Browsing by Subject "beta-diversity"

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  • Leboucher, Thibault; Budnick, William R.; Passy, Sophia; Boutry, Sebastien; Jannoneau, Aurelien; Soininen, Janne; Vyverman, Wim; Tison-Rosebery, Juliette (2019)
    Aim To quantify the relative contributions of local community assembly processes versus gamma-diversity to beta-diversity, and to assess how spatial scale and anthropogenic disturbance (i.e. nutrient enrichment) interact to dictate which driver dominates. Location France and the United States. Time period 1993-2011. Major taxa studied Freshwater stream diatoms. Methods beta-diversity along a nutrient enrichment gradient was examined across multiple spatial scales. beta-diversity was estimated using multi-site Sorensen dissimilarity. We assessed the relative importance of specialists versus generalists using Friedley coefficient, and the contribution of local community assembly versus gamma-diversity to beta-diversity across spatial scales, with a null model. Finally, we estimated the response of beta-diversity to environmental and spatial factors by testing the correlations between community, environmental and geographical distance matrices with partial Mantel tests. Results beta-diversity generally increased with spatial scale but the rate of increase depended on nutrient enrichment level. beta-diversity decreased significantly with increasing nutrient enrichment level due to the loss of specialist species. Local assembly was an important driver of beta-diversity especially under low nutrient enrichment. Significant partial Mantel correlations were observed between diatom beta-diversity and pure environmental distances under these conditions, highlighting the role of species sorting in local assembly processes. Conversely, in heavily enriched sites, only spatial distances were significantly correlated with beta-diversity, which indicated a substantial role of dispersal processes. Main conclusions Nutrient concentration mediated the expected increase in beta-diversity with spatial scales. Across spatial scales, beta-diversity was more influenced by local assembly processes rather than by gamma-diversity. Nutrient enrichment was associated with an overall decline in diatom beta-diversity and a shift in assembly processes from species sorting to dispersal, notably due to the elimination of some specialists and their subsequent replacement by generalists.
  • Graco-Roza, Caio; Aarnio, Sonja; Abrego, Nerea; Acosta, Alicia T. R.; Alahuhta, Janne; Altman, Jan; Angiolini, Claudia; Aroviita, Jukka; Attorre, Fabio; Baastrup-Spohr, Lars; Barrera-Alba, Jose J.; Belmaker, Jonathan; Biurrun, Idoia; Bonari, Gianmaria; Bruelheide, Helge; Burrascano, Sabina; Carboni, Marta; Cardoso, Pedro; Carvalho, Jose C.; Castaldelli, Giuseppe; Christensen, Morten; Correa, Gilsineia; Dembicz, Iwona; Dengler, Jurgen; Dolezal, Jiri; Domingos, Patricia; Erös, Tibor; Ferreira, Carlos E. L.; Filibeck, Goffredo; Floeter, Sergio R.; Friedlander, Alan M.; Gammal, Johanna; Gavioli, Anna; Gossner, Martin M.; Granot, Itai; Guarino, Riccardo; Gustafsson, Camilla; Hayden, Brian; He, Siwen; Heilmann-Clausen, Jacob; Heino, Jani; Hunter, John T.; Huszar, Vera L. M.; Janisova, Monika; Jyrkankallio-Mikkola, Jenny; Kahilainen, Kimmo K.; Kemppinen, Julia; Kozub, Lukasz; Kruk, Carla; Kulbiki, Michel; Kuzemko, Anna; Christiaan le Roux, Peter; Lehikoinen, Aleksi; Teixeira de Lima, Domenica; Lopez-Urrutia, Angel; Lukacs, Balazs A.; Luoto, Miska; Mammola, Stefano; Marinho, Marcelo M.; Menezes, Luciana S.; Milardi, Marco; Miranda, Marcela; Moser, Gleyci A. O.; Mueller, Joerg; Niittynen, Pekka; Norkko, Alf; Nowak, Arkadiusz; Ometto, Jean P.; Ovaskainen, Otso; Overbeck, Gerhard E.; Pacheco, Felipe S.; Pajunen, Virpi; Palpurina, Salza; Picazo, Felix; Prieto, Juan A. C.; Rodil, Ivan F.; Sabatini, Francesco M.; Salingre, Shira; De Sanctis, Michele; Segura, Angel M.; da Silva, Lucia H. S.; Stevanovic, Zora D.; Swacha, Grzegorz; Teittinen, Anette; Tolonen, Kimmo T.; Tsiripidis, Ioannis; Virta, Leena; Wang, Beixin; Wang, Jianjun; Weisser, Wolfgang; Xu, Yuan; Soininen, Janne (2022)
    Aim: Understanding the variation in community composition and species abundances (i.e., beta-diversity) is at the heart of community ecology. A common approach to examine beta-diversity is to evaluate directional variation in community composition by measuring the decay in the similarity among pairs of communities along spatial or environmental distance. We provide the first global synthesis of taxonomic and functional distance decay along spatial and environmental distance by analysing 148 datasets comprising different types of organisms and environments. Location: Global. Time period: 1990 to present. Major taxa studied: From diatoms to mammals. Method: We measured the strength of the decay using ranked Mantel tests (Mantel r) and the rate of distance decay as the slope of an exponential fit using generalized linear models. We used null models to test whether functional similarity decays faster or slower than expected given the taxonomic decay along the spatial and environmental distance. We also unveiled the factors driving the rate of decay across the datasets, including latitude, spatial extent, realm and organismal features. Results: Taxonomic distance decay was stronger than functional distance decay along both spatial and environmental distance. Functional distance decay was random given the taxonomic distance decay. The rate of taxonomic and functional spatial distance decay was fastest in the datasets from mid-latitudes. Overall, datasets covering larger spatial extents showed a lower rate of decay along spatial distance but a higher rate of decay along environmental distance. Marine ecosystems had the slowest rate of decay along environmental distances. Main conclusions: In general, taxonomic distance decay is a useful tool for biogeographical research because it reflects dispersal-related factors in addition to species responses to climatic and environmental variables. Moreover, functional distance decay might be a cost-effective option for investigating community changes in heterogeneous environments.
  • Hakkila, Matti; Abrego, Nerea; Ovaskainen, Otso; Monkkonen, Mikko (2018)
    Protected areas are meant to preserve native local communities within their boundaries, but they are not independent from their surroundings. Impoverished habitat quality in the matrix might influence the species composition within the protected areas through biotic homogenization. The aim of this study was to determine the impacts of matrix quality on species richness and trait composition of bird communities from the Finnish reserve area network and whether the communities are being subject of biotic homogenization due to the lowered quality of the landscape matrix. We used joint species distribution modeling to study how characteristics of the Finnish forest reserves and the quality of their surrounding matrix alter species and trait compositions of forest birds. The proportion of old forest within the reserves was the main factor in explaining the bird community composition, and the bird communities within the reserves did not strongly depend on the quality of the matrix. Yet, in line with the homogenization theory, the beta-diversity within reserves embedded in low-quality matrix was lower than that in high-quality matrix, and the average abundance of regionally abundant species was higher. Influence of habitat quality on bird community composition was largely explained by the species' functional traits. Most importantly, the community specialization index was low, and average body size was high in areas with low proportion of old forest. We conclude that for conserving local bird communities in northern Finnish protected forests, it is currently more important to improve or maintain habitat quality within the reserves than in the surrounding matrix. Nevertheless, we found signals of bird community homogenization, and thus, activities that decrease the quality of the matrix are a threat for bird communities.
  • Reverte Saiz, Sara; Reverte Saiz, Sara; Arnan, Xavier; Roslin, Tomas; Stefanescu, Constanti; Antonio Calleja, Juan; Molowny-Horas, Roberto; Hernández-Castellano, Carlos; Rodrigo, Anselm (2019)
    Large-scale spatial variability in plant-pollinator communities (e.g. along geographic gradients, across different landscapes) is relatively well understood. However, we know much less about how these communities vary at small scales within a uniform landscape. Plants are sessile and highly sensitive to microhabitat conditions, whereas pollinators are highly mobile and, for the most part, display generalist feeding habits. Therefore, we expect plants to show greater spatial variability than pollinators. We analysed the spatial heterogeneity of a community of flowering plants and their pollinators in 40 plots across a 40-km(2) area within an uninterrupted Mediterranean scrubland. We recorded 3577 pollinator visits to 49 plant species. The pollinator community (170 species) was strongly dominated by honey bees (71.8% of the visits recorded). Flower and pollinator communities showed similar beta-diversity, indicating that spatial variability was similar in the two groups. We used path analysis to establish the direct and indirect effects of flower community distribution and honey bee visitation rate (a measure of the use of floral resources by this species) on the spatial distribution of the pollinator community. Wild pollinator abundance was positively related to flower abundance. Wild pollinator visitation rate was negatively related to flower abundance, suggesting that floral resources were not limiting. Pollinator and flower richness were positively related. Pollinator species composition was weakly related to flower species composition, reflecting the generalist nature of flower-pollinator interactions and the opportunistic nature of pollinator flower choices. Honey bee visitation rate did not affect the distribution of the wild pollinator community. Overall, we show that, in spite of the apparent physiognomic uniformity, both flowers and pollinators display high levels of heterogeneity, resulting in a mosaic of idiosyncratic local communities. Our results provide a measure of the background of intrinsic heterogeneity within a uniform habitat, with potential consequences on low-scale ecosystem function and microevolutionary patterns.
  • Carrie, Romain; Ekroos, Johan; Smith, Henrik G. (2022)
    Biodiversity-benefits of organic farming have mostly been documented at the field scale. However, these benefits from organic farming to species diversity may not propagate to larger scales because variation in the management of different crop types and seminatural habitats in conventional farms might allow species to cope with intensive crop management. We studied flowering plant communities using a spatially replicated design in different habitats (cereal, ley and seminatural grasslands) in organic and conventional farms, distributed along a gradient in proportion of seminatural grasslands. We developed a novel method to compare the rates of species turnover within and between habitats, and between the total species pools in the two farming systems. We found that the intrahabitat species turnover did not differ between organic and conventional farms, but that organic farms had a significantly higher interhabitat turnover of flowering plant species compared with conventional ones. This was mainly driven by herbicide-sensitive species in cereal fields in organic farms, as these contained 2.5 times more species exclusive to cereal fields compared with conventional farms. The farm-scale species richness of flowering plants was higher in organic compared with conventional farms, but only in simple landscapes. At the interfarm level, we found that 36% of species were shared between the two farming systems, 37% were specific to organic farms whereas 27% were specific to conventional ones. Therefore, our results suggest that that both community nestedness and species turnover drive changes in species composition between the two farming systems. These large-scale shifts in species composition were driven by both species-specific herbicide and nitrogen sensitivity of plants. Our study demonstrates that organic farming should foster a diversity of flowering plant species from local to landscape scales, by promoting unique sets of arable-adapted species that are scarce in conventional systems. In terms of biodiversity conservation, our results call for promoting organic farming over large spatial extents, especially in simple landscapes, where such transitions would benefit plant diversity most.