不同起源时间的植物叶凋落物在中亚热带的分解特性

选择9种起源时间不同的植物的凋落叶,采用分解袋法,在浙江千岛湖地区从2006年6月到2008年6月进行了分解试验,试图探索植物进化过程中凋落物分解特性的演变趋势.所选的9种植物分属于4个类群,按起源时间由早到晚依次为蕨类植物(芒萁和桫椤)、裸子植物(苏铁、水杉、杉木和马尾松)、双子叶植物(木荷和青冈)及单子叶植物(毛竹).每隔一个月取样,每种凋落物3次重复.结果表明:不同植物类群凋落物基质的氮(N)、木质素(Lignin)含量及Lignin/N比值与分解速率具有良好的相关性.起源时间越晚的植物凋落物的基质N含量越高,为单子叶植物>双子叶植物>裸子植物>蕨类植物.Lignin含量和Lignin/N比值的趋势一致,均为起源时间越晚而值越低,即蕨类植物>裸子植物>双子叶植物>单子叶植物.凋落物分解系数k值的范围在0.25～0.63之间,表现出毛竹>青冈>木荷>水杉>马尾松>杉木>苏铁>桫椤>芒萁的趋势.4个植物类群的凋落物分解速率的均值为单子叶植物>双子叶植物>裸子植物>蕨类植物.试验结果初步表明:植物凋落物分解的进化趋势是由分解缓慢逐渐演变为分解较快.

Leaf litter decomposition of plants with different origin time in the mid\| subtropical China

Leaf litter decomposition of 9 species with different origin time was studied from June 2006 to June 2008 in the Qiandaohu region of Zhejiang province using litterbag method, trying to explore the evolution trends of the leaf litter decomposition characteristics in the plant evolution process. The 9 species belong to 4 taxa, pteridophyta (Dicranopteris dichotoma and Alsophila spinulosa), gymnosperm (Cycas panzhihuaensis, Metasequoia glyptostroboides, Cunninghamia lanceolata and Pinus massoniana), dicotyledon (Schima superba and Cyclobalanopsis glauca), monocotyledon (Phyllostachys pubescens), which are ranked in the order of the origin time from earlier to later. The litterbags were collected every other month; there are three repeats for each species. The results indicated that the decomposition rate of litter of different taxa showed more correlation with the initial N contents, lignin contents and lignin/ N ratio of litter. The initial N contents of litter are increased with the origin time from earlier to later, the pattern is monocotyledon > dicotyledon > gymnosperm > pteridophyte. The patterns of the Lignin contents and Lignin/N ratio are similar. The values are decreased with the origin time from earlier to later, the pattern is pteridophyte > gymnosperm > dicotyledon > monocotyledon. The range of the annual litter decomposition coefficient (k) is 0.25 to 0.63, the trend is P. pubescens > C. glauca > S. superba > M. glyptostroboides > P. massoniana> C. lanceolata> C. panzhihuaensis > A. spinulosa > D. dichotoma. The mean litter decomposition rate of the 4 taxa is monocotyledon > dicotyledon > gymnosperm > pteridophyte. The results preliminary showed the evolution trends of the leaf litter decomposition rate are from slow gradually evolved to fast.