Armenteras D., Rodríguez N., Retana J. (2015) National and regional relationships of carbon storage and tropical biodiversity. Biological Conservation. 192: 378-386.EnllaçDoi: 10.1016/j.biocon.2015.10.014
Tropical forests host the highest levels of biodiversity and maintain some of the largest carbon stocks of all terrestrial ecosystems. Policies resulting from the United Nations Framework Convention on Climate Change (UNFCC) for forest-based climate change mitigation (e.g., Reducing Emissions from Deforestation and forest Degradation (REDD. +)) have been considered win-win solutions for both C storage and biodiversity conservation. Win-win solutions are indeed apparent when there is geographical overlap of high carbon density forests with high biodiversity, as suggested by many global studies. However, strong congruence between high carbon storage and biodiversity at the national and subnational levels is less obvious. To improve national policies and expectations of REDD. + outcomes, it is necessary to account for the potential risks of relocating deforestation activities from high-carbon areas to low-carbon areas, as such relocation may negatively affect high-biodiversity habitats. Using a combined dataset of global and national biodiversity and C storage, we examined whether the optimization of carbon and biodiversity is, as suggested, a win-win situation. We identified hotspots of C storage and of biodiversity within Colombia and the demographic and land use factors that affect the spatial distribution of the current patterns of biodiversity and C. We also identified and mapped two additional forest carbon and biodiversity relationships (areas with high carbon and low biodiversity and areas with low carbon and high biodiversity) that represented relevant conservation trade-offs at national and subnational levels. Our results suggest that, although C storage and biodiversity hotspots still overlap nationally and subnationally, the relationship between these two types of hotspots is weaker than that at the global level. Additionally, areas where high carbon and high biodiversity do not overlap are more extensive than potential win-win areas. Simultaneous carbon and biodiversity conservation is not as straightforward as it appears to be at the global level. Countries must swiftly identify areas where unintentional negative biodiversity consequences may result from national REDD. + strategies, and future research should identify the factors that affect C storage and biodiversity both at the national and subnational levels. © 2015 Elsevier Ltd.
Arnan X., Cerdá X., Retana J. (2015) Partitioning the impact of environment and spatial structure on alpha and beta components of taxonomic, functional, and phylogenetic diversity in European ants. PeerJ. 2015: 0-0.EnllaçDoi: 10.7717/peerj.1241
We analyze the relative contribution of environmental and spatial variables to the alpha and beta components of taxonomic (TD), phylogenetic (PD), and functional (FD) diversity in ant communities found along different climate and anthropogenic disturbance gradients across western and central Europe, in order to assess the mechanisms structuring ant biodiversity. To this aim we calculated alpha and beta TD, PD, and FD for 349 ant communities, which included a total of 155 ant species; we examined 10 functional traits and phylogenetic relatedness. Variation partitioning was used to examine how much variation in ant diversity was explained by environmental and spatial variables. Autocorrelation in diversity measures and each trait's phylogenetic signal were also analyzed.We found strong autocorrelation in diversity measures. Both environmental and spatial variables significantly contributed to variation in TD, PD, and FD at both alpha and beta scales; spatial structure had the larger influence. The different facets of diversity showed similar patterns along environmental gradients. Environment explained a much larger percentage of variation in FD than in TD or PD. All traits demonstrated strong phylogenetic signals. Our results indicate that environmental filtering and dispersal limitations structure all types of diversity in ant communities. Strong dispersal limitations appear to have led to clustering of TD, PD, and FD in western and central Europe, probably because different historical and evolutionary processes generated different pools of species. Remarkably, these three facets of diversity showed parallel patterns along environmental gradients. Trait-mediated species sorting and niche conservatism appear to structure ant diversity, as evidenced by the fact that more variation was explained for FD and that all traits had strong phylogenetic signals. Since environmental variables explained much more variation in FD than in PD, functional diversity should be a better indicator of community assembly processes than phylogenetic diversity. © 2015 Arnan et al.
Pascual D., Pla E., Lopez-Bustins J.A., Retana J., Terradas J. (2015) Impacts of climate change on water resources in the Mediterranean Basin: a case study in Catalonia, Spain [Impacts du changement climatique sur les ressources en eau dans le bassin méditerranéen : une étude de cas en Catalogne, Espagne]. Hydrological Sciences Journal. : 0-0.EnllaçDoi: 10.1080/02626667.2014.947290
Most climate change projections show important decreases in water availability in the Mediterranean region by the end of this century. We assess those main climate change impacts on water resources in three medium-sized catchments with varying climatic conditions in northeastern Spain. A combination of hydrological modelling and climate projections with B1 and A2 IPCC emission scenarios is performed to infer future streamflows. The largest reduction (34%) in mean streamflows (for 2076–2100) is expected in the headwaters of the two wettest catchments, while lower decreases (25% of mean value for 2076–2100) are expected in the drier one. In all three catchments, autumn and summer are the seasons with the most notable projected decreases in streamflow, of 50% and 30%, respectively. Thus, ecological flows in the study area might be noticeably influenced by climate change, especially in the headwaters of the wet catchments.Editor Z.W. Kundzewicz © 2015 IAHS
Retana J., Arnan X., Cerdá X. (2015) A multidimensional functional trait analysis of resource exploitation in European ants. Ecology. 96: 2781-2793.EnllaçDoi: 10.1890/14-2326.1
The major factors explaining ecological variation in plants have been widely discussed over the last decade thanks to numerous studies that have examined the covariation that exists between pairs of traits. However, multivariate relationships among traits remain poorly characterized in animals. In this study, we aimed to identify the main multivariate trait dimensions that explain variance in important functional traits related to resource exploitation in ants. To this end, we created a large ant trait database. This database includes information on 11 traits that are important in ant resource exploitation; data were obtained for 150 European species found in different biomes. First, we examined the pairwise correlations between the traits included in the database. Second, we used multivariate analyses to identify potential trait dimensions. Our study shows that, to a great extent, resource exploitation strategies align along two main trait dimensions. The first dimension emerged in both the overall and group-specific analyses, where it accounted for the same pairwise trait correlations. The second dimension was more variable, as species were grouped by levels of taxonomy, habitat, and climate. These two dimensions included most of the significant pairwise trait correlations, thus highlighting that complementarity, but also redundancy, exists among different pairs of traits. The first dimension was associated with behavioral dominance: dominance was associated with large colony size, presence of multiple nests per colony, worker polymorphism, and a collective foraging strategy. The second dimension was associated with resource partitioning along dietary and microhabitat lines: it ranged from species that consume liquid foods, engage in group foraging, and mainly nest in the vegetation to species that consume insects and seeds, engage in individual foraging, and demonstrate strictly diurnal activity. Our findings establish a proficient ecological trait-based animal research that minimizes the number of traits to be measured while maximizing the number of relevant trait dimensions. Overall, resource exploitation in animals might be framed by behavioral dominance, foraging strategy, diet, and nesting habitat; the position of animal species within this trait space could provide relevant information about their distribution and abundance, for today as well as under future global change scenarios. © 2015 by the Ecological Society of America.
Vilà-Cabrera A., Martínez-Vilalta J., Retana J. (2015) Functional trait variation along environmental gradients in temperate and Mediterranean trees. Global Ecology and Biogeography. 24: 1377-1389.EnllaçDoi: 10.1111/geb.12379
Aim: Characterizing the variation of functional traits in nature is a first step towards linking environmental changes to changes in ecosystem function. Here we aim to characterize the spatial variability of major plant functional traits along wide environmental gradients in Mediterranean and temperate forests, and assess to what extent this variability differs between two dominant families in Northern Hemisphere forests: Fagaceae and Pinaceae. Location: Catalonia (north-east Iberian Peninsula). Methods: Four functional traits were selected to incorporate information on both the leaf and the wood economic spectra: maximum tree height (Hmax), wood density (WD), leaf mass per area (LMA) and nitrogen content of leaves (Nmass). We quantified the variance distribution of each functional trait across three nested ecological scales: population, species and family. Through such scales, we explored the spatial variation of functional traits through climatic and biotic gradients, as well as the covariation among traits. Results: Functional trait variability was distributed across all the ecological scales considered, but mostly at the family level, with functional traits differing markedly between Fagaceae and Pinaceae. Within families, variation in functional traits was similar or higher within species than between species. The spatial variability in functional traits was related to biotic and abiotic gradients, although this effect was quantitatively small compared with differences between families. Covariation among functional traits was not necessarily conserved across ecological scales. Trait covariation across all species was structured along the Hmax-WD and LMA-Nmass axes, but this structure was partially lost within families, where variation was mostly structured along the Hmax-LMA and WD-Nmass axes. Main conclusions: Intraspecific variation emerges as a fundamental component of functional trait structure along wide environmental gradients. Understanding the sources of intraspecific variation, as well as how it contributes to community assembly and ecosystem functioning, thus becomes a primary research question. © 2015 John Wiley & Sons Ltd.
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