降水减少对红锥和马尾松温室气体排放的影响

Effect of precipitation reduction on soil greenhouse emission in Castanopsis hystrix and Pinus massoniana plantations

为了揭示降水变化对森林土壤CO2、N2O、CH4通量的影响,本研究以南亚热带红锥和马尾松人工林为研究对象,设置穿透雨减少50%和不减雨(对照),2013—2015年开展野外降水控制实验,结果表明:穿透雨减少仅导致红锥雨季土壤CO2排放通量比对照显著增加了39.1%,而对红锥全年和旱季土壤CO2排放通量、以及红锥全年、旱季和雨季土壤N2O排放和CH4吸收通量均无影响。对马尾松而言,穿透雨减少对其全年、旱季和雨季土壤CO2排放、N2O排放和CH4吸收通量的影响均不显著。另外红锥土壤温室气体排放通量大于马尾松,在减雨处理下更加明显。相关分析表明,红锥和马尾松土壤CO2排放通量与5 cm土壤温度呈指数正相关,与5 cm土壤温、湿度呈二元线性正相关;红锥和马尾松土壤N2O排放通量与5 cm土壤温、湿度的线性关系不显著;红锥土壤CH4吸收通量与5 cm土壤湿度和5 cm土壤温、湿度呈显著的线性负相关,而马尾松土壤CH4吸收通量与5 cm土壤温、湿度的线性关系不显著。总之,短期降水减少可能导致红锥雨季土壤CO2排放显著增加,然而不会改变马尾松土壤CO2、N2O和CH4通量。未来降水减少可能扩大红锥和马尾松土壤温室气体排放通量的差异。

In order to reveal the effect of precipitation changes on the CO2,N2O and CH4 fluxes in forest soils,a precipitation experiment including 50%throughfall reduction and without throughfall reduction(control)was carried out in the Castanopsis hystrix and Pinus massoniana plantations,respectively in southern subtropical region over the years 2013-2015.The results showed that throughfall reduction treatment only resulted in a significant increase of 39.1%in the soil CO2 emission flux at rainy season compared with the control,while did not significantly affect the soil CO2 emission fluxes in whole year and dry season,as well as the soil N2O emission and CH4 uptake fluxes during whole year,dry and wet seasons in C.hystrix.For P.massoniana,there were no significant differences in the soil CO2 emission,N2O emission and CH4 uptake fluxes during whole year,dry and wet seasons.In addition,the soil greenhouse gases of C.hystrix were greater than those of P.massoniana,which was more obvious under the throughfall reduction treatment.According to the correlation analyses,the soil CO2 emission flux showed a positive exponential correlation with soil temperature and a binary linear correlation with soil temperature and moisture at soil depth of 5 cm.However,the soil N2O emission flux was not significantly correlated with soil temperature and moisture at soil depth of 5cm in both C.hystrix and P.massoniana.The linear negative relationship of soil CH4 uptake flux against soil moisture,or soil temperature and moisture at soil depth of 5cm were significant in C.hystrix rather than in P.massoniana.In short,short-term precipitation reduction probably lead to a significant increase of soil CO2 emission flux at rainy season in C.hystrix,but will not alter the soil CO2,N2O and CH4 fluxes in P.massoniana.The precipitation reduction may increase the difference between C.hystrix and P.massoniana in the greenhouse gases.