Untangling the determinants of macrophyte beta diversity in tropical floodplain lakes: insights from ecological uniqueness and species contributions

Deconstructing beta diversity patterns into site or species contributions is a modern approach to understand the factors affecting variation in biodiversity. In this context, estimating the Local Contribution to Beta Diversity (LCBD) and the individual Species Contribution to Beta diversity (SCBD) have been shown to be a good approach to improve knowledge of the drivers of beta diversity. We examined the beta diversity of macrophytes surveyed at 49 floodplain lakes in the Pantanal Wetlands in Brazil during the dry season. We found that, unexpectedly, total species richness was not correlated to LCBD values, but the number of rare species per site was possibly related to LCBD values. Three variables from Moran's Eigenvector Maps (MEM), water transparency and organic matter were the main variables related to LCBD values. The species with highest contributions to beta diversity were those that occurred at approximately half of the surveyed sites. The same patterns were observed when analysing macrophyte data divided by life forms. Of the life forms, floating macrophytes contributed most to beta diversity. The understanding of which factors drive variation in LCBD and which kind of species most contribute to SCBD are fundamental to performing efficient conservation and restoration programs to maintain the structural, functional and ecological diversity of the macrophyte communities in dynamic floodplain ecosystems.