Ch4 and n2 o fluxes from planted forests and native cerrado ecosystems in brazil

Abstract

Forest soils are N2 O sources and commonly act as CH4 sinks. This study evaluated the dynamics of the CH4 and N2 O fluxes of soils under Eucalyptus plantations and native Cerrado vegetation, as well as possible interactions between environmental factors and fluxes. The study was carried out in the Distrito Federal, Brazil, during 26 months, in three areas: in two stands of the hybrid Eucalyptus urophylla × Eucalyptus grandis, planted in 2011 (E1), and in 2009 (E2) and native Cerrado vegetation (CE). Measurements to determine the fluxes in a closed static chamber were carried out from Oct 2013 to Nov 2015. Soil and climate factors were monitored. During the study period, the mean CH4 fluxes were –22.48, –8.38 and –1.31 μg CH4 m–2 h–1 and the mean N2 O fluxes 5.45, 4.85 and 3.85 μg N2 O m–2 h–1 from E1, E2 and CE, respectively. Seasonality affected plantations in the studied sites. Cumulative CH4 influxes were calculated (year-1: –1.86 to-0.63 kg ha–1 yr–1; year-2: –1.85 to –1.34 kg ha–1 yr–1 ). Cumulative N2 O fluxes in the three sites were ≤ 0.85 kg ha–1 yr–1 . The change in land use from Cerrado to Eucalyptus plantations did not significantly changed regarding greenhouse gases (GHG), compared to the native vegetation. Flux rates of both gases (N2 O and CH4 ) were low. Temporal variations in GHG fluxes and different ages of the stands did not cause significant differences in cumulative annual fluxes.