Strong soil–vegetation relationship in riparian forests of the middle Rio Doce watershed, south-eastern Brazil

Abstract

Phytosociological surveys and soil quality studies are relevant tools for the implementation of restoration programmes. This study aimed to characterise the vegetation of the tree and sapling strata in preserved riparian forests of the middle portion of the Rio Doce watershed in the Atlantic Rain Forest, Brazil. In addition, we tested the association between edaphic factors and the vegetation community. We sampled three sites of the middle sector of the Rio Doce watershed in Itueta (two sites) and Santa Rita do Itueto (one site) municipalities in Minas Gerais, south-eastern Brazil. At each sampling site, we inventoried 15 plots of 100 m2 (10 × 10 m) for the tree stratum. Within each plot of the tree stratum we delimited a 25 m2 (5 × 5 m) plot, totalling 4 500 m2 and 1 125 m2 respectively for the tree and sapling strata. We employed co-inertia analysis to test the relationship between soil factors and the plant community and to highlight the taxon– environment relationship. We recorded 157 species belonging to 31 families, with 105 species from 24 families in the tree stratum, and 85 species from 22 families in the sapling stratum. Edaphic factors were highly heterogeneous among plots, although most of the plots presented soils with neutral pH and high fertility (base saturation > 50%). Co-inertia analyses showed highly significant associations between edaphic factors and the plant community, both for the tree (RV = 0.486, p < 0.001) and the sapling strata (RV = 0.692, p < 0.001). We highlighted the existence of a clear edaphic– floristic gradient, with a significant association of certain species with contrasting soil conditions. Knowledge about the association between environmental characteristics and floristic composition can assist in the selection of species with greater chances to establish in specific environmental conditions.