Efeitos do manejo florestal sustentável sobre a decomposição da serapilheira em uma floresta de terra firme na Amazônia Brasileira

Abstract

The rainforest has been drastically altered due to human actions, with increasing deforestation rates around the world and continually reducing its area. Thus, sustainable forest management emerges as an alternative to the use of forests, aiming to reduce the impacts of logging and enable the sustainable use of its resources. However, sustainable forest management still causes changes in the ecosystem, modifying species composition and ecosystem processes. Among these processes is nutrient cycling, which plays a key role in ecosystems, affecting productivity and vegetation structure. Thus, the aim of this study was to evaluate the effects of sustainable forest management and time elapsed after logging on the litter decomposition rate in a dryland forest in the Brazilian Amazon. The experiment was conducted in 11 areas with different years of exploration (2003 to 2017) and in a control area. To evaluate the effects of forest management on litter decomposition, 960 litter bags containing 10g of dry plant material were installed during the dry season and during the rainy season, totaling 80 litter bags in each evaluated area. From its installation, at 30, 60, 90 and 120 days, 20 litter bags were collected from each sampled area. To obtain decomposition rates, the weight of the plant material was calculated after 30, 60, 90 and 120 days of exposure. The results showed that the litter decomposition rate varied according to the year of harvest, the sampling period and the volume of wood harvested. Also, canopy cover had no influence on decomposition rate and there was no correlation between precipitation and decomposition rate. The results show a noticeable effect of increased litter decomposition rates in the exploited areas. This increased decomposition rate may contribute to post-logging growth and restructuring of the forest, releasing nutrients that will be used by pioneer species and remnant trees of the medium extract for growth. Changes in decomposition rates in areas 15 years after logging suggest that sustainable forest management causes long-term impacts on the nutrient cycling dynamics of the forest environment.