Plant community assembly is predicted by an environmental gradient in high-altitude wetlands in the semiarid western Bolivian Andes

Abstract

The floristic composition and distribution of plant communities is the product of species-specific responses to localized environmental conditions often structured following environmental gradients. Although the importance of Andean high-elevation wetlands (bofedales) for provisioning ecosystem services has been critically emphasized in various studies, very little is known about how different micro-environmental factors shape their zonation and community assembly. Here we examined and quantified differences in herbaceous plant composition, alpha diversity, and aboveground biomass within waterlogged and dry habitats in three bofedales located in western Bolivia. Our results show that although alpha diversity was similar between both habitats, obligate wetland taxa were more abundant in waterlogged habitats whereas upland graminoids and halophytes were predominant in desiccated habitats. Furthermore, aboveground biomass of obligate wetland graminoids was higher in waterlogged habitats, while saline tolerant forbs exhibited higher aboveground biomass in desiccated habitats. Together these results suggest that soil water and organic matter content largely governs plant composition and biomass production but not alpha diversity in the studied high-altitude Andean wetlands. These results have important consequences for predicting plant species’ response to changes in the hydrological cycle due to habitat degradation and aridification caused by land use intensification and global climate change.