西双版纳热带雨林凋落叶分解的生态过程Ⅰ.凋落叶分解动态  

ECO-PROCESS OF LEAF LITTER DECOMPOSITION IN TROPICAL RAIN FOREST IN XISHUANGBANNA,CHINA. Ⅰ. DECOMPOSITION DYNAMIC OF MIXED LEAF LITTERS

作　　者：张瑞清[1] 孙振钧[1] 王冲[1] 葛源[1] 李云乐[1] 乔玉辉[1] 庞军柱[1] 张录达[1] 

机构地区：[1]中国农业大学资源与环境学院,北京100094

出　　处：《植物生态学报》2006年第5期780-790,共11页Chinese Journal of Plant Ecology

基　　金：国家科技部"973"重大基础研究前期研究专项(2002CCA00800)

摘　　要：通过野外试验和室内模拟相结合,系统研究了西双版纳热带雨林生态系统混合凋落叶分解的生态过程。野外试验采用网袋法,即1mm和100μm网眼网袋,分别限制大型土壤动物和螨类的进入,从而分别观测小型土壤动物(螨类)、线虫的分解作用;室内试验则通过控制温、湿度条件,采用灭菌_接种法分别观测微生物和线虫对凋落叶的分解。研究结果表明,凋落叶的分解是一个先快后慢的过程,在这个过程中存在分解“滞留”阶段,分解速率变化发生波动,且波动的程度与食物链的复杂程度有关,食物链越复杂,波动程度越强烈。利用单指数衰减模型xt/x0=exp(-kt)和双指数模型xt/x0=a×exp(-k1t)+b×exp(-k2t)对凋落叶分解过程进行模拟,后者将凋落叶前欺的快速分解和后期的慢速分解两个过程分别拟合,不但弥补了分解前期单指数衰减模型与观测值之间不能吻合的缺陷,而且消除了单指数模型对长期分解进程的过高预测,因此能更好地反映实际分解进程。利用双指数生物模型研究生物和非生物因子对凋落叶分解速率的贡献表明,土壤动物是影响分解进程的最重要因子,占影响因子总量的78.1%,非生物因素的作用为14.1%,微生物对分解速率的贡献只有7.8%。在热带森林生态系统中,土壤动物是最重要的分解者。Background and Aims Decomposition of mixed leaf litters in Xishuangbanna tropic rain forest was studied both in the field and laboratory. Negative exponential model x1/x0 = exp（ - kt ） and binomial exponential model xt/ xo= a ×exp（ - k1t） ＋ b × exp（ - k2t ） were used to simulate the observed decomposition process with. Bio-models were introduced to analysis the contribution of biotic and abiotic factors to the decay rates of leaf litters. Methods Coarse （with mesh size of 1 mm） and fine （with mesh size of 100 μm） litterbags were used in the field to examine the effects of different components of soil fauna on litter decomposition by restricting access by most soil macrofauna and mites, respectively, i.e. feasible for most mites to coarse mesh and nematodes to fine mesh. In the laboratory, sterilization and inoculation were adopted to investigate the effects of nematodes and microbiota on leaf litters. Key Results The decomposition process was a course fast incipiently then slowdown with stagnation periods. The decay rate of mixed leaf litters fluctuated over the decomposing period with the magnitude of fluctuation positively related to complexity of food-web. The binomial exponential model simulated the two different courses of leaf litter decomposition whereas the negative exponential model did not simulate the initial stage well and overestimated the long-term decay process. Soil fauna accounted for 78.1% of the decay rates while abiotic factors for 14.1% and microorganisms only for 7.8%. Conclusions This study suggests that the decomposition of leaf litters was a cascade process and binomial exponential model can describe the process better than the negative exponential model. Soil fauna played a dominating role in litter decomposition in tropic rain forest.

关 键 词：西双版纳 热带雨林 混合凋落叶 分解 模型 

分 类 号：Q948[生物学—植物学]