Tree species composition and richness along altitudinal gradients as a tool for conservation decisions: the case of Atlantic semideciduous forest

Altitude is one of the major environmental variables influencing the distribution of tree taxa around the world, and can be a useful parameter for the development of conservation strategies. Our objectives were to obtain an overview of the conservation status of taxa from the Atlantic semideciduous seasonal forests of southeastern Brazil and check, among the floristically consistent altitudinal zones, which had the largest number of endemic, threatened and indicator species. To accomplish this, we used species occurrence and geo-climatic data from the 'NeoTropTree' database. First, we checked which zones were floristically consistent using an ordination method (non-metric multidimensional scaling, NMS) followed by an analysis of variance. Then, we conducted an indicator species analysis, estimated species richness, calculated the taxonomic distinctness index for all zones and evaluated important aspects for conservation, such as endemism and threat of extinction. Taxa richness, and number of endemic and threatened species decreased with increasing altitude, while the amount of indicator species for each zone increased with altitudinal elevation. These variations related to the altitudinal gradient should be considered when developing conservation strategies. We also should prioritise the conservation of the entire gradient and, whenever possible, include endemic and endangered species in forest recovery programs.