Effects of afforestation on soil CH4 and N2O fluxes in a nsubtropical karst landscape
2020
Chen, Ping | Zhou, Minghua | Wang, Shijie | Luo, Weijun | Peng, Tao | Zhu, Bo | Wang, Tao
Afforestation is of importance for terrestrial carbon sequestration as well as soil and water conservation in karst landscapes. However, few studies have evaluated the effects of afforestation on soil CH₄ and N₂O emissions in subtropical karst areas. Thus, a year-round field experiment was conducted to quantify the effects of afforestation on soil CH₄ and N₂O fluxes from a subtropical karst landscape in South China. In this study, soil CH₄ and N₂O fluxes were simultaneously monitored using static chamber-gas chromatography from three paired sites, including a cropland site (SC) and adjacent sites at two stages of afforestation, a shrubland (SD) and a woodland (AF). The results showed that annual soil CH₄ uptake for SC, SD, and AF sites were 1.53 ± 0.20 kg C ha⁻¹ yr⁻¹, 2.90 ± 0.20 kg C ha⁻¹ yr⁻¹, and 5.68 ± 0.18 kg C ha⁻¹ yr⁻¹, respectively. Afforestation (i.e., SD and AF sites) significantly increased soil CH₄ uptake compared with the adjacent cropland. Annual soil N₂O fluxes for SC, SD, and AF sites were 2.38 ± 0.17 kg N ha⁻¹ yr⁻¹, 0.94 ± 0.14 kg N ha⁻¹ yr⁻¹, and 0.47 ± 0.01 kg N ha⁻¹ yr⁻¹, respectively. Afforestation significantly decreased soil N₂O fluxes compared with the adjacent cropland. The effects of afforestation on soil CH₄ and N₂O fluxes in the present study were mainly attributed to changes in soil characteristics, such as temperature and moisture, as these were significantly correlated with soil CH₄ and N₂O fluxes across different experimental sites. The present study highlights that afforestation is an effective land use management practice to mitigate non-CO₂ greenhouse gas emissions from subtropical karst landscapes in South China.
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