Which regionalization scheme is the best to predict wetland plant distribution in Western Patagonia?

Abstract

Questions: Given the current multiplicity of threats to pond biodiversity, there is a clear need to examine which environmental drivers determine the composition and distribution of species. Using wetland plants as pond biodiversity surrogates, two questions led to this work: How do wetland plant species assemblages and abundance vary across local- and regional-scale classification schemes in wetlands? How does wetland plant beta-diversity vary within these wetland classification schemes?. Location: Western Patagonia, Argentina, from 36°S to 56°S and from 73°W to 65°W. Methods: Wetland plant distribution constrained by water and climatic factors was analyzed using canonical correspondence analysis. Variance partitioning analysis was performed to assess which classification scheme (phytogeographical units, wetland regions, wetland genesis and hydrogeomorphological types) better explained variation in plant composition. An IndVal analysis was also carried out to detect taxa with the highest association values (indicator taxa) for the different categories of wetland classification. Beta-diversity was calculated to evaluate variation patterns within classification schemes. Results: Plant distribution was mainly related to site location across the latitudinal gradient, following a decreasing pattern of air temperature from northern to southern wetlands. Variance partitioning analysis confirmed the effectiveness of a regional-scale classification (wetland regions) in predicting plant associations, and the IndVal analysis also highlighted this classification scheme above the remainder, sustaining the highest number of indicator taxa. Wetland plant beta-diversity patterns were explained by relatively high species turnover, with species composition showing low nestedness values. Conclusion: Climate factors rather than local characteristics were the main drivers of plant distribution at the wide regional scale analyzed. Wetland region (classification based on climatic criteria) was the most effective scheme in predicting plant associations and sustaining the highest number of indicator taxa. Also, ponds located in the Patagonian Andes and those with a glacigenic origin contribute most to the regional wetland plant diversity. Therefore, these aspects should be taken directly into account in the future delineation of protected areas to increase the resilience of Patagonian wetland habitats and their associated biota, and to maintain the ecosystem services that they provide.