模拟氮沉降对华西雨屏区苦竹林细根特性和土壤呼吸的影响  

Effects of simulated nitrogen deposition on the fine root characteristics and soil respiration in a Pleioblastus amarus plantation in Rainy Area of West China

作　　者：涂利华[1] 胡庭兴[1] 张健[1] 何远洋[1] 田祥宇[1] 肖银龙[1] 

机构地区：[1]四川农业大学林学院林业生态工程四川省重点实验室,四川雅安625014

出　　处：《应用生态学报》2010年第10期2472-2478,共7页Chinese Journal of Applied Ecology

基　　金：国家"十一五"科技支撑计划项目(2006BAC01A11-03);四川省重点学科建设项目(SZD0419)资助

摘　　要：细根在森林生态系统地下碳循环过程中具有核心地位.2007年11月—2009年11月,对华西雨屏区苦竹人工林进行了模拟氮沉降试验.氮沉降水平分别为对照(CK,0 g N.m-2.a-1)、低氮(5 g N.m-2.a-1)、中氮(15 g N.m-2.a-1)和高氮(30 g N.m-2.a-1)处理,研究氮沉降对苦竹人工林细根和土壤根际呼吸的影响.结果表明:不同处理氮沉降下,<1 mm和1～2 mm细根特性差异较大,与<1 mm细根相比,1～2 mm细根的木质素、磷和镁含量更高,而纤维素、钙含量更低;氮沉降显著增加了<2 mm细根生物量,对照、低氮、中氮和高氮处理的细根生物量分别为(533±89)、(630±140)、(632±168)和(820±161)g.m-2,氮、钾、镁元素含量也明显增加;苦竹林各处理年均土壤呼吸速率分别为(5.85±0.43)、(6.48±0.71)、(6.84±0.57)和(7.62±0.55)t C.hm-2.a-1,氮沉降对土壤呼吸有明显的促进作用;苦竹林的年均土壤呼吸速率与<2 mm细根生物量和细根N含量呈极显著线性相关.氮沉降使细根生物量和代谢强度增加,并通过增加微生物活性促进了根际土壤呼吸.Fine root is critical in the belowground carbon（C）cycling in forest ecosystem.Aimed to understand the effects of nitrogen（N）deposition on the fine root characteristics and soil respiration in Pleioblastus amarus plantation,a two-year field experiment was conducted in the Rainy Area of West China.Four treatments with different levels of N deposition were installed,i.e.,CK （0 g N·m^-2·a^-1low N（5 g N·m^-2·a^-1medium N（15 g N·m^-2·a^-1and high N （30 g N·m^-2·a^-1There were great differences in the biomass and element contents of 〈1 mm and 1-2 mm fine roots among the treatments.Comparing with〈1 mm fine roots,1-2 mm fine roots had higher contents of lignin,P,and Mg,but lower contents of cellulose and Ca.Nitrogen deposition increased the biomass of 〈2mm fine roots significantly,with the values being （533±89）g·m^-2in CK,and（630±140）,（632±168）,and（820±161）g·m^-2in treatments low N,medium N,and high N,respectively.The N,K,and Mg contents of2 mm fine roots also had an obvious increase under N deposition.The annual soil respiration rate in treatments CK,low N,medium N,and high N was（5.85±0.43）,（6.48±0.71）,（6.84±0.57）,and （7.62±0.55）t C·hm-2·a-1,respectively,indicating that N deposition had obvious promotion effects on soil respiration.There were significant linear relationships between the annual soil respiration rate and the biomass and N content of〈2 mm fine roots.N deposition increased the fine root biomass and promoted the root metabolism,and stimulated the rhizospheric soil respiration rate via promoting microbial activities.

关 键 词：氮沉降 土壤呼吸 根际呼吸 细根 苦竹林 华西雨屏区 

分 类 号：S795[农业科学—林木遗传育种] S714[农业科学—林学]