Carbono em vulnerabilidade: o estoque de carbono diante da perda de dispersores de semente

Abstract

Landscape management practices act unsustainably, leading to extinction of species and reducing ecosystem services offered by them. Carbon storage is one of the services that demonstrates high fragility in the face of animal species loss. Despite advances in understanding the relationship between the carbon storage and patterns of animal species extinction, we are missing information due natural ecosystems diversity and their threats. This dissertation sought to investigate how vulnerable is carbon stored by tree species dispersed by animals in different physiognomies of tropical ecosystems and what are the human and environmental variables influencing vulnerability. We used data from 136 vegetation areas. We split the tree species with diameter at breast height ≥ 5 cm in two categories: zoochorous (tree species dispersed by animals) and not zoochorous (tree species dispersed abiotically).The tree species dispersed by animals wereclassified regarding their vulnerability according to the diameter of the seed for each forest physiognomies. We calculate the amount of total carbon, carbon stored by the species dispersed by animals and vulnerable species. We build generalized linear models to analyze the differences in carbon between phytophysiognomies and logistic regression models to investigate the effect of anthropogenic and environmental variables that drives carbon storage in species dispersed by animals and vulnerable species. Finally, we simulated extinction scenarios for two environments: defaunated and random, and estimate the total amount of carbon lost. The proportion of carbon stored by the species dispersed by animals and vulnerable species showed differences between the physiognomies. The proportion of carbon stored in the species dispersed by animals presented significant and positive relationship with the amount of native vegetation and climates with higher temperatures and greater precipitation. The carbon stored in vulnerable species is positively driven by the amount of native vegetation coverage and also for high temperatures and greater precipitation; however, it is negatively affected by the average size of the fragments. The biggest carbon losses occur in defaunated environments, and the semideciduous forest is the more affected one. Our findings reinforce the fragility of carbon storage service, demonstrating that the loss of large vertebrates dispersers of seeds can affect about 20% of the carbon stored in aboveground biomass, worsening the climate crisis on the planet.