Influência da estrutura da floresta na respiração do solo em diferentes sítios na Amazônia Central

Abstract

The role of tropical forests in global change has been studied for several years and by various researchers in the world, due to its size and interrelation with the greenhouse gases that influence the global warming. The objective of this study is to investigate the influence of forest structure on soil respiration in different sites. This research was carried out in the central Amazonia, in the metropolitan region of Manaus, covering 5 municipalities, Manaus, Itacoatiara, Rio Preto da Eva, Iranduba and Manacapuru. The dependent variables selected for the analyzes were the efflux of CO2, CH4 and N2O, which presented a mean of 6.23 μmolCO2m-²s-¹; -4.86 μmolCH₄m-².h-¹ and 1.33 μmolN₂Om-²h-¹, respectively. Correlation analyzes were performed to evaluate the relationships between forest variables, where basal area, maximum DAP and shannon index showed signs of correlation with soil respiration; in turn the soil air humidity, soil moisture and air temperature variables also presented correlations with CO2, CH4 and N2O fluxes. Regression analyzes were performed to investigate the possibility of prediction of CO2, CH4 and N2O fluxes. Prediction models were adjusted with forest structure variables such as Basal area, mean dap and Shannon index as well as from the edaphoclimatic variables. The averages of the parameters of the forest structure showed significant differences between the studied sites. The efflux of greenhouse gases from the ground, in the sites under forest cover did not present differences related to CO2, however they presented significant differences among some sites for CH4 and N2O efflux. The present study presented differences when comparing gas outflows between forest sites and at sites that have changed land use (after-forests).