Natural regeneration of tree species following reduced-impact logging in eastern Amazonia

Abstract

Logging activities may reduce the potential for establishment and growth of natural regeneration in tropical forests through changes in soil properties such nutrient concentration and community dynamics. However, the sustainability of forest management is supported by the natural regeneration of species, whose mechanisms have been investigated by foresters and ecologists with the objective of identifying the longterm impacts of logging disturbances on tropical forests, crucial to biodiversity conservation. Numerous studies have addressed the dynamics of tropical forests after gaps formations, always based on a previously existing vegetation and floristic composition. Canopy gaps are fundamental importance to maintain diversity in tropical forests, providing environments that allow the establishment of new individuals due to an availability of resources. The objective of this work was to evaluate the responses of the natural regeneration of tree species present in logging gaps through a chronosequence of 14 years of logged forests, evaluating density of individual and species richness in each of the years studied, comparing with a control area of mature unlogged forest. The study was carried out in Fazenda Rio Capim, a forest management area (FMA) belonging to the company Cikel Brasil Verde Madeiras Ltda. The data were sampled in November 2014 and November 2015 within canopy gaps opened due to tree felling in the years of 2000, 2001, 2002, 2003, 2004, 2006, 2008, 2010, 2012. A total of 243 gaps from eight years of logging were sampled over a 14-year chronosequence and a control area. Considering the values found in this thesis in relation to the diversity of individuals and species in the logged areas, the results did not show statistical differences, demonstrate that the intensity of logging used in the areas studied did not generate an increase in regeneration. About the environments inside gaps (Center, Intermediate and border), confirming again the intensity of logging was not enough to generate changes in the environments, no statistical differences were found. Considering logging still occurs in rainforests around the world, our results may provide valuable knowledge to understand long-term intensive logging impacts and forest recovery ability.