One sixth of Amazonian tree diversity is dependent on river floodplains

Abstract

Amazonia’s foodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of foodplains, our understanding of their species composition and how this may difer from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape foodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region’s foodplain forests. We show that the majority of Amazonian tree species can inhabit foodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on foodplains. The degree of specialization in foodplain communities is driven by regional food patterns, with the most compositionally diferentiated foodplain forests located centrally within the fuvial network and contingent on the most extraordinary food magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of foodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon’s tree diversity and its function.