Fatores locais e espaciais influenciam a diversidade beta de macrófitas na Baía de Caxiuanã (Amazônia oriental).

Abstract

Understanding the patterns that determine species diversity among different localities arouses scientific interest, especially in the Amazon, which is one of the largest holders of biodiversity on the planet. Diversity patterns vary according to spatial scale, and beta diversity has been the focus of ecology in understanding community structure. Thus, the objective of this work was to analyze the beta diversity of macrophytes and their components in a region in the Caxiuanã National Forest (Eastern Amazon) and to investigate which environmental factors determine the change in species composition among the sampled sites. Our hypothesis is that spatial factors such as geographical distance and local factors (such as temperature, turbidity, conductivity, dissolved oxygen, depth and pH) influence macrophyte diversity in the Anapu River, Caxiuanã National Forest. For this purpose we collected macrophytes at 45 sites in a black water river (Rio Anapu). The species composition was determined by observation and recording of species. We measured limnological variables of the water and estimated the transparency of the water column. Aquatic macrophyte species responded well to physicochemical variations by changing species composition between sites, leading to higher beta diversity. This change was mainly due to species replacement (turnover) or at the expense of species loss and gain (nesting). In addition, the geographical distance between sites, electrical conductivity, turbidity, and pH were responsible for structuring the macrophyte community, corroborating our hypothesis. Our work brings new information about the patterns of macrophyte beta diversity in Amazonian ecosystems and especially in blackwater rivers. Besides helping to better understand the processes that structure the change in macrophyte species composition in these environments, it can also serve as a basis for future studies that address conservation.