Changes in plant community driven by environment and space: an analysis in an Atlantic montane forest in southeastern Brazil

Abstract In tropical montane forests, floristic composition is shaped by a combination of edaphic, spatial, and climatic factors that reflect the environmental heterogeneity of these ecosystems. These characteristics, along with the diversification of species niches, contribute to the high rates of diversity in tropical regions. Our hypothesis was that tree species present a heterogeneous distribution pattern, that distribution is driven by edaphic and spatial variables, and phylogenetic variations occur along the altitudinal gradient. We demarcated eight plots (20 × 50 m, 0.8 ha), in which all individuals from the woody stratum with DBH ≥ 2.5 cm were sampled. We carried out soil collections and evaluated the canopy opening. We sampled 3584 individuals distributed across 399 species and morphospecies. Shannon’s diversity was 5.04 and Pielou’s evenness was 0.84. The variation partitioning analysis showed that only 12.8% of the variation in species composition was explained by environmental variables, spatial variables, and their shared fraction, while 87.2% remained unexplained. However, the tb-RDA ordination model combining edaphic and spatial predictors was statistically significant and its first two axes explained 45.9% of the variation in the species matrix, indicating strong species-environment relationships. There was a strong positive correlation between species and phylogenetic diversity. This study represents the first assessment of phylogenetic diversity in montane forests of Espírito Santo, demonstrating that plant communities and phylogenetic structure in highland tropical forests can be influenced by the joint effect between edaphic and spatial environmental variables, and that high species diversity in these environments is due to the occurrence of different niches and environmental heterogeneity.