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Back into the past: Resurveying random plots to track community changes in Italian coastal dunes
Abstract
Resurveying studies are commonly appreciated as a means to monitoring temporal changes in plant diversity. However, most of them still rely on phytosociological plots, which, although representing an invaluable source of data, can lead to biased estimates of vegetation changes. At the community-level, temporal changes can be quantified by means of beta-diversity measures. However, compositional variation can be the result of two different, often contrasting, processes: turnover and nestedness. In this context we test the effectiveness of resurveying approaches based on quasi-permanent plots in revealing temporal changes in herbaceous communities of Mediterranean coastal dune systems. Indeed, due to their being highly dynamic, coastal dunes can be considered ideal habitats for implementing such tools. In particular, we quantified temporal changes in species composition occurred over 10-15 years by calculating Sørensen index of dissimilarity and, in order to determine whether the change was really driven by species turnover, we partitioned Sørensen index into its two components of turnover and nestedness. At the same time, since diagnostic species are considered to be particularly sensitive to habitat modifications and helpful in assessing changes in the ecological structure of a community, we analyzed temporal changes in the occurrence and cover of diagnostic species of the investigated habitats. Results show that coastal dune communities of our study area underwent consistent changes during the analyzed time-span. Almost 25% of the historical plots disappeared. Major transformations, mainly driven by species turnover, involved upper beach communities, embryonic and mobile dunes, as revealed by the parallel analysis of beta diversity and diagnostic species. This work shows how resurveying approaches can efficiently reveal useful insights on vegetation dynamics, therefore providing a solid basis for the implementation of effective conservation strategies, especially in endangered habitats.
... Baseline distribution data are needed to recognize and monitor vegetation community shifts, but are typically not consistently available (Austin, 2002;Austin et al., 2006;Sperandii et al., 2018). Landscape-and habitat-level species distribution data can be rare and invaluable (e.g., Charbonneau et al., 2020;Jackson & Nordstrom, 2019;Martin, 1959). ...
... Remote vegetation indices (e.g., normalized difference vegetation index, enhanced vegetation index) can be used to infer vegetation distribution where in situ field distributions are missing, but often at too low of a resolution for examining community shifts (Sciandrello et al., 2015;Silleos et al., 2006). Similarly, where vegetation distribution data exist, it must often be necessarily localized to repeat measures of transects over time, as opposed to habitat level (Álvarez-Molina et al., 2012;Charbonneau, 2019;Kuiters et al., 2009;Sperandii et al., 2018). As a result, vegetation community shifts can go unnoticed until a related ecogeomorphic change occurs such as the shifting of a high-barrier island dune system to a low-barrier island dune system (Dur an Vinent & Moore, 2014). ...
... The large loss of heath habitat supports the occurrence of woody expansion into H. tomentosa habitat (Figure 2). Heath to woody conversion (87%) is consistent with more sensitive species being most likely to decline compared with more robust associated species (Sciandrello et al., 2015;Sperandii et al., 2018). Heath species have been documented as capable of surviving moderate shading, but are generally sensitive, establishing and thriving in xeric full sunlight-sheltered backdune areas, almost all of which was converted in the north-mapped area (Griffiths, 2006;Moral et al., 1978;Skaradek & Miller, 2009). ...
Vegetation shifts can directly alter habitat dynamics and indirectly impact habitat stability relative to disturbance response. Barrier island dune habitats exhibit spatiotemporally dynamic topography that is affected by vegetation. However, vegetation distribution data can be rare and vegetation persistence is largely unknown such that species turnover over in communities can occur unnoticed. This is true despite concerns and documented cases of woody encroachment related to climate change in these ecogeomorphic habitats where physical stability to resist storm erosion varies with vegetation distribution and density. In 1956 and 1957, the vegetation of Island Beach State Park, NJ, was mapped as a permanent record for subsequent ecological study. In June 2020, we remapped the vegetation of 5.4 of 17 km north to south, seaward of the thicket community boundary. We maintained the same classification system as the historic record, physically mapping vegetation patches via GPS. We quantified changes in thicket, heather, and grass community distribution between the two time periods. Habitat persistence and conversion varied in the 63 years. Heath communities saw 80%–97% habitat loss in conversion to woody thicket. Conversely, thicket community distribution drastically increased, replacing heath where it was previously prevalent. This represents the first known documented instances of woody encroachment for Morella pensylvanica. When they did not expand, thicket communities receded landward or underwent turnover to an invasive species. Woody species of interest for dune stabilization occupied areas of similar habitat characteristics. Dune vegetation distribution persistence from 1957 to 2020 was relatively consistent and stable with the exception of heath habitat conversion. Barrier island stability is directly related to vegetation stability such that understanding where community shifts might occur over time can aid in managing and modeling efforts surrounding these dynamic ecogeomorphic habitats.
... Coastal dune systems cover relatively small areas but provide fundamental ecosystem services (Arkema et al. 2013) and feature unique biodiversity (Maun 2009). These transitional ecosystems at the meeting point of land and sea are characterized by harsh environmental conditions that limit survival and successful reproduction to a relatively small set of highly specialized plant species (Marcenò et al. 2018;Sperandii et al. 2019). Coastal dunes are highly dynamic ecosystems where significant vegetation changes can take place in a short time . ...
... Coastal erosion may be one of the most significant factors affecting the integrity of coastal dunes, since most of the world's coastlines are in a state of erosion or retreat as a consequence of local as well as global natural processes or anthropogenic factors (Douglas 1991;Hansom 2001). This problem affects about 45% of the Italian sandy coasts (Valpreda and Simeoni 2003), posing serious threats for the conservation of these environments (Carranza et al. 2008;Sperandii et al. 2019 Though psammophilous plant species (i.e., living in sandy habitats) are adapted to this harsh and dynamic environment characterized by seasonal and interannual retreat and advance of the seashore, intense and quick coastal erosion patterns could alter the sea-inland environmental gradient, which is a key factor in determining species distribution in these systems (Fenu et al. 2013;Prisco et al. 2013). In addition, intense erosion processes could lead to a significant retreat of the coastline, causing the reduction or disappearance of vegetated areas, as already reported by Sperandii et al. (2019). ...
... This problem affects about 45% of the Italian sandy coasts (Valpreda and Simeoni 2003), posing serious threats for the conservation of these environments (Carranza et al. 2008;Sperandii et al. 2019 Though psammophilous plant species (i.e., living in sandy habitats) are adapted to this harsh and dynamic environment characterized by seasonal and interannual retreat and advance of the seashore, intense and quick coastal erosion patterns could alter the sea-inland environmental gradient, which is a key factor in determining species distribution in these systems (Fenu et al. 2013;Prisco et al. 2013). In addition, intense erosion processes could lead to a significant retreat of the coastline, causing the reduction or disappearance of vegetated areas, as already reported by Sperandii et al. (2019). However, not all plant species may be affected in the same way by such events. ...
Climate change and human infrastructures heavily affect seashore dynamics with cascading consequences on coastal sand
dunes. While there is a high number of studies conducted on plant communities, there is a lack of monitoring approaches
conducted at population level. We studied the variations in spatial patterns of the population of three plant species in response
to interannual coastline variation in a coastal Nature Reserve. We performed eight diachronic field observations over the
course of eleven years, in which we registered the coastline variation and the position of each functional individual of the
selected species. The population of the alien-naturalized and highly clonal Sporobolus pumilus demonstrated the ability to
follow the interannual variations of the coastline, thus maintaining a constant distance from the seashore. In contrast, the
native Polygonum maritimum and the dune-builder Thinopyrum junceum showed a progressive reduction of the distance from
the seashore (− 21 m and − 16 m, respectively). However, this effect was detected only at a finer spatial scale, thus revealing
the scale-dependence of this phenomenon. In addition, the spatial distribution patterns of T. junceum changed with the
variation and stability of the seashore, showing spatial dispersion and aggregation patterns, respectively. Our study reveals
how the plant response to the coastline variation was species-specific, probably depending on species functional strategies.
Besides highlighting the importance of frequent diachronic surveys, our population-level approach may help in explaining
the compositional changes observed at higher organizational level. Finally, our findings indicate that coastal erosion poses
a serious threat for the conservation of dune ecosystems.
... The study was carried out on Mediterranean coastal dunes along the Tyrrhenian and Adriatic coasts (Lazio and Molise region, Central Italy). The study area is characterized by a Mediterranean climate and consists of low sandy Holocenic dunes that generally occupy a narrow strip along the seashore [48,49]. Coastal dune systems, in well-preserved condition, present a characteristic vegetation zonation influenced by a steep sea-inland ecological gradient with a wide diversification of habitats, from annual communities on Sustainability 2021, 13, 13946 3 of 12 sand beach driftlines to Mediterranean shrubs further inland. ...
... Sustainability 2021, 13, x FOR PEER REVIEW 3 of 12 by a Mediterranean climate and consists of low sandy Holocenic dunes that generally occupy a narrow strip along the seashore [48,49]. Coastal dune systems, in well-preserved condition, present a characteristic vegetation zonation influenced by a steep sea-inland ecological gradient with a wide diversification of habitats, from annual communities on sand beach driftlines to Mediterranean shrubs further inland. ...
... We further analyzed temporal changes in diagnostic species-those species with occurrences concentrated in a particular habitat that play a crucial role in supporting the structure and functions of their reference habitat [49,53]. Diagnostic species were identified following Chytrý et al. [53], resulting in 34 species attributable to the four EUNIS habitats mentioned above. ...
Alien plants represent a significant threat to species diversity and composition in natural habitats. Nevertheless, little is known about the dynamic of the invasion process and how its effects on native species change over time. In this study, we explored vegetation changes that occurred in invaded coastal dune habitats over the last 10–15 years (2005–2020), particularly addressing impacts on alien and diagnostic species. To monitor temporal trends, we used data resulting from a revisitation study. After detecting overall changes in alien species occurrence and cover over time, 127 total plots were grouped into plots experiencing colonization, loss, or persistence of alien species. For these three categories, we compared historical and resurveyed plots to quantify changes in native species composition (using the Jaccard dissimilarity index) and to measure variations in diagnostic species cover. The number of alien species doubled over time (from 6 to 12) and two species, Yucca gloriosa and Agave americana, strongly increased their cover (+5.3% and +11.4%, respectively). Furthermore, plots newly invaded appeared to record the greatest changes in both native and diagnostic species. Our results suggest the need for regular monitoring actions to better understand invasion processes over time and to implement effective management strategies in invaded coastal dune habitats.
... In this context, assessing and monitoring how coastal dune habitats change through time is particularly urgent. Though recent studies suggested that indeed changes are occurring across Mediterranean sandy habitats, they either did not directly compare historical and recent surveys (Prisco et al., 2016; or only assessed one facet of diversity (Del Vecchio et al., 2015;Sperandii et al., 2019), and never tested if observed changes were beyond average fluctuations (e.g. sensu Legendre, 2019). ...
... In particular, we first asked how much vegetation changed in the last 15 years and tested how much of this change was greater than expected by chance. Even under natural conditions, a certain degree of temporal change is to be expected because of natural stochasticity, succession and species-specific extinction and colonization processes, all of which are highly dynamic in coastal dune (Maun, 2009;Sperandii et al., 2019). However, using null models to reproduce average extinction and colonization rates, it is possible to identify communities and habitats that have changed in exceptional ways (Legendre, 2019). ...
... However, using null models to reproduce average extinction and colonization rates, it is possible to identify communities and habitats that have changed in exceptional ways (Legendre, 2019). Given the widespread evidence of threats to coastal dunes (Defeo et al., 2009;Malavasi et al., 2013;Pakeman et al., 2017a) and some first records of biodiversity alterations in these ecosystems (Pakeman et al., 2017b;Sperandii et al., 2019), we predict large compositional or dominance changes, coupled with biodiversity losses beyond expectations in many communities, although the pattern and extent of change are likely to differ among habitat types. Second, we asked how the dominant ecological functions changed and if functional diversity changes mirrored taxonomic changes. ...
Assessing temporal changes in plant communities is a core aim of temporal ecology and a shared priority of global conservation agendas which is particularly urgent in threatened ecosystems. Mediterranean coastal dunes harbour some of the most threatened habitats in Europe. Yet, surprisingly, studies capturing the recent temporal dynamics of biodiversity in these systems by accounting for multiple diversity facets and different aspects of community structure are missing.
Here, using data from a resurveying study, we provide a first comprehensive, habitat‐based, multi‐faceted assessment of recent (10–15 years) temporal changes in threatened Mediterranean coastal dunes. To this aim, we quantified taxonomic and functional changes in plant communities using indices capturing multiple biodiversity features, and we explored trends at both the community level and the species level. We compared observed biodiversity changes across habitats (to look for evidence of generalized biodiversity loss) and across facets (to infer the potential loss of unique functions), and tested their significance using a null model. Overall, we predicted large compositional shifts and biodiversity loss beyond expectations in many communities, although with differences among habitat types.
Our results reveal severe shifts in the taxonomic profile of the communities, mostly driven by a non‐random species loss, and little temporal overlap in functional space, implying large changes in both community structure and ecological strategies of the investigated habitats. This, together with the disappearance of c. 23% of historical plots and with substantial losses in focal species, suggests that intense degradation processes are occurring in coastal dune habitats, particularly on the upper beach and on shifting dunes.
Synthesis. This study provides the first evidence of large, often non‐random, taxonomic and functional changes occurring in Mediterranean coastal dune plant communities in a surprisingly short time‐span. Along with furthering our knowledge of the recent dynamics affecting these endangered ecosystems, our results also pinpoint the types of habitats that are most at risk, helping to direct future conservation efforts and management. Future research should now be directed at more precisely testing potential drivers of these changes.
... These represent a coastal vegetation zonation including structurally and functionally distinct plant communities closely related to the sea-inland gradient (Acosta et al., 2009;Bazzichetto et al., 2016): drift-line annual communities (upper beach), communities dominated by dune-building perennial rhizomatous grasses (embryo and mobile dunes), backdune communities colonized by small chamaephytes (fixed dunes) and species-rich therophytic grasslands (dune grasslands). Differently from other habitats, coastal dunes are highly dynamic environments, where short time-spans have already proven sufficient to reveal significant vegetation changes, especially in herbaceous plant communities (Sperandii et al., 2019). During field sampling, we recorded all species present in each plot and estimated their cover using a percentage cover scale ranging from 1 to 10 (1 = 1-10%; 2 = 10-20%; …; 10 = 90-100%) (see Sperandii et al., 2019 for details about the resurveying protocol). ...
... Differently from other habitats, coastal dunes are highly dynamic environments, where short time-spans have already proven sufficient to reveal significant vegetation changes, especially in herbaceous plant communities (Sperandii et al., 2019). During field sampling, we recorded all species present in each plot and estimated their cover using a percentage cover scale ranging from 1 to 10 (1 = 1-10%; 2 = 10-20%; …; 10 = 90-100%) (see Sperandii et al., 2019 for details about the resurveying protocol). ...
... In this paper, we evaluated the effectiveness of Natura 2000 in maintaining or restoring habitat quality in endangered Mediterranean coastal dunes by investigating, in a counterfactual scenario, habitat loss and temporal trends in two informative plant groups: focal and alien species. During the analyzed time-span, about 27% of the historical plots disappeared, suggesting a diffused habitat loss consistent with trends reported for both Mediterranean (Sperandii et al., 2019) and Oceanic systems (Pakeman et al., 2017). Habitat loss represents one of the most severe threats in coastal dune systems, and it is particularly intense in the Mediterranean, where multitemporal analyses at the landscape scale documented substantial reductions in the extent of dune habitats from the 1950s onwards mostly due to urbanization, agricultural and afforestation activities (Malavasi et al., 2013;Romano and Zullo, 2014). ...
Though protected areas are recognized as the cornerstone of global conservation efforts, their effectiveness in safeguarding biodiversity is currently debated. In particular, studies evaluating the counterfactual influence of protection status on community metrics derived from field-collected data are still scarce.
In this paper, using data from a resurveying study, we assessed the contribution of the European Natura 2000 network to maintaining and/or improving through time habitat quality and functional integrity in Mediterranean coastal dune habitats, which appear among the most threatened ecosystems worldwide. Using multiple regression techniques, we tested the influence of protection status on habitat loss and on 10–15 years changes in the richness and cover of two highly informative plant groups: focal and alien species. Next to a substantial habitat loss, we observed an overall decrease in focal species richness and cover, whereas alien species were stable or slightly increasing, depending on the habitat.
Surprisingly, changes in the analyzed metrics did not differ between protected and non-protected sites, thus providing no substantial evidence of the effectiveness of Natura 2000 in conserving and/or improving dune habitats. Taken together, such results suggest negative implications for the whole ecosystem structure and functionality, to be expected regardless of the protection status.
This led us to reflect about the general inadequacy in the implementation of actual conservation measures in coastal habitats, discuss potential causes (lack of ad-hoc management plans and targeted conservation measures, scarcity of dedicated funding, bureaucratization), and stress the value of monitoring activities for evaluating conservation outcomes and reformulating current strategies.
... Local species decline or become extinct, while alien species tend to 1 3 increase Malavasi et al. 2016;Croce et al. 2019). In addition, when strong and prolonged disturbance is present environmental changes become irreversible (Acosta et al. 2006;Sperandii et al. 2019). For these reasons, the typical dune vegetation zonation, characteristic of the dune habitats is disappearing (Prisco et al. 2012). ...
... Still, it is difficult to preserve the shorelines from, e.g. trampling and coastal erosion, also within areas where a form of protection is applied (Ciccarelli et al. 2012;Sperandii et al. 2019). It turns out that also along the Tuscan sandy shorelines many vegetation communities are heavily disturbed and floristically impoverished (Viciani et al. 2007(Viciani et al. , 2014. ...
... On the other hand, other characteristic species as Cyperus capitatus, Eryngium maritimum and Medicago marina were not recorded. The habitat confirms its vulnerability being one of the most exposed to natural and anthropogenic disturbances (Ciccarelli 2014;Sperandii et al. 2019). ...
Coastal dunes are rich in habitats with a high heterogeneity in species composition. Though widely recognized as very fragile and dynamic ecosystems, they are systematically overexploited. In addition, mismanagement contributes making
these habitats highly endangered, especially in the Mediterranean area. In this study, an impoverished dune system was used to investigate whether the lack of indicator species, including characteristic, main diagnostic, alien and non-typical, could mislead habitat assignment. Coastal dune plant communities used in this study are embedded into a high anthropogenic pressure territory, primarily due to the vicinity to a city and by hosting bathing facilities. A cluster analysis based on 49 vegetation plots (relevés) was performed in order to assign dune vegetation units to EU habitats (92/43/EEC Habitat Directive) and corresponding phytosociological units. Eight habitat types were classified and two of them were of priority importance. Twelve plant communities belonging to eight different phytosociological classes were recognized. The plant cover value of
characteristic, main diagnostic, alien and non-typical plant species, was used to assess the conservation status of each habitat type. Despite the presence of well-preserved plant community, almost all habitats were in unfavourable conservation status. Furthermore, a floristic impoverishment and a zonation interruption on the stabilized dunes were found. This study underlines the difficulty to identify typical coastal dune plant communities and associated habitats when anthropogenic disturbance dramatically changes the environmental conditions. Specific conservation and management actions for the sustainable maintenance of these endangered habitats are suggested.
... The dune habitats at the front part (closer to the sea) are very important for the conservation of the characteristic psammophytic biodiversity. At the same time, embryonic and white dune communities are certainly the most exposed not only to natural but also to anthropogenic sources of disturbance, such as seaside mass tourism [52,[110][111][112]. A likely reason for the severe decline in the cover of psammophytes registered in the embryonic and white dunes is anthropogenic pressure; in this regard, we did not even establish embryonic dunes at the end of the transect from the largest beach resort in Bulgaria-Sunny Beach. ...
... Sarmati et al. [108] reported a decrease in diagnostic species present in coastal dune habitats where the anthropogenic disturbance is high. Sperandii et al. [110] detected a significant decrease in the cover of some diagnostic species for upper beach and embryonic dune habitats, such as Ammophila arenaria, Salsola kali and Euphorbia peplis, and revealed that all diagnostic species experiencing a statistically significant change in time decreased in their occurrence and/or in their cover. The vegetation data comparison between 2003 and 2017 also showed that, aside from typical psammophyte plants, the cover of other plant groups has undergone negligible changes over time. ...
Coastal dunes are valuable and vulnerable habitats that require scientific exploration and understanding of their natural processes; therefore, the aims of this study were to determine the current vegetation characteristics of dune habitats along the Bulgarian Coast in terms of species richness and cover of typical psammophytes and different non-psammophytic plant groups, and to analyze how they respond to certain environmental drivers. Data were collected from 12 dune systems. The research was focused on embryonic, white and grey dunes. The field work was conducted throughout July and August 2017. The vegetation was sampled at 154 phytosociological plots (5 m × 5 m). To understand how the vegetation responds to different drivers, we tested the correlation of defined species group richness and cover in relation to (1) the soil pH and EC values, (2) the distance from inland to the sea and (3) the range of different categories of land cover in the surrounding area. In order to track temporal vegetation changes, we compared the cover of defined species groups between 2003 and 2017. We registered a total number of 269 vascular plants, 12 bryophytes and 5 lichens. The strongest presence in all dune types, both in species richness and cover, was the group of grass- and shrubland plants. Weeds and ruderal plants had significant coverage in grey dunes, while the richness and cover of forest and alien plants were negligible among the studied dune habitats. The comparison of data between 2003 and 2017 revealed a substantial decline in the cover of psammophytes. We observed a clear pattern regarding the share of species richness of psammophytes and non-psammophytes among different locations. We detected that grey dunes were the most affected by the penetration of non-psammophytes.
... Coastal dune landscapes represent complex patchworks evolving in the transitional interface between terrestrial and marine domains, spanning along the shoreline [1]. In Mediterranean areas, the degradation and deterioration of sand dune ecosystems have been impressive in recent decades [2]. This phenomenon is driven by a number of environmental and anthropic constraints, such as urban development [3], coastal erosion [4], the spread of invasive alien species [5], drought [6], low soil fertility [7], substrate instability [8], sea wind [9], and salinity stress [10]. ...
The increase in atmospheric and soil temperatures in recent decades has led to unfavorable conditions for plants in many Mediterranean coastal environments. A typical example can be found along the coast of the Campania region in Italy, within the “Volturno Licola Falciano Natural Reserve”, where a pine forest suffered a dramatic loss of trees in 2021. New pines were planted in 2023 to replace the dead ones, with a larger tree layout and interspersed with Mediterranean bushes to replace the dead pine forest. A direct (in situ) monitoring program was planned to analyze the determinants of the pine salinity stress, coupled with Sentinel-2 L2A data; in particular, multispectral indices NDVI and NDMI were provided by the EU Copernicus service for plant status and water stress level information. Both the vadose zone and shallow groundwater were monitored with continuous logging probes. Vadose zone monitoring indicated that salinity peaked at a 30 cm soil depth, with values up to 1.9 g/L. These harsh conditions, combined with air temperatures reaching peaks of more than 40 °C, created severe difficulties for pine growth. The results of the shallow groundwater monitoring showed that the groundwater salinity was low (0.35–0.4 g/L) near the shoreline since the dune environment allowed rapid rainwater infiltration, preventing seawater intrusion. Meanwhile, salinity increased inland, reaching a peak at the end of the summer, with values up to 2.8 g/L. In November 2023, salts from storm-borne aerosols (“sea spray”) deposited on the soil caused the sea-facing portion of the newly planted pines to dry out. Differently, the pioneer vegetation of the Mediterranean dunes, directly facing the sea, was not affected by the massive deposition of sea spray. The NDMI and NDVI data were useful in distinguishing the old pine trees suffering from increasing stress and final death but were not accurate in detecting the stress conditions of newly planted, still rather short pine trees because their spectral reflectance largely interfered with the adjacent shrub growth. The proposed coupling of direct and remote sensing monitoring was successful and could be applied to detect the main drivers of plant stress in many other Mediterranean coastal environments.
... Interestingly, several unique sites are covered by the pioneer vegetation of drift lines, a naturally species-poor habitat characterized by highly specialized species like Cakile maritima, Salsola tragus, Convolvulus soldanella(Prisco et al. 2012). As emerged from other works, this habitat is often in an unfavourable conservation status (Bertacchi 2017;Sperandii et al. 2019;Sarmati et al. 2019), because it is highly vulnerable to tourism and mechanical cleaning(Attorre et al. 2013), while being also sensitive to erosion(Bazzichetto et al. 2020). Nonetheless, our analysis also revealed the presence of unique sites characterized by Calamagrostis arenaria subsp. ...
Effective conservation planning requires identifying priority hotspots to allocate resources. To preserve biodiversity, it is crucial to consider α, and γ-diversity and protect ecologically unique sites, which can host uncommon and irreplaceable species assemblages that would be lost if only species-rich sites were protected. Coastal dunes, hosting highly specialized plant communities, are among the most threatened ecosystems worldwide. In this study, we identified conservation priority hotspots to assess the effectiveness of the network of protected areas in coastal dunes of Tuscany (central Italy), using data on plant communities collected in 506 plots. We additively partitioned -diversity in its and components, observing a significant variation at all spatial levels only for dune species. In terms of -diversity, we found that Northern protected sites were richer in dune species, while synanthropic and alien species were equally present inside and outside protected areas. By partitioning the total -diversity into its components (replacement and richness difference), we found a prevalence of replacement for dune species, indicating the most unique sites as the ones to favor for conservation. Unique sites were identified through Local Contributions to Beta-Diversity and their conservation value was determined by their species composition and the relationship with landscape variables. Unique sites with high conservation value were only partly protected, while some protected sites were altered and required restoration. Our approach proved effective for identifying the most unique sites, indicating some issues in the existing protected network, while providing valuable information on sites to prioritize for future conservation actions.
... Sørensen's index of dissimilarity was used to characterize the beta diversity and indicate the degree of biological information exchange between sampling sites. The calculation of Sørensen's index of dissimilarity was presented as Eq. 3 (Sperandii et al., 2019). ...
Ecological connectivity in landscapes is crucial for plant diversity conservation. The barrier risk to ecological connectivity represents the risk to ecological connectivity loss or weakening, resulting from the barrier to biological information exchange among habitats. Therefore, clarifying the barrier risk to the ecological connectivity of plant diversity in space can reveal the spatial impacts of reduced ecological connectivity on plant diversity. This study analyzed effects of karst peak, river network, arable land, and impervious surface on plant diversity in karst natural, countryside, urban, and island landscapes in Guizhou Province with fragile environment. Then, we calculated the barrier distance of ecological connectivity to reveal the barrier risk to the ecological connectivity of plant diversity in space. The results showed that karst peak was the source of high plant diversity, and plant diversity could diffuse about 400 m around karst peaks. River network and arable land enhanced the connectivity among karst peaks to maintain plant diversity, and the effect on enhancing the connectivity was about 300 m and 450 m, respectively, while the weakening effect of impervious surface on connectivity was about 350 m. Based on the distance for plant diversity diffusing around karst peaks, the barrier distance of ecological connectivity was determined by the combination type of river network, arable land and impervious surface in landscapes. From low to high, the barrier risk to the ecological connectivity of plant diversity was about 1,110 m in the combination of river network and arable land, about 790 m in the combination of river network, arable land and impervious surface, about 520 min the combination of arable land and impervious surface, about 400 m in the combination of river network and impervious surface. Our findings clarify the barrier risk to the ecological connectivity of plant diversity in space, and provide a scientific basis for plant diversity conservation from the perspective of ecological connectivity.
... Some records may have been collected intentionally to provide scientific data, whereas others may have been collected for personal use but still contain data relevant to current questions. Ecologists can compare data from historic records of plants and animals with modern surveys to investigate such topics as changes in community composition, species' abundance, and phenology (Sparks and Carey 1995, Alfonsi et al. 2017, Socolar et al. 2017, Sperandii et al. 2019, Gotelli et al. 2021. Researchers have used resurveys such as these to help understand the loss of native species in locations around the world, the lengthening of growing seasons across temperate regions, and variations in species' responses to human activities (Johnson et al. 2003, Cornish and DiDonato 2004, Lips et al. 2004, Vellend et al. 2013a, Dornelas et al. 2014. ...
Ecologists are increasingly combining historical observations made by naturalists with modern observations to detect the ecological effects of climate change. This use of historical observations raises the following question: How do we know that historical data are appropriate to use to answer current ecological questions? In the present article, we address this question for environmental philosopher Henry David Thoreau, author of Walden. Should we trust his observations? We qualitatively and quantitatively evaluate Thoreau's observations using a three-step framework: We assess the rigor, accuracy, and utility of his observations to investigate changes in plants and animals over time. We conclude that Thoreau was an accurate observer of nature and a reliable scientist. More importantly, we describe how this simple three-step approach could be used to assess the accuracy of other scientists and naturalists.
... In particular, SdM1 and SdM2 are located on the same coastal sector that was previously surveyed by . These sites are characterized by relatively wellpreserved dune systems, with low dunes (less than 10 m height) harboring remnant coastal vegetation highly threatened by several human activities [19,29]. All study sites are characterized by Mediterranean climatic conditions, are South/South-west oriented, and occupy a narrow strip along the seashore (less than 500 m from the shoreline to inland). ...
Italy banned the sale of plastic cotton buds, which is one of the most abundant litter items entering the sea and then washing ashore. However, since the ban came into force, no studies have been carried out to assess whether the measure has actually led to the reduction of plastic cotton buds accumulating on Italian coasts. Here we aim at evaluating the effectiveness of the ban in reducing the amount of cotton buds reaching sandy beaches of the Tyrrhenian coast. Specifically, we monitored the accumulation of beach litter for one year since the ban came into force. By surveying eight coastal sites from winter 2019 to winter 2020, we collected a total of 52,824 items mostly constituted by plastic debris (97.6%). We found that cotton buds were the most abundant item (42.3% of total litter), followed by plastic (28.5%) and polystyrene (5.43%) fragments. Our preliminary assessment suggests that the ban has so far not led to a sensible reduction in the amount of cotton buds entering the marine ecosystem. This was to be expected since implementation strategies are still lacking (i.e. no economic sanctions can be imposed in case of non-compliance) and bans are differently implemented among countries facing the Mediterranean Sea, calling for law enforcement and implementation at the national and international levels.
... Sulla base dei risultati ottenuti in questo studio, possiamo affermare che il totale di specie campionate nel litorale della Tenuta è in linea con il numero di specie riscontrato in altri studi relativi al litorale Laziale [32,33]. Inoltre, bisogna sottolineare che, ad oggi, la Tenuta di Castelporziano rappresenta uno dei pochi esempi rimasti nella penisola italiana, e probabilmente l'unico nel Lazio, che conserva completa la zonazione dunale costiera tipica dell'ambiente mediterraneo, rendendolo un sito unico dal punto di vista ecologico e naturalistico lungo la costa tirrenica peninsulare. ...
By occupying the transition zones between the marine and terrestrial world, coastal dunes are valuable ecosystems with a highly specialized flora and fauna, providing also crucial services to humans. However, despite their high naturalistic value, coastal dunes are among the most threatened ecosystems in Italy and the Mediterranean basin. High anthropic impact due to urban expansion and tourism combined with the spread of invasive alien species have led to extensive degradation of coastal habitats, particularly in recent years. The Tenuta Presidenziale di Castelporziano, given the limited human presence, is one of the few spots in Italy where the coastal dune system is well conserved, maintaining a complex habitat zonation along the sea-inland environmental gradient. To date, a comprehensive analysis of the dune habitats present in the Tenuta based on floristic data is still missing. We collected all available published and unpublished data to build a database recording 119 floristic relevés of dune habitats, performed from 1981 to 2017. We conducted an explorative analysis through DCA and accumulation curves to classify and describe the dune habitats. Based on the floristic and ecological information provided by the interpretation manuals of the Habitats Directive (93/42/CEE), we identify 10 EU habitats belonging to 6 categories of the EUNIS habitat classification: the habitat 1210 of the drift line (N12 EUNIS code); the shifting coastal dunes habitats 2110 and 2120 (N14); 2210, 2230, 2240 habitat types, i.e. N16 coastal stable dune grasslands; the coastal dune scrub habitats 2250* and 2260 (N1B); the coastal dune pinewoods 2270* (N1G); and the oaks woodlands 9340 (T21). Overall, plant species recorded were 185, distributed among the 10 habitats, showing the coexistence of several plant communities in a relatively small area. Results confirm the Tenuta as a unique coastal dune ecosystem with exceptionally rich flora, therefore representing one of the last coastal biodiversity hotspots of the Italian peninsula.
... Al tractar-se d'hàbitats amb un grau alt d'amenaça, es dediquen molts esforços per a la seva conservació (Roig-Munar, 2016;Sperandii et al., 2019b). De fet, tots els hàbitats dunars de Catalunya són hàbitats d'interès comunitari a nivell europeu (HIC; CEE, 1992), amb les implicacions en gestió i conservació corresponents. ...
The Bartsia trixaginis-Scirpoidetum holoschoeni association in Catalonia The coastal fixed sands grassland of Bartsia trixaginis-Scirpoidetum holoschoeni O. Bolòs 1962, comprises a community of great ecological interest due to its unique character. Up to now, its known distribution in Catalonia has been limited to the county of Baix Llobregat, where Bolòs (1962) described the association on the basis of a single inventory made in 1950. In the course of a dune vegetation study conducted in the province of Girona, new localities for this association were identified in the Alt Empordà and Baix Empordà counties, bringing the total number of localities to six. This paper presents 12 unpublished inventories that have enabled us to analyse the community from phytosociological and ecological perspectives. These backdune meadows are very limited in both distribution and extent, due to habitat destruction and the loss of natural dynamics. The variability of the association allows us to distinguish up to three new ecological varieties , always marked by the presence of Thero-Brachypodietea species. The community is ephemeral, in transition between Ammophilion arundinaceae dune units and Mediterranean vegetation, and is of great conservation interest as well as being highly threatened. Based on the observations and inventories made, this paper highlights the importance of these meadows and the need to increase our knowledge of them, in order to preserve them within a profoundly transformed coastline.
... In particular, the functional traits of typical species are studied to better understand functional characteristics (plant height, specific leaf area, leaf dry matter content, leaf size, leaf thickness, seed mass, seed shape) and the strategies adopted by plants in response to disturbances (Jiménez-Alfaro et al., 2015;Mahdavi and Bergmeier, 2016). Plot monitoring to follow changes in specific composition can be used to quantify temporal changes in species composition (Sperandii et al., 2019). Despite being challenging and time consuming, revisitation studies are highly recommended tools for analyzing temporal dynamics in plant communities (Del Vecchio et al., 2019). ...
Research on the habitats protected by the European Union’s Habitats Directive (HD) has increased rapidly since its adoption in 1992. However, the methods and tools used to assess their conservation status are varied. In this context, we reviewed and summarized the scientific literature related to the coastal Natura 2000 habitats to list and sort parameters used to assess and map their conservation status. We found 225 papers that specifically focused on the assessment of conservation status of coastal habitats. An analysis of the papers was conducted based on the four parameters (range, area, structure and functions, future prospects) specified in the guidelines. Results highlight knowledge gaps regarding the availability of data and methods that measure the range, area, structure and functions and trends. Most of the papers focused on coastal dunes and were located in the Mediterranean biogeographic region. Therefore, the process of assessing the conservation status of coastal habitats remains complicated to implement because methodological approaches are mainly dominated by expert statements and all the procedures of the Habitats Directive are carried out within each member country and the final assessments are often the synthesis of these partial assessments. However, the multiscalar approach and the use of innovative technologies (databases, remote sensing) can be particularly relevant to develop replicable approaches and facilitate monitoring and the implementation of management measures.
... Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License demand for coastal areas for leisure purposes (Langa, 2007;Teixeira et al., 2016) exert great pressure on the dunes, stripping them of vegetation (Langa, 2007;Sperandii et al., 2019) and causing the aggravation of coastal erosion processes (Maueua et al., 2007;Bar et al., 2016). ...
... Moreover, R/E curves show that B1.1 communities tend to be less even when occurring in coastal sectors undergoing strong erosion. However, it should be noticed that, as pioneer communities of the upper beach are characterized by a restricted pool of species discriminated by a relatively low cover (Prisco et al., 2012;Sperandii et al., 2019b), even a minimum loss in their species assemblage can cause a significant reduction in their diversity, evenness and cover. Nevertheless, the loss of species characterizing drift line communities (B1.1) is able to trigger the weakening of the ecomorphodynamic processes that are the basis of dune building and formation. ...
Coastal erosion, in combination with sea-level rise and extreme meteorological events, is globally threatening the biodiversity and functioning of dune ecosystems, along with the essential ecosystem services they provide. In this study, by quantifying the intensity of erosion and accretion processes occurred over two decades in a wide Mediterranean dune system, we explore the influence of sand processes on dune plant communities focusing on a large portion of the sea-inland gradient. In particular, using different regression techniques, we assess how erosion and accretion processes affect richness, cover and diversity of Mediterranean coastal dune plant communities. Results show that the influence of coastal erosion and accretion varies along the sea-inland gradient, with foreseeable consequences on the integrity of dune systems. The negative effect of erosion seems to be particularly marked on foredunes, which play a key role in dune formation, while decreasing in landward communities. On the other hand, accretion features an opposite trend, unexpectedly influencing only Mediterranean shrubs. We highlight the importance of monitoring the effects of erosion and accretion processes on coastal vegetation in order to support the conservation of dune habitats and preserve the associated ecosystem services, especially in the context of climate and human-induced changes.
... In spite of their high biodiversity value and complex ecosystem functioning, coastal dunes are among the most threatened ecosystems worldwide [33,34]. In the Mediterranean areas, the loss and degradation of coastal dune ecosystems have been particularly severe in the last few decades [34][35][36], with the main threats being urban expansion [10,37,38], coastal erosion [39] and invasion by alien species [40][41][42][43]. In order to prevent these and other endangered habitats from further degradation, all European Member States adopted the Council Directive 92/43/EEC (hereafter Habitats Directive, HD). ...
Coastal areas harbor the most threatened ecosystems on Earth, and cost-effective ways to monitor and protect them are urgently needed, but they represent a challenge for habitat mapping and multi-temporal observations. The availability of open access, remotely sensed data with increasing spatial and spectral resolution is promising in this context. Thus, in a sector of the Mediterranean coast (Lazio region, Italy), we tested the strength of a phenology-based vegetation mapping approach and statistically compared results with previous studies, making use of open source products across all the processing chain. We identified five accurate land cover classes in three hierarchical levels, with good values of agreement with previous studies for the first and the second hierarchical level. The implemented procedure resulted as being effective for mapping a highly fragmented coastal dune system. This is encouraging to take advantage of the earth observation through remote sensing technology in an open source perspective, even at the fine scale of highly fragmented sand dunes landscapes.
... However, in the last decades, anthropogenic modifications of the landscape , together with a steep growth of the tourism industry and all connected activities (Mir-Gual et al., 2015), severely damaged these fragile ecosystems. For this reason, coastal dunes currently appear among the most threatened ecosystems worldwide (Hesp and Martínez, 2007;Schlacher et al., 2007;Janssen et al., 2016), and largely require conservation efforts (Sperandii et al., 2019). ...
In light of the global biodiversity loss, syntheses of the available knowledge about drivers of biodiversity are becoming increasingly important. However, despite the high number of studies analyzing patterns of plant species diversity, few attempts have been made to synthesize findings within different ecosystems. In this work, the relative role of a wide set of predictors imputable to three conceptual-methodological domains (abiotic, human-mediated disturbance and landscape domain, hereafter AD, DD and LD) was simultaneously analyzed in 644 random plots distributed along the coastal dunes of Central Italy. Native species richness and focal species cover, both field-recorded, were used as response variables. Predictors pertaining to the three domains were derived from both field surveys and high-resolution remotely sensed imagery (LiDAR and orthophotos).To test how AD, DD and LD affect native species richness and focal species cover, a GLM and a linear model were fitted respectively. The three domains were then ranked according to their relative importance.
Although the role of the three domains was always significant, they turned out to unequally contribute to the explanation of native species richness and focal species cover patterns. For Mediterranean coastal dune ecosystems, AD appears to be the key biodiversity driver, followed by DD and LD. Our results suggest that as long as human disturbance is limited, plant diversity will distribute according to species abiotic tolerances, regardless of habitat loss and fragmentation per se. Representing a first effort towards a synthesis of plant diversity drivers in coastal dunes, this work points to the importance, in Mediterranean coastal dune ecosystems, of zonation dynamics, whose occurrence should be addressed as a priority issue by efficient conservations strategies.
Evidence of the effects of alien plant colonisation on plant communities is often hindered by the fact that similar patterns in community composition can arise through a variety of processes. The objective of this study is to determine whether changes in species composition in coastal dune communities depend on the colonisation of a neophyte plant, Oenothera stucchii, or on concurrent processes that favour its colonisation. We hypothesised two scenarios: 1) a direct impact of O. stucchii on colonised communities, leading to displacement of native species; or 2) no direct impact of O. stucchii, i.e., the species colonises plant communities by exploiting disturbances that lead to the rearrangement of plant communities. We used the species-habitat network approach to identify potential drivers of changes in species composition, assuming that changes in the structure of the species-habitat network depend on the nature of the driving process. We demonstrated that changes in species composition in plant communities were due to species rearrangement, with colonised communities characterised by more homogeneous composition of species. We suggest that changes in plant communities may not depend on colonisation by O. stucchii per se, but on concomitant processes that affect coastal dune communities while promoting colonisation by O. stucchii.
This study explores use the of remotely sensed satellite data for monitoring environmental impact of MSW open dumps on their surroundings using bio-thermal indicators. The study has made use of 66 images of Lansat-8 from January 2014 to December 2017, to monitor main MSW dump of Gujranwala, Pakistan. On average thermally influence zone of the dump has been found extended to 480 m around it. Whereas the seasonal average radius of the influence in the zone is measured as 375 m, 425 m, 450 m, 527 m, 590 m and 600 m for spring, monsoon, wet summer, winter-II, winter-I and dry summer respectively. Extreme temperatures and dry weather conditions increase the range of the zone. The range of the bio-influence zone around the dump has been measured using satellite driven VIs of MSAVI, SAVI and NDVI that averages to 590 m. The seasonal averages measured by averaging results from all three VIs are 326 m, 410 m, 430 m, 620 m, 692 m and 1100 m for spring, monsoon, winter-II, wet summer, winter-I and dry summer respectively. In addition, max-min gap of the measurements has been used to assess operational stability of individual parameters and seasons for the used spatial analysis. Development of bio-thermally influence zone with time and a comparison with previous studies a positive correlation between measured range of bio-thermal influence zone and amount of MSW dumped at sites has been verified.
Aims
Although many phytosociological studies have provided detailed local and regional descriptions of coastal dune vegetation, a unified classification of this vegetation in Europe and the Mediterranean Basin has been missing. Our aim is to produce a formalized classification of this vegetation and to identify the main factors driving its plant species composition at a continental scale.
Location
Atlantic and Baltic coasts of Europe, Mediterranean Basin and the Black Sea region.
Methods
We compiled a database of 30 759 plots of coastal vegetation, which were resampled to reduce unbalanced sampling effort, obtaining a dataset of 11 769 plots. We classified these plots by TWINSPAN, interpreted the resulting clusters and used them for developing formal definitions of phytosociological alliances of coastal dune vegetation, which were included in an expert system for automatic vegetation classification. We related the alliances to climatic factors and described their biogeographical features and their position in the coastal vegetation zonation. We examined and visualized the floristic relationships among these alliances by means of DCA ordination.
Results
We defined 18 alliances of coastal dune vegetation, including the newly described Centaureo cuneifoliae‐Verbascion pinnatifidi from the Aegean region. The main factors underlying the differentiation of these alliances were biogeographical and macroclimatic contrasts between the Atlantic‐Baltic, Mediterranean and Black Sea regions, along with ecological differences between shifting and stable dunes. The main difference in species composition was between the Atlantic‐Baltic and Mediterranean‐Black Sea regions. Within the former region, the main difference was driven by the different ecological conditions between shifting and stable dunes, whereas within the latter, the main difference was biogeographical between the Mediterranean and the Black Sea.
Main conclusions
The first formal classification of the European coastal dune vegetation was established, accompanied by an expert system containing the formal definitions of alliances, which can be applied to new datasets. The new classification system critically revised the previous concepts and integrated them into a consistent framework which reflects the main gradients in species composition driven by biogeographical influences, macroclimate and the position of the sites in the coast‐inland zonation of the dune systems. A revision of the class concept used in EuroVegChecklist is also proposed.
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Multi-year temporal studies are invaluable tools for monitoring changes in biodiversity through time. However, their applications in coastal ecosystems are still scarce. We investigated temporal trends in coastal dunes analyzing a set of 858 randomly-sampled georeferenced relevés performed between 2002 and 2015 along Central Italy’s sandy coastlines. Specifically, we explored changes in species richness and cover of targeted sandy habitats, we investigated trends in the cover of selected psammophilous native species and we assessed patterns of invasion by means of regression techniques. We observed a significant decrease in species richness and cover of the dune grasslands habitat. The species-level analysis confirmed a negative trend for two characteristic species of dune grasslands, Cutandia maritima and Medicago littoralis, while revealing a similar decline for Crucianella maritima and for Ammophila arenaria subsp. australis, key species of mobile dunes. The most striking trends emerged analyzing patterns in the cover of an invasive alien species, Carpobrotus sp., which showed a concerning increase in shifting dunes. In conclusion, our analyses reveal concerning changes involving dune grasslands, and at the same time hint at “early warnings” of degradation processes traceable in shifting dunes.
We introduce RanVegDunes (GIVD ID EU-IT-020), the first Italian database gathering standardized, randomly- sampled vegetation data in coastal dune environments. RanVegDunes currently consists of 979 original georeferenced relevés randomly collected over about 160 km of Holocenic dune systems of central Italy between 2002 and 2015. Plots were located in five Italian administrative regions (Lazio, Campania, Abruzzo, Molise and Puglia), where sandy vegetation was randomly recorded in standardized 4-m² plots across the whole coastal zonation, thus including upper beach, embryo dunes, shifting dunes, dune grasslands, wooded dunes and Mediterranean forests. Each plot was georeferenced with a high level of accuracy using a GPS unit. For each plot, a list of vascular plant species based on updated nomenclature was compiled, and an estimate of abundance was calculated for each species using a percentage cover scale ranging from 1 to 10 (1 = 1-10%; 2 = 10-20%; ...; 10 = 90-100%). Two habitat classification systems were used for the description of collected plots: specifically, each vegetation plot was classified according to the Interpretation Manual of the 92/43/EEC Habitats Directive and also to the hierarchical structure of the EUNIS habitat classification. Currently, RanVegDunes includes vegetation plots belonging to nine EU Habitats (1210, 2110, 2120, 2210, 2230, 2250, 2260, 2270, 9340), which in turn correspond to five EUNIS Habitats (B1.1, B1.3, B1.4, B1.6, B1.7). RanVegDunes is a powerful tool for a variety of studies addressing topics such as temporal trends in coastal vegetation, ecological modeling, re-visitation studies, spatio-temporal patterns of invasion and will therefore greatly benefit from further collection of data.
The European Red List of Habitats provides an overview of the risk of collapse (degree of endangerment) of marine, terrestrial and freshwater habitats in the European Union (EU28) and adjacent regions (EU28+), based on a consistent set of criteria and categories and detailed data and expertise from involved countries (http://ec.europa.eu/environment/nature/knowledge/redlist_en.htm). Amongst terrestrial and freshwater habitats the highest percentage of threatened types (categories Critically Endangered, Endangered, Vulnerable) was found amongst mires and bogs (85% in the EU28, 54% in the EU28+), followed by grasslands (53%, 49%), freshwater habitats (46%, 38%) and coastal habitats (45%, 43%). Relatively low percentages of heathland and scrub, forests, and sparsely vegetated habitats were assessed to be threatened. Overall the amount of threatened habitats was higher in the EU28 (36%) than in the wider range of the EU28+ (31%). The European Red List of Habitats provides extensive additional information on habitat classification and definition, pressures and threats, conservation and restorability of habitats, distribution, status and trends in individual countries, and sub-habitats that may possibly be threatened. The information provided can inform and support European nature and biodiversity policy in a variety of ways, particularly in relation to the EU2020 Biodiversity Strategy targets. Further applications include the revitalisation of the EUNIS habitat classification, synergies with the Mapping and Assessment of Ecosystems and their Services initiative, and the improvement of Red List methodologies.
More and more ecologists have started to resurvey communities sampled in earlier decades to determine long-term shifts in community composition and infer the likely drivers of the ecological changes observed. However, to assess the relative importance of and interactions among multiple drivers, joint analyses of resurvey data from many regions spanning large environmental gradients are needed. In this article, we illustrate how combining resurvey data from multiple regions can increase the likelihood of driver orthogonality within the design and show that repeatedly surveying across multiple regions provides higher representativeness and comprehensiveness, allowing us to answer more completely a broader range of questions. We provide general guidelines to aid the implementation of multiregion resurvey databases. In so doing, we aim to encourage resurvey database development across other community types and biomes to advance global environmental change research.
Background:
Resurveying historical vegetation plots has become more and more popular in recent years as it provides a unique opportunity to estimate vegetation and environmental changes over the past decades. Most historical plots, however, are not permanently marked and uncertainty in plot location, in addition to observer bias and seasonal bias, may add significant error to temporal change. These errors may have major implications for the reliability of studies on long-term environmental change and deserve closer attention of vegetation ecologists.
Material & methods:
Vegetation data obtained from the resurveying of non-permanently marked plots are assessed for their potential to study environmental-change effects on plant communities and the challenges the use of such data have to meet. We describe the properties of vegetation resurveys distinguishing basic types of plots according to relocation error, and we highlight the potential of such data types for studying vegetation dynamics and their drivers. Finally, we summarise the challenges and limitations of resurveying non-permanently marked vegetation plots for different purposes in environmental change research.
Results and conclusions:
Resampling error is caused by three main independent sources of error: error caused by plot relocation, observer bias, and seasonality bias. For relocation error, vegetation plots can be divided into permanent and non-permanent plots, while the latter are further divided into quasi-permanent (with approximate relocation) and non-traceable (with random relocation within a sampled area) plots. To reduce the inherent sources of error in resurvey data, the following precautions should be followed: (i) resurvey historical vegetation plots whose approximate plot location within a study area is known; (ii) consider all information available from historical studies in order to keep plot relocation errors low; (iii) resurvey at times of the year when vegetation development is comparable to the historical survey to control for seasonal variability in vegetation; (iv) keep a high level of experience of the observers to keep observer bias low; and (v) edit and standardise datasets before analyses.
The monitoring of biodiversity has mainly focused on the species level. However, researchers and land managers are making
increasing use of complementary assessment tools that address higher levels of biological organisation, i.e. communities,
habitats and ecosystems. Recently, a variety of frameworks have been proposed for assessing the conservation status of communities
or ecosystems. Among the various criteria proposed, all the protocols suggest considering (a) spatial aspects (range and area),
and (b) qualitative aspects of specific structures and functions. However, changes to ecological function are difficult to
quantify and many protocols end up by using qualitative criteria. The aim of this work was to test the efficacy of some plant
community attributes for the detection of vegetation quality in sand dune plant communities. We chose plant community attributes
that either help to distinguish a habitat from others (diagnostic components) or play a significant role in habitat function
and persistence over time. We used a diachronic approach by contrasting up-to-date vegetation data with data from previous
studies carried out within the same areas. Changes in species composition were detected through detrended correspondence analyses
(DCA), Multi-Response Permutation Procedures (MRPP) and Indicator Species Analysis, while structural changes were analysed
by comparing species richness, total species cover, ecological groups of species and growth forms through null models. Ecological
groups such as native focal species and aliens, and growth forms proved their efficacy in discriminating between habitat types
and in describing their changes over time. The approach used in the current study may provide an instrument for the assessment
of plant community quality that can be applied to other coastal ecosystems.
Our beautiful blue Planet-Earth nurture several kinds of ecosystem. study of ecology will be useful for conservation and management. Sand dune is less studied when compared to coral, mangrove, lagoon and estuary. Survey of sand dunes in Cuddalore Tamil Nadu, revealed that, a total of 14 dunes were found in this area. large dunes with 150 meters length and 5 meters height were found. Few dunes in this area are with small temples and houses near Pudukuppam and Samiyarpettai coastal villages. Recent industrialisation in this area destroyed few dunes which needs special attention for conservation of this natural ecosystem. Flora and Fauna and the types of dunes were discussed in this book. Restoration of dune plants, dissemmination of the importance of the sand dunes to the public were also made. Therefore, this book will be useful for the students, teachers and naturalists as well as the Coastal Regulation Zone Authority.
Sandy beaches surrounding the Molise coast, facing to the Adriatic sea, are relatively well preserved if compared with other Italian littorals. In this study we present the results from a short term monitoring analyses of coastal habitats (six/eight-years) using permanent transects as part of the LTER network (Long Term Ecological Research-Italy). Vegetation monitoring was carried out along 4 belt transects along the beach-inland ecological gradient, following the coastal zonation and ranging from pioneer annual communities on the beach to Mediterranean scrubs on fixed dunes. Plant communities were sampled in contiguous 1 m x 1 m plots using a 1-10 ordinal transform scale to estimates the species' cover-abundance. All transects were conducted in sites subjected to a similar touristic pressure. Through cluster analysis we identified 5 Habitats of community interest: Annual vegetation of drift lines (Habitat 1210), Embryonic shifting dunes (Habitat 2110), Shifting dunes along the shoreline with Ammophila arenaria (Habitat 2120), Malcolmietalia dune grasslands (Habitat 2230) and Coastal dunes with Juniperus spp. (Habitat 2250). Main temporal changes were probably related to different erosion/accretion processes acting in each transect: two transects were relatively stable (without evident coastal erosion nor accretion processes), one suffered a strong retreat while the last transect showed a slight accretion process. Moreover, our study evidences that, as coastal plant communities are highly dynamic systems, even relatively short time periods could offer useful insights of annual vegetation trends.
Disturbed and natural sites are compared in a belt of rehabilitated coastal dune on the Tyrrhenian coast of Italy. The goal was to evaluate rehabilitation success by comparing structure and plant composition in three different vegetation types. Vegetational attributes were used to indicate the trajectory of the vegetation dynamic, by recording increases or decreases in these parameters. The variations in attributes and similarities in composition were investigated using multivariate methods. In general, significant changes between the disturbed and natural sites were indicated by a decrease in annual graminoids, trees, and wind-dispersal species and an increase in rare species. In the rehabilitated site, there was a high rate of recruitment of wind-dispersal species, and rehabilitation seems to have been successful from the point of view of the decrease in annual graminoids and increase in rare species. However, each vegetation type of dune environment was associated with a different number of attributes and different rehabilitation success. Specifically: (i) open sands with annual vegetation growing along drift lines were the most similar among the three sites, from the point of view of both structure and species composition, and are therefore the easiest to rehabilitate; (ii) dunes partially or densely vegetated by herbaceous species showed an increase in rare species in the natural site and were characterized by successful rehabilitation; (iii) dunes densely vegetated by shrubs differed significantly between sites and are consequently the most difficult to rehabilitate. Our comparisons suggest that initial planning efforts should focus on this last type of vegetation cover.
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 aim of the present work was to assess the conservation status of coastal dune systems in Tuscany (Italy). Emphasis was given to the presence and abundance of plant communities identified as habitat in accordance with the Directive 92/43/EEC. Twenty transects perpendicular to the shoreline were randomly positioned on the whole coastal area (30 km in length) in order to sample the full spectrum of plant communities. Vegetation zonation and relationships with the most frequent disturbance factors in the study area-beach cleaning, coastline erosion, presence of paths and roads, bathing settlements and trampling-were investigated through principal coordinate analysis and canonical correspondence analysis. Natural factors, such as distance from the sea and total length, were also considered. Differences in the conservation status of the sites were found, ranging from the total disappearance of the foredune habitats to the presence of the complete psammophilous (sand-loving) plant communities. Erosion, trampling, and paths were found to be closely correlated with degradation and habitat loss. Furthermore, the overall plant species diversity of dunes was measured with NHDune, a modified version of the Shannon index; while the incidence of invasive taxa was calculated using N, a naturalness index. However, these diversity indices proved to be a weaker bioindicator of ecosystem integrity than habitat composition along transects. A possible strategy for the conservation and management of these coastal areas could be to protect the foredunes from erosion and limit trampling through the installation of footbridges or the use of appropriate fences.
Coastal dunes constitute complex interface ecosystems between the land and sea, providing important ecological and socio-economic services like coastal protection, recreation, regulation, food supply and biodiversity. They are characterized by high ecological diversity and also by extremely specialized and endemic species. Coastal areas, because of their position between land and sea, are attractive for many human activities. Unfortunately coastal systems have had a long history of exploitation and mismanagement.
Coastal dune ecosystems show strongly dynamic interactions between abiotic and biotic factors. The relationship between plant communities and environmental factors has been previously studied in oceanic dune systems, but few studies have been conducted along Mediterranean coasts. In this study we analyze the relative contribution of environmental factors associated with two of the main drivers of vegetation zonation: soil and wind. We chose two representative coastal dune systems in the western Mediterranean Basin subject to low levels of human disturbance.
Within 54 plots we recorded floristic and environmental data. Vegetation zonation and relationships with environmental variables were investigated through unconstrained and constrained ordinations, correlation, and variance partitioning.
Environmental factors shift along the gradient from coastal to inland dunes, concomitantly with the pattern of community types from annual beach communities to
shrub-covered fixed dunes. This general gradient is similar both in the Mediterranean and in the oceanic coastal ecosystems, with the same factors that show similar trends along the dune profile. However, our results highlight some peculiarities of the Mediterranean dune systems in relation to the amount of variation explained by environmental factors. While most studies conducted in oceanic ecosystems find that
wind-related parameters may control the vegetation zonation, in our study areas we observed a minor importance of the wind-related variables when compared to soil properties. In particular, organic matter and grain-size variability were found to be closely correlated with the distribution of plant communities along the gradient.
Amongst the various functions of European coastal ecosystems the information functions are by far the most important. Information is provided mainly through the various aspects of biodiversity: taxon diversity, genetic diversity, community (β) diversity, phylogentic distinctiveness, rarity and endemism. Coastal ecosystems are relatively rich in coastal ecotypes of species with a broader amplitude and in endemic species. Phylogenetically distinctive taxa occur in saline waters, and some on beaches and in foredunes. These particular features of coastal ecosystems are related to the long geological history of European, especially eastern Mediterranean, coasts. Information functions are threatened through the use of European coastal ecosystems for other purposes, notably urbanization and recreational development.
This study describes the vegetation zonation of the coastal sandy landscapes of the Lazio region (Central Italy) and analyses the effects of disturbance (in the main human, but also natural) on this vegetation. A comparison is made between real and potential coastal vegetation using a hierarchical landscape classification approach, which identifies land units on the basis of a combination of climatic, lithological, geomorphological and hydrogeological factors, integrated with phytosociological data. Information about the coastal phytocoenoses was obtained both from previous studies and from original phytosociological data (241 releves). Observation of real vegetation showed that coastal zonation is relatively well-preserved at only a few sites along the Lazio coast. At these sites real vegetation distribution is very similar to the potential zonation. However, widespread disturbance means that real vegetation is drastically different from the hypothetical phyto-topo sequence along most of the coast. Where
Coastal sand dune landscapes hold habitats of high economic, social and ecological value on a global scale. At the same time, they are among the most threatened ecosystems worldwide, facing escalating anthropogenic pressures, drawing attention to their resilience as a necessary condition for both biodiversity conservation and sustainable development. This study describes the vegetation zonation of the North-Adriatic coastal landscape which suffers from a severe and complex human utilization meanwhile holding high landscape, faunal and floral values. As plant communities, because of their specific nature, are considered good indicators of overall biodiversity and of ecosystem integrity of coastal dune environments, effects of both human and natural disturbance have been analysed through a comparison between real and potential coastal vegetation, using a hierarchical landscape classification approach. To provide a comprehensive framework for sustainable coastal management and development, a multiscale method for the assessment of the conservation status of sandy coastal environment has been applied. The assessing methodology focused first on landscape level by means of structural and compositional indicators. At a more detailed scale, floristic, vegetational and structural aspects of plant communities were analyzed along the main environmental gradient, which develops moving inland from the sea edge. Conservation status of N-Adriatic coastal zonation resulted fairly good at only few sites along the coast, mostly located where urban development and tourism are limited by legislation or simply because of the difficulty in reaching them. Elsewhere, real vegetation is deeply different from the potential zonation: erosion and tourism pressures truncate the first elements of the zonation, while towns and villages, coastal roads, pines plantations and agriculture truncate the last stages and sandy systems are trapped between erosion on the sea side and human settlements inlands, with no space for natural sediment dynamics and communities development.
This account reviews information on all aspects of the biology of Cakile maritima that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles : distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation.
Cakile maritima (sea rocket) is a succulent, annual species that is confined to maritime strandlines on sand or shingle, and associated foredunes. British material is ssp. integrifolia (= ssp. maritima ), found around the Atlantic and Mediterranean coasts of Europe. Cakile maritima shows considerable variation, within and between subspecies, especially in fruit morphology and leaf shape. A very closely related species, Cakile edentula , is native to the east coast of North America. Both species have been introduced to Pacific North America and Australia.
Populations of C. maritima tend be ephemeral and shifting, depending on dispersal by tides and wind. The fruits are 2‐segmented: the distal segments are readily detached and can float considerable distances in seawater; the proximal segments tend to shed their seed while attached to the maternal plant. Seeds require cold stratification and do not germinate at high salinity, or usually while retained in intact fruit segments. There is often a flush of germination in strandlines left by early season, equinoctial spring tides. Cakile maritima shows great phenotypic plasticity of form and reproductive output. Work on C. edentula suggests that abundance is regulated by a combination of density‐dependent and density‐independent processes. Landward dispersal of seeds from strandline populations may subsidise foredune populations, which themselves experience severe mortality from predators.
Cakile maritima is tolerant of salt spray and transient seawater inundation. Although beach and dune sand is a meagre source of macronutrients, C. maritima shows large growth responses to nitrogen addition and can exploit local nitrogen enrichment associated with mineralisation of organic detritus washed up on the strandline. Growth is stimulated by burial with blown sand and plants sometimes form the nuclei of early successional foredunes. The tissues are rich in glucosinolates; these may be responsible for the limited ranges of herbivores and fungal pathogens, and the absence of mycorrhiza.
We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recog-nition of a physical–biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not been widely implemented in sandy beaches, could be a key tool for biodiversity conservation and should also facilitate spillover effects into adjacent beach habitats. Setback and zoning strategies need to be enforced through legislation, and all relevant stakeholders should be included in the design, implementation and institutionalisation of these initiatives. New perspectives for rational management of sandy beaches require paradigm shifts, by including not only basic ecosystem principles, but also incentives for effective governance and sharing of management roles between government and local stakeholders.
In European phytosociology, variable plot sizes are traditionally used for sampling different vegetation types. This practice may generate problems in current vegetation or habitat survey projects based on large data sets, which include relevés made by many authors at different times. In order to determine the extent of variation in plot sizes used in European phytosociology, we collected a data set of 41 174 relevés with an indication of plot size, published in six major European journals focusing on phytosociology from 1970 to 2000. As an additional data set, we took 27 365 relevés from the Czech National Phytosociological Database. From each data set, we calculated basic statistical figures for plot sizes used to sample vegetation of various phytosociological classes.
The results show that in Europe the traditionally used size of vegetation plots is roughly proportional to vegetation height; however, there is a large variation in plot size, both within and among vegetation classes. The effect of variable plot sizes on vegetation analysis and classification is not sufficiently known, but use of standardized plot sizes would be desirable in future projects of vegetation or habitat survey. Based on our analysis, we suggest four plot sizes as possible standards. They are 4 m ² for sampling aquatic vegetation and low‐grown herbaceous vegetation, 16 m ² for most grassland, heathland and other herbaceous or low‐scrub vegetation types, 50 m ² for scrub, and 200 m ² for woodlands. It has been pointed out that in some situations, sampling in either small or large plots may result in assignment of relevés to different phytosociological classes or habitat types. Therefore defining vegetation and habitat types as scale‐dependent concepts is needed.
Many authors apply statistical tests to sets of relevés obtained using non-random methods to investigate phytosociological
and ecological relationships. Frequently applied tests include thet-test, ANOVA, Mann-Whitney test, Kruskal-Wallis test, chi-square test (of independence, goodness-of-fit, and homogeneity),
Kolmogorov-Smirnov test, concentration analysis, tests of linear correlation and Spearman rank correlation coefficient, computer
intensive methods (such as randomization and re-sampling) and others. I examined the extent of reliability of the results
of such tests applied to non-random data by examining the tests requirements according to statistical theory. I conclude that
when used for such data, the statistical tests do not provide reliable support for the inferences made because non-randomness
of samples violated the demand for observations to be independent, and different parts of the investigated communities did
not have equal chance to be represented in the sample. Additional requirements, e.g. of normality and homoscedasticity, were
also neglected in several cases. The importance of data satisfying the basic requirements set by statistical tests is stressed.
Coastal dunes are eolian landforms that develop in coastal situations where an ample supply of loose, sand-sized sediment
is available to be transported inland by the ambient winds. They are part of unique ecosystems which are at the spatial transition
between continental/terrestrial and marine/aqueous environments. Coastal dunes are part of the sand-sharing system composed
of the highly mobile beach and the more stable dune. A large variety of coastal dune forms are found inland of and above the
storm-water level of sandy beaches and occur on ocean, lake, and estuary shorelines. They are distributed worldwide in association
with sandy beaches, producing a wide range of coastal dune forms and dimensions related to spatial and temporal variations
in sediment input and wind regime
The following paper describes patterns of diversity across major habitat types in a relatively well preserved coastal dune
system in central Italy. The research addresses the following questions: (a) whether different habitats defined on the base
of a land cover map support similar levels of biodiversity in terms of vascular flora richness and number of rare and endangered
species, and (b) how each habitat contributes to the total species diversity of the coastal environment. A random stratified
sampling approach based on a detailed land cover map was applied to construct rarefaction curves for each habitat type and
to estimate total species richness. In addition, the number of exclusive, rare and endangered species was calculated for each
habitat type. Results highlight the importance of the coastal dune zonation (embryo-dune, main dune, transition and stabilized
dune) in species conservation because they harbour progressively higher species richness. However, differences among these
habitats were not significant, so no particular species rich “hotspots” could be evidenced. On the contrary, rarefaction curves
show that the upper beach (strand) habitat sustains significantly smaller number of species, but surprisingly, it shows the
highest rarity values and highest proportion of endangered species. Therefore, for the establishment of successful biodiversity
conservation programs in these coastal environments, it is imperative not only to conserve biologically rich hotspots but
also to include species poor habitats containing endangered or unique elements. Thus, the complete coastal vegetation mosaic
including all coastal habitats is important to adequately characterize the plant species diversity of coastal dune ecosystems.
Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1–2 years) and effective method for improving and safeguarding the diversity of dune plant communities.
This paper presents a survey of vegetation studies on permanent plots, with an emphasis on the long-term character of these studies. It makes remarks on the external and internal causes of succession, pays attention to the pathways of succession, links up permanent plots studies and chronosequences, discusses internal causes and mechanisms of succession, and finally mentions the significance of long-term vegetation dynamics for nature conservation.
Many recent developments in coastal science have gone against the demands of European Union legislation. Coastal dune systems which cover small areas of the earth can host a high level of biodiversity. However, human pressure on coastal zones around the world has increased dramatically in the last 50 years. In addition to direct habitat loss, the rapid extinction of many species that are unique to these systems can be attributed to landscape deterioration through the lack of appropriate management. In this paper, we propose to use of an ecosystem classification technique that integrates potential natural vegetation distribution as a reference framework for coastal dune EU Habitats (92/43) distribution analysis and assessment. As an example, the present study analyses the EU Habitats distribution within a hierarchical ecosystem classification of the coastal dune systems of central Italy. In total, 24 land elements belonging to 8 land units, 5 land facets, 2 land systems and 2 land regions were identified for the coastal dunes of central Italy, based on diagnostic land attributes. In central Italy, coastal dune environments including all the beach area, mobile dunes and all the fixed-dune land elements contain or could potentially hold at least one EU habitat of interest. Almost all dune slack transitions present the potentiality for the spontaneous development of EU woodlands of interest. The precise information concerning these ecosystems distribution and ecological relationships that this method produces, makes it very effective in Natura 2000 European network assessment. This hierarchical ecosystem classification method facilitates the identification of areas to be surveyed and eventually bound, under the implementation of EU Habitat directive (92/43) including areas with highly disturbed coastal dune ecosystems.
Understanding the response of plant species to soil factors on coastal sand dunes is critical for effective conservation of coastal habitats in the Mediterranean basin. Our main objectives were to investigate: i) the main soil factors driving species composition in a Mediterranean coastal dune environment; ii) the ecological requirements of focal plant species with respect to single soil factors; iii) whether the focal species of a given macrohabitat (including EU habitats) have similar edaphic needs. We identified 108 plots with three macrohabitats as strata (embryo dunes; mobile dunes; fixed dunes) by random stratified sampling design along the Tyrrhenian coast of central Italy in areas with a high degree of biodiversity and naturalness. Vegetation and soil data were collected in the plots.
Questions
Terrestrial vegetation is assumed to be highly vulnerable to climate change in the Arctic, which has experienced the highest rates of temperature increase globally over the past decades. However, long‐term studies at the community scale are rare, particularly for the European High Arctic. We ask: (1) has Arctic vegetation changed over the past century; (2) can observed changes be related to recent climate change; and (3) do observed changes in vegetation prevail for specific species or species functional groups?
Location
The Svalbard Archipelago, High Arctic Norway.
Methods
In 2009 we resurveyed three plant sociological studies up to 85 yrs after the first surveys. Vegetation data were recorded from 1‐m ² non‐permanently marked plots, and soil pH was measured. We applied restricted permutation tests to evaluate whether observed changes in vegetation (species richness, occurrence frequency, coverage) and in soil pH were significant and independent of plant community type. We compared species co‐occurrences over time to study changes in species composition and to identify the species most likely causing these changes.
Results
Total number of species and average number of species per plot has not changed, and are 75 and nine, respectively. Occurrence frequency changed significantly for 34% of the 64 species tested (11 species increased, 11 decreased). Species cover decreased significantly for 27% of the species and increased for one species. Observed changes in frequency and cover are not significantly related to species’ functional groups or species affiliated to moist or dry habitats. Polygonum viviparum , Saxifraga cernua and Alopecurus borealis have changed most in co‐occurring with other species. Soil pH increased significantly from 6.4 to 6.8.
Conclusions
Our results suggest that the strong climatic warming in the High Arctic over the past decades has contributed to significant changes in the vegetation studied on Svalbard over the past 85 yrs. Internal community restructuring and the overall stability in species richness may be explained by time‐delayed responses of well‐established communities, and/or by a limited size of the species pool in the area.
Detailed monitoring studies on permanent sites are a promising tool for an accurate evaluation of short, medium or long term vegetation dynamics. This work aims to evaluate short-term changes in coastal dune herbaceous plant species and EU Habitats through a multi-temporal analysis using permanent vegetation transects. In particular, (I) we analyze changes in species richness of coastal habitats; (II) we identify changes in plant cover of selected focal plants; and (III) we relate the changes to selected climatic variables and erosion/accretion processes. We selected one of the Italian's peninsula best preserved coastal dune areas (ca. 50 km along the Adriatic sea) with a relatively homogeneous coastal zonation and low anthropic pressure but with different erosion/accretion processes. We explored changes in richness over time using generalized linear models (GLMs). We identified different ecological guilds: focal, ruderal and alien plant species and investigated temporal trends in these guilds' species richness. We also applied GLMs to determine how plant cover of the most important focal species have changed over time.
Coastal habitats are particularly vulnerable to recreational impacts because these environments are highly dynamic and continually change in response to biotic and abiotic factors. Sand dune communities are worldwide characterized by high levels of biodiversity, but are often affected by human-induced impacts as those caused by tourist trampling. To understand the effects of human frequentation, trampling, and other human-induced impacts, fencing experiments have been traditionally carried out on coastal dunes. Since in touristic areas dune systems are subjected to different intensities of human frequentations rather than to opening or fencing, in this study we explore the effects of accessibility on vascular plants cover. This study tests the hypothesis that human frequentation on beaches affects spatio-temporal variability of vascular plant abundance on dunes by comparing the plant assemblages of high and low accessible sites in North-East Sardinia (Italy). Our results show that accessibility plays a crucial role in conditioning the percentage of vegetation cover in Mediterranean dunes. In fact, not only we found a perennial vegetation cover that was significantly higher in the sites with low accessibility (and consequently low frequentation), but we also showed that at the sites with high accessibility there were significant differences in vegetation cover between times of sampling (cover was higher before than after summer): on the contrary, differences in perennial vegetation cover among times were not significant at the low frequentation sites. After summer, the difference among low and high frequentation sites in species composition and cover was >90%. Multivariate analysis identified those species that play a pivotal role in differentiating the low and the high frequentation sites. Among them, Crucianella maritima and Sporobolus virginicus can be considered as differential species. Overall, our data show vegetation and plant species responses to human-induced impacts, and are therefore important to support conservation actions in Mediterranean coastal areas interested by mass tourism.
Aim
Data from vegetation plots can be used for the assessment of past vegetation change in three ways: (1) comparison of old and new records from permanent plots established for vegetation monitoring; (2) revisiting historical phytosociological plots and subsequent comparison of old and new records; (3) comparison of large sets of old and new phytosociological records from the same area but different plots. Option (3) would be the cheapest in regions where large vegetation‐plot databases are available, but there is a risk of incorrect results due to a spatial mismatch of old and new plots. Here we assess the accuracy of such analyses.
Methods
We used three data sets of permanent plots from C zech mountain bogs and D utch oak forests and heathlands to quantify vegetation change. We selected subsets to simulate analyses based on (1) data from permanent plots or revisited phytosociological plots, i.e. containing old and new records from the same plots, (2) vegetation‐plot databases with old and new records from different, randomly selected sites, and (3) vegetation‐plot databases with old and new records from different but close sites. We repeated each subset selection 1000 times and analysed vegetation change in each of the three data sets and each variant of subset selection using permutational multivariate analysis of variance.
Results
For data sets with no actual vegetation change, analyses of some subsets simulating vegetation‐plot databases incorrectly suggested significant changes. For a data set with real change, a change was detected in analyses of simulated vegetation‐plot databases, but in several cases it had a different direction or magnitude to the real change.
Conclusions
The assessment of vegetation change using vegetation‐plot databases should be either avoided or interpreted with extreme caution because of the risk of incorrect results. Analyses such as these may be used to propose hypotheses about past vegetation change, but their results should not be considered valid unless confirmed using more reliable data. In many contexts, re‐visitation studies of historical phytosociological plots may be the best strategy to assess past vegetation change, while new networks of carefully stratified permanent plots are preferable for monitoring future change.
An ‘ ’ of climate change.
A Wilcoxon one-sample signed rank test may be made when some of the observations are 0 by dropping the 0's before ranking. However, a sample can be not significantly positive while a more negative sample (obtained by decreasing each observation equally), is significantly positive by the ordinary Wilcoxon test. The reverse is also possible. Two-piece confidence regions result. A procedure for avoiding these difficulties is proposed, namely to rank the observations including the 0's, drop the ranks of the 0's, and reject the null hypothesis if the sum of the remaining negative (or positive) ranks falls in the tail of its null distribution (given the number of 0's). If observations are tied in absolute value, their ranks may be averaged before attaching signs. This changes the null distribution. A sample may be significantly positive which is not significant if the observations are increased (unequally), or if the ties are broken in any way.* This research was supported by the United States Navy through the Office of Naval Research, under con tract Number Nonr 1866(37). Reproduction in whole or in part is permitted for any purpose of the United States Government.
1. Beta diversity, that is, the variation in species composition among sites, can be the result of species replacement between sites (turnover) and species loss from site to site (nestedness).
2. We present betapart, an R package for computing total dissimilarity as Sørensen or Jaccard indices, as well as their respective turnover and nestedness components.
3. betapart allows the assessment of spatial patterns of beta diversity using multiple-site dissimilarity measures accounting for compositional heterogeneity across several sites or pairwise measures providing distance matrices accounting for the multivariate structure of dissimilarity.
4. betapart also allows computing patterns of temporal difference in assemblage composition, and its turnover and nestedness components.
5. Several example analyses are shown, using the data included in the package, to illustrate the relevance of separating the turnover and nestedness components of beta diversity to infer different mechanisms behind biodiversity patterns.
Aim Beta diversity can be partitioned into two components: dissimilarity due to species replacement and dissimilarity due to nestedness ( Baselga, 2010 , Global Ecology and Biogeography , 19 , 134–143). Several contributions have challenged this approach or proposed alternative frameworks. Here, I review the concepts and methods used in these recent contributions, with the aim of clarifying: (1) the rationale behind the partitioning of beta diversity into species replacement and nestedness‐resultant dissimilarity, (2) how, based on this rationale, numerators and denominators of indices have to match, and (3) how nestedness and nestedness‐resultant dissimilarity are related but different concepts.
Innovation The rationale behind measures of species replacement (turnover) dictates that the number of species that are replaced between sites (numerator of the index) has to be relativized with respect to the total number of species that could potentially be replaced (denominator). However, a recently proposed partition of Jaccard dissimilarity fails to do this. In consequence, this partition underestimates the contribution of species replacement and overestimates the contribution of richness differences to total dissimilarity. I show how Jaccard dissimilarity can be partitioned into meaningful turnover and nestedness components, and extend these new indices to multiple‐site situations. Finally the concepts of nestedness and nestedness‐resultant dissimilarity are discussed.
Main conclusions Nestedness should be assessed using consistent measures that depend both on paired overlap and matrix filling, e.g. NODF, whereas beta‐diversity patterns should be examined using measures that allow the total dissimilarity to be separated into the components of dissimilarity due to species replacement and dissimilarity due to nestedness. In the case of multiple‐site dissimilarity patterns, averaged pairwise indices should never be used because the mean of the pairwise values is unable to accurately reflect the multiple‐site attributes of dissimilarity.
Given a resource gradient (e.g. light intensity, prey size) in a community, species evolve to use different parts of this gradient; competition between them is thereby reduced. Species relationships in the community may be conceived in terms of a multidimensional coordinate system, the axes of which are the various resource gradients (and other aspects of species relationships to space, time, and one another in the community). This coordinate system defines a hyperspace, and the range of the space that a given species occupies is its niche hypervolume, as an abstract characterization of its intra‐community position, or niche. Species evolve toward difference in niche, and consequently toward difference in location of their hypervolumes in the niche hyperspace. Through evolutionary time additional species can fit into the community in niche hypervolumes different from those of other species, and the niche hyperspace can become increasingly complex. Its complexity relates to the community's richness in species, its alpha diversity.
Species differ in the proportions of the niche hyperspace they are able to occupy and the share of the community's resources they utilize. The share of resources utilized is expressed in species' productivities, and when species are ranked by relative productivity (or some other measurement) from most to least important, importance‐value or dominance‐diversity curves are formed. Three types of curves may represent manners in which resources are divided among species: (a) niche pre‐emption with strong dominance, expressed in a geometric series, (b) random boundaries between niches, expressed in the MacArthur distribution, and (c) determination of relative importance by many factors, so that species form a frequency distribution on a logarithmic base of importance values, a lognormal distribution. The forms of importance‐value curves do not permit strong inference about resource division, but are of interest for their expression of species relationships and bearing on measurement of diversity.
Question: Can vegetation relevé databases be used to analyse species losses and gains in specific vegetation types in Germany over time? Does the type of response (increase or decline in relative frequency) conform to observed large-scale environmental trends in the last decades?
Location: Germany. Exploring the German Vegetation Reference Database Halle (GVRD) that was established for forest and grassland vegetation within the framework of German Biodiversity Exploratories.
Methods: Use of generalized linear models (GLMs) for testing changes in temporal frequency of plant taxa in a semi-dry grassland data set (Mesobromion) and a beech forest data set (Fagion). Data were either aggregated by year, decade or by a balanced re-sampling approach. Interpretation of the observed changes was based on species traits.
Results: In both data sets significant temporal changes were observed, although the frequency of the majority of species remained unchanged. In both data sets, species with a temporal increase in frequency had higher Ellenberg N and F indicator values, compared to species that decreased, thus indicating effects of widespread atmospheric nitrogen deposition. In the forest data set, the observed increase in recruitment of deciduous trees pointed to a change in management, while trends in the grassland data set suggested use abandonment, as seen in an increased frequency of woody species.
Conclusion: We demonstrate that vegetation databases represent very valuable resources for analysis of temporal changes in species frequencies. GLMs proved their value in detecting these trends, as also shown by the interpretability of model results with species traits. In contrast, the method of aggregation or re-sampling had little influence on the general outcome of analyses.
Aim: Vegetation plots collected since the early 20th century and stored in large vegetation databases are an important source of ecological information. These databases are used for analyses of vegetation diversity and estimation of vegetation parameters, however such analyses can be biased due to preferential sampling of the original data. In contrast, modern vegetation survey increasingly uses stratified-random instead of preferential sampling. To explore how these two sampling schemes affect vegetation analyses, we compare parameters of vegetation diversity based on preferentially sampled plots from a large vegetation database with those based on stratified-random sampling.
Location: Moravian Karst and Silesia, Czech Republic.
Methods: We compared two parallel analyses of forest vegetation, one based on preferentially sampled plots taken from a national vegetation database and the other on plots sampled in the field according to a stratified-random design. We repeated this comparison for two different regions in the Czech Republic. We focussed on vegetation properties commonly analysed using data from large vegetation databases, including alpha (within-plot) diversity, cover and participation of different species groups, such as endangered and alien species within plots, total species richness of data sets, beta diversity and ordination patterns.
Results: The preferentially sampled data sets obtained from the database contained more endangered species and had higher beta diversity, whereas estimates of alpha diversity and representation of alien species were not consistently different between preferentially and stratified-randomly sampled data sets. In ordinations, plots from the preferential samples tended to be more common at margins of plot scatters.
Conclusions: Vegetation data stored in large databases are influenced by researcher subjectivity in plot positioning, but we demonstrated that not all of their properties necessarily differ from data sets obtained by stratified-random sampling. This indicates the value of vegetation databases for use in biodiversity studies; however, some analyses based on these databases are clearly biased and their results must be interpreted with caution.
Impacts of long-term climate shifts on the dynamics of intact communities within species ranges are not well understood. Here, we show that warming and drying of the Southwestern United States over the last 25 years has corresponded to a shift in the species composition of Sonoran Desert winter annuals, paradoxically favoring species that germinate and grow best in cold temperatures. Winter rains have been arriving later in the season, during December rather than October, leading to the unexpected result that plants are germinating under colder temperatures, shifting community composition to favor slow growing, water-use efficient, cold-adapted species. Our results demonstrate how detailed ecophysiological knowledge of individual species, combined with long-term demographic data, can reveal complex and sometimes unexpected shifts in community composition in response to climate change. Further, these results highlight the potentially overwhelming impact of changes in phenology on the response of biota to a changing climate.
Sandy beaches line most of the world's oceans and are highly valued by society: more people use sandy beaches than any other type of shore. While the economic and social values of beaches are generally regarded as paramount, sandy shores also have special ecological features and contain a distinctive biodiversity that is generally not recognized. These unique ecosystems are facing escalating anthropogenic pressures, chiefly from rapacious coastal development, direct human uses — mainly associated with recreation — and rising sea levels. Beaches are increasingly becoming trapped in a ‘coastal squeeze’ between burgeoning human populations from the land and the effects of global climate change from the sea. Society's interventions (e.g. shoreline armouring, beach nourishment) to combat changes in beach environments, such as erosion and shoreline retreat, can result in severe ecological impacts and loss of biodiversity at local scales, but are predicted also to have cumulative large-scale consequences worldwide. Because of the scale of this problem, the continued existence of beaches as functional ecosystems is likely to depend on direct conservation efforts. Conservation, in turn, will have to increasingly draw on a consolidated body of ecological theory for these ecosystems. Although this body of theory has yet to be fully developed, we identify here a number of critical research directions that are required to progress coastal management and conservation of sandy beach ecosystems.
A table is presented of the most important species of the fore-dune complex in various parts of the world, representing all continents. The complex is divided into six zones or habitat types, which have proved to be widely applicable for this purpose. The zones are briefly described in terms of floristics, geomorphology, ecology (sand movement, salinity, organic matter) and climate. A major division is indicated between tropical (including subtropical) and temperate (including cold) regions. The former are subdivided into those with humid and those with arid climates, the latter into those with cool to warm-temperate and those with boreal to subarctic climates. The highest, most extensive and most complicated dune areas occur in those regions where the effects of disturbance by wind and fixation by plant growth are about equally strong. A number of species show the retraction phenomenon: a shift from a certain zone towards a more sheltered zone in an area with more harsh conditions (e.g. a shorter vegetation period). The filling of empty niches by introduced species (e.g. in connection with the scarcity of native tidemark species in temperate Australia) is also quite common. Most communities are rich in (sub)cosmopolitan species.
Aim Beta diversity (variation of the species composition of assemblages) may reflect two different phenomena, spatial species turnover and nestedness of assemblages, which result from two antithetic processes, namely species replacement and species loss, respectively. The aim of this paper is to provide a unified framework for the assessment of beta diversity, disentangling the contribution of spatial turnover and nestedness to beta‐diversity patterns.
Innovation I derive an additive partitioning of beta diversity that provides the two separate components of spatial turnover and nestedness underlying the total amount of beta diversity. I propose two families of measures of beta diversity for pairwise and multiple‐site situations. Each family comprises one measure accounting for all aspects of beta diversity, which is additively decomposed into two measures accounting for the pure spatial turnover and nestedness components, respectively. Finally, I provide a case study using European longhorn beetles to exemplify the relevance of disentangling spatial turnover and nestedness patterns.
Main conclusion Assigning the different beta‐diversity patterns to their respective biological phenomena is essential for analysing the causality of the processes underlying biodiversity. Thus, the differentiation of the spatial turnover and nestedness components of beta diversity is crucial for our understanding of central biogeographic, ecological and conservation issues.