Avaliação da dinâmica do Carbono em uma floresta manejada comercialmente no Amazonas

Abstract

Forests are important carbon sinks that contribute to mitigate climatic changes; therefore, measure carbon stock is fundamental to dimension this potential. This study aimed to evaluate the short and long term effects of a polycyclic silvicultural system, in the stock and carbon dynamics of a commercial managed forest in Amazonas. Data used in this study are from 41 permanent plots of one hectare of area. Every tree with DBH equal or above 15 cm was identified by the common name and had its diameter measured. Also the following variables were measured: stem identification class, silvicultural treatment, canopy lighting, form of canopy, damage and the presence of lianas. For biomass above ground quantification it was used equation of Chave et al. (2014) adjusted to humid rainforest. For carbon equation it was considered 50% of dry biomass. Carbon stock above ground estimated in the study area is 165,7 t.ha-1. Annual rates of recruitment and mortality in carbon were 2,94 and 0,38%, respectively, with values of Periodic Annual Increment in Carbon (PAIc) varying from 1,6 to 2,7 t.ha-1.year-1. The variables crown lighting and form of canopy presented significant correlation with the periodic annual increment in carbon for the periods evaluated, which didn’t occur with the variables stem identification class and presence of lianas. In the analysis of variance there was significant difference between PAIc and the canopy lighting and canopy form in every period analyzed. Comparing forest carbon stock before and after logging, considering recruitment and mortality, only carbon stocks of 2001 and 2014 in UPA C did not present significant difference, in relation to UPAs B and D, all comparisons of before and after logging presented significant difference. For the carbon paired average there was significant difference before and after logging for all UPAs and intervals, showing that the carbon stock has been presenting a tendency of growth over time. In the analyses of variance with repeated averages, stocks analyzed varied significantly over time, it did not occur in the interaction time x UPA. Accordingly to Markov chains projections the units of annual production (UPA B, C and B) presented statistic difference of projections estimated and observed for 2014. Markov chain was not fit to medium term projections.