森林土壤是CO2、CH4和N2O等温室气体的主要排放源.本研究采用静态箱/色谱分析技术,对中国科学院鹤山丘陵综合开放试验站内厚荚相思林土壤CO2、CH4和N2O通量进行原位测定，研究剔除林下灌草和添加翅荚决明对土壤温室气体排放的影响.结果表明：厚荚相思林土壤CO2通量在湿季维持较高水平，在旱季则明显降低.CH4和N2O在9—11月波动幅度较大，峰值出现在10月.在不同处理下，厚荚相思林土壤可能是CH4的源也可能是CH4的汇，而于CO2和N2O则是源.林下剔除灌草能显著增大土壤CO2排放(P<0.05)，而添加翅荚决明能加快土壤CH4的排放(P<0.05).林下剔除灌草及添加翅荚决明两种处理都能够加大N2O的排放通量.表层土壤温度、湿度、NO3--N和微生物生物量碳都是影响土壤温室气体排放的重要因子.
Forest soil is one of the main sources of greenhouse gases CO2, CH4, and N2O. By using static chamber and GS technique, this paper measured in situ the CO2, CH4, and N2O fluxes of Acacia crassicarpa plantation in Heshan Hilly Land Interdisciplinary Experimental Station under Chinese Academy of Sciences (CAS), and studied the soil CO2, CH4 and N2O emissions from the plantation under effects of understory removal and Cassia alata addition. The CO2 flux of the plantation maintained at a higher level during rainy season but decreased obviously in dry season, while the CH4 and N2O fluxes varied widely from September to November, with the peaks in October. Under the effects of understory removal and C. alata addition, the soil in the plantation could be a sink or a source of CH4, but consistently a source of CO2 and N2O. Understory removal enhanced the soil CO2 emission (P<0.05), C. alata addition increased the soil CH4 emission (P<0.05), while both understory removal and C. alata addition increased the soil N2O emission (P<0.05). Surface soil temperature, moisture content, NO3--N concentration, and microbial biomass carbon were the main factors affecting the soil CO2, CH4 and N2O emissions.