Examinando por Autor "de Bello, Francesco"

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Evidence of functional species sorting by rainfall and biotic interactions: A community monoliths experimental approach
(Wiley, 2019) Peralta, Ana M.L.; Sánchez, Ana M.; Luzuriaga, Arantzazu L.; de Bello, Francesco; Escudero, Adrián
1. Different abiotic and biotic sources of environmental heterogeneity have been proposed as determinants of community assembly, but few experimental studies have identified the processes and functional traits through which they operate. Thus, we aimed to experimentally determine the relationships between variations in functional structure according to spatiotemporal environmental heterogeneity to understand how biotic and abiotic drivers affect the highly dynamic nature of annual plant communities. 2. Entire annual plant communities were subjected to experimental manipulation of rain regimes (timing and amount) and perturbation of the biological soil crust (BSC; intact vs. perturbed) in a community common garden. We surveyed the experimental assemblages at different life stages (seedlings to reproductive adults) and characterized their functional structure (community weighted means and Rao) based on key functional traits. 3. We found an important filtering effect of rain timing and amount on the composition and functional structure. Drought conditions limited the community weighted means and diversity to better functionally equipped species in terms of stress resistance (high leaf dry matter content and low specific leaf area) and resource economy (short species with low reproductive ratios and higher root:shoot ratios), although the timing of drought could determine the intensity of the filtering effect. BSC acted as a filter on germination via seed mass and as a ‘biotic buffer’ in later stages by minimizing the stressful conditions during severe droughts decreasing evapotranspiration. 4. Synthesis. We found clear cause–effect relationships among abiotic and biotic factors and their interaction, and the experimental communities in terms of species composition and functional structure. We demonstrated the importance of rain regimes for shaping annual plant communities and identified germination as the main process determining the community assembly, suggesting phenotypic integration of a complete set of functional traits for resisting drought throughout the whole life cycle. The BSC–annual plant relationship shifted from negative by acting as a germination filter to positive by acting as a biotic buffer in later stages. We demonstrate the importance of evaluating these relationships at multiple 37 plant stages. The temporal and spatial heterogeneity related to the factors considered are key sources of niche differentiation that promote species coexistence.
Intraspecific variability drives functional changes in lichen epiphytic communities across Europe
(Ecological Society of America (ESA) ; Wiley, 2020-02-21) Hurtado, Pilar; Prieto, María; Aragón, Gregorio; de Bello, Francesco; Martínez, Isabel
Traditional approaches in trait-based community ecology typically expect that trait filtering across broad environmental gradients is largely due to replacement of species, rather than intraspecific trait adjustments. Recently, the role of intraspecific trait variability has been largely highlighted as an important contributor mediating the ability of communities to persist under changing conditions and determining the community-level trait variation, particularly across limited environmental gradients. Unfortunately, few studies quantify the relative importance of species turnover versus intraspecific variability mediating the response of communities different from vascular plants. Here, we studied the functional changes in epiphytic lichen communities within 23 beech forests across large latitudinal (ca. 3,000 km) and environmental gradients in Europe to quantify the relative contribution of species turnover and intraspecific variability and the role of climate controlling community-level trait changes. For 58 lichen species, we focused on a set of 10 quantitative functional traits potentially affected by climatic conditions and related to photosynthetic performance (n = 1,184 thalli), water use strategy (n = 1,018 thalli), and nutrient uptake (n = 1,179 thalli). Our results showed that intraspecific trait variability explained most of the functional changes in lichen communities in response to the latitudinal gradient. Further, such functional changes were determined by the covariation between intraspecific trait variability and species turnover, which varied in sign depending on the trait considered. Finally, different climatic predictors explained functional variation due to both intraspecific trait variability and species turnover. We propose that lichen communities cope with contrasting climatic conditions by adjusting the functional trait values of the most abundant species within the communities rather than by the replacement of the species. Consequently, intraspecific variability should be explicitly incorporated to understand the effect of environmental changes on lichen communities, even over large environmental variations, better. Our results challenge the universality of the hypothesis that species turnover chiefly drives functional trait changes across large environmental gradients and call for a wider test of such important assumptions in trait ecology in different organism types and ecosystems.