Small-scale edaphic heterogeneity as a floristic–structural complexity driver in Seasonally Dry Tropical Forests tree communities

Abstract

Our work aimed to test the hypothesis that soil microscale heterogeneity act as a community ecological driver, increasing diversity and promoting structural shifts on the Seasonally Dry Tropical Forest (SDTF) tree community. We evaluated the relationship between microscale edaphic variations and floristic–structural patterns of tree communities in a SDTF fragment located in the southern end of the Brazilian Caatinga domain. Vegetation and soil data were obtained through 27 sample units of 400 m2 (20 m × 20 m), within each one we measured and identified at species level all arboreal individuals with Circumference at the Breast Height greater or equal to 10 cm, and also collected the soil samples. Through the data we evaluated soil variation influence on the tree community structural and floristic patterns trough generalized linear models. Soil explained the small-scale structural and floristic variations, contributing significantly to biomass, sprouting and to floristic relationships between sample units. It was also observed a possible relation of the result with the Caatinga domain biogeographic history, due the presence of Sedimentary Caatinga species, which are not expected for the study region. Soil plays an important role in driving small-scale complexity and diversity of SDTF, but we also suggest that Caatinga biogeographic events have influence on the high heterogeneity patterns.