降水变化、氮添加对鼎湖山主要森林土壤有机碳矿化和土壤微生物碳的影响

全球变化对土壤有机碳(SOC)存贮与分解的影响在全球碳(C)循环中具有重要地位.分别通过室内土壤培养法和氯仿熏蒸法,研究了降水变化和氮(N)添加处理对鼎湖山3种不同演替阶段的季风常绿阔叶林、针阔混交林和马尾松针叶林SOC矿化和土壤微生物量碳(SMBC)的影响.结果表明:1)降水量增加能够提高森林演替晚期SOC累积矿化量和矿化速率,而对森林演替早期SOC累积矿化量和矿化速率没有显著影响(P>0.05).2)干旱条件(降水量减少)降低森林SMBC含量,且在鼎湖山季风林表层土壤(0～10 cm)中SMBC的减少达到显著水平(P<0.05).3)N添加处理对鼎湖山3种森林类型SOC累积矿化量、矿化速率以及SMBC都没有显著影响(P>0.05).未来关于SOC矿化对全球变化响应的研究,要综合考虑土壤有机质质量、C/N比例、外源性氮输入等因素的作用.图4表2参37

Effects of Precipitation Change and Nitrogen Addition on Organic Carbon Mineralization and Soil Microbial Carbon of the Forest Soils in Dinghushan, Southeastern China

Soil organic carbon(SOC) mineralization and soil microbial carbon(SMBC) play an important role in global C cycle.With method of incubation and chloroform fumigation extraction,the effects of precipitation change and nitrogen(N) addition on the SOC mineralization and SMBC were studied along a forest succession series including pine forest(PF),mixed pine and broadleaved forest(MF) and monsoon evergreen broadleaved forest(MEBF) at Dinghushan,Southestern China.The results showed that:(1) Increased precipitation could improve the mineralization of SOC in the late-successional forest plots,but the effect in the early-successional forest plots were not significant(P>0.05).(2) Less precipitation(drought) resulted in lower content of SMBC in the monsoon forest soil(0～10 cm),while the doubled precipitation treatment had no significant effect on the SMBC content.(3) N deposition did not affect SMBC mineralization and SMBC in all of the three forests.It is important to take the quality of organic matter,C/N ratio,exogenous nitrogen and many other combined effects into consideration in the future studies on the responses of SOC mineralization and SMBC to climate change.Fig 4,Tab 2,Ref 37