川西亚高山生态系统三种典型植物凋落物分解动态特征

摘要

Plant litter is the reservoir for nutrients in alpine and subalpine ecosystems and plays an important role in the geobiochemical cycling of elements.In this study,the dynamics as well as the differences in the decomposition of three types of litter,including Pleurozium schreberi,Abies fabri and Rhododendron williamsianum,were investigated in subalpine ecosystems in Western Sichuan,China,with the litter bag method.The litter of R.williamsianum had the highest decomposition rates when compared with the A.fabri and P.schreberi litter.The litter decomposition rates of A.fabri was 3 ％ higher than that of P.schreberi in the coniferous forest,while it was not differed with that of P.schreberi in the shrubland ecosystem.The decomposition dynamics of the three litter types could be descripted well with Olson classic model.After 3 years of decomposition,the carbon (C) content was decreased by 5.66％ ～ 14.58％,the nitrogen (N) content was increased by 6.46％～42.10％ relative to their initial values,and the phosphorus (P) content was increased in the A.fabri and R.williamsianum litters but was decreased in the P.schreberi litter.%植物凋落物是高山生态系统重要的养分存储库,凋落物的分解在高山生态系统生物地球化学循环中具有重要作用.本研究采用凋落物分解袋法,分析了贡嘎山亚高山暗针叶林和高山灌丛中赤茎藓(Pleurozium schreberi)、峨眉冷杉(Abies fabri)和杜鹃(Rhododendron williamsianum)三种植物凋落物的分解速率和养分释放动态及差异.结果表明:1)经三年分解后,无论是暗针叶林还是高山灌丛,杜鹃凋落物分解率均最高;峨眉冷杉凋落物分解率在暗针叶林略高于赤茎藓凋落物,但在高山灌丛和赤茎藓无显著差异;2)三种植物凋落物的分解动态均能用Olson经典指数模型拟合;3)分解三年后,三种凋落物碳(C)含量下降了5.66％ ～ 14.58％;氮(N)含量增加了6.46％～42.10％;峨眉冷杉和杜鹃凋落物磷(P)含量增高,赤茎藓凋落物中P含量降低.