Soil-atmosphere exchange of greenhouse gases from typical subalpine forests on the eastern Qinghai-Tibetan Plateau: Effects of forest regeneration patterns

Forest regeneration plays an important role in the carbon (C) and nitrogen (N) budgetafter clear-cutting. Nonetheless, the effects of regeneration pattern on soilatmosphereexchange of greenhouse gases (GHG; CO2,CH4and NO) remain poorlyunderstood on the eastern Qinghai-Tibetan Plateau. This study reports measuredfield layer GHG fluxes from Picea asperata broadleaved mixed forest (MF, mixed forestswith planted P. asperata and natural regeneration of broadleaved species), naturalsecondary forest (NF, natural without assisted regeneration), and P. asperataplantation forest (PF, artificial planting) to investigate the influence of regenerationpatterns on soil GHG fluxes. The soils of the three forest types acted as CO2andN2O sources and CHsinks. The seasonal variation in GHG fluxes was related to soiltemperature, rather than soil moisture. Forest types originating from different regenerationprocesses exhibited different gaseous C fluxes (CO421and CH), but did notexhibit significant effect on N2O emissions. NF and MF had higher COemissionsthan PF. The difference was related to soil C and N density, NH4+concentration, andsoil ?-glucosidase activity, rather than the soil microbial community. NF had higherCHuptake than the other two forest types, which is possibly related to specific individualphospholipid fatty acids. Overall, forest types differing in regeneration patternshad a significant impact on the C balance from the perspective of soil-atmosphereexchange of gaseous C at our site. Therefore, the GHG fluxes should be consideredwhen taking measures of forest management and regeneration practices in thisregion.