Large-sized trees and altitude drive aboveground carbon stock in Brazilian Atlantic Cloud Forests: An approach based on carbon hyperdominant taxa.

Research about patterns of aboveground carbon stock (AGC) across different tropical forest types is central to climate change mitigation efforts. However, the aboveground carbon stock (AGC) quantification for Brazilian cloud forest ecosystems along the altitudinal gradient is still scarce. We aimed to evaluate the effects of abiotic and biotic on AGC and the AGC distribution between species and families of tree communities along an altitudinal Brazilian Atlantic cloud forest gradient of the Mantiqueira Mountain Range, Southeastern Brazil. We analyzed the relationships between AGC and biotic (taxonomic and functional diversity based on structural attributes) and abiotic factors (altitude and soil properties) across seventy plots (10 × 20 m) distributed in seven cloud forest sites at different elevations (from 1.100 to 2.330 m a.s.l.) using linear mixed models and machine learning approaches. We found significant variations in AGC stock along the altitudinal gradient, which was explained mainly by altitude and large-sized trees. We observed that approximately 5 % of the total sampled individuals were responsible for >50 % of the AGC stock of the tree community in the different sites. This result demonstrates how carbon-dominant tree species' have a higher relative contribution to the AGC at community level than species richness and abundance. The Myrtaceae was the most species-rich and carbon-dominant family, which holds four of the total hyperdominant species in the study region. This study reveals new and important ecological patterns of AGC stock in Southeastern Brazil's cloud forest tree communities, where large-sized trees and altitude are the main biotic and abiotic factors, respectively. These insights enhance our understanding of AGC stock in these unique forest ecosystems and emphasize the need for targeted conservation strategies that protect dominant species and their habitats.