华西雨屏区不同退耕模式细根、草根分解及主要土壤微生物功能群动态  

Major Microbial Functional Groups Related to Fine Root and Grass Root Decomposition in Different Models of Conversion of Farmland to Forest in the Rainy Zone of West China

作　　者：荣丽[1] 李贤伟[1] 张健[1] 朱天辉[2] 范川[1] 蒲德强[2] 

机构地区：[1]四川农业大学生态林业工程省级重点实验室,四川雅安625014 [2]四川农业大学森林保护省级重点实验室,四川雅安625014

出　　处：《自然资源学报》2009年第6期1069-1079,共11页Journal of Natural Resources

基　　金：国家自然科学基金面上项目(30771717);国家"十一五"科技支撑项目(2006BAC01A11);教育部重点建设学科博士点基金(20050626001);四川省教育厅重点实验室项目(2006ZD006);四川农业大学长江上游植被恢复与重建创新项目

摘　　要：采用原状土芯(intact core)法,探讨了四川洪雅柳江退耕还林模式:光皮桦(Betula luminif-era)与扁穗牛鞭草(Hemarthria compressa)复合模式(HN)、光皮桦人工林(H)、扁穗牛鞭草牧草地(NC)、柳杉(Cryptameria fortunei)人工林(LS)细根、草根分解速率以及其与细根、草根分解密切相关的土壤微生物功能群变化,结果表明:①细根、草根分解速率符合Olson单指数分解模型,年分解常数(k)分别为1.06、0.93、1.32、0.86/年,分解1年后干重损失率分别为65.49%、60.55%、73.32%、57.51%;②在一年的分解期间的各个阶段HN模式的好气固氮细菌、氨化细菌、硝化细菌、纤维素分解菌数量都显著大于其他3种模式(p<0.01);③4种模式固氮细菌与氨化细菌数量呈显著正相关关系,与C/N呈显著负相关关系,氨化细菌数量与硝化细菌数量呈显著正相关,HN、LS模式固氮细菌数量与细根、草根N相对含量呈显著正相关关系(p<0.05),表明细根、草根的分解受到土壤微生物生理类群相互作用的影响,自生固氮在林草复合模式与柳杉人工林生态系统的自肥作用中扮演着重要角色。Fine root decomposition often plays an important role in maintaining soil fertility and mass cycle in soil ecosystem. As an irreplaceable decomposer in fine root decomposition, soil microorganism is closely linked to the chemical components in fine roots. Many compound models for vegetation restoration were founded in the process of converting farmland to forest （ grass）, which is beneficial to the development of environment and economy. As yet there is a lack of soil microbial functional group variation related with fine root decomposition although only a few reports have been published. Therefore, we placed 560 intact soil cores in nylon bags with 0. 25 mm mesh in Birch （ Betula luminifera） -grass （ Hemarthria compressa） compound model （ HN）, birch （ Betula luminifera） plantation （ H）, grassland （ Hemarthria compressa） （ NC ） and cedar （ Cryptomeria fortunei ） plantation （LS） using intact-core technique for 1 year. Intact soil cores were sampled at 30, 90, 180, 270 and 365 days from the starting date. On each sampling date, we collcted fine roots and soils （grass roots） from each soil core for analysis. Decomposition rates and major microbial functional groups （aerobic azotobacter, ammonifiers, nitrifiers, cellulolytic bacteria） in relation to fine root and grass root decomposition were analyzed. The percentage of initial mass remaining of decomposing roots fitted a single-exponential model. The decomposition constant （k） for the four models were 1.06,0.93,1.32 and 0. 86 per year respectively, with an annual loss of 65.49% ,60. 55% ,73.32% and 57.51%. The numbers of aerobic azotobacter and ammonifiers increased consistently until 90 or 180 days, while nitrifiers and cellulolytic bacteria decreased during 30 days, followed by an increase in four models. The numbers of aerobic azotobacter, ammonifiers, nitrifiers and cellulolytic bacteria in HN model were much higher than the other three models during the decomposition period. Aerobic azotobacter in four models

关 键 词：退耕还林 华西雨屏区 分解 细根、草根 土壤微生物功能群 

分 类 号：S714[农业科学—林学]