Demographic dynamics of a tropical montane rainforest: resilience to drought and implications for biodiversity conservation

Abstract

Understanding how montane rainforests respond to disturbances is essential for identifying mechanisms that sustain biodiversity and ecosystem services under climate change. This study examined the structure, diversity, and dynamics of a tropical montane rainforest in Caparaó National Park, Brazil, over 10 years, following a severe drought. We analyzed biotic (e.g., species richness and canopy cover) and abiotic variables (e.g., elevation and slope) influencing demographic processes across forest strata and species groups. Data were collected from two inventories of permanent plots, and analyses included diversity indices, demographic rates, and linear models to assess relationships between environmental factors and forest dynamics. The results showed no significant changes in stem density or total basal area, indicating structural stability. Diversity indices were high (Shannon = 5.00; Pielou = 0.84) and exceeded those of nearby montane forests. Mortality rates (2.06 % yr⁻¹) aligned with patterns in tropical forests at dynamic equilibrium, while recruitment (1.68 % yr⁻¹) and basal area gain (2.80 % yr⁻¹) highlighted the forest's resilience to drought. Tree survival was higher at lower elevations, on sun-exposed slopes, in soils with lower acidity, under dense canopies, and in areas with greater species richness (p = 0.042). Conversely, tree growth was more pronounced at higher elevations and in less dense canopies (p = 0.013). These findings underscore the importance of preserving montane forests as potential climate refugia due to their structural complexity and topographic heterogeneity, which buffer microclimatic extremes and enhance ecosystem resilience under climate change scenarios.