Dinâmica populacional e da biomassa acima do solo em floresta ombrófila densa montana, Espírito Santo, Brasil

Abstract

Tropical forests in montane environments are complex ecosystems essential for biodiversity conservation and carbon sequestration and storage. Understanding the dynamics of these ecosystems and the biotic and abiotic factors influencing them (e.g., altitude, slope, stem density, and canopy cover) is crucial for assessing their resilience to climate change and guiding conservation strategies. This study aimed to evaluate the effects of biotic and abiotic factors on the dynamics of Montane Ombrophilous Dense Forest located in Caparaó National Park, Espírito Santo. The understory and overstory strata were analyzed, along with dominant and low-abundance species groups. The study was conducted in eight permanent plots (50 m × 20 m), with a forest inventory carried out in 2012, before a severe drought period (2014 2017), and another in 2022, five years after the drought. During the inventories, all trees with a diameter at breast height (dbh identified. In the second inventory, records were made of whether the trees were dead, survived, or reached the minimum dbh for inclusion. Diversity indices and forest structure, as well as demographic rates for the entire community, diameter classes, and specific species groups, were calculated. Aboveground biomass (AGB) was estimated using an allometric equation applied to all components of forest dynamics. Topographic, structural, and functional variables were collected and related to ecological hypotheses of environmental filtering, vegetation quantity, biomass ratio, and niche complementarity. The results indicated high diversity indices (Shannon = 5.00) and evenness (Pielou = 0.84), as well as stability in individual density and total basal area between inventories (t-test, p > 0.05). The observed average mortality rate (2.06 % year 1 ) was consistent with typical patterns of tropical forests, while recruitment rates (1.68 % year 1 ) and basal area gain (2.80 % year 1 ) suggested active forest growth. AGB increased significantly between inventories: from 286.41 Mg ha in 2012 to 317.18 Mg ha 1 1 in 2022. Demographic dynamics were largely influenced by the understory due to the higher density of individuals in this stratum. Factors such as elevation, slope shading, canopy opening, and soil acidity contributed to higher turnover rates. AGB increments were more evident in plots with species exhibiting resource-conservative traits. Environmental filters associated with local topography and elevation drove initial biomass gains through young tree growth, while limiting conditions restricted increments for larger trees. These results suggested forest resilience to the drought experienced and that local topography and canopy structure may have been crucial for maintaining stable microclimates, indicating that the area may contain climate refugia for tree biodiversity and carbon storage. Therefore, identifying areas with high structural and topographic complexity and integrating them into management and conservation networks is fundamental to preserve their resilience and contribute to the local mitigation of ongoing climate change.