Effects of Anthropogenic Activity on Aboveground Biomass and Carbon Stock in Upland and Seasonally Flooded Forests in Sierra Del Divisor National Park, Perú

Tropical Amazonian forests serve as critical carbon reservoirs, although their storage capacity varies significantly depending on the topographic, hydrologic, and successional heterogeneity of the landscape. This study quantified aboveground biomass (AGB) and carbon stocks across four vegetation units in the Tacshitea sector, Sierra del Divisor Na-tional Park (Peru): semi-dense flooded forest (Z1), hill forest (Z2), hill forest associated with secondary growth (Z3), and Mauritia flexuosa palm forest (Z4). We established 100 plots of 20 × 20 m (1 ha per zone), assessing all individuals with diameter at breast height (DBH) ≥ 10 cm using allometric equations validated for Amazonian ecosystems. A total of 2,363 individuals belonging to 158 species from 41 families were recorded. AGB varied sig-nificantly among vegetation units (Kruskal-Wallis, p < 0.001), with the highest values in Z1 (414.09 Mg ha⁻¹; 194.62 Mg C ha⁻¹) and Z2 (332.01 Mg ha⁻¹; 156.05 Mg C ha⁻¹), whereas Z3 and Z4 recorded substantially lower values (145.27–153.18 Mg ha⁻¹; 68.28–71.99 Mg C ha⁻¹). The Fabaceae family dominated carbon storage at the landscape scale (33.82%). Floristic diversity showed positive but weak associations with carbon storage (R² = 0.045–0.056), and this relationship lost significance when controlling for spatial structure using linear mixed-effects models (p = 0.409), indicating that structural attributes—particularly basal area and wood density—are more robust predictors of storage capacity than taxo-nomic richness per se. Beta diversity analysis revealed that floristic differentiation among zones was dominated by species turnover, explaining 26.5% of the variation by vege-tation unit (PERMANOVA, F = 11.55; p = 0.001). These results support the relevance of Sierra del Divisor National Park as a priority carbon sink in the western Peruvian Amazon and underscore the necessity of conservation strategies that integrate the structural heterogeneity of the forest mosaic.