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Inventari ecologic i forestal de Catalunya

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... Tree biomass (above-ground + below-ground) of each live tree in each forest inventory plot were computed from DBH using species-specific allometric equations developed by Lambert et al. (2005) for Quebec and by Gracia et al. (2004) and Montero et al. (2005) for Spain. We then applied the widely established relationship of 1:0.5 between tree biomass and carbon (McGroddy et al., 2004). ...
... The data consisted of a systematic sampling of permanent plots with a sampling density of one plot in every 1 km 2 of forest area, where woody species were identified and measured within variable circular size. Tree biomass (aboveground + belowground) of each live tree in each forest inventory plot was computed from DBH using species-specific allometric equations developed by Gracia et al. (2004) and Montero et al. (2005). ...
... Aboveground and belowground biomass of trees was derived for each species from allometric equations from Gracia et al. (2004). ...
Thesis
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Forest ecosystems provide a wide variety of benefits for human well-being, commonly referred to as ecosystem services (ES). Understanding how these ES are distributed across the landscape and identifying their main drivers is essential to inform policy to protect, enhance and restore these ecosystems. Besides, protected areas (PAs) are fundamental for biodiversity conservation and the provision of ES, yet their effectiveness in maintaining ES and biodiversity is still unclear. Currently, forests are increasingly under pressure from climate change, resulting in changes in disturbance regimes (e.g., wildfires, drought, insect-outbreaks, and windstorms). Predicting where these natural hazards will occur in the future and to what extent forest ES will be affected are also fundamental research challenges. The general objective of this thesis is to analyze the spatial distribution of forest ES, their relevance in conservation and their vulnerability and risk to climate change hazards, especially wildfires. To do so, 1) we have analyzed the spatial distribution, relationship, and drivers of forest carbon stocks and biodiversity in two regions (Spain and Quebec) and five subclimates (steppe, dry Mediterranean, humid Mediterranean, temperate, and boreal); 2) we have determined the role of PAs in preserving ES and biodiversity in forests and hrublands of Catalonia (NE Spain); 3) we have developed a general framework of forest vulnerability and risk of losing ES due to different climate change hazards; and 4) we have assessed the spatial patterns and drivers of forest vulnerability to wildfires and the corresponding risk of losing ES in Catalonia (NE Spain). We have found a general positive relationship between carbon stocks and biodiversity, with the highest values in northern Spain (humid Mediterranean subclimate) and southern Quebec (temperate subclimate). High density and structural diversity have simultaneously favored carbon stocks, tree and overall biodiversity. The variables positively affecting carbon and biodiversity have been also driving their hotspots, emphasizing the viability of ‘win-win’ solutions. Regarding PAs, we have found more carbon stocks, coverage of community-interest habitats, priority- habitats and geological-interest sites in PAs than in buffer zones, but none of the biodiversity variables considered (i.e., tree and bird richness) have showed differences between PAs and buffer zones. PAs with higher degree of protection (i.e., moderate vs partial protection) have not provided higher levels of ES and biodiversity, or vice versa. Furthermore, we have proposed a general framework to assess forest vulnerability and risk based on the components of exposure, hazard magnitude, susceptibility and lack of adaptive capacity. We have suggested a standardized procedure to define and combine these components, as well as a list of indicators readily applicable to the main climate change-related hazards to forests. Finally, we have applied this general framework to the particular case of wildfires in Catalonia. The results have indicated that hazard magnitude is the most important factor defining ES at risk from wildfires. Climate is the main driving factor of ES at risk under average conditions, but forest functional type - in particular non-Mediterranean conifers that have low adaptive capacity - have gained importance under extreme conditions. The highest increases in risk have been found in relatively wet forests with currently low risk, which according to climate trends will become common in the future. Overall, this thesis has gained evidence on the positive relationship between carbon stocks and biodiversity and their main drivers in five subclimates, and has showed that the conservation strategy in Catalonia is only effective at maintaining some of the ES and conservation variables considered. It has also contributed with an innovative conceptual framework of forest vulnerability and risk of losing ES due to climate change hazards, constituting a basis for a systematic operationalization of forest risk and vulnerability. The application of this framework to the case of wildfires has showed relevant implications on the future risk of losing ES due to wildfires, which could contribute to future-oriented policies by anticipating conditions associated with particularly high risks and guiding efficient forest management.
... The landscape in the NE Iberian Peninsula is extremely diverse due to the heterogeneous orography and climate in the territory. (Gracia et al., 2001) and a riparian forest with Fraxinus angustifolia, Alnus glutinosa and Salix atrocinerea. ...
... The minimum monthly precipitation (10 mm) occurs during summer and in December. (Gracia et al., 2001). ...
... The minimum monthly precipitation (ca. 10 mm) occurs during summer and in December. (Gracia et al., 2001) and a riparian forest with Fraxinus angustifolia, Alnus glutinosa and Salix atrocinerea. ...
Thesis
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Landscape evolution was mostly controlled by climate change until the Neolithisation (after ca. 7.4-7.0 cal ka BP in the Iberian Peninsula) when human impact started to interfere in the natural development of vegetation. Thus, the Neolithisation process involved significant socioeconomic and ecological transformations. Changes in food production, in natural resource management and in settlement patterns originated a new way in which humans and the environment interacted. In that context, archaeoecological evidence obtained by the analyses developed in the framework of this thesis provided relevant data about three main objectives: 1) Vegetation history, climate change and human impact during the Middle Holocene in the Lake Banyoles area; 2) Socio-ecological consequences of Neolithisation in the NE Iberian Peninsula and 3) Potential and contributions of archaeopalynology in lakeside settlement research. This thesis is presented as a compilation of published scientific papers, all based on the application of multi-proxy analysis of both intra-site and off-site deposits in order to reconstruct environmental evolution and Neolithic landscape transformation. The methods applied have been pollen and non-pollen palynomorph (NPP) analysis, macrofossils, sedimentology and sedimentary charcoal analysis, as well as the integration of data from other archaeological and bioarchaeological studies. Broadleaf deciduous forests around Lake Banyoles reached their maximum expansion in the phase 9.0-7.5 cal ka BP, a decline in 7.5-6.5/5.5 cal ka BP, but a recovery afterwards, showing the persistence of oak forests as the dominant vegetation until the Late Holocene. The regression of deciduous forests occurred in the context of the arrival of the first farming societies in the area in 7.27 cal ka BP but also in the context of a cooling phase evidencing the important role of climate change in amplifying the footprint of Neolithic human impact, as well as in settlement dynamics in the Lake Banyoles shore. The practice of intensive farming models during the Early Neolithic, implying small-scale and labour-intensive cultivation, left little evidence of the impact of agriculture in off-site pollen records. While a sustainable small-scale and intensive farming system would have left scarce evidence of the impact of agriculture during the Early Neolithic, the intensive and reiterative exploitation of natural resources associated with permanent settlements led to significant landscape transformation. The archaeopalynological study developed at La Draga was able to obtain relevant data for comprehending site formation processes, the reconstruction of palaeo-environmental evolution and human impact at a local scale and provided new data about socioeconomic practices during the Early Neolithic as well as about the use of space within a pile-dwelling site. This work evidenced the need to carry out spatial analysis in palynological studies at archaeological sites, owing to the spatial heterogeneity of results caused by human impact in terms of soil erosion, arrangement of structures and in the input of plants to the settlement (gathering, cultivation, storage, foddering).
...  Average height (H) -Tree height was measured in all IFN plots and experimental plots except Armallones, where H values were derived from diameter-height allometries (Burriel et al. 2004). ...
...  Specific leaf area (SLA) -Specific leaf area was measured in situ for each species in Prades, Puéchabon and Armallones experimental plots; the remaining values were obtained from Burriel et al. (2004). SLA values for IFN plots were species-specific, taking the values of the corresponding species in experimental plots (SLA for P. halepensis was taken FontBlanche). ...
... For IFN plots, LAI estimates were derived from tree data using foliar biomass allometries and SLA. Foliar biomass allometries were calibrated using data from (Burriel et al. 2004) and the leaf biomass of a given tree cohort (  Crown ratio (CR) -Crown ratio estimates were obtained using available allometries based on tree diameter data (Hasenauer and Monserud 1996).  Root maximum hydraulic conductance (kroot,max) -Maximum root conductances were estimated assuming that roots represented 40% of total whole-plant resistance, even though empirical evidence suggests that this proportion is species-dependent and varies with tree height/age , Martínez-Vilalta et al. 2007). ...
Article
Understanding how water use and drought stress in woody plants change in relation to compositional, structural and environmental variability of mixed forests is key to understand their functioning and dynamics. Observational and experimental studies have so far shown a complex array of water use and drought stress responses to species mixing, but progress is hampered by the costs of replicating measurements. A complementary approach consists in using in silico experiments with trait-based forest ecosystem models, which have the advantage of allowing the interpretation of the net mixing effect as the result of specific combinations of trait differences. We explore the potential of such an approach using a novel trait-based forest ecosystem model with a strong focus on plant hydraulics and data from 186 mixed forest inventory plots including holm oak (Quercus ilex L.) and eight co-occurring species. Sensitivity analyses focusing on the effect of differences in individual plant traits indicate that water use and summer drought stress of holm oak trees respond primarily to the variation in competitor's height, root distribution and xylem hydraulic efficiency and safety. Simulations of pure and mixed stands across different combinations of climate aridity and stand leaf area index indicate that differences in traits may compensate for one another, so that the influence of a given trait (e.g. tree height) on water use or drought stress can be decreased or offset by the influence of another one (e.g. hydraulic efficiency). Importantly, we show that species mixing does not always have positive effects at the stand level. Overall, our simulation study shows that the complexity of species-and stand-level mixing effects on water use and drought stress arises primarily as the result of differences in key functional traits of the competitor, although stand structure and climate aridity may modulate mixing effects.
... The region of Catalonia is located in the north-eastern part of Spain, covering 32 106 km 2 . The region has a Mediterranean climate with large climatic variations due to the influence of the mountainous topography (Gracia et al. 2004). Catalonia can be divided into eight climatic regions: semiarid, dry sub-humid, sub-humid, humid I to IV and very humid (Thornthwaite 1948;Clavero et al. 1997). ...
... Pure forests (defined as forest where at least 80% of the basal area belongs to a single tree species) cover approximately 8040 km 2 , of which 5540 km 2 are pure coniferous and 2500 km 2 pure broadleaf forest. The rest of the forest lands are mixed forest, covering almost 12 000 km 2 (Gracia et al. 2004). The landscape of the region has undergone transformations due to reforestation and abandonment of traditional land-use practices during recent decades. ...
... Mediterranean forest environments are extremely variable in both their soil and vegetation structure. Shrub vegetation under the forest canopies in particular can have high spatial variation, which affects the potential source of sediments on forest lands (Scarascia-Mugnozza et al. 2000;Gracia et al. 2004;Palahí et al. 2008). In addition, the protective function varies between shrub and tree species due to morphological characteristics such as the leaf form and height of the plants (Martínez Raya et al. 2006). ...
... Remote sensing of canopy N is often limited to local-scale studies due to the spatial restrictions associated with N data acquisition in the field and treatment of high spatial resolution remote sensing imagery with limited spatial coverage (Lepine et al., 2016). Our case study exploits the broadly and readily available MTCI time series at 1 km spatial resolution from the ESA Envisat mission and combines it with canopy N data, both concentration and content, from 846 forest plots measured between 1988 and 2001 by the Catalonian National Forest Inventory (Gracia et al., 2004). First, we develop a methodology to overcome the time discrepancy between our two sets of data. ...
... The canopy N data used in this research were collected by the Ecological and Forestry Applications Research Centre (CREAF), Universitat Autònoma de Barcelona. The data included 2300 closed canopy forest plots sampled between 1988 and 2001 by the Catalonian National Forest Inventory (Gracia et al., 2004). ...
... The leaf samples were dried and then ground using a Braun Mikro-Dismembrator U (B. Braun Biotech International, Melsungen, Germany). They were analysed for foliar N concentration using the combustion technique coupled to gas chromatography using a Thermo Electron gas chromatograph (model NA 2100, CE Instruments, Thermo Electron, Milan, Italy) (Gracia et al., 2004). To scale from leaf to canopy level, we used the leaf nitrogen concentration averaged over three individuals as the plot level value (Schlerf et al., 2010). ...
... Remote sensing of canopy N is often limited to local-scale studies due to the spatial restrictions associated with N data acquisition in the field and treatment of high spatial resolution remote sensing imagery with limited spatial coverage (Lepine et al., 2016). Our case study exploits the broadly and readily available MTCI time series at 1 km spatial resolution from the ESA Envisat mission and combines it with canopy N data, both concentration and content, from 846 forest plots measured between 1988 and 2001 by the Catalonian National Forest Inventory (Gracia et al., 2004). First, we develop a methodology to overcome the time discrepancy between our two sets of data. ...
... The canopy N data used in this research were collected by the Ecological and Forestry Applications Research Centre (CREAF), Universitat Autònoma de Barcelona. The data included 2300 closed canopy forest plots sampled between 1988 and 2001 by the Catalonian National Forest Inventory (Gracia et al., 2004). ...
... The leaf samples were dried and then ground using a Braun Mikro-Dismembrator U (B. Braun Biotech International, Melsungen, Germany). They were analysed for foliar N concentration using the combustion technique coupled to gas chromatography using a Thermo Electron gas chromatograph (model NA 2100, CE Instruments, Thermo Electron, Milan, Italy) (Gracia et al., 2004). To scale from leaf to canopy level, we used the leaf nitrogen concentration averaged over three individuals as the plot level value (Schlerf et al., 2010). ...
Article
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Canopy nitrogen (N) concentration and content are linked to several vegetation processes. Therefore, canopy N concentration is a state variable in global vegetation models with coupled carbon (C) and N cycles. While there are ample C data available to constrain the models, widespread N data are lacking. Remotely sensed vegetation indices have been used to detect canopy N concentration and canopy N content at the local scale in grasslands and forests. Vegetation indices could be a valuable tool to detect canopy N concentration and canopy N content at larger scale. In this paper, we conducted a regional case-study analysis to investigate the relationship between the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) time series from European Space Agency (ESA) Envisat satellite at 1 km spatial resolution and both canopy N concentration (%N) and canopy N content (N g m-2, of ground area) from a Mediterranean forest inventory in the region of Catalonia, in the northeast of Spain. The relationships between the datasets were studied after resampling both datasets to lower spatial resolutions (20, 15, 10 and 5 km) and at the original spatial resolution of 1 km. The results at higher spatial resolution (1 km) yielded significant log–linear relationships between MTCI and both canopy N concentration and content: r2 = 0.32 and r2 = 0.17, respectively. We also investigated these relationships per plant functional type. While the relationship between MTCI and canopy N concentration was strongest for deciduous broadleaf and mixed plots (r2 = 0.24 and r2 = 0.44, respectively), the relationship between MTCI and canopy N content was strongest for evergreen needleleaf trees (r2 = 0.19). At the species level, canopy N concentration was strongly related to MTCI for European beech plots (r2 = 0.69). These results present a new perspective on the application of MTCI time series for canopy N detection.
... All rights reserved. 6 oaks show a much more continuous distribution and later seeding while hazels often appear in more discontinuous patches and have an earlier production of fruits (Gracia et al. 2004). Concerning weevils, the three species overwinter underground, but they differ in the duration of their diapause, the phenology of emergence, oogenesis and dispersal ability. ...
... avellana and Q. ilex or Q. humilis based on the Catalan Forest Inventory (Gracia et al. 2004) and field observations of their reproductive status (i.e. presence of seeds). ...
... 18 adult emergence in spring, synovigenic females and a fixed diapause of two years (see Hughes & Vogler 2004a, Bel-Venner et al. 2009, Pélisson et al. 2012a, make us consider they may have a similar dispersal ability. Therefore the differences we observed in their genetic characteristics would be probably due to their different diet breadth and the more patchy and discontinuous distribution of hazels in comparison to the more abundant and constant presence of oaks (Gracia et al. 2004, see also Figure 1), along the geographical gradient sampled (ca. 225 km from Ripoll to Prades). ...
Article
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Synchrony between seed growth and oogenesis are suggested to largely shape trophic breadth of seed-feeding insects and ultimately contribute to their co-existence by means of resource partitioning or in the time when infestation occurs. Here we investigated: i) the role of seed phenology and sexual maturation of females in the host specificity of seed-feeding weevils (Curculio spp) predating in hazel and oak mixed forests and ii) the consequences that trophic breadth and host distribution have in the genetic structure of the weevil populations. DNA analyses were used to establish unequivocally host specificity and to determine the population genetic structure. We identified four species with different specificity, namely C. nucum females matured earlier and infested a unique host (hazelnuts) while three species (C. venosus, C. glandium, C. elephas) predated upon the acorns of the two oaks (Q. ilex and Q. humilis). The high specificity of C. nucum coupled with a more discontinuous distribution of hazel trees resulted in a significant genetic structure among sites. Also, the presence of an excess of local rare haplotypes indicated that C. nucum populations went through genetic expansion after recent bottlenecks. Conversely, these effects were not observed in the more generalist C. glandium predating upon oaks. Ultimately, co-existence of weevil species in this multi-host-parasite system is influenced by both resource and time partitioning. To what extent the restriction in gene flow among C. nucum populations may have negative consequences for their persistence in a time of increasing disturbances (e.g. drought in Mediterranean areas) deserves further research.
... Our case-study exploits the broadly and readily available MTCI time series at 1 km spatial resolution from the ESA ENVISAT 105 mission and combines it with canopy N data, both concentration and content, from 1075 forest plots measured between 1988 and 2001 by the Catalonian National Forest Inventory (Gracia et al., 2004). First, we develop a methodology to overcome the time discrepancy between our two sets of data. ...
... Following this pattern, the mean annual temperature varies from 1 °C in the north to 17 °C in the south (Sardans et al., 2011). While mean annual precipitation (MAP) is 1400 mm in the the Catalonian National Forest Inventory (Gracia et al., 2004). ...
... The foliar biomass data were obtained for each plot from allometric equations relating the diameter of the branches to the leaves dry weight (Gracia et al. (2004) , Fig. A1). These foliar biomass data were used to calculate canopy N content (N[area], g m -2 ) for each plot following Eq. ...
Article
Full-text available
Canopy nitrogen (N) concentration and content are linked to several vegetation processes and canopy N concentration is a state variable in global vegetation models with coupled carbon (C) and N cycles. While there is ample C data available to constrain the models, widespread N data are lacking. Remote sensing and vegetation indices have been used to detect canopy N concentration and canopy N content at the local scale in grasslands and forests. In this paper we conducted a regional case-study analysis investigating the relationship between the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) time series from ESA ENVISAT at 1 km spatial resolution and both canopy N concentration (%N) and canopy N content (g m−2) from a Mediterranean forests inventory in the region of Catalonia, NE of Spain. The relationships between the datasets were studied after resampling both datasets to lower spatial resolutions (20 km, 15 km, 10 km and 5 km) and at the initial higher spatial resolution of 1 km. The results at the higher spatial resolution yielded significant relationships between MTCI and both canopy N concentration and content, r² = 0.32 and r² = 0.17, respectively. We also investigated these relationships per plant functional type. While the relationship between MTCI and canopy N concentration was strongest for deciduous broadleaf and mixed plots (r² = 0.25 and r² = 0.47, respectively), the relationship between MTCI and canopy N content was strongest for evergreen needleleaf trees (r² = 0.20). At the species level, canopy N concentration was strongly related to MTCI for European Beech plots (r² = 0.71). These results present a new perspective on the application of MTCI time series for canopy N detection, ultimately leading towards the generation of canopy N maps that can be used to constrain global vegetation models. Keywords: vegetation index, MERIS, foliar nitrogen concentration, foliar nitrogen content, plant functional types, Mediterranean forest, remote sensing
... Forests dominated by silver fir are scattered through mountain altitudes ranging from 1000 to 2000 m a.s.l. where the mean annual precipitation is between 1000 and 1500 mm ( Blanco et al. 1997;Gracia et al. 2004). Silver fir typically grows on northern aspects, on steep slopes and has high productivity of about 8.7 m 3 ha −1 a −1 ( Solano et al. 2007). ...
... Silver fir typically grows on northern aspects, on steep slopes and has high productivity of about 8.7 m 3 ha −1 a −1 ( Solano et al. 2007). Silver fir occupies about 12,400 ha, of which about 9500 ha (76%) are on slopes steeper than 40% ( Gracia et al. 2004). Typical management method for shade-tolerant silver fir has been cutting all trees over 35 cm in diameter every 10 years ( Solano et al. 2007). ...
Article
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Key message Multi-objective forest planning methods were used to assess the trade-offs between three ecosystem services: timber production, erosion protection and biodiversity. The use of trade-off analysis helps to define proper weights for the management objectives and evaluate the feasibility of obtaining economic profit from timber while controlling the erosion risk and maintaining biodiversity of Abies alba Mill. ContextForests provide several ecosystem services (ES), many of which are in trade-off. The assessment of relationships between ES helps to optimize forest management.AimsThis study analyses the trade-offs between timber production, erosion protection and biodiversity in uneven-aged mountain forest of Abies alba Mill.Methods Multi-functional forest management was optimized using a simulation-optimization software. Timber production was measured with present value, erosion risk was modelled as a function of stand structure, and biodiversity was dealt with by setting a minimum number of 10 large trees (dbh > 60cm) per hectare as a requirement. Optimizations were conducted for slopes of 10%, 45% and 80% and cutting cycles of 10, 30 and 50 years. Discount rate 2% was used in all optimizations. Trade-offs were evaluated with production possibility boundaries.ResultsWe found relevant trade-offs between timber production and erosion protection, which depended on the slope steepness and the length of the cutting cycle. Trade-offs were marginal on 10% slope (50-year cycle) and large on 80% slope (10-year cycle). Biodiversity constraint reduced both economic profits and erosion protection values.Conclusion In multifunctional mountain forest, defining proper weights for ecosystem services that are in trade-off is important for satisfying different management objectives in a sustainable way.
... Aboveground and belowground biomass of trees was derived for each species from allometric equations from Gracia et al. (2004). ...
... • Tree belowground biomass from species-specific allometric equations from Gracia et al. (2004). ...
... Details on site characteristics and general soil properties of the sampling sites are summarized in Table 1. In the area of study forest productivity on carbonated soils ranges from 0.27 to 1.24 Mg/ha/yr, while in non-carbonated soils it ranges from 1.31 to 2.02 Mg/ha/yr (Gracia et al., 2004). In carbonated fertilized cultivated area agronomic productivity ranges from 0.45 in Table 1 Site characteristics and general soil properties (0-10 cm) cultivated fields (Fi), abandoned fields (AFi) and forests (Fo). ...
... This pattern cannot be explained by a greater organic matter input in carbonated soils because forest productivity in Mediterranean areas is at least equal or even lower on carbonated than on non-carbonated soils. In the study region, forest productivity on non-carbonated soils is 1.7 ± 0.2 Mg/ ha/y while on carbonated soils it is only 0.86 ± 0.3 Mg/ha/y (Gracia et al., 2004). We, thus relate the greater SOM contents in carbonated forest soils rather to a greater SOM stabilization, which is supported by the smaller C mineralization rates of bulk soils and particle size fractions in carbonated than in non-carbonated forest soils. ...
Article
Soil organic matter (SOM) is sensitive to land use and to physico-chemical soil properties as well soil microbial communities controlling SOM stabilization. Our study aimed at exploring how carbonates of Mediterranean soils – known to stabilize SOM by enhancing soil aggregation and binding SOM by calcium – are affecting SOM and microbial communities under different land uses. In soils with and without carbonates sampled in forests, cultivated and abandoned fields, we have fractionated SOM-pools according to particle sizes and determined C mineralization rates and polyvalent cations in these fractions. In agreement with larger scale assessments in the Mediterranean, our results show that SOM contents are greater in forest than in agricultural soils, but that the differences among land use types depend on carbonate contents. While SOM contents are greater in carbonated soils of forests, cultivated soils have low SOM levels independent of the carbonate content, presumably due to a reduced protection of particulate SOM by century-long intense tillage. Forest soils contain particularly large amounts of SOM associated with the coarser soil fraction. In this fraction, C mineralization was smallest in the carbonated forest soil, possibly due to a low SOM quality indicated by high C/N ratios and low δ ¹⁵ N values. Greater contents of Ca, Fe and Al in carbonated soils also suggests that stabilization through Ca and phyllosilicates was important. Mineralization of sand-associated SOM was highest in cultivated and abandoned soils, which is indicative for a small SOM stabilization, which in turn might restrict SOM accumulation after land abandonment. Microbial communities assessed by phospho-lipid fatty acid signatures and microbial carbon use efficiency were more closely associated with land use than with carbonate content – a pattern that reflects the distribution of C pools among size fractions which differed more strongly among land use types than between soils with and without carbonates.
... In order to obtain the revegetation land-use scenario (RLU), an orographic criteria defined in [53] (Figure 4) was used. The experiment is based on a multi-criteria analysis (MCA) technique where the elevation, aspect, and slope maps were reclassified in groups of cells, where it is more probable to find each land cover type according to [53], assuming those areas are optimal. ...
... In order to obtain the revegetation land-use scenario (RLU), an orographic criteria defined in [53] (Figure 4) was used. The experiment is based on a multi-criteria analysis (MCA) technique where the elevation, aspect, and slope maps were reclassified in groups of cells, where it is more probable to find each land cover type according to [53], assuming those areas are optimal. The results were combined to determine optimum areas for deciduous forests and were substituted gradually by linear progress if the actual land cover was ENF. ...
Article
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This paper evaluates the response of streamflow in a Mediterranean medium-scaled basin under land-use and climate change scenarios and its plausible implication on the management of Boadella–Darnius reservoir (NE Spain). Land cover and climate change scenarios supposed over the next several decades were used to simulate reservoir inflow using the Regional Hydro-Ecologic Simulation System (RHESsys) and to analyze the future impacts on water management (2021–2050). Results reveal a clear decrease in dam inflow (−34%) since the dam was operational from 1971 to 2013. The simulations obtained with RHESsys show a similar decrease (−31%) from 2021 to 2050. Considering the ecological minimum flow outlined by water authorities and the projected decrease in reservoir’s inflows, different water management strategies are needed to mitigate the effects of the expected climate change.
... The vast majority (98%) of the Catalan forested area is composed of dense forests (canopy cover > 20%). Coniferous species dominate 60% of the Catalan forest area while 26% is dominated by broadleaf sclerophyllous species, 10% by broadleaf winter deciduous species and the remaining 4% are mixed forests (Gracia et al., 2004). ...
... Where i is the target tree, SLA is the specific leaf area of the species considered, S the plot surface and a, b, c and d are species-specific parameters calibrated against measurements from Gracia et al. (2004) (across all plots and species R 2 = 0.72). Additionally, because allometries were not available for shrubs, their LAI was estimated at the SFI3 plots by assuming a proportional relationship between LAI and shrub cover (Balandier et al., 2013), with a factor of 0.01. ...
Article
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Drought is a key driver of vegetation dynamics, but plant water‐uptake patterns and consequent plant responses to drought are poorly understood at large spatial scales. The capacity of vegetation to use soil water depends on its root distribution (RD). However, RD is extremely variable in space and difficult to measure in the field, which hinders accurate predictions of water fluxes and vegetation dynamics. We propose a new method to estimate RD within water balance models, assuming that vegetation is at Eco‐Hydrological Equilibrium (EHE). EHE conditions imply that vegetation optimizes RD such that transpiration is maximized within the limits of bearable drought stress, characterized here by species‐specific hydraulic thresholds. Optimized RD estimates were validated against RD estimates obtained by model calibration from sap flow or soil moisture from 38 forest plots in Catalonia (NE Spain). In water‐limited plots, optimized RD was similar to calibrated RD but estimates diverged with higher water availability, suggesting that the EHE may not be assumed when water is not limiting. Thereafter we applied the optimization procedure at the regional scale, to estimate RD for the water‐limited forests of Catalonia. Regional variations of optimum RD reproduced many expected patterns in response to climate, soil physical properties, forest structure and species hydraulic traits. We conclude that RD optimization, based on the EHE hypothesis and a simple description of plant hydraulics, produces realistic estimates of RD that can be used for model parameterization and shows promise to improve our ability to forecast vegetation dynamics under increased drought.
... En los datos comarcales del IEFC (Gracia et al., 1993) se presenta una muestra de más de 200 árboles tipo de la especie, con un crecimiento radial medio de 1,26 mm/año. Ibáñez et al. (1993), analizando estos datos, definen para cada clase diamétrica un colectivo de árboles de «crecimiento lento» (Ai < 1mm) y otro de «crecimiento rápido» (Ai > 1,25 mm). ...
Article
An adult stand (mean age = 139 years) of Pinus nigra ssp. salzmannii var. pyrenaica has been studied in the W of the Solsonès district (Lleida province, NE of Spain). Cores from 97 adult trees have been bored and measured, obtaining 13.340 annual rings that have been measured and cross-dated, thus building a growth chronology from 1818 to 1996. The relationships between the measured dendrometrical parameters and the observed growth increments have been analysed, finding generally low correlations. Three growth mean series have been built (average chronology, standarized, and age-based), in order to analyse the stand evolution. A long period of growth slowing and supression that lasted for nearly 80 years was followed by a strong cutting and a growth release reaction, when the mean age of the stand was already of 101 years.
... Human presence since pre-historical times has led to changes in plant composition and distribution. According to Gracia et al. (2004), current land cover consists of 31% forests, 29% shrublands, and 33% agricultural land. Fire is a significant landscape driver in the region, with 25% of land being burnt between 1975 and 2010 (González & Pukkala, 2007). ...
Article
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Rodents respond quickly to changes in habitat structure after wildfires. They constitute important prey items for vertebrate predators and influence vegetation structure and regeneration. Assessing the population dynamics of rodents in burnt areas, whether individuals originate from in situ survival or from ex situ immigration, is therefore a key question in understanding the recovery of trophic networks after disturbance. This study aimed to identify the recovery strategies of rodent populations in recently burnt forests in the Mediterranean basin using body condition, reproductive output, sex ratios, and distance covered by wood mice and Algerian mice. Sampling stations were set up at increasing distances from the perimeter of recently burnt areas. Rodents were captured using Sherman traps and measured. Wood mice and Algerian mice lived syntopically within the recently burnt areas studied, the former species being more abundant and the second one selecting drier areas. Results indicated that time since fire, shrub cover, and distance to the perimeter of the burnt area influenced wood mice and Algerian mice population structures. Adult female wood mice mainly remained close to the burnt area perimeter, due to this species' matriarchal structure, while juvenile males dispersed farther into the burnt area. Adult females were also recaptured more frequently than other age and sex categories over time, whereas males covered greater distances. These findings suggest that the recovery strategy of these widespread Mediterranean rodents is mainly driven by ex situ immigration from unburnt areas. These results will be useful for post‐fire management decisions such as non‐intervention, salvage logging or the conservation of open areas, given that mice are a fundamental component of the ecosystem. Results also suggest that management should focus on maintaining good connectivity between burnt and adjacent unburnt areas to support mice populations and facilitate other longer‐term conservation benefits.
... We used available allometric relationships for shrub and tree leaf biomass and crown base height assembled from multiple sources (Hasenauer, 1997;Burriel et al., 2004;De Cáceres et al., 2019) to populate 19 (16 %) model parameters. In turn, 49 (42 %) model parameters were matched to plant trait definitions from existing plant trait databases (see Table S1). ...
Article
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Regional-level applications of dynamic vegetation models are challenging because they need to accommodate the variation in plant functional diversity, which requires moving away from broadly defined functional types. Different approaches have been adopted in the last years to incorporate a trait-based perspective into modeling exercises. A common parametrization strategy involves using trait data to represent functional variation between individuals while discarding taxonomic identity. However, this strategy ignores the phylogenetic signal of trait variation and cannot be employed when predictions for specific taxa are needed, such as in applications to inform forest management planning. An alternative strategy involves adapting the taxonomic resolution of model entities to that of the data source employed for large-scale initialization and estimating functional parameters from available plant trait databases, adopting diverse solutions for missing data and non-observable parameters. Here we report the advantages and limitations of this second strategy according to our experience in the development of MEDFATE (version 2.9.3), a novel cohort-based and trait-enabled model of forest dynamics, for its application over a region in the western Mediterranean Basin. First, 217 taxonomic entities were defined according to woody species codes of the Spanish National Forest Inventory. While forest inventory records were used to obtain some empirical parameter estimates, a large proportion of physiological, morphological, and anatomical parameters were matched to measured plant traits, with estimates extracted from multiple databases and averaged at the required taxonomic level. Estimates for non-observable key parameters were obtained using meta-modeling and calibration exercises. Missing values were addressed using imputation procedures based on trait covariation, taxonomic averages or both. The model properly simulated observed historical changes in basal area, with a performance similar to an empirical model trained for the same region. While strong efforts are still required to parameterize trait-enabled models for multiple taxa, and to incorporate intra-specific trait variability, estimation procedures such as those presented here can be progressively refined, transferred to other regions or models and iterated following data source changes by employing automated workflows. We advocate for the adoption of trait-enabled and population-structured models for regional-level projections of forest function and dynamics.
... We used available allometric relationships for shrub/tree leaf biomass and crown base height assembled from multiple sources (Hasenauer, 1997;Burriel et al. 2004;De Cáceres et al., 2019) to populate 19 (16%) of model parameters. In turn, 49 (42%) model parameters were mapped to plant trait definitions from existing plant trait databases (see Table B1). ...
Preprint
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Regional-level applications of dynamic vegetation models are challenging because they need to accommodate the variation in plant functional diversity, which requires moving away from broadly-defined functional types. Different approaches have been adopted in the last years to incorporate a trait-based perspective into modeling exercises. A common parametrization strategy involves using trait data to represent functional variation between individuals while discard taxonomic identity, but this strategy ignores the phylogenetic signal of trait variation and cannot be employed when predictions for specific taxa are needed, as in applications to inform forest management planning. An alternative strategy involves adapting the taxonomic resolution of model entities to that of the data source employed for large-scale initialization and estimating functional parameters from available plant trait databases while adopting alternative solutions for missing data and non-observable parameters. Here we report the advantages and limitations of this second strategy according to our experience in the development of MEDFATE (v. 2.8.1), a novel cohort-based and trait-enabled model of forest dynamics, for its application over a region in the Western Mediterranean Basin. First, 217 taxonomic entities were defined according to woody species codes of the Spanish National Forest Inventory. While forest inventory data were used to obtain some empirical parameter estimates, a large proportion of physiological, morphological, and anatomical parameters were mapped to measured plant traits, with estimates extracted from multiple databases and averaged at the required taxonomic level. Estimates for non-observable key parameters were obtained using meta-modeling and calibration exercises. Missing values were filled using imputation procedures based on trait coordination, taxonomic averages or both. The model properly simulated observed historical basal area changes, with a performance similar to an empirical model trained for the same region. While strong efforts are still required to parameterize trait-enabled models for multiple taxa, estimation procedures can be progressively refined, transferred to other regions or models and iterated following data source changes by employing automated workflows. We advocate for the adoption of trait-enabled population-structured models for regional-level projections of forest function and dynamics.
... The experimental design and general sampling scheme has been previously outlined in Rosas et al. (2019). Briefly, we selected six of the most dominant tree species in Catalonia (3 Pinaceae and 3 Fagaceae), accounting for ~75% of the total forest area (Gracia et al., 2004): Pinus sylvestris L, Pinus nigra J.F.ARNOLD., Pinus ...
Article
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A major foundation of trait‐based ecology is that traits have an impact on individual performance. However, trait–growth relationships have not been extensively assessed in trees, especially outside tropical ecosystems. In addition, measuring traits directly related to physiological processes remains difficult and the differences between inter‐ and intraspecific relationships are seldom explored. Here, we use individual‐level data on a set of hydraulic, leaf and stem traits to assess their ability to predict basal area increment (BAI) and growth efficiency (BAI per unit of tree leaf area, GE) among and within species for six dominant tree species along a water availability gradient under Mediterranean climate (Catalonia, NE Spain). Measured traits include: leaf mass per area (LMA), leaf nitrogen concentration (N), leaf C isotopic composition (δ¹³C), the leaf water potential at turgor loss (Ptlp), stem wood density (WD) and branch‐level estimates of the Huber value (Hv), sapwood‐ and leaf‐specific hydraulic conductivity (KS and KL) and resistance to xylem embolism (P50). Trait–growth associations were generally weak, particularly for BAI and within species. High values of both growth metrics were associated with ‘conservative’ leaf and hydraulic traits. In particular, BAI was negatively associated with KL (and wood density), while GE increased with LMA, allocation to sapwood relative to leaves (Hv) and resistance to xylem embolism (P50). Climate effects on BAI and GE were indirectly mediated by changes in traits, stand structure and tree basal area. Overall, these results suggest that maintaining functionality over extended periods of time may be more important than maximum gas exchange or hydraulic capacity to achieve high radial growth under Mediterranean climates. Our study reveals that widely used ‘functional traits’ may be poor predictors of tree growth variability along environmental gradients. Moreover, trait effects (when present) do not necessarily conform to simple hypotheses based on our understanding of organ‐level processes. An improved understanding of trait coordination along common axes of variation together with a revaluation of the variables that better reflect whole‐tree performance can greatly improve our understanding of trait–growth relationships. A free Plain Language Summary can be found within the Supporting Information of this article.
... About 42% of forests are pine forests (Pinus halepensis), 24% holm oak forests (Quercus ilex ssp. ilex), and 12% mixed forests (Pinus + Quercus) (Gracia et al., 2001). Deciduous oak trees (Quercus pubescens) appear in small humid patches. ...
Article
Crop replacement by secondary forests increases soil organic carbon (OC) stocks. Quantifying this increase is subject to biases: the changes in soil compaction and, in calcareous zones, the changes in soil inorganic carbon (IC) content, which affect the carbon balance. How relevant are both biases, though? We studied this problem in NE Spain, subhumid Mediterranean, in a set of current crops, old forests, and new forests grown on croplands abandoned after 1956. We compared soil OC stocks on a fixed-depth basis (30 cm), and on an equivalent-mass basis: uppermost 425 kg m—2 of fine mineral matter (amount in crop soils). Down to 30 cm, OC stocks were lowest in crops (5.45 kg m—2) and highest in old forests (7.50), which gives a potential OC sequestration in the mineral soil of 2.05 kg m—2. On an equivalent-mass basis the potential is 2.50 kg m—2, meaning that the fixed-depth criterion underestimates OC sequestration by more than 20%. These figures are surpassed by those of IC: crops store 17.73 kg IC m—2 down to 30 cm, old forests 12.28, suggesting a potential loss upon afforestation of 5.45 kg IC m—2. Nevertheless, the lack of negative relationships between IC losses and OC gains within a given land use suggests that the contrasting IC stocks result from past management, mainly tillage. The decarbonation is only apparent. Our results stress the need of accounting for changes in carbonate content and soil compaction in future studies about carbon sequestration in soils. This article is protected by copyright. All rights reserved.
... Shrublands (Erica arborea, Rosmarinus oficinalis) are also well represented. On the lakeshore, there are helophytic communities represented by Phragmites australis, Typha angustifolia, Lythrum salicaria and several Cyperaceae species (Gracia et al., 2001). ...
... We calculated tree-level aboveground biomass using speciesspecific allometric equations from the Ecological and Forest Inventory of Catalonia (Gracia et al., 2004) and tree DBH and height. To estimate forest plot productivity (Mg ha −1 year −1 ), we first aggregated the biomass at the plot level for the SFI ini and SFI fin , and then we calculated for each plot the change in total biomass, accounting for the time interval between surveys for each plot. ...
Article
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Many temperate forests are changing in composition due to a combination of changes in land‐use, management and climate‐related disturbances. Previous research has shown that in some regions these changes frequently favour drought‐tolerant tree species. However, the effects of these changes in composition on forest functioning (e.g., productivity) are unclear. We studied 25 years of change in individual tree biomass growth, ingrowth and mortality, and community composition and total plot biomass, and across 2 663 permanent forest plots in Catalonia (NE Spain) comprising 85 220 trees of 59 species. We focused on the relationship between community‐level forests productivity and drought tolerance, which was estimated using hydraulic traits as well as biogeographic indicators. We found that there was a small increase (1.6 – 3.2% on average) in community‐mean drought tolerance during the study period, concurrent with a strong increase (12.4 – 19.4% on average) in drought tolerance richness (i.e. trait range). Most importantly, we found that the community‐mean drought tolerance was negatively related to forest productivity, which was explained because drought‐tolerant tree species have lower tree‐level growth. In contrast, drought tolerance richness was strongly and positively related to forest productivity, probably because it allowed for a more stable production along wet and dry periods. These results suggest a negative impact of ongoing climate change on forest productivity mediated by functional composition shifts (i.e., selection of drought‐tolerant species), and a positive effect of increased drought tolerance richness as a consequence of land‐use legacies. Such a trend towards functional diversification, although temporary, would increase forests’ capacity to resist drought and place them in a better position to face the expected change in climate.
... Up to 42 per cent of Catalonia is covered with forests (Anonimus, 2014). Also, according to Burriel et al. (2004), Catalonia has ∼12 240 ha of forests containing chestnut trees (C. sativa), usually mixed with native species of oak, Quercus petraea (Matt.) ...
Article
The Asian chestnut gall wasp (ACGW), Dryocosmus kuriphilus (Hymenoptera: Cynipidae), is an invasive pest that affects chestnut trees. The first record of this pest in Spain was in 2012, in Catalonia, and it is now distributed in virtually every chestnut growing area in the country. In this study, we present an overview of parasitoid recruitment by ACGW in Catalonia over a 4-year period (2013–2016) comparing parasitoid communities attacking galls on oak and chestnut trees at the same sites. A total of 22 species of native parasitoids that normally attack oak cynipids emerged from ACGW galls, together with the non-native Torymus sinensis. The most abundant species were Bootanomyia dorsalis, Torymus flavipes, Ormyrus pomaceus and Eupelmus urozonus. The study also found that 20 of the 22 native parasitoids in ACGW galls were also reared from galls of 13 species of oak gall inducer (12 Cynipidae, 1 Cecidomyiidae).
... = 2 C × × on el Dn és el diàmetre normal de l'arbre, H és l'alçada de l'arbre i Kf és el coeficient de forma de l'arbre, que és la relació entre el volum d'un cilindre d'alçada i radi iguals als de l'arbre i el volum d'un con d'iguals mides (Gracia et al. 2004). ...
Technical Report
La present memòria correspon a un recull, avaluació i anàlisi de tots els indicadors prioritaris de la biodiversitats desenvolupar pel Centre de Monitoratge de la Biodiversitat de Muntanyes Mediterrànies realitzats al Parc Natural de Sant Llorenç del Munt i l’Obac referents a l’estat de les espècies, dels hàbitats i dels processos ecològics i els efectes dels factors de canvi. Concretament s’avaluen els seguiments de la flora amenaçada, invertebrats cavernícoles, gasteròpodes, ortòpters, ropalòcers, processionària del pi, invertebrats del medi aquàtic, els peixos, els amfibis, els rèptils, ocells, rapinyaires nocturns i diürns, els quiròpters cavernícoles, micromamífers, esquirols, lagomorfs, carnívors, ungulats, l’estructura i la composició de l’hàbitat, necromassa, producció de bolets, producció de pinyes producció d’aglans, producció de fruits carnosos, l’alteració del medi aquàtic, l’explotació dels recursos naturals o les dades meteorològiques.
... Foliar biomass of trees was derived for each species from allometries based their DBH and the total Basal Area of Larger trees in the plot (BAL), to account for competition effects. Equations were calibrated using data from Gracia et al. (2004). Biomass values were transformed to leaf area index, using specific leaf area coefficients (SLA in m 2 /kg; from the same source). ...
... Rubisco Kc, Ko, and CO 2 compensation point were considered temperature-dependent for both tree species, with activation and deactivation energies obtained from Bernacchi et al. (2001). Stand structure and allometric relations parameters for both tree species were obtained from Catalan Forest Inventory (IEFC, Gracia et al., 2004). See Supplementary Material SM Table 1 for further details. ...
Article
Mediterranean riparian forests are comparably humid environments that provide shelter for several broadleaved deciduous tree species at their southernmost distribution margin. The stability of these communities, however, is threatened by climate change as well as invasive tree species, such as black locust (Robinia pseudoacacia L.). So far, black locust's European distribution appears to be mostly limited by low temperatures, but global warming might enhance its growth in colder areas. Moreover, R. pseudoacacia can better access water from the phreatic level than some native non-phreatophytic tree species such as European ash (Fraxinus excelsior L.). In this study, we compare the performance of European ash, a native deciduous tree species at its southernmost distribution border, with the invasive black locust, under a range of climate change projections, in a stand located at N.E. Spain. We first use Bayesian inference to calibrate the GOTILWA + vegetation model against sap flow data for both tree species. We then project each tree species' performance under several climate change scenarios. Our results indicate that increasing temperatures will enlarge black locust's vegetative period, leading to substantially increased annual productivity if the phreatic water table keeps reachable. For European ash, we project a slight increase in productivity, but with higher uncertainty. Our findings suggest that black locust will profit more from global warming than the native European ash, which is concerning because of the already detrimental impact of black locust for the local ecosystems. We conclude that climate change has the potential to stimulate black locust growth on Mediterranean riparian forests. Forest management should therefore include mechanisms to avoid black locust establishment, such as avoid clear-cutting and maintaining closed riparian forest canopies.
... acdc/). We selected six of the most dominant tree species in Catalonia (three Pinaceae and three Fagaceae), accounting for c. 75% of the total forest area (Gracia et al., 2004; see also Supporting information Table S1): Pinus sylvestris L, Pinus nigra J.F.Arnold., Pinus halepensis Mill., Fagus sylvatica L., Quercus pubescens Willd. and Quercus ilex L. For each species, 15 plots from the Spanish forest inventory (IFN) were resampled in which the target species was dominant (minimum 50% of the total basal area), maximizing the water availability gradient occupied by each species in the study region. ...
Article
Full-text available
Trait variability in space and time allows plants to adjust to changing environmental conditions. However, we know little about how this variability is distributed and coordinated at different organizational levels. For six dominant tree species in northeastern Spain (three Fagaceae and three Pinaceae) we quantified the inter‐ and intraspecific variability of a set of traits along a water availability gradient. We measured leaf mass per area (LMA), leaf nitrogen (N) concentration, carbon isotope composition in leaves (δ¹³C), stem wood density, the Huber value (Hv, the ratio of cross‐sectional sapwood area to leaf area), sapwood‐specific and leaf‐specific stem hydraulic conductivity, vulnerability to xylem embolism (P50) and the turgor loss point (Ptlp). Differences between families explained the largest amount of variability for most traits, although intraspecific variability was also relevant. Species occupying wetter sites showed higher N, P50 and Ptlp, and lower LMA, δ¹³C and Hv. However, when trait relationships with water availability were assessed within species they held only for Hv and Ptlp. Overall, our results indicate that intraspecific adjustments along the water availability gradient relied primarily on changes in resource allocation between sapwood and leaf area and in leaf water relations.
... Along the lakeshore, there are helophytic communities represented by Phragmites australis (Cav.) Steud., Typha angustifolia L., Lythrum salicaria L. and several cyperaceous species (Gracia et al. 2001). ...
... The stem it is not very straight, large branches are common, which sometimes weakens the wood quality. Around the Mediterranean basin, Aleppo Pine tree has an average growth of 2.4 m 3 /ha/year (Gracia et al., 2004). Natural discontinuous bands and large geographical distributions of Aleppo Pine were recorded in the Mediterranean region ( figure 1). ...
Article
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Pinus halepensis Mill. was introduced into regions with a Mediterranean climate as an ornamental tree, and is now often found in parks and gardens. At present, Aleppo pine (Pinus halepensis Mill.) forests cover approximately 2,500,000 ha in the Mediterranean Basin, mostly at low altitudes (less than 500 m) and along the coast. It has become naturalized outside cities in North Africa to the extent that it is now listed as an invasive species there. Because of its size (over 15 m in height and 30 cm in diameter), Pinus halepensis could be a good potential green resource for structural material in Tunisia. The focus of this study was to assess rot resistance and the physical and mechanical properties of reforestation Aleppo pine from the Mediterranean basin. The Pinus halepensis wood samples studied were collected from 6 tree provenances in Tunisia for physical and mechanical characterization and from Morocco for decay and termite resistance tests. Densities and shrinkage were determined and mechanical and rot resistance tests performed. Preliminary results showed that Tunisian Pinus halepensis wood has great dimensional stability. Although the compressive strength of Pinus halepensis wood is high, its bending strength is rather low for each of the provenances. MOR in bending is lower than in other Tunisian softwood species. Finally, Pinus halepensis sapwood has low resistance to fungi and termites. This timber species could be valuable for furniture and/or as a building material provided that a wood preservation method is applied before it is used.
... Previous to the wildfire, this region was mainly occupied by Spanish black pine in pure natural stands or dominating the overstory of twolayered stands, with resprouting species (mostly deciduous sub-Mediterranean oaks) growing in the understory (Gracia et al., 2000). The wildfire triggered a wide resprout of hardwood species that are now dominant in most of the affected area, with some disperse individuals of black pine that regenerated from close unburned patches (Martín-Alcón et al., 2015;Puerta-Piñero et al., 2012). ...
Article
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The persistence of non-serotinous pines in Mediterranean forests can be threatened by climate-mediated changes in fire regimes that may favor the dominance of resprouters or other fire-adapted species. Recovery of non-serotinous pines after large wildfires is often determined by their ability to grow under the canopy of promptly established resprouters. Mechanisms of facilitation or competition between resprouters and pines will thus have a profound effect on forest dynamics. We examined here the effect of neighboring oak resprouts on Pinus nigra Arn. ssp. salzmannii saplings 18 years after a wildfire. We determined the net outcome of interactions between oaks and pines and how they vary with the life stage and size of the interacting plants or the environmental conditions. We did not find any net facilitative effects of oaks on pine sapling growth. The sensitivity of pines to neighbors varied markedly with pine size, and to a lesser extent, with water availability during the growing season. Our findings suggest a self-reinforcing hierarchical process by which early-dispersed seedlings growing in low-competitive microsites can grow faster, mitigating neighboring competition in the later stage of canopy closure. These results entail a potentially critical role of management practices to promote post-fire recovery of non-serotinous pines under expected changing conditions of disturbance regimes.
... Land cover scenario for three time windows ( 20212030, 2031-2040 and 2041-2050) were developed, based on the expected evolution of revegetation within the study area: ENF substitution by EDF and Shrubland by ENF. Optimum areas for EDF and ENF cover types were selected with a multi-criteria analysis (MCA) technique under orographic criteria defined in Ecologic and Forest Inventory of Catalonia [17] ( Figure 3). The elevation, aspect and slope maps were reclassified in groups of cells where is more probable to find each land cover type according to IEFC. ...
... Pinus uncinata inhabits the Pyrenean subalpine zone and has an important forest crop in the French Pyrenees. About 86% of the woods of the species stand between 1,600 and 2,200 metres above sea level and the total altitudinal range of the species goes from 1,000 metres up to 2,400 metres just below the alpine zone [19]. Nowadays Pinus uncinata is more abundant than in the past because the ancient pasturelands that existed at the top of the Pyrenean Mountains have turned into forest. ...
Article
Pinus uncinata is a native pine from the mountain zones of Spain and of the centre and west of the Alps. Since centuries, it has been known that this species presents an excellent structural competence and his heartwood is perceived as highly durable. Nevertheless, its properties have not been studied in depth. The timber characterized comes from the French and the Spanish Pyrenees. The study analyses the mechanical and the physical properties of the clear wood, as well as the durability and the treatability. All the tests were done according the European standards. Pinus uncinata is soft, lightweight and not as stiff as the native pines of southern Europe. The natural durability was evaluated and the mountain pine was classified as non-durable. The sapwood wood is treatable while the heartwood is little or non-treatable.
... Dicha eficiencia se corrigió por la densidad de la madera para tener un estimador relacionado con la producción de biomasa y no únicamente con el incremento de diámetro. Las densidades consideradas fueron de 0.68, 0.43 y 0.51 g·cm-3 para fresno, aliso y chopo, respectivamente (Gracia et al., 2004), y de 0.75 g·cm-3 siguiendo a Adamopoulos et al., (2007). ...
Conference Paper
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La falsa acacia (Robinia pseudoacacia L.) es una especie invasora originaria de los montes Apalaches. Se introdujo en Europa durante el siglo XVIII y desde entonces, se ha expandido a lo largo de las regiones húmedas del continente Europeo, incluyendo hábitats de especial interés ecológico protegidos en el marco de la red Natura 2000. Su gran capacidad invasora se acentúa en zonas perturbadas como los bosques de ribera mediterráneos, dónde se le abren espacios de oportunidad. En el presente estudio se comparan características eco-fisiológicas y estructurales de esta especie invasora con las de especies autóctonas de un bosque de ribera mediterráneo. El objetivo es aportar información que puede ayudar a entender mejor el éxito de esta especie frente a las otras especies autóctonas. La falsa acacia presenta una gran plasticidad, ocupando todos los gradientes espaciales de disponibilidad hídrica del bosque de ribera. Tiene la mayor tasa de transpiración, siendo también la que transpira menos por unidad de área basimétrica. Destaca además su gran eficiencia en el uso del agua, por encima de las demás especies, aunque es la que presenta el período vegetativo más corto. El chopo negro (Populus nigra L.) es la especie de mayor crecimiento, pero su presencia depende de ser introducida por plantación. El aliso (Alnus glutinosa Gaertn.) es la especie que transpira más por unidad de área basimétrica y la menos eficiente en el uso del agua. El fresno (Fraxinus excelsior L.) es la única especie que reacciona al déficit de humedad del suelo. La falsa acacia, una vez se ha establecido en el bosque de ribera, favorecida por gestiones forestales intensivas, muestra su gran capacidad de persistencia en él y el acopio de recursos hídricos en detrimento de las demás especies autóctonas.
Article
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L’interès creixent per l’estudi del paisatge i de la seva dinàmica pretèrita i present dóna lloc a la utilització d’un gran nombre de metodologies que requereixen una aproximació transdisciplinària a partir de mètodes i de tècniques molt diferents. La proposta que es presenta aquí consisteix a interpretar el funcionament de l’espai geogràfic (entès com un sistema complex) mitjançant l’ús complementari de diversos tipus de fonts d’informació (paleobotàniques, documentals i edàfiques). El resultat és un paisatge condicionat per la dinàmica dels elements que en formen part, dels quals l’acció humana és el factor decisiu.
Article
Aim The aim was to create global maps of foliar nitrogen‐to‐phosphorus (N:P) ratios across ecosystems, based on modelled climate, soil, and N and P deposition data, to identify global drivers of woody vegetation N:P ratios and to explore the role of genetic legacy (phylogenetics) in foliar N:P ratios of woody plants. Location Woody cover globally. Time period Present; data collected from 1990 to 2016. Major taxa studied Woody plants. Methods We compiled a database of 20,851 foliar N:P records and assigned them into boreal, temperate coniferous, temperate broadleaved and tropical groups. We applied neural networks to predict N:P global distribution maps, generalized linear models to assess environmental drivers and generalized linear mixed models to disentangle the effect of genetic legacy. Results and main conclusions Foliar N:P ratios are negatively associated with latitude, with higher N:P ratios occurring in tropical forests and lower N:P ratios in boreal forests. Globally, N:P ratios indicate greater levels of P limitation than N limitation. The influence of environmental factors varied among the four forest biomes, probably owing to contrasting combined environmental conditions; this finding would have been obscured had we conducted a single “forest biome” analysis. Genetic legacy explained significant variation in woody plant foliar N:P ratios, and we suggest its inclusion in future studies to improve N:P ratio predictions.
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This paper investigates the mechanisms involved in the dispersion, structure, and mixing in the vertical column of atmospheric pollen. The methodology used employs observations of pollen concentration obtained from Hirst samplers (we will refer to this as surface pollen) and vertical distribution (polarization-sensitive lidar), as well as nested numerical simulations with an atmospheric transport model and a simplified pollen module developed especially for this study. The study focuses on the predominant pollen type, Pinus, of the intense pollination event which occurred in the region of Barcelona, Catalonia, NE Spain, during 27–31 March 2015. First, conversion formulas are expressed to convert lidar-derived total backscatter coefficient and model-derived mass concentration into pollen grains concentration, the magnitude measured at the surface by means of aerobiological methods, and, for the first time ever, a relationship between optical and mass properties of atmospheric pollen through the estimation of the so-called specific extinction cross section is quantified in ambient conditions. Second, the model horizontal representativeness is assessed through a comparison between nested pollen simulations at 9, 3, and 1 km horizontal resolution and observed meteorological and aerobiological variables at seven sites around Catalonia. Finally, hourly observations of surface and column concentration in Barcelona are analyzed with the different numerical simulations at increasing horizontal resolution and varying sedimentation/deposition parameters. We find that the 9 or 3 km simulations are less sensitive to the meteorology errors; hence, they should be preferred for specific forecasting applications. The largest discrepancies between measured surface (Hirst) and column (lidar) concentrations occur during nighttime, where only residual pollen is detected in the column, whereas it is also present at the surface. The main reason is related to the lidar characteristics which have the lowest useful range bin at ∼ 225 m, above the usually very thin nocturnal stable boundary layer. At the hour of the day of maximum insolation, the pollen layer does not extend up to the top of the planetary boundary layer, according to the observations (lidar), probably because of gravity effects; however, the model simulates the pollen plume up to the top of the planetary boundary layer, resulting in an overestimation of the pollen load. Besides the large size and weight of Pinus grains, sedimentation/deposition processes have only a limited impact on the model vertical concentration in contrast to the emission processes. For further modeling research, emphasis is put on the accurate knowledge of plant/tree spatial distribution, density, and type, as well as on the establishment of reliable phenology functions.
Article
Droughts chronically alter resource availability in forest ecosystems. The increased frequency and severity of such extreme climate events challenge the acclimation potential of tree species especially across the drought-prone Mediterranean region. Pinus nigra is a widely distributed tree species in the Mediterranean region and considered vulnerable to extreme droughts. We used a 1000 km latitudinal gradient from northern Morocco to north-eastern Spain incorporating four regions (Edge-South, Core-South, Core-North and Edge-North) and including different P. nigra provenances. We aim to identify the climate and forest structure related drivers that influence tree radial growth (BAI, basal area increment). We developed statistical models for BAI by incorporating the potential effects of climate and forest structure (diameter and age distributions). Then, we forecasted the future growth of P. nigra forests during the 21 st century considering the emission scenario A2 with an expected increase of +2.7º C at the end of this century. Our results showed large variability across P. nigra populations in terms of environmental conditions, forest structure, and growth. The northernmost P. nigra populations, subjected to wetter and cooler conditions were those presenting the lowest BAI (4.9 cm 2 ), whereas the southernmost P. nigra populations subjected to drier and warmer conditions presented the highest BAI values (11.5 cm 2 ). Pinus nigra growth was enhanced by high spring precipitation, but this positive effect was probably modulated by forest structure. Temperature explained a higher proportion of the BAI variance than precipitation, with warmer summer conditions decreasing growth. Growth projections forecasted a decline in BAI (from 9.6 to 7.0 cm 2 ) across all ecological regions starting around the mid-21 st century but being lower in Edge-North populations compared to the other populations. Our study provides quantitative knowledge related to how P. nigra populations have been growing across four distinctive ecological regions. We also provide a forecasting tool that incorporates both climate and stand structure related information to project dynamics in tree populations.
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Technical Report
En present document hi trobem tot allò referent a les metodologies, les escales de seguiment i els protocols de seguiment específics dels indicadors de la biodiversitat. Cal destacar que aquests són les metodologies i protocols a data de 15 de març i, per tant, poden estar sotmesos a canvis donat que alguns encara no s'han implementat i/o que un cop implementats necessiten d'una avaluació.
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This case study illustrates the equivalency analysis for estimating ex post environmental damage and appropriate compensatory remediation following a severe wildfire caused by a power line in a forest protected under the European Union Habitats Directive (HD). The study addresses long-term environmental damage (e.g., over several decades) by a large-scale disturbance in a terrestrial ecosystem, and includes an analysis of uncertainty associated with the potential occurrence of natural future fire events in the area. Accounting for the probability of natural future forest fires directly affects both baseline and compensatory remediation options by reducing the habitat area compared to an assumption of no future forest fires. Only natural forest fires, i.e., 10% of all forest fires, have been included in the calculations of both the baseline and the compensatory remediation, since the operator may not be made liable for accidental or provoked forest fires. The impact of this hypothesis is tested by means of a sensitivity analysis. The case study illustrates: • Considerations in selecting a metric from various potential ones (hectares, trees, biomass, habitat quality) for terrestrial habitats included in the HD; • Application of a value equivalency approach (specifically, value-to-value); • Analysis of key variables (e.g., differences in metrics, single/multiple metrics, on-site/off-site implementation); and • Sensitivity of the results to changes in four key model parameters (i.e. area of future forest fires, tree mortality, percentage of natural forest fires and tree minimum diameter at breast height).
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The increase in aridity, mainly by decreases in precipitation but also by higher temperatures, is likely the main threat to the diversity and survival of Mediterranean forests. Changes in land use, including the abandonment of extensive crop activities, mainly in mountains and remote areas, and the increases in human settlements and demand for more resources with the resulting fragmentation of the landscape, hinder the establishment of appropriate management tools to protect Mediterranean forests and their provision of services and biodiversity. Experiments and observations indicate that if changes in climate, land use and other components of global change, such as pollution and overexploitation of resources, continue, the resilience of many forests will likely be exceeded, altering their structure and function and changing, mostly decreasing, their capacity to continue to provide their current services. A consistent assessment of the impacts of the changes, however, Forests 2017, 8, 463; doi:10.3390/f8120463 www.mdpi.com/journal/forests Forests 2017, 8, 463 2 of 37 remains elusive due to the difficulty of obtaining simultaneous and complete data for all scales of the impacts in the same forests, areas and regions. We review the impacts of climate change and other components of global change and their interactions on the terrestrial forests of Mediterranean regions, with special attention to their impacts on ecosystem services. Management tools for counteracting the negative effects of global change on Mediterranean ecosystem- services are finally discussed.
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A positive relationship between tree diversity and forest productivity is reported for many forested biomes of the world. However, whether tree diversity is able to increase the stability of forest growth to changes in climate is still an open question. We addressed this question using 36,378 permanent forest plots from National Forest Inventories of Spain and Québec (Eastern Canada), covering five of the most important climate types where forests grow on Earth and a large temperature and precipitation gradient. The plots were used to compute forest productivity (aboveground woody biomass increment) and functional diversity (based on the functional traits of species). Divergence from normal levels of precipitation (dryer or wetter than 30-year means) and temperature (warmer or colder) were computed for each plot from monthly temperature and precipitation means. Other expected drivers of forest growth were also included. Our results show a significant impact of climate divergences on forest productivity, but not always in the expected direction. Furthermore, although functional trait diversity had a general positive impact on forest productivity under normal conditions, this effect was not maintained in stands having suffered from temperature divergence (i.e., warmer conditions). Contrary to our expectations, we found that tree diversity did not result in more stable forest’s growth conditions during changes in climate. These results could have important implications for the future dynamics and management of mixed forests worldwide under climate change.
Conference Paper
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Los itinerarios de gestión forestal ORGEST son un conjunto de actuaciones silvícolas preestablecidas desarrollados en Catalunya para la gestión de distintas masas forestales con distintos objetivos de gestión. Los criterios de actuación en los modelos ORGEST se establecen en relación a unas condiciones ambientales que en el actual contexto de cambio climático se verán alteradas. El objetivo de este estudio es evaluar y comparar algunos de los itinerarios ORGEST para el pino silvestre (Pinus sylvestris L.) y la encina (Quercus ilex L.), bajo distintos escenarios de cambio climático, para un conjunto de variables objetivo, y para una misma parcela. Para ello, se ha utilizado el modelo de simulación de crecimiento forestal GOTILWA+. Se observa que en un escenario de cambio climático moderado los bosques de ambas especies ven reducido su stock de carbono. En el caso de un escenario de cambio climático más extremo, por contra, se observa como el bosque de Q. ilex aumenta su stock de carbono. El bosque de P. sylvestris, si bien en un inicio incrementa la capacidad de almacenar carbono, al final dicho incremento termina siendo contrarrestado por el aumento en aridez. Los distintos itinerarios de gestión aplicados incrementan entre un 60-90% la producción primaria neta (PPN), siendo los itinerarios de turno más corto los que más la incrementan. Los itinerarios de Q. ilex no modifican su transpiración de forma sensible, mientras que, para un bosque gestionado de P. sylvestris, se proyecta una reducción de la transpiración de entre un 4 - 10%. Además, para P. sylvestris, se proyecta una extracción anual de madera de 3,1-4,3 m3·ha-1·año-1 (itinerarios largo y corto, respectivamente) para un escenario climático actual, con una reducción del 25-15% en un escenario de clima moderado, y un incremento del 15-40% en un escenario de cambio extremo. Para Q. ilex, la extracción anual es de 1,6-2,3 m3·ha-1·año-1, con una reducción del 40-45% en condiciones de cambio climático moderado, y un aumento del 35-40 % en el escenario de cambio climático más extremo. Los itinerarios de turno más largo reducen la vulnerabilidad de la masa forestal a los incendios más que los de turno más corto. Escenarios de cambio climático más extremos incrementan, en ambas especies, su vulnerabilidad a los incendios. Los itinerarios de turno más corto, por contra, tienen valores superiores de producción neta por unidad de agua transpirada, y menor respiración de mantenimiento en relación a su producción. Dicha tendencia se mantiene en condiciones de cambio climático, aunque en el caso del pino la eficiencia de la gestión baja en condiciones de cambio climático, tanto moderado como extremo. Se concluye que, a parte de las características ambientales de la parcela, un gestor forestal debe de tener en cuenta también las proyecciones de cambio climático a la hora de determinar la gestión óptima, de un rodal.
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