., 2013;Pérez-Harguindeguy et al., 2013;Liancourt et al., 2015). ...
In ecological theory, it is currently unclear if intraspecific trait responses to environmental variation are shared across plant species. We use one of the strongest environmental variations in alpine ecosystems, i.e., advanced snowmelt due to climate warming, to answer this question for alpine snowbed plants. Snowbeds are extreme habitats where long-lasting snow cover represents the key environmental factor affecting plant life. Intraspecific variation in plant functional traits is a key to understanding the performance and vulnerability of species in a rapidly changing environment. We sampled snowbed species after an above-average warm winter to assess their phenotypic adjustment to advanced snowmelt, based on differences in the natural snowmelt dynamics with magnitudes reflecting predicted future warming. We measured nine functional traits related to plant growth and reproduction in seven vascular species, comparing snowbeds of early and late snowmelt across four snowbed sites in the southern Alps in Italy. The early snowbeds provide a proxy for the advanced snowmelt caused by climatic warming. Seed production was reduced under advanced snowmelt in all seed-forming snowbed species. Higher specific leaf area (SLA) and lower leaf dry matter content (LDMC) were indicative of improved growth potential in most seed-forming species under advanced snowmelt. We conclude, first, that in the short term, advanced snowmelt can improve snowbed species’ growth potential. However, in the long term, results from other studies hint at increasing competition in case of ongoing improvement of conditions for plant growth under continued future climate warming, representing a risk for snowbed species. Second, a lower seed production can negatively affect the seed rain. A reduction of propagule pressure can be crucial in a context of loss of the present snowbed sites and the formation of new ones at higher altitudes along with climate warming. Finally, our findings encourage using plant functional traits at the intraspecific level across species as a tool to understand the future ecological challenges of plants in changing environments.
... For example, in cold and humid ecosystems with abundant soil water, warming generally has positive effects on plant growth directly by stimulating temperature-driven physiological processes and indirectly by extending the growing season length (Wan et al., 2005;Liu et al., 2018). In contrast, in high-elevation ecosystems that face water shortage, warming will cause further water limitation for the carbon uptake process, and negatively influence plant growth (Xue et al., 2009;Chelli et al., 2017). ...
The plant productivity of alpine meadow is predicted to generally increase under a warming climate, but it remains unclear whether the positive response rates will vary with soil water availability. Without consideration of the response of community composition and plant quality, livestock grazing under the current stocking rate might still lead to grassland degradation, even in meadows with high plant biomass. We have conducted a warming experiment from 2010 to 2017 to examine the interactive effects of warming and soil water availability on plant growth and forage quality at individual and functional group levels in an alpine meadow located in the permafrost region of the Qinghai–Tibetan Plateau. Warming-induced changes in community composition, biomass, and forage quality varied with soil water availability. Under dry conditions, experimental warming reduced the relative importance of grasses and the aboveground biomass by 32.37 g m⁻² but increased the importance value of forbs. It also increased the crude fat by 0.68% and the crude protein by 3.19% at the end of summer but decreased the acid detergent fiber by 5.59% at the end of spring. The increase in crude fat and protein and the decrease in acid detergent fiber, but the decrease in aboveground biomass and increase the importance value of forbs, which may imply a deterioration of the grassland. Under wet conditions, warming increased aboveground biomass by 29.49 g m⁻² at the end of spring and reduced acid detergent fiber by 8.09% at the end of summer. The importance value of grasses and forbs positively correlated with the acid detergent fiber and crude protein, respectively. Our results suggest that precipitation changes will determine whether climate warming will benefit rangelands on the Qinghai–Tibetan Plateau, with drier conditions suppressing grassland productivity, but wetter conditions increasing production while preserving forage quality.
... Besides land-use change, climate change is considered as an important trigger for the future development of flora and fauna in the Mediterranean region. Several studies already point to ongoing biotic changes due to climate change (Chelli et al. 2017). Giorgi (2006) identified the Mediterranean area as one of the two regions most affected by climate change on earth. ...
Forests worldwide suffer from over-utilization, clearing and degradation. In the Mediterranean region, human activities have almost completely transformed native vegetation into secondary communities, leaving mostly fragmented woodlands within cultural landscapes. Those secondary habitats are often highly diverse. However, forests are key ecosystems that fulfill multiple ecosystem services, such as provision of habitats for a variety of species. Taking the island and National Park of Asinara (NW Sardinia, Italy) as an example, we address the controversy of the maintenance of open cultural landscapes and forest restoration efforts. This paper aims to compare the relative value of open to forest habitats for the provision of ecosystem services related to biodiversity. We further propose scenarios regarding forest development for Asinara Island, giving implications for implementation and management. To assess plant diversity and natural tree regeneration we conducted plot-based vegetation surveys. A germination trial was performed to evaluate the potential of the soil seed bank. Our study shows, that several secondary habitats are characterized by a high phytodiversity but that forest remnants play a crucial role regarding overall biodiversity. Since the remaining forest is highly fragmented and natural regeneration of tree species is very low management measures are needed. We therefore suggest to extend the forest area on Asinara Island by connecting remnants as initial points but also to maintain secondary habitats to obtain a heterogenic landscape mosaic. Trees will have to be introduced by seeding or planting and need special care due to water shortage, grazing pressure and insect herbivory.
... High mountain habitats are vulnerable because of human impacts, such as global change (e.g., rising temperatures, changes in precipitation patterns, and nitrogen deposition) and land abandonment, which influence biodiversity and ecosystem functioning [1][2][3][4]. Consistent changes in biodiversity have been observed in numerous central European mountains using short-term [5][6][7] and long-term vegetation analyses [8][9][10][11][12][13][14][15][16], and upward migration of alpine species toward mountain summits, shrub displacement, changes in community composition, and local extinctions have also been documented [17][18][19][20][21][22]. ...
Mountain ecosystems are vulnerable because of land-use and climate change. In this study, we performed a re-visitation study using historical and newly collected vegetation plots to explore the primary trends in the floristic, ecological, and structural features of Mediterranean Pinus mugo krummholz over past decades. The plant community composition over time (1992 vs. 2016-17) was analyzed by a detrended correspondence analysis followed by a statistical comparison of time steps and an analysis of the contribution of each species to temporal differences. Ecological and structural changes were analyzed by a permutational multivariate analysis of variance followed by a post hoc comparison. We observed relevant changes in the floristic composition, structure, and ecological characteristics of Pinus mugo scrub. Some subalpine and treeline species that characterize the early stages of Pinus mugo succession declined as several warm-adapted species increased. Furthermore, these changes were most likely due to the natural evolution of high-mountain krummholz combined with a thermophilization process occurring in alpine habitats. In contrast, a small group of cold-adapted species also increased, probably because the patchy spatial pattern of Pinus mugo scrubs gives rise to "mesic patches" in a matrix of arid grasslands. The re-visitation approach adopted for long-term analysis in this study can potentially be applied to other mountainous regions to better understand long-term ecological changes in high alpine vegetation.
... Overall, the patterns we found indicate that grazing abandonment causes the replacement of the more specialized plant species (small-sized herbs and graminoids) by generalists: large graminoids, tall herbs, shrubs and trees (Theurillat and Guisan 2001;Amezaga et al. 2004;Baur et al. 2006;Sheil 2016;Campagnaro et al. 2017;Chelli et al. 2017). Thus, changes in land use lead to the homogenization of mountain flora and vegetation (Amezaga et al. 2004;Baur et al. 2006;Sheil 2016), and constitute a serious threat for plant species diversity of lower elevation mountain grasslands that are located below the treeline, which are hotspots of biodiversity (Chemini and Rizzoli 2003;Sitzia et al. 2010). ...
Changes in the local flora of mountains are often explained by climate warming, but changes in grazing regimes may also be important. The aim of this study was to evaluate whether the alpine flora on summits in the Tatra Mts, Poland and Slovakia, has changed over the last 100 years, and if the observed changes are better explained by changes in sheep grazing or climate. We resurveyed the flora of 14 mountain summits initially investigated in the years 1878–1948. We used ordination methods to quantify changes in species composition. We tested whether changes in plant species composition could be explained by cessation of grazing and climate change, and whether these factors have influenced shifts in Ellenberg’s plant ecological indicator values and Raunkiaer’s life forms. Changes in alpine flora were greater on lower elevation summits, and lower on summits less accessible for sheep. More accessible summits were associated with a decrease in mean values of plant species’ light ecological indicator values over time, and a concurrent increase in temperature and nitrogen ecological indicator values. No significant relationships were found between accessibility for sheep and changes in Raunkiaer’s life-forms. Greater accessibility for sheep (meaning high historical grazing pressure) led to greater compositional changes of mountain summits compared with summits with low accessibility. Our results suggest that cessation of sheep grazing was the main factor causing changes in the species composition of resurveyed mountain summits in the Tatra Mts, while climate change played a more minor role.
... This data can further help to parameterise and evaluate models designed to predict shifts in ecosystem functions and services caused by global change (Dieleman et al., 2012). Although a bulk of recent work has focused on single effects of global change drivers on different ecosystem functions, we still lack an integrated understanding of how climate and atmospheric changes interactively may alter ecosystem processes in the course of this century (Dieleman et al., 2012;Greaver et al., 2016;Chelli et al., 2017). This regards the effects of climate change and N deposition in particular, because only few studies have quantified the interactive processes at the species or ecosystem level (Gaudnik et al., 2011;Law, 2013;Dziedek et al., 2017). ...
Global change affects the functioning of forest ecosystems and the services they provide, but little is known about the interactive effects of co-occurring global change drivers on important functions such as tree growth and vitality. In the present study we quantified the interactive (i.e. synergistic or antagonistic) effects of atmospheric nitrogen (N) deposition and climatic variables (temperature, precipitation) on tree growth (in terms of tree-ring width, TRW), taking forest ecosystems with European beech (Fagus sylvatica L.) as an example. We hypothesised that (i) N deposition and climatic variables can evoke non-additive responses of the radial increment of beech trees, and (ii) N loads have the potential to strengthen the trees' sensitivity to climate change. In young stands, we found a synergistic positive effect of N deposition and annual mean temperature on TRW, possibly linked to the alleviation of an N shortage in young stands. In mature stands, however, high N deposition significantly increased the trees' sensitivity to increasing annual mean temperatures (antagonistic effect on TRW), possibly due to increased fine root dieback, decreasing mycorrhizal colonization or shifts in biomass allocation patterns (aboveground vs. belowground). Accordingly, N deposition and climatic variables caused both synergistic and antagonistic effects on the radial increment of beech trees, depending on tree age and stand characteristics. Hence, the nature of interactions could mediate the long-term effects of global change drivers (including N deposition) on forest carbon sequestration. In conclusion, our findings illustrate that interaction processes between climatic variables and N deposition are complex and have the potential to impair growth and performance of European beech. This in turn emphasises the importance of multiple-factor studies to foster an integrated understanding and models aiming at improved projections of tree growth responses to co-occurring drivers of global change.
The response of vegetation productivity to precipitation is becoming a worldwide concern. Most reports on responses of vegetation to precipitation trends are based on the growth season. In the soil freeze/thaw process, the soil water phase and heat transport change can affect root growth, especially during the thawing process in early spring. A field experiment with increased precipitation (control, increased 25% and increased 50%) was conducted to measure the effects of soil water in early spring on above- and below-ground productivity in an alpine steppe over two growing seasons from June 2017 to September 2018. The increased 50% treatment significantly increased the soil moisture at the 10 cm depth, there was no difference in soil moisture between the increased 25% treatment and the control in the growing season, which was not consistent in the freeze/thaw process. Increased soil moisture during the non-growing season retarded root growth. Increased precipitation in the freezing-thawing period can partially offset the difference between the control and increased precipitation plots in both above- and below-ground biomass.
plant-associated Italian Ascomycota
Climate change and natural disasters might increase the vulnerability of populations in affected regions. This article investigates the link between climatic events and bilateral migration from countries in the Global South to OECD countries. A gravity model is estimated using panel data techniques and bearing in mind potential sources of heterogeneity across subsamples. The main novelty is to distinguish by climatic zones, while also considering commonly used social and economic stresses, such as income levels and incidence of conflict. The analysis is based on bilateral emigration flows from 76 developing countries to OECD countries in the last decades. The results show that increasing extreme temperatures and storms in arid and semi-arid zones act as triggers of bilateral migration from South to North and that the estimated effects are non-negligible. The results are robust to a battery of tests, including dividing the sample according to the levels of conflict and poverty.
Background: Worldwide mountain regions are recognized as hotspots of ethnopharmacologically relevant species diversity. In South Tyrol (Southern Alps, Italy), and due to the region’s high plant diversity and isolated population, a unique traditional botanical knowledge of medicinal plants has flourished, which traces its history back to prehistoric times. However, changes in rural life and culture may threaten this unique biodiversity and cultural heritage. Our study aims to collect and analyze information on native plants used in traditional folk medicine, focusing on the preservation of botanical and cultural diversity.
Methods: Data were collected through a review of published material that documents traditionally used medicinal plants of South Tyrol in order to capture the total diversity of plants and their usage. We evaluated different parameters, comprising the ethnobotanicity index (EI), ethnophytonomic index (EPI), relative frequency of citation (RFC), red list status, and regional legislation with regard to the plant species.
Results: A total of 276 species, including 3 mushrooms and 3 lichens, were identified. These belonged to 72 families, most frequently to the Asteraceae, Rosaceae, and Lamiaceae. The most frequently cited species were Hypericum perforatum L., Urtica dioica L., and Plantago lanceolata L. According to 12 ICPC-2 disease categories, the most frequently treated human health symptoms were from the digestive and respiratory systems as well as the skin. A total of 27 species were listed as endangered, of which 16 are not protected and two are now already extinct. Among the 59 predominantly alpine species, 11 species are restricted to the high altitudes of the Alps and may be threatened by global warming.
Conclusions: Our research revealed that the ethnobotanical richness of South Tyrol is among the highest in Italy and throughout the Alps. Nevertheless, it is evident that biodiversity and traditional knowledge have been heavily eroded. Furthermore, we point out particularly sensitive species that should be reconsidered for stronger protections in legal regulations.
Climate change significantly impacts the vegetation growth and terrestrial ecosystems. Using satellite remote sensing observations, here we focus on investigating vegetation dynamics and the likelihood of vegetation-related drought under varying climate conditions across China. We first compare temporal trends of Normalized Difference Vegetation Index (NDVI) and climatic variables over China. We find that in fact there is no significant change in vegetation over the cold regions where warming is significant. Then, we propose a joint probability model to estimate the likelihood of vegetation-related drought conditioned on different precipitation/temperature scenarios in growing season across China. To the best of our knowledge, this study is the first to examine the vegetation-related drought risk over China from a perspective based on joint probability. Our results demonstrate risk patterns of vegetation-related drought under both low and high precipitation/temperature conditions. We further identify the variations in vegetation-related drought risk under different climate conditions and the sensitivity of drought risk to climate variability. These findings provide insights for decision makers to evaluate drought risk and vegetation-related develop drought mitigation strategies over China in a warming world. The proposed methodology also has a great potential to be applied for vegetation-related drought risk assessment in other regions worldwide.
Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 58 % and 220 %, respectively, as compared to the control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction in precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodlands. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long-term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long-term soil C stocks.
Background and Aims. Climate warming has major impacts on seed germination of several alpine species, hence on their regeneration capacity. Most studies have investigated the effects of warming after seed dispersal, and little is known about the effects a warmer parental environment may have on germination and dormancy of the seed progeny. Nevertheless, temperatures during seed development and maturation could alter the state of dormancy, affecting the timing of emergence and seedling survival. Here, the interplay between pre- and post-dispersal temperatures driving seed dormancy release and germination requirements of alpine plants were investigated.
Methods. Three plant species inhabiting alpine snowbeds were exposed to an artificial warming treatment
(i.e. +1,5 K) and to natural conditions in the field. Seeds produced were exposed to six different periods of cold stratification (0, 2, 4, 8, 12 and 20 weeks at 0°C), followed by four incubation temperatures (5, 10, 15 and 20°C) for germination testing.
Key Results. A warmer parental environment produced either no or a significant increase in germination, depending on the duration of cold stratification, incubation temperatures and their interaction. In contrast, the speed of germination was less sensitive to changes in the parental environment. Moreover, the effects of warming appeared to be linked to the level of (physiological) seed dormancy, with deeper dormant species showing major changes in response to incubation temperatures and less dormant species in response to cold stratification periods.
Conclusions. Plants developed under warmer climates will produce seeds with changed germination responses to temperature and/or cold stratification, but the extent of these changes across species could be driven by seed dormancy traits. Transgenerational plastic adjustments of seed germination and dormancy shown here may result from increased seed viability, reduced primary and secondary dormancy state, or both, and may play a crucial role in future plant adaptation to climate change.
Key words. Adaptation, Cerastium cerastoides, climate warming, Leucanthemopsis alpina, parental effects, plastic responses, seed dormancy, seed germination, seed phenology, Veronica alpina.
Alpine snowbed communities are among the habitats most threatened by climate change. The warmer temperature predicted, coupled with advanced snowmelt time, will influence flowering phenology, which is a key process in species adaptation to changing environmental conditions and plant population dynamics. However, we know little about the effects of changing micro-climate on flowering time in snowbeds and the mechanisms underlying such phenological responses. The flowering phenology of species inhabiting alpine snowbeds was assessed with weekly observations over five growing seasons. We analysed flowering time in relation to micro-climatic variation in snowmelt date, soil and air temperature, and experimental warming during the snow-free period. This approach allowed us to test hypotheses concerning the processes driving flowering phenology. The plants were finely tuned with inter-annual and intra-seasonal variations of their micro-climate, but species did not track the same micro-climatic feature to flower. At the growing-season time-scale, the air surrounding the plants was the most common trigger of the blooming period. However, at the annual time-scale, the snowmelt date was the main controlling factor for flowering time, even in warmer climate. Moreover, spatial patterns of the snowmelt influenced the developmental rate of the species because in later snowmelt sites the plants needed a lower level of heat accumulation to enter anthesis. Phenological responses to experimental warming differed among species, were proportional to the pre-flowering time-span of plants, and did not show consistent trends of change over time. Finally, warmer temperature produced an overall increase of flowering synchrony both within and among plant species.
High-mountain ecosystems are increasingly threatened by climate change, causing biodiversity loss, habitat degradation and landscape modifications. However, very few detailed studies have focussed on plant biodiversity in the high mountains of the Mediterranean. In this study, we investigated the long-term changes that have occurred in the composition, structure and ecology of high-mountain vegetation in the central Apennines (Majella) over the last 42 years. We performed a re-visitation study, using historical and newly collected vegetation data to explore which ecological and structural features have been the most successful in coping with climatic changes. Vegetation changes were analysed by comparing geo-referenced phytosociological relevés collected in high-mountain habitats (dolines, gentle slopes and ridges) on the Majella massif in 1972 and in 2014. Composition analysis was performed by detrended correspondence analysis, followed by an analysis of similarities for statistical significance assessment and by similarity percentage procedure (SIMPER) for identifying which species indicate temporal changes. Changes in ecological and structural indicators were analysed by a permutational multivariate analysis of variance, followed by a post hoc comparison. Over the last 42 years, clear floristic changes and significant ecological and structural variations occurred. We observed a significant increase in the thermophilic and mesonitrophilic plant species and an increment in the frequencies of hemicryptophytes. This re-visitation study in the Apennines agrees with observations in other alpine ecosystems, providing new insights for a better understanding of the effects of global change on Mediterranean high-mountain biodiversity. The observed changes in floristic composition, the thermophilization process and the shift towards a more nutrient-demanding vegetation are likely attributable to the combined effect of higher temperatures and the increase in soil nutrients triggered by global change. The re-visitation approach adopted herein represents a powerful tool for studying climate-related changes in sensitive high-mountain habitats.
The nitrogen (N) cycle and N balance have primarily been modified by anthropogenic activities and environmental changes at various scales, including biological individual, ecosystem, local landscape, continental region, and global. These modifications have drastically affected the structures and functions of natural and agricultural ecosystems in terrestrial and aquatic areas. In this manuscript, we first present a modified view of the global N cycle that includes N transport, conversion, and exchange processes. Second, several crucial issues concerning N balance, including N deposition and excessive addition and the dynamics of N and other nutrients, are reviewed. Third, the effects of climate change factors, including water status, warming, and elevated CO2 concentrations, on N balance and the N cycle and their interactions within and with other environmental factors are outlined. Finally, intervention strategies for improving N balance and N cycling to address rapid continual climatic change and socio-economic development are presented and discussed. It is highlighted that the altered N balance and N cycle between the geosphere, biosphere, and atmosphere have produced the profoundly critical challenge of maintaining N levels within an appropriate range, which should be considered by relevant people and sectors, including researchers, managers, and policy makers from ecological, environmental, and sustainable development sectors.
In high mountain environments, microbial communities are key players of soil formation and pioneer plant colonization and growth. In the last 10 years, many researches have been carried out to highlight their contribution. Bacteria, fungi, archaea, and algae are normal inhabitants of the most common habitats of high altitude mountains, such as glacier surfaces, rock wall surfaces, boulders, glacier waters, streams, and mineral soils. Here, microbial communities are the first colonizers, acting as keystone players in elemental transformation, carbon and nitrogen fixation, and promoting the mineral soil fertility and pioneer plant growth. Especially in high mountain environments, these processes are fundamental to assessing pedogenetic processes in order to better understand the consequences of rapid glacier melting and climate change. This review highlights the most important researches on the field, with a particular view on mountain environments, from glaciers to pioneer plant growth.
Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence suggest that there may be major implications for future plant population size and structure.
Glacier foreland plants are highly threatened by global warming. Regeneration from seeds on deglaciated terrain will be crucial for successful migration and survival of these species, and hence a better understanding of the impacts of climate change on seedling recruitment is urgently needed to predict future plant persistence in these environments. This study presents the first field evidence of the impact of climate change on recruitment success of glacier foreland plants.
Seeds of eight foreland species were sown on a foreland site at 2500 m a.s.l., and at a site 400 m lower in altitude to simulate a 2·7 °C increase in mean annual temperature. Soil from the site of origin was used to reproduce the natural germination substrate. Recruitment success, temperature and water potential were monitored for 2 years. The response of seed germination to warming was further investigated in the laboratory.
At the glacier foreland site, seedling emergence was low (0 to approx. 40 %) and occurred in summer in all species after seeds had experienced autumn and winter seasons. However, at the warmer site there was a shift from summer to autumn emergence in two species and a significant increase of summer emergence (13-35 % higher) in all species except two. Survival and establishment was possible for 60-75 % of autumn-emerged seedlings and was generally greater under warmer conditions. Early snowmelt in spring caused the main ecological factors enhancing the recruitment success.
The results suggest that warming will influence the recruitment of glacier foreland species primarily via the extension of the snow-free period in spring, which increases seedling establishment and results in a greater resistance to summer drought and winter extremes. The changes in recruitment success observed here imply that range shifts or changes in abundance are possible in a future warmer climate, but overall success may be dependent on interactions with shifts in other components of the plant community.
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A deficit in precipitation may impact greatly on soil moisture, snowpack, stream flow, groundwater, and reservoir storage. Among the several approaches available to analyze this phenomenon, one of the most applied is the analysis of dry spells. In this paper, an investigation of the spatial and temporal patterns of dry spells, in a region of southern Italy, has been carried out on a daily precipitation dataset. First, the frequency distributions of the sequences of dry days have been analyzed. Then, the regional areas most affected by dry events have been evaluated at annual and seasonal scale. Finally, the long-term trend of the dry spells has been estimated at annual and seasonal scale. Results show that the lower probabilities of long dry spells occur in the main reliefs of the region, while the highest values have been detected in the Ionian side. The spatial distribution of the mean and maximum length values of the dry spells evidenced a west-east gradient. The trend analysis mainly revealed a negative behavior in the duration of the dry spells at annual scale and a positive trend in the winter period.
Coastal sandy ecosystems are increasingly being threatened by human pressure, causing loss of biodiversity, habitat degradation and landscape modifications. However, there are still very few detailed studies focusing on compositional changes in coastal dune plant communities over time. In this work, we investigated how coastal dune EU habitats (from pioneer annual beach communities to Mediterranean scrubs on the landward fixed dunes) have changed during the last twenty years. Using phytosociological relevés conducted in 1989-1990 and in 2010-2012, we investigated changes in floristic composition over time. We then compared plant cover and the proportion of ruderal, alien and habitat diagnostic species (“focal species”) in the two periods. Finally, we used Ellenberg indicator values to define the “preferences” of the plant species for temperature and moisture. We found that only fore dune habitats showed significant differences in species cover between the two time periods, with higher plant cover in the more recent relevés and a significant increase in thermophilic species. Although previous studies have demonstrated consistent habitat loss in this area, we observed that all coastal dune plant communities remain well represented, after a twenty-year period. However, fore dunes have been experiencing significant compositional changes. Although we cannot confirm whether the observed changes are strictly related to climatic changes, to human pressure or to both, we hypothesise that a moderate increment in average yearly temperature may have promoted the increase in plant cover and the spread of thermophilic species. Thus, even though human activities are major driving forces of change in coastal dune vegetation, at the community scale climatic factors may also play important roles. Our study draws on re-visitation studies which appear to constitute a powerful tool for the assessment of the conservation status of EU habitats.
The fate of alpine species in response to climate warming is still unclear. We analyze effects of climate warming on the composition of alpine plants communities and unravel the range filling of communities within a belt from long-term true upward shift processes. In the European Alps we re-sampled in 2003 the vegetation at sites studied in 1953 and analyzed the changes at intra- and inter-community level. Since 1953 all communities experienced a high species turnover, leading to an overall increase in species richness as new species exceeded species losses. The dominant species mainly declined allowing the potential expansion of competitors and/or of new species. The main recruitment sources are neighbor communities within the same elevation belt performing biotic exchanges with other plant communities in the same altitudinal belts. The changes of species distribution curves with elevation emphasized that more than half of the most widespread persisting species exhibited downward shifts instead of upward shifts. Upward shifts from lower elevation belts and of nonnative species were very limited. One third of the persisting species declined and could be used as a proxy to measure the extinction debt. Therefore the fate of plant communities will depend on the ability of the original species to persist and fill the available ecological gaps. Species persistence may be crucial in developing adaptation and environmental protection strategies.
Climate, land use and fire are strong determinants of plant diversity, potentially resulting in local extinctions, including rare endemic and economically valuable species. While climate and land use are decisive for vegetation composition and thus the species pool, fire disturbance can lead to landscape fragmentation, affecting the provisioning of important ecosystem services such as timber and raw natural resources. We use multi-proxy palaeoecological data with high taxonomic and temporal resolution across an environmental gradient to assess the long-term impact of major climate shifts, land use and fire disturbance on past vegetation openness and plant diversity (evenness and richness). Evenness of taxa is inferred by calculating the probability of interspecific encounter (PIE) of pollen and spores and species richness by palynological richness (PRI). To account for evenness distortions of PRI, we developed a new palaeodiversity measure, which is evenness-detrended palynological richness (DE-PRI). Reconstructed species richness increases from north to south regardless of time, mirroring the biodiversity increase across the gradient from temperate deciduous to subtropical evergreen vegetation. Climatic changes after the end of the last ice age contributed to biodiversity dynamics, usually by promoting species richness and evenness in response to warming. The data reveal that the promotion of diverse open-land ecosystems increased when human disturbance became determinant, while forests became less diverse. Our results imply that the today's biodiversity has been shaped by anthropogenic forcing over the millennia. Future management strategies aiming at a successful conservation of biodiversity should therefore consider the millennia-lasting role of anthropogenic fire and human activities.
Short-term changes occurring in high mountain vegetation were analysed using the data from two Italian sites already part of the GLORIA (GLobal Observation Research Initiative in Alpine environments network - central Apennines and southwestern Alps). The study focused on a set of floristic (endemics), structural (life forms), and ecological (thermic vegetation indicator) variables. Vegetation data was collected according to the GLORIA multi-summit standardised method during the last decade. The re-visitation revealed a moderate decrease of regional endemic flora and significant variations of structural and ecological parameters. The increase of caespitose hemicryptophytes in both sites, the increase of suffruticose chamaephytes in the central Apennines and of rosette-forming hemicryptophytes in the southwestern Alps emerged, highlighting the rapid responses of the alpine vegetation to climate warming. The increase of perennial life forms is related with the expansion of graminoids and small woody plants. These life forms seem to be the most suitable to face climate warming in Italian summits. The increase of the thermic vegetation indicator exceeds the mean European summits increment and is due to the expansion of thermophilic species. Short-term analyses with fine spatial and temporal resolutions are still necessary to improve our understanding concerning species behaviour in high-elevation ecosystems.
In snowbed habitats, characterized by a long-lasting snow cover, the timing of snowmelt can be included among the major factors controlling plant phenology. Nevertheless, only a few ecological studies have tested the responses of flowering phenology of species growing in very late snow-free habitats to an advanced snowmelt (AS) date. The aim of this study was to determine the impacts of an extremely earlier melt-out of snow on flowering phenology of vascular plant species inhabiting an alpine snowbed. The study
was conducted in the high Gavia Valley (Italy, 2,700 m a.s.l.). On 30th May 2012, we removed manually the snow cover and set up an experiment with 5 AS and 5 control plots. Phenological observations of the most abundant vascular species were conducted every 4–6 days. Moreover, we calculated cumulative soil temperature and recorded the mortality of reproductive structures of three species. For several species flowering occurred earlier, and the prefloration period was extended in the AS treatment in comparison with the control. For the majority of species, cumulative soil temperatures in the AS treatment and the control were comparable, confirming that temperature exerts the main control on the flowering of the species inhabiting snowbeds. Earlier flowering species resulted more affected by an AS date in comparison with later flowering species. The mortality of reproductive structures did not increase in the AS treatments in comparison with the control suggesting that few and weak frost events in late spring do not affect the survival of reproductive structures of the species studied.
The rhizobacterial communities of 29 pioneer plants belonging to 12 species were investigated in an alpine ecosystem to assess if plants from different species could select for specific rhizobacterial communities. Rhizospheres and unvegetated soils were collected from a floristic pioneer stage plot at 2,400 m a.s.l. in the forefield of Weisskugel Glacier (Matsch Valley, South Tyrol, Italy), after 160 years of glacier retreat. To allow for a culture-independent perspective, total environmental DNA was extracted from both rhizosphere and bare soil samples and analyzed by Automated Ribosomal Intergenic Spacer Analysis (ARISA) and Denaturing Gradient Gel Electrophoresis (DGGE). ARISA fingerprinting showed that rhizobacterial genetic structure was extremely different from bare soil bacterial communities while rhizobacterial communities clustered strictly together according to the plant species. Sequencing of DGGE bands showed that rhizobacterial communities were mainly composed of Acidobacteria and Proteobacteria whereas bare soil was colonized by Acidobacteria and Clostridia. UniFrac significance calculated on DGGE results confirmed the rhizosphere effect exerted by the 12 species and showed different bacterial communities (P < 0.05) associated with all the plant species. These results pointed out that specific rhizobacterial communities were selected by pioneer plants of different species in a high mountain ecosystem characterized by oligotrophic and harsh environmental conditions, during an early primary succession.
In the context of global warming, the impact of extreme drought events on trees and biotic interactions with
herbivore insects is widely unknown. A faster range expansion of insects in a changing climate could lead to mass propagations of pests in forests. Therefore, the aim was to investigate the influence of climatic alterations on leaf palatability. We exposed juvenile Quercus pubescens Willd. individuals of four European provenances (Bulgaria, Germany, Hungary, and Italy) to warming and drought. In addition, we conducted a palatability experiment with the pre-exposed Q. pubescens leaves and the caterpillars of the generalist forest pest Lymantria dispar L. (gypsy moth). Consumed leaf dry material, density of trichomes, and specific
leaf area were examined. Surprisingly, neither warming nor drought affected the leaf palatability, but palatability was related to the density of trichomes. The Bulgarian provenance of Q. pubescens, which had the lowest density of trichomes, was most palatable. These findings suggest that global warming and drought might not lead to more frequent infestations of the four tested European Q. pubescens provenances
by L. dispar caterpillars in the future.
In the context of climatic changes, the adaptive potential of organisms toward new environmental challenges is becoming of central interest in modern ecology. Here we investigate the response of growth haracteristics and survival in juveniles of four European provenances (Bulgaria, Germany, Hungary and Italy) of Quercus pubescens Willd. to extreme drought and warming in a full factorial common garden experiment. Our results show that extreme durations of drought exceed the tolerance of Quercus pubescens of all provenances. Plants of Italian provenance showed the highest capacity of whole-individual survival, and those of Bulgarian
provenance showed the highest maintenance of the apex under extreme drought. Bud bank characteristics showed no general differences among provenances but responded to warming manipulations. The warming effect resulted in a reduction of collar buds and biomass. In Italian individuals it caused an increase of the apical budbank. This is suggestive of a better adaptation for height growth under warming. Our results imply that significant local adaptation of growth characteristics and survival occurs in Quercus pubescens. However, our findings do not support the idea that southern provenances are a general predictor of better plant performance.
This report provides a preliminary analysis of discharges, precipitation and temperature data since 1923 for 18 closure sections of Po river and its tributaries. First we have investigated the consistency of the data, evaluating the inter-basin correlations, and the relationship between precipitation and discharge timeseries. This analysis provides a coherent picture, suggesting that the data used are reliable. Then we have explored the variation in temperature, precipitation and discharge in each sub-basin. While temperatures show a clear positive trend, precipitation and, generally discharge series did not show any trend at annual scale. Greater changes have been observed at monthly scale, with discharge increasing in May and October. However, the higher values of interannual variability (estimates with the standard deviation of the series), compared to these variations, suggest care in interpreting these results.
The growth behavior of coexisting tree species under climate change is important from an ecological, silvicultural and economic perspective. While many previous studies are concerned with climatic limits for species occurrence, we focus on climate related shifts in interspecific competition. A landmark for these changes in competition is the 'climatic turning point' (CTP): those climate conditions under which a rank reversal between key tree species occurs. Here, we used a common type of temperate mixed forest in Central Europe with European beech (Fagus sylvatica L.) and sessile oak (Quercus petraea (Matt.) Liebl.) to explore the CTP under a future climate projection of increasing temperature and aridity. We selected a dry region where the prerequisite of differential climate sensitivity in mixed beech-oak forests was fulfilled: In-situ dendrochronological analyses demonstrated that the currently more competitive beech was more drought sensitive than sessile oak. We then used two complementary forest growth models, namely SILVA and LandClim, to investigate the climate induced rank-reversal in species dominance and to quantify it as the CTP from beech to oak by simulating future forest development from the WETTREG 2010 A1B climate projection. Utilizing two models allowed us to draw conclusions robust against the assumptions of a particular model. Both models projected a CTP at a mean annual temperature of 11–128C (July temperature .188C) and a precipitation sum of 500–530 mm. However, the change in tree species composition can exhibit a time-lag of several decades depending on past stand development and current stand structure. We conclude that the climatic turning point is a simple yet effective reference measure to study climate related changes in interspecific competition, and confirm the importance of competition sensitivity in climate change modeling.
Sensitivity to climate change and anthropogenic disturbance is a typical feature of
Mediterranean forests, which grow under dynamic and manipulated environmental conditions.
In this study, we examine stone pine (Pinus pinea L.) along the Tyrrhenian coast of Italy to
analyse the tree-growth variability on a temporal scale and to evaluate the radial growth response
to climate trends over the last century. The analysis of tree ring widths at the decadal and
multidecadal scale, which were standardised to remove the age trend, showed primarily significant
downward trends and time periods with lower growth rates. Characterised by a clear
decline in tree ring widths, the two periods of 20 years from the mid-1920s and the early 1970s
appeared to be the least favourables for tree growth. Precipitation was the main factor driving
growth, and the effect was cumulative over consecutive years because of the increase in soil
water content. Including the current year of ring formation, correlations between decline in
precipitation and tree growth were greatest with 3-year precipitation sums. The shifting influence
of winter rainfall on tree ring growth toward not significant values during the last decades,
together with the lack of significant correlation between the current year’s precipitation and
growth decline from the 1970s, might suggest an increasingly dependence on long periods of
water supply to utilise the water content stored due to the previous rainy years. The negative
effect on tree-growth decline of summer and early-fall temperatures appeared as a forcing
influence related to long-term changes in climate rather than high-frequency climate fluctuations.
The recent increase in European temperatures led to a strong enhancement in the occurrence of extremely warm events, with relevant consequences for environment and everyday life. Here, we investigate the evolution of very intense warm and cold events in a south-western European zone during 1961–2007 at a seasonal level. Special attention is given to summertime when warming is the most pronounced. Using a previously developed theoretical model, we discuss how the average properties and long-term trends observed in probability density functions of daily temperatures can explain changes in the frequency of severe, isolated events. In this perspective, the recent intensification of extremely warm events, especially experienced by the Mediterranean zone, is proved to be well consistent with a pure shift of seasonal mean temperatures. On the other hand, any change in the second and higher distributional moments of daily temperatures is ruled out by the data, whereas the average values of these properties, that is, variability and asymmetry, do play a role by shaping the temporal behavior of very intense events.
An analysis is presented of an ensemble of regional climate model (RCM) experiments from the ENSEMBLES project in terms of mean winter snow water equivalent (SWE), the seasonal evolution of snow cover, and the duration of the continuous snow cover season in the European Alps. Two sets of simulations are considered, one driven by GCMs assuming the SRES A1B greenhouse gas scenario for the period 1951–2099, and the other by the ERA-40 reanalysis for the recent past. The simulated SWE for Switzerland for the winters 1971–2000 is validated against an observational data set derived from daily snow depth measurements. Model validation shows that the RCMs are capable of simulating the general spatial and seasonal variability of Alpine snow cover, but generally underestimate snow at elevations below 1,000 m and overestimate snow above 1,500 m. Model biases in snow cover can partly be related to biases in the atmospheric forcing. The analysis of climate projections for the twenty first century reveals high inter-model agreement on the following points: The strongest relative reduction in winter mean SWE is found below 1,500 m, amounting to 40–80 % by mid century relative to 1971–2000 and depending upon the model considered. At these elevations, mean winter temperatures are close to the melting point. At higher elevations the decrease of mean winter SWE is less pronounced but still a robust feature. For instance, at elevations of 2,000–2,500 m, SWE reductions amount to 10–60 % by mid century and to 30–80 % by the end of the century. The duration of the continuous snow cover season shows an asymmetric reduction with strongest shortening in springtime when ablation is the dominant factor for changes in SWE. We also find a substantial ensemble-mean reduction of snow reliability relevant to winter tourism at elevations below about 1,800 m by mid century, and at elevations below about 2,000 m by the end of the century.
Question
Climate change will likely modify patterns of precipitation, with an expected increase in intra‐annual variability and increased frequency and magnitude of extreme events. The Mediterranean area is expected to be very sensitive to such events because water availability is already limited. However, the effect of precipitation variability on ecosystem services, such as plant productivity, is little known. What is the short‐term effect of an experimental precipitation gradient on above‐ground net primary productivity ( ANPP ) of two contrasting sub‐Mediterranean grassland ecosystems? How does early season precipitation, i.e. dry or wet spring, influence ANPP ? Do the functional groups of grasses and forbs differ in their response?
Location
Torricchio Nature Reserve, Central Apennines, Italy.
Methods
We selected two grasslands characterized by contrasting geophysical and soil chemical parameters (north‐ and south‐facing slopes). In both sites, during two climatically different years, mid‐season (summer) precipitation was manipulated in order to obtain a gradient of rainfall availability, comprising additional rainfall, ambient rainfall conditions and rainfall reduction. The above‐ground biomass, subdivided according to the functional groups of forbs and grasses, was collected at the end of each treatment period.
Results
A significant increase in ANPP due to experimental increase in summer rainfall appeared in the year with the wet spring, but only in the mesic north‐facing slope. This response was driven by the increased productivity of perennial forbs, while grasses showed stable above‐ground production. In contrast, in the year with the dry spring, ANPP did not respond to the experimental rainfall gradient, meaning that a dry spring leads to lower ANPP even under increased summer rainfall. The variability of ANPP increased significantly in the xeric south‐facing slope in the year with the wet spring, most likely reflecting indirect effects of small‐scale heterogeneity such as variations in soil depth.
Conclusions
Intra‐annual precipitation variation can have noticeable implications for sub‐Mediterranean montane grassland agriculture: to avoid degradation due to overgrazing, livestock pressure should be limited in years with a spring drought, regardless of summer precipitation, especially in mesic grasslands.
Vegetation on mountains is expected to react in a highly sensitive way to climate change and species losses are predicted in the near future. By means of monitoring studies changes in species diversity can be continuously recorded. In this paper the results of a 7-year study in the Southern Alps are reported. As part of the worldwide network GLORIA (The Global Observation Research Initiative in Alpine Environments) four summits, at altitudes ranging from the treeline to the alpine-subnival ecotone (2199, 2463, 2757 and 2893 m a.s.l.) in the Dolomites (northern Italy) were studied. Sites on the four summits were used to determine the effects of climate warming and observe changes in the numbers of species of vascular plants, frequency and composition. It is hypothesized that 'thermophilization' is likely to occur over a period of 7 years (i.e. species from lower altitudes are expected to migrate to the summits due to climate warming). It is also hypothesized that nival, alpine-subnival and endemic species might decrease due to competitive displacement by species from lower altitudes. The summit areas were comprehensively sampled (from the highest point down to the 10 m contour line) in 2001, 2006 and 2008. In addition, 4 × 1 m2 permanent plots located 5 m below the highest summit point on the north, south, east and west sides of each summit were sampled. The results of revisiting the summits indicate that the numberof species increased on all four summits, with the greatest gains (15% and 18%) recorded on the two highest summits and moderate gains (4% and 9%) on the two lower summits. Species' frequencies within the 1 m2 plots also increased during the 2001-2008 period. A thermophilization trend was demonstrated in which species with distribution centres in the montane or tree line zones were found for the first time on three of the summits. On the lowest summit, the vigorous growth of trees and establishment of new saplings indicate an upward migration of the forest boundary. Species that disappeared from the four summits belonged to species with different altitudinal ranges; however, nival and subnivalalpine species remained. One endemic species, Potentilla nitida, disappeared from the highest summit. Further changes and clearer trends are expected in the next decade.
Plant–plant interactions may critically modify the impact of climate change on plant communities. However, the magnitude and even direction of potential future interactions remains highly debated, especially for water‐limited ecosystems. Predictions range from increasing facilitation to increasing competition with future aridification.
The different methodologies used for assessing plant–plant interactions under changing environmental conditions may affect the outcome but they are not equally represented in the literature. Mechanistic experimental manipulations are rare compared with correlative approaches that infer future patterns from current observations along spatial climatic gradients.
Here, we utilize a unique climatic gradient in combination with a large‐scale, long‐term experiment to test whether predictions about plant–plant interactions yield similar results when using experimental manipulations, spatial gradients or temporal variation. We assessed shrub–annual interactions in three different sites along a natural rainfall gradient (spatial) during 9 years of varying rainfall (temporal) and 8 years of dry and wet manipulations of ambient rainfall (experimental) that closely mimicked regional climate scenarios.
The results were fundamentally different among all three approaches. Experimental water manipulations hardly altered shrub effects on annual plant communities for the assessed fitness parameters biomass and survival. Along the spatial gradient, shrub effects shifted from clearly negative to mildly facilitative towards drier sites, whereas temporal variation showed the opposite trend: more negative shrub effects in drier years.
Based on our experimental approach, we conclude that shrub–annual interaction will remain similar under climate change. In contrast, the commonly applied space‐for‐time approach based on spatial gradients would have suggested increasing facilitative effects with climate change. We discuss potential mechanisms governing the differences among the three approaches.
Our study highlights the critical importance of long‐term experimental manipulations for evaluating climate change impacts. Correlative approaches, for example along spatial or temporal gradients, may be misleading and overestimate the response of plant–plant interactions to climate change.
Under climate change, regeneration from seeds is becoming increasingly important for species persistence, migration and conservation, especially in high-elevation environments. In this regard, the ability of seeds to remain viable for a long time is a crucial prerequisite for seed persistence in the soil and in germplasm banks. However, little is known about the effects of climate warming on seed longevity of alpine plants. Here, we analysed the effects of a moderately warmer parental growth environment generated by open top chambers on subsequent seed longevity of four alpine snowbed species. Seeds from plants exposed to natural and warmed climate during the growing season were subjected to laboratory-controlled accelerated ageing and then regularly sampled for germination tests. Initial viability (Ki), deterioration rate (σ
−1
) and time taken for viability to fall to 50 % (p
50) were estimated using probit analysis. Across species and treatments, p
50 varied from 4.9 to 23.1 days. Seeds produced by plants exposed to warmer temperatures were significantly longer lived than those from plants at natural conditions. Under warming, the seed progeny showed either a higher Ki or a slower σ
−1
. Under moderate climate warming (about + 2 K), alpine snowbed species produced seeds with an extended resistance to heat stress indicating an effective rapid response to the new environment. Such plastic response may play a key role for survival and persistence of alpine snowbed species facing climate change and may also have important implications for ex situ conservation.
This paper includes investigations on 9-year-old plants of 16 European beech provenances (fig. 1). The plantation was established in 1991 with two-year-old container seedlings from Germany, central and southern Italy, from Bosnia and Herzegovina, Slovenia and Romania (tab. 1). The aim of the research was to gain indicators on resistance of the beech to frost, as well as on its phenological characteristics. The tested beech provenances were grouped into 4 region-groups: Central-European region (Hasbruch HA, Lensahn LE, Freising FR, Scheßlitz SZ). Southeastern European region (Mrzla Rupa SL, Vlasenica VLR, Maramures R88). Central-Italian region (Riffredo R1, Lagopesole LA, Capracotte CA, S. Masimo MA). Southern-Italian region (Aspromonte C1, Ferdinandea C2, Fossiata C3, Cinquemiglia C4, Tortorici S1). The test of frost resistance was carried out in January, where cuttings were treated in climate-chamber on various degrees of cold (-5 to -35°C, fig. 2). Following the test, the cuttings were cultivated in the greenhouse in containers with sand. The temperature at which 50% of the tested plants die was used for calculating resistance to frost. Resistance to frost (LT50) of the buds was on the average of -16.5°C. Beech provenances showed a wide range of resistance to frost (tab. 3). Provenances from Germany, as well as provenances from southeastern European region have shown especially high resistance. Provenances from South Italy have proven to be the most sensitive to frost (tab. 4). In the spring of 1999, phenological observations on beech provenances were performed. During that period, time of buds opening in certain beech provenances was estimated. A narrow dependence between resistance to frost and climate conditions of the site where from the beech provenances originate was determined (fig. 4). A good correlation between resistance to frost and opening of buds of beech provenances was also determined. There is a difference in opening of buds between beech provenances from southern Italy and those from Central Europe in the amount of seven days (tab. 6). As a consequence, phenological observations, i.e. time of buds opening can be used as an indirect method for estimate relative frost resistance of the young trees.
The aim of this study is to investigate the microclimates of the different plant communities in the Castelporziano Estate to identify changes at short and medium time, caused by interacting factors at local scale like anthropic disturbance, climatic change and territory management. Air temperature and humidity, soil temperature and PAR (Photosynthetic Active Radiation) were monthly monitored. Measurements were taken in 21 stations, 6 of which along a transect in the vegetation of the dunes and the other 15 stations in forest associations. The dataset have been processed using different statistical treatments: (1) analysis of variance to evaluate the homeostatic capacity of the different communities; (2) analysis of microclimatic deviations values from mesoclimatic data, represented by Castelporziano Estate meteo-climatic stations, to detect microclimatic differences; (3) Multivariate Cluster Analysis to classify the different microclimates. Three main results were obtained: (1) comparison between microclimatic parameters measured during 2007-2008 and previous ones (2003) showed a general tendency of all forest types to shift towards xerophile conditions: air humidity decreased in a large percentage (20%). The woodland with major risk is the Lauro-Carpinetum that looses the 18% of air humidity in a very short period (5 years); (2) vegetation of the dunes displays homeostatic capacity in relationship with structural complexity increasing from pioneer communities of Cakiletum maritimae to mature stands of Viburno- Quercetum ilicis; (3) Cluster Analysis, performed on microclimatic data, allowed to classify vegetation in three different groups, confirming the same patterns obtained by floristic composition. Microclimate resulted a valid and robust tool to detect the ecological status of species and communities, and to follow their temporal changes.
AimClimate change is expected to modify growth trends of forests around the world. However, this modification may vary in strength and intensity across a species' biogeographical range. Here, we study European populations of silver fir (Abies alba) across its southern distribution limits in Spain, Italy and Romania. We hypothesized that growth trends of silver fir will differ across its distribution range, with a marked decline in growth in drought-prone regions near the species' southernmost biogeographical limits.LocationEurope (Spain, Italy, Romania).Methods
We collected tree-ring data from at least 1300 silver fir trees located in 111 sites. The dataset was used to assess and model growth trends, quantified as changes in basal area increment, and to determine how growth responds to climate.ResultsWe found contrasting patterns of basal area increments among countries and sites. Populations of silver fir located outside the Mediterranean area (e.g. northern Italy, Romania) have shown a clear increase in growth over the last two decades, whereas most populations in Spain and southern Italy have displayed a marked decline in growth since the 1980s. The growth of silver fir forests at the south-western distribution limit is severely constrained by low spring–summer water availability, whereas growth of silver fir forests in non-Mediterranean areas is limited by cold conditions in late winter to early spring.Main conclusionsClimate warming is distinctly modifying growth patterns and responses to climate in silver fir across most of the species' European distribution area. In south-western Europe the reduction in growth of many populations is related to an observed increase in aridity, whereas in more temperate areas warming is enhancing growth. Our results confirm a decline in the growth of silver fir at its south-western distribution limits as a consequence of climate warming.
The Mediterranean Basin accounts for more than 10% of the world's vascular plant biodiversity in an area less than 1.5% the size of continental Earth. Forest tree taxa are also exceptionally diverse: more than 100 species have been recorded around the Mediterranean, but less than 30 species can be found in Temperate Europe. This amazing biodiversity was developed over millions of years due to the highly heterogeneous geology and climate of the Mediterranean. Did these factors also affect biodiversity within species, i.e., the genetic diversity of populations? Heterozygosity (the within-population gene diversity), and differentiation (the among-population spatial genetic structure), of neutral genes (isozymes) were used to measure within-species biodiversity in four conifer genera commonly found in the Mediterranean: Abies Mill., Cedrus Trew, Cupressus L., Pinus L. Their within-species biodiversity was significantly higher than that of other conifer species worldwide and did not correspond to expected values in terms of biogeography or levels of endemism. Gene diversity was significantly higher in the Eastern than in the Western Mediterranean Basin, and, surprisingly, was only mildly affected by human impact. A specific post-glacial recolonization model is proposed for the Mediterranean Basin, in which effective glacial refugia are more numerous, and genetic drift is less, than what is proposed for Europe. The within-species approach to biodiversity can help solve taxonomic questions, and when used as an indicator of evolutionary potentials, is an essential component of conservation strategies.
During the last decades, a significant warming was observed in the Alps, cascading into a decrease in snowfall and snow-cover duration. Within the alpine landscape, snowbed communities are regarded as especially vulnerable to the predicted warmer temperatures and earlier snowmelt time. Albeit snowbeds represent a prominent component of the tundra biome, the current vegetation dynamics of these habitats are not yet well understood. In this study, the changes of vascular species richness, co-occurrence, composition, and abundance were evaluated within a late snowbed in the south-eastern Alps. The study was based on a re-survey of 11 permanent plots after a 6-year period. Species richness and abundance significantly increased and species co-occurrence shifted toward higher species segregation. Moreover, the changes in species richness at different spatial scales were related to different environmental factors, and a change in the proportion between snowbed and non-snowbed plants was found. The results suggest an increasing importance of competitive interaction among species in determining the future structure and composition of this community. In conclusion, there is strong evidence that this snowbed community is not in equilibrium with the current climate, and that changes in floristic composition and functional processes of this habitat are underway.
For the purpose of the present study we considered as Italian endemics those specific and subspecific taxa occurring in Italy that are not found elsewhere with the exception of Corsica (France) and Malta. This study presents an updated list of the endemic taxa in the Italian flora, including their geographical distribution at regional level. Italy is characterized by 1371 endemic species and subspecies (18.9% of the total vascular flora): three taxa belong to Lycopodiidae, one to Polypodiidae, two to Pinidae and 1365 to Magnoliidae (three paleoherbs, 221 monocots and 1144 eudicots). The endemic flora belongs to 29 orders, 67 families and 304 genera. Sicily, Sardinia, Calabria and Abruzzo are the four regions richest in endemics. About 58% of endemics are confined to a single administrative region. The most represented orders, families and genera are: Asterales, Caryophyllales and Asparagales, Asteraceae, Plumbaginaceae and Caryophyllaceae, Limonium, Centaurea and Hieracium, respectively. The phytogeographic isolation of Sardinia and Sicily and the separation of peninsular Italy from Northern Italy is confirmed. The relative isolation of Puglia with respect the remaining southern Italian pensinsular regions is also confirmed. Alpine region endemics (from northern Italy) are underrepresented.
AimsOur objective was to investigate how the after-effects of a heatwave interacted with nutrient addition in affecting the vegetation of an alpine mire. We also aimed to assess if the responses of vegetation to the environmental changes differed between mire habitats. LocationA mire in the Dolomites (southeastern Alps, Italy, 1800 m a.s.l.). Methods
We carried out an 8-yr (2002–2009) experiment of nutrient addition in an alpine mire that experienced, in summer 2003, an unprecedented heatwave. The cover of vascular plants and mosses was assessed non-destructively and the presence of all vascular plant and moss species was recorded in 60 plots. ResultsInteracting effects of the heatwave and experimental fertilization brought about profound changes in the vegetation of the mire. Patterns of change varied considerably between two habitats (hummocks and lawns). In the short term (2003–2005), the 2003 heatwave triggered a change in vegetation structure and PFT cover, with vascular plants expanding at the expense of mosses in both habitats. In the mid-term (2005–2009), moss cover increased in hummocks because Sphagnum mosses recovered and non-Sphagnum mosses expanded, especially under N addition. Conversely, in lawns vascular plants expanded while mosses did not recover. These trends were strengthened when N was added with no concomitant P addition. A decline in species richness was observed in lawns, most likely due to stronger interactions among species. Conclusions
Hummocks have a greater ability than lawns to recover from extreme climatic events under higher levels of N influx. Conversely, a persistent increase in vascular plant cover at the expense of moss cover in lawns may jeopardize the carbon sink function of lawn habitats.
Changes in annual and seasonal temperatures were studied from 18 stations, distributed all over the Basilicata region (southern Italy), for the 1951–2010 period. The analysis is based on high-quality and homogenous daily minimum and maximum temperatures. Both minimum (Tmin) and maximum (Tmax) temperatures increase, especially after 1971. Seasonal results show upward trends in Tmin in winter, spring and summer, whereas they show downward trends in Tmin in autumn, especially in the last normal 1981–2010. Tmax also shows upward trends in spring and summer, whereas it tends to decrease during winter and autumn. The intra-annual extreme temperature range (ETR) index also shows a general positive trend, especially during spring. Eleven indices were used to assess the changes in both the cold and warm tails of the daily temperature distribution. The presence of trends was assessed by means of the Mann-Kendall test. The results reveal a general upward tendency on warm days (TX90), warm nights (TN90) and tropical nights (T20) especially because of an increase in temperature after 1971. This datum is fully confirmed in summer which is the season mainly responsible for this trend. The annual occurrence of summer days (SU) and very warm days (TX99) is weakly increasing. The majority of cold extremes, i.e. very cold nights (TN1), cold days (TX10), cold nights (TN10), frost days (FD) and ice days (ID) showed negative trends, thus confirming the overall warming trend in the Basilicata region. This negative trend could stem from the strong increase of Tmin during winter, spring and summer.
For the purpose of the present study we considered as Italian endemics those specific and subspecific taxa occurring in Italy that are not found elsewhere with the exception of Corsica (France) and Malta. This study presents an updated list of the endemic taxa in the Italian flora, including their geographical distribution at regional level. Italy is characterized by 1371 endemic species and subspecies (18.9% of the total vascular flora): three taxa belong to Lycopodiidae, one to Polypodiidae, two to Pinidae and 1365 to Magnoliidae (three paleoherbs, 221 monocots and 1144 eudicots). The endemic flora belongs to 29 orders, 67 families and 304 genera. Sicily, Sardinia, Calabria and Abruzzo are the four regions richest in endemics. About 58% of endemics are confined to a single administrative region. The most represented orders, families and genera are: Asterales, Caryophyllales and Asparagales, Asteraceae, Plumbaginaceae and Caryophyllaceae, Limonium, Centaurea and Hieracium, respectively. The phytogeographic isolation of Sardinia and Sicily and the separation of peninsular Italy from Northern Italy is confirmed. The relative isolation of Puglia with respect the remaining southern Italian pensinsular regions is also confirmed. Alpine region endemics (from northern
Italy) are underrepresented.
Higher atmospheric CO2 concentrations (ca) can under certain conditions increase tree growth by enhancing photosynthesis, resulting in an increase of intrinsic water-use efficiency (iWUE) in trees. However, the magnitude of these effects and their interactions with changing climatic conditions are still poorly understood under xeric and mesic conditions.
We combined radial growth analysis with intra- and interannual δ13C and δ18O measurements to investigate growth and physiological responses of Larix decidua, Picea abies, Pinus sylvestris, Pinus nigra and Pseudotsuga menziesii in relation to rising ca and changing climate at a xeric site in the dry inner Alps and at a mesic site in the Swiss lowlands.
iWUE increased significantly over the last 50 yr by 8–29% and varied depending on species, site water availability, and seasons. Regardless of species and increased iWUE, radial growth has significantly declined under xeric conditions, whereas growth has not increased as expected under mesic conditions. Overall, drought-induced stomatal closure has reduced transpiration at the cost of reduced carbon uptake and growth.
Our results indicate that, even under mesic conditions, the temperature-induced drought stress has overridden the potential CO2 ‘fertilization’ on tree growth, hence challenging today's predictions of improved forest productivity of temperate forests.
Background and aims In cold biomes, litter decomposition, which controls the nutrient availability for plants
and the ecosystem carbon budget, is strongly influenced by climatic conditions. In this study, focused on the
early litter decay within snowbed habitats, the magnitude of the short- and long-term influences of climate
warming, the direction of the effects of warmer temperature and advanced snowmelt, and the control of microclimatic features and plant traits were compared.
Methods Combining experimental warming and space-for-time substitution, mass loss and nutrient release of different plant functional types were estimated in different climatic treatments with the litter bag method.
Results Plant functional types produced a larger variation in the early-decomposition compared to that produced by climatic treatments. Litter decay was not affected by warmer summer temperatures and reduced by advanced snowmelt. Structural-related plant traits exerted the major control over litter decomposition.
Conclusions Long-term effects of climate warming, resulting from shifts in litter quality due to changes in
the abundance of plant functional types, will likely have a stronger impact on plant litter decomposition than shortterm variations in microclimatic features. This weaker response of litter decay to short-term climate changes may be partially due to the opposite influences of higher summer temperatures and advanced snowmelt time.
Global warming will likely exacerbate the negative effects of limited water availability in the Mediterranean area. The Italian Aleppo pine (Pinus halepensis Mill.) provenances are distributed along the coasts except Otricoli provenance growing in an unusual location between 300 and 1,000 m a. s. l., in Umbria (central Italy). The aim of the present study was to investigate the photosynthetic response to a 28-day-long drought and to a subsequent reestablishment of water availability in Otricoli and North Euboea (Greece) provenances, representing different locations along a rainfall gradient in the natural range of this species. Six-month-old seedlings were used in this experiment since at this age Aleppo pine plants in Mediterranean climate face their first water stress potentially affecting plant survival. Water potential (ψw), net photosynthesis and stomatal conductance decreased during drought in both provenances and showed minimal values 28 days after beginning the treatment (DAT). Otricoli seedlings adjusted ψw gradually as the stress level increased and 21 DAT showed a lower ψw than North Euboea. In contrast, in North Euboea seedlings ψw that was not affected until 21 DAT rapidly dropped to a minimum of −3.81 MPa 28 DAT. At the onset of the stress the intercellular CO2 concentration (C
i) was reduced, and the “instrinsic” water-use efficiency (WUEi) was enhanced in both provenances, as stomatal conductance decreased more rapidly than photosynthesis. However, 28 DAT, C
i increased and WUEi decreased as stomatal conductance and photosynthesis declined to minimum levels, revealing nonstomatal limitations of photosynthesis. A rapid decrease in PSII maximal photochemical efficiency estimated by chlorophyll (Chl) fluorescence (Fv/Fm) was also observed when the stress became severe. At the final stage of water stress, North Euboea seedlings maintained significantly higher values of Fv/Fm than Otricoli seedlings. Upon rewatering, photosynthesis did not fully recover in Otricoli seedlings (41 DAT), while all other parameters recovered to control levels in both provenances. No drought-induced physiological differences were consistent with the regional climatic features of these two provenances. Our results suggest that phenotypic plasticity in drought response may help Otricoli provenance cope with global warming, but that recurrent drought episode may slow down the primary productivity of this provenance.
Recent studies examining changes in temperature record frequency over the continental United States have reported that the number of Tmax records has been increasing over the past 50 years and occurring at twice the frequency of Tmin records. In a stationary climate, the number of records should decrease with time as 1/n, where n is the number of years of record-keeping. Here we seek to understand how European temperature records have changed during the late 20th century and how they are expected to change as greenhouse gases increase during the 21st century, using a new ensemble method to filter out the effect of the starting year in the calculation of the records. We find that until 1980, the ratio of Tmax to Tmin records remains close to one, indicating that the climate was relatively stationary. After 1980, there is a distinct positive trend where the observed ratio averages around four during the early part of the 21st century, indicative of a warming trend. We note considerable spatial variability in the observations. Further, the ratio of Tmax to Tmin records set by the year 2100 as simulated by five RCM simulations reaches values of up to several hundred by the end of the 21st century. However, the changes in record frequency vary spatially over Europe. The models project the highest numbers of Tmax records over the Mediterranean during summer, and Scandinavia during the spring and fall. Tmin records decrease most substantially over eastern Europe and western Russia, and the Mediterranean. Our analysis confirms the value of the use of maximum and minimum temperature records in regional climate change studies.
Climate change resulting from the enhanced greenhouse effect is expected to have great impacts on hydrological cycle and consequently on ecosystems. The effects of climate variability have direct implications on water management, as water availability is related to changes in temperature and precipitation regimes. At the same time, this kind of alterations drives ecological impacts on flora and fauna. For these reasons, many studies have been carried out to investigate the existence of some tendency in temperature and/or precipitation series in different geographic domains. In order to verify the hypothesis of temperature increase in Sicily (Italy), temperature data from about 80 spatially distributed weather stations have been deeply analysed. In this study, trend of annual, seasonal and monthly temperature time series have been examined for the period 1924–2006 to investigate possible evidences of climate changes in this region. In addition, also a long series (more than 200 years) has been analysed in order to individuate possible anomalies in the 20th century and to verify the presence, in the last decades, of a temperature increase larger than in the past. The Mann–Kendall non-parametric statistical test has been used to identify trends in temperature time series data. The test has been applied at local and regional scale for three different confidence level, considering the influence of serial correlation as well. The field significance of the regional results has been evaluated using a bootstrap technique of resampling that allows to eliminate the influence of data spatial correlation on Mann–Kendall test. The application of Mann–Kendall test on temperature data provides the evidence of a general warming in Sicily during the analysed period. The analysis of the long series demonstrates that the temperature trend is mainly due to the strong rising observed in the last years of the past century. In order to determine the spatial patterns of temperature trends and identify areas with a similar temperature evolution, the detected trends have been first subjected to the spatial auto correlation analysis and then interpolated using spatial analysis techniques in a GIS framework. Temperature trend maps have allowed to argue on the risk of aridity increase, in particular in the central and western part of the island. Copyright © 2013 Royal Meteorological Society
1. Altitudinal gradients provide a useful space-for-time substitution to examine the capacity for plant competition and facilitation to mediate responses to climate change. Decomposing net interactions into their facilitative and competitive components, and quantifying the performance of plants with and without neighbours along altitudinal gradients, may prove particularly informative in understanding the mechanisms behind plant responses to environmental change.
2. To decouple the inherent responses of species to climate from the responses of plant–plant interactions to climate, we conducted a meta-analysis. Using data from 16 alpine experiments, we tested if changes in net interactions along altitudinal gradients were due to a change in the performance of target species without neighbours (i.e. environmental severity effects only) or with neighbours (neighbour trait mediated effects).
3. There was a global shift from competition to facilitation with increasing altitude driven by both environmental severity and neighbour trait effects. However, this global pattern was strongly influenced by the high number of studies in mesic climates and driven by competition at low altitude in temperate climates (neighbour trait effect), and facilitation at high altitude in arctic and temperate climates (environmental severity effect).
4. In Mediterranean systems, there was no significant effect of competition, and facilitation increased with decreasing altitude. Changes in facilitation with altitude could not unambiguously be attributed to either neighbour trait effects or environmental severity effects, probably because of the opposing stress gradients of cold and aridity in dry environments.
5. Partitioning net interactions along altitudinal gradients led to the prediction that climate change should decrease the importance of facilitation in mesic alpine communities, which might in turn exacerbate the negative effects of climate change in these regions. In xeric climates, the importance of facilitation by drought-tolerant species should increase at low altitudes which should mitigate the negative effect of climate change. However, the importance of facilitation by cold-tolerant species at high altitudes may decrease and exacerbate the effects of climate change.