Vegetation structure: Fine scale relationships with soil in a cerrado site

Abstract

There is a lack of understanding on factors influencing the occurrence of high species heterogeneity at fine scale in the Brazilian cerrado. Soil is a major determinant of vegetation in the Brazilian cerrado and an important candidate to influence species distribution at fine scales, since soil features vary at very small distances, whereas many environmental variables are relatively homogeneous at such scale. We tested plant–soil relationships at fine scales in a cerrado site. We placed 100 contiguous 25 m 2 plots, where we identified all woody individuals and measured several soil features. We did partial redundancy analysis, controlling for spatial autocorrelation, to test for relationships between soil features and floristic composition. We also did multiple regressions or spatial autoregressive models to test for relationships between soil features and: (1) the abundance of the five most common species, (2) total abundance, (3) richness, (4) evenness, and (5) diversity. We found weak relationships between soil and floristic composition, richness, and total abundance, which, coupled with also weak relationship found in another study with plant available water, indicate there is no major environmental variable influencing vegetation at fine scales, but several of them interacting. Organic matter was positively related with the abundance of Myrsine umbellata and was negatively related to evenness. Although a causal relationship cannot be inferred with certainty, the dominance of Myrsine umbellata seems to be related to a positive feedback with soil.