Greenhouse Gas Emissions and Global Warming Potential of Reclaimed Forest and Grassland Soils

Abstract

Although greenhouse gas (GHG) emissions from soils are important, reclaimed mine soil (RMS) ecosystems are not widely assessed. Postreclamation land uses (forest, hay, and pasture) were investigated to: (i) monitor the magnitude of GHG fluxes, (ii) estimate their global warming potential (GWP), (iii) identify the relationship between GHG fluxes and soil properties, and (iv) develop a soil quality index by principal component analysis (PCA). The GHG fluxes were measured for 1 yr cycle and simultaneous measurements were also made for soil moisture and temperature. The RMS-forest, -hay, and -pasture land uses had weighted average fluxes of 1.16, 1.66, and 3.06 g CO(2)-C m(-2) d(-1); 0.33, 0.48 and 1.1 mg CH(4)-C m(-2) d(-1); and 0.33, 0.70, and 1.06 mg N(2)O-N m(-2) d(-1), respectively. The CO(2), CH(4), and N(2)O fluxes were consistently high in the RMS-pasture and low in the RMS-forest. The GWP (CO(2)-C equivalent) of the postreclamation land uses was in the order of RMS-forest (4.5 Mg ha(-1) yr(-1)) = RMS-hay (6.8 Mg ha(-1) yr(-1)) < RMS-pasture (12.3 Mg ha(-1) yr(-1)). The PCA showed that four PCs with eigenvalues > 1 explained 88.8% of the total variance in the soil properties. The first PC is mostly characterized by soil physical properties and the second by chemical properties. Soil and air temperatures were positively correlated with CO(2), CH(4), and N(2)O fluxes. The results suggest that GWP from RMS can be minimized by establishing forest land use.