Demanda conflitante entre serviços ecossistêmicos florestais: investigando a conversão de regulação em provisão em uma área de proteção integral no Nordeste do Brasil

Abstract

Currently, it is estimated that around 60% of forest ecosystem services have been degraded by human activities, which have dramatically transformed landscapes, with both acute and chronic disturbances. Our study investigated the conversion of the ecosystem service of regulation into provision through selective logging, and its drivers, in a chronosequence of Atlantic Forest under full protection regime. Our hypothesis was that the forest age, as a proxy for its physiognomy, the access to the forest and the structure of the vegetation determine the conversion of forest ecosystem services. The study was carried out at the Dois Irmãos State Park (PEDI), a protected area of Atlantic Forest, covering 1,157 ha and with three succession ages (mature forest, MF; late regenerating, LRF and initial regenerant, IRF). The data were collected in a PPBio module, in 10 plots of 1 ha, in which all the trees cut (stumps) were sampled. In the three ages, we evaluated as drivers of conversion of ecosystem services, variables of access (distance from urban area and slope) and supply in the assembly of live plants (PPBio database), collected in the same plots (total biomass, density, species richness). A mixed generalized linear model (GLMM) was performed to test our hypotheses. As a result, 290 stumps were registered, distributed as follows in the chronosequence: 216 in MF; 15 in LRF and 59 in IRF, which corresponds to 54 ind.ha-1, 5 ind.ha-1 and 20 ind.ha-1, respectively. Of the total stumps, 267 (92%) were in the degree of decomposition 1 and 2, and most were identified at the species level, generating a list of 55 species being explored (21% of that recorded in the assemblage of live plants). It was observed that the conversion reduced the assemblage by 2.8% of the available abundance of 9511 individuals and 0.37% (5.11 Mg / ha) of the total biomass (1393.89 Mg / ha) in one year. The cut was greater in abundance and richness in MF, significantly influenced by access (p <0.01) and by supply in the living assembly (p <0.05). Access also influenced the cut in the IRF, even with less richness (p = 0.024); while the lowest conversion was in LRF, despite the greater available supply of plants. The conversion takes place in more accessible areas, where the exploited abundance and richness will depend on the available supply. Such results show how deforestation has been chronically affecting the stability of the forest in question, pointing out that a portion of the human population living in the surrounding area is highly dependent on forest resources. We emphasize that over time the extraction of wood and the consequent subtraction of live biomass will lead to irreversible threat to forest resources, since most of the logged plants are small in diameter and affect forest regeneration. Thus, we emphasize that these practices are restrained by the managers of the protected area, and that strategies for monitoring forest resources are outlined.