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Wasof, S., Lenoir, J., Hattab, T., Jamoneau, A., Gallet-Moron, E., Ampoorter, E., et al. (2018). Dominance of individual plant species is more important than diversity in explaining plant biomass in the forest understorey. J. Veg. Sci., 29(3), 521–531.
Résumé: QuestionsHow does plant community diversity influence variation in plant biomass? There are two competing hypotheses: the biomass ratio' hypothesis, where biomass is influenced by the abundance and traits of the most dominant species, and the diversity' hypothesis, where the diversity of organisms influences biomass through mechanisms such as niche complementarity. However, no studies have tested which one of these two hypotheses better explains the variation in plant biomass in the forest understorey. LocationTemperate deciduous forests in northern France. MethodsFor the forest understorey, we assessed species diversity and biomass as well as soil and light conditions in 133 forest plots of 100m(2) each. Using mixed-effect models and after controlling for potential confounding factors, we tested the biomass ratio' hypothesis by relating the relative abundance of the most dominant species across our study sites and the CWM of plant traits (leaf area and plant height) to biomass. The diversity' hypothesis was tested by relating biomass to various measures of taxonomic, functional and phylogenetic diversity. ResultsBiomass of the forest understorey was mainly related to the relative abundance and the trait values of the most dominant species, supporting the biomass ratio' hypothesis. In contrast to the diversity' hypothesis, functional diversity indices had a negative impact on biomass. We found no contribution of taxonomic or phylogenetic diversity indices. ConclusionThe abundance and traits of the most dominant species matter more than taxonomic, functional or phylogenetic diversity of the forest understorey in explaining its biomass. Thus, there is a need for experiments that aim to fully understand keystone species' responses to on-going changing biotic and abiotic conditions and to predict their effects on ecosystem functioning and processes.
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Qian, H., Jin, Y., Leprieur, F., Wang, X., & Deng, T. (2020). Geographic patterns and environmental correlates of taxonomic and phylogenetic beta diversity for large-scale angiosperm assemblages in China. Ecography, .
Résumé: A full understanding of the origin and maintenance of beta-diversity patterns in a region requires exploring the relationships of both taxonomic and phylogenetic beta-diversity (TBD and PBD, respectively), and their respective turnover and nestedness components, with geographic and environmental distances. Here, we simultaneously investigated all these aspects of beta-diversity for angiosperms in China. Specifically, we evaluated the relative importance of environmental filtering vs dispersal limitation processes in shaping beta-diversity patterns. We found that TBD and PBD as quantified using a moving window approach decreased towards higher latitudes across the whole of China, and their turnover components were correlated with latitude more strongly than their nestedness components. When quantifying beta-diversity as pairwise distances, geographic and climatic distances across China together explained 60 and 53% of the variation in TBD and PBD, respectively. After the variation in beta-diversity explained by climatic distance was accounted for, geographic distance independently explained about 23 and 12% of the variation in TBD and PBD, respectively, across China. Overall, our results suggest that environmental filtering based on climatic tolerance conserved across lineages is the main force shaping beta-diversity patterns for angiosperms in China.
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Qian, H., Jin, Y., Leprieur, F., Wang, X., & Deng, T. (2020). Patterns of phylogenetic beta diversity measured at deep evolutionary histories across geographical and ecological spaces for angiosperms in China. J. Biogeogr., .
Résumé: Aim Understanding patterns and drivers of phylogenetic beta diversity in a region is important to understanding the origin and maintenance of the regional species diversity and variation in species diversity between local sites. Here we used a phylogenetic beta diversity metric quantifying deep evolutionary histories to explore geographical and ecological patterns of phylogenetic beta diversity in angiosperm assemblages across China. Location China. Taxon Flowering plants (angiosperms). Methods China was divided into 100 x 100 km grid cells. Species composition in each grid cell was documented. We used a basal-weighted metric (D-pw) to quantify phylogenetic beta diversity among angiosperm assemblages with two sampling approaches (neighbourhood approach and pairwise approach). D-pw was related to latitude and climatic conditions of angiosperm assemblages and to geographical and climatic distances between angiosperm assemblages across China. Results We found that the southeastern portion of China has much higher D-pw than the northwestern portion of China. The line of high versus low values of D-pw across China is generally consistent with the line of 500-mm precipitation per year. Our study shows that precipitation is associated with D-pw more strongly than temperature, and D-pw decreases with latitude, particularly in the eastern part of China. Main conclusions The emergence of the observed pattern of basal-weighted phylogenetic beta diversity is at least partly because the southeastern portion of China retains a large number of Tertiary relicts, making it a biogeographical museum, whereas many Tertiary relicts went extinct from the northwestern portion of China, particularly the Tibetan Plateau, due to the uplift of the plateau and the Himalayas, which makes the region a biogeographical grave for Tertiary relicts.
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Gaboriau, T., Albouy, C., Descombes, P., Mouillot, D., Pellissier, L., & Leprieur, F. (2019). Ecological constraints coupled with deep-time habitat dynamics predict the latitudinal diversity gradient in reef fishes. Proc. R. Soc. B-Biol. Sci., 286(1911), 20191506.
Résumé: We develop a spatially explicit model of diversification based on palaeohabitat to explore the predictions of four major hypotheses potentially explaining the latitudinal diversity gradient (LDG), namely, the 'time-area', 'tropical niche conservatism', 'ecological limits' and 'evolutionary speed' livpotheses. We compare simulation outputs to observed diversity gradients in the global reef fish fauna. Our simulations show that these hypotheses are nonmutually exclusive and that their relative influence depends on the time scale considered. Simulations suggest that reef habitat dynamics produced the LDG during deep geological time, while ecological constraints shaped the modern LDG, with a strong influence of the reduction in the latitudinal extent of tropical reefs during the Neogene. Overall, this study illustrates how mechanistic models in ecology and evolution can provide a temporal and spatial understanding of the role of speciation, extinction and dispersal in generating biodiversity patterns.
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