Together yet separate: variation in soil chemistry determines differences in the arboreal-shrub structure of two contiguous rupestrian environments

ABSTRACT Rupestrian landscapes are characterized by vegetation mosaics comprised of different plant communities and strongly linked to environmental filters. These environments are nutrient-impoverished, and possess water retention deficits and high solar exposure. This study aimed to determine whether chemical properties of the soil shape the arboreal-shrub vegetation structure in two neighboring habitats; a rupestrian cerrado and a rupestrian grassland. We hypothesized that the habitat with higher soil chemical properties would have higher parameters for vegetation structure, and different species composition. We expected higher chemical properties of the soil to favor a greater variety of plant life-forms. A total of 1349 individuals of 85 species belonging to 24 families were recorded; 1141 individuals (65 species) in the rupestrian cerrado, and 208 individuals (20 species) in the rupestrian grassland. Overall, Asteraceae, Fabaceae and Melastomataceae had greater species richness in both areas. Both habitats floristic composition was strongly influenced by differences in soil chemistry. In the cerrado, species richness, composition, soil nutrient availability and acidity were greater than in the grassland. We demonstrated that variation in soil chemistry influences plant species richness and composition, and structural complexity of vegetation, in both contiguous rupestrian environments, and that soil chemistry heterogeneity yields different plant life-form strategies.