Estrutura e filogenia de espécies arbóreas associadas a cavernas ao longo do rio Peruaçu

Abstract

Quaternary climatic oscillations were determinant in structuring Neotropical plant communities, promoting the contraction and expansion of forest formations. In transition zones between phytogeographic domains, caves in limestone outcrops may create stable microclimates that function as refugia for humid forest lineages within dry vegetation matrices. This study investigated how microscale environmental heterogeneity determines floristic and structural variation in vegetation, and whether cave-associated habitats show phylogenetic affinity with humid forests, functioning as paleorefugia. The study was conducted in Cavernas do Peruaçu National Park (MG), in a Cerrado-Caatinga transition zone, where 41 plots of 400 m² were established along the Peruaçu River, encompassing five distinct habitats: skylights, cave entrances, swampy areas, riparian forest, and deciduous forest. All trees with DBH ≥ 5 cm were sampled and soil samples were collected. The phylogenetic structure of habitats was compared with 108 regional areas of humid and dry forests. A total of 1,989 individuals of 154 species, 120 genera, and 46 families were sampled, with predominance of Fabaceae (21.6%), Rutaceae (11.3%), and Meliaceae (8.4%). Floristic composition included species typical of Cerrado, Caatinga, and Atlantic Forest. Beta diversity revealed high turnover among habitats and low nestedness, indicating strong environmental filtering. Models showed that edaphic variables (texture and phosphorus availability) explained 43-59% of structural variation. Phylogenetic analysis revealed distinct patterns: Entrada do Janelão (EJA) showed affinity with semi-deciduous forests, while Lapa do Rezar (LR) clustered exclusively with deciduous forests. Recent phylogenetic differentiation better explained variation among habitats. Results indicate that cave-associated habitats function as humid forest enclaves in dry environments, where stable microclimatic conditions favored lineage persistence during Quaternary climatic variations. These environments constitute important lithorefugia for regional phylogenetic diversity conservation