Geographical patterns of terrestrial herbs: a new component in planning the conservation of the Brazilian Atlantic Forest

The Brazilian Atlantic Forest (sensu lato) is constituted by Dense Ombrophilous Forest, Mixed Ombrophilous Forest and Seasonal Semideciduous Forest, in which tree species are distributed in gradients, whichever latitude, longitude, or altitude is considered. We investigated whether herb species living on the floor of these forests would have the same geographic distribution pattern. If tree and herb-layer species have coincident distribution patterns, the same conservation units can conserve both species sets; otherwise, specific conservation actions should be taken. We built a presence/absence matrix of 803 terrestrial native species in 80 surveys across the southern and southeastern Brazilian Atlantic Forest. We performed UPGMA, CA and RDA multivariate analyses in order to investigate the distribution patterns. The high degree of agreement among the analyses led us to assume that the geographic distribution of the herb-layer flora occurs as gradients among three main floristic groups: Tropical Ombrophilous forests (mostly lowland forests), Subtropical Ombrophilous forests (mostly montane and upper-montane forests in lower latitudes and sub-montane and lowland forests in higher latitudes, i.e., where temperature is lower), and Seasonal Semideciduous forests (with a marked dry season). Based on different patterns and processes between herbs and trees, and in order to encompass the highest flora diversity, we highlight the importance of creating more reserves in each one of the three main floristic groups of herb-layer species in the Brazilian Atlantic Forest.