| In the subtropic montane forest, bamboos can quickly invade into the forest gaps or other types of disturbed spaces. Bamboos with the strong rhizome could be quickly recovery to a secondary bamboo forest. Bamboos often become dominat species in shrub layer, and they may significantly impact the diversity of tree species in forest. Most of bamboos grow in cluster and have a dense canopy, consequently, a thick bamboo litter layer usually accumulates on the forest floor. Bamboo leaf litter decompose slowly, and contain higher lignin/N, lignin/P and N/P ratio, which can affect litter decomposition. The linear and flat leaves of bamboo results in a compact litter layer, especially when moist. Accumulation of bamboo leaf litter modifies forest floor microenvironment conditions and can thereby influence seed germination and seedling establishment, and ultimately affect plant community structure.In this paper the decomposition characteristics of bamboo leaf litter, herb leaf litter and tree leaf litter were discussed, as well as their effects of litter depth on the seed germination and seedling emergence of canopy6species trees. The decomposition rate and decomposition rate per month of leaf litter from different life forms were analyzed. The influences of litter depth, litter types and seed-sowing position on seed germination, seedling emergence were analyzed as well. The main results are as follows:(1) The decomposition rate and decomposition rate per month of leaf litter were faster during the first5months then slowly later on. Leaf litter decomposition rates of varied plant life forms differ. Bamboo leaf litter had lower decomposition rate than herb leaf litter, but faster than tree leaf litter. The decomposition rate of six genera bamboo leaf litter had significant difference. Bamboo leaf litter from Bambusa had lower decomposition rate than other five genera, while, they from Pleioblastus had the fastest decomposition rate. The dry matter content of mature leaves and the decomposition rate and decomposition rate per month of leaf litter have a significant linear negative correlation relationship. The t95%(the time of95%mass loss) of different life form plant leaf litter needed different time, herb leaf litter were40.6months, trees leaf litter were56.5months and bamboo leaf litter were43.4months. Different genera of bamboo leaf litter to decompose95%needed different time as well. The t95%of Neosinocalamus leaf litter and Lingnania leaf litter were31.9and68.1months, respectively. In all12kinds of bamboo species, the mass loss95%of Phyllostachys glauca leaf litter needed shortest time that was24.6months, and Lingnania chungii needed longest time that was78.8months.(2) The seed-sowing position had a significant influence on the total seed germination and total seedling emergence. The litter depth and litter type had a different influence on seed germination of six canopy trees. Seeds were sowed on the litter surface had much lower germination rate or failed to germinate but sowed under the litter had higher germination rate. Litter cover could promote the germination rate and shorten the time of seed germination. Seed germination rate was higher under the bamboo leaf litter than under the tree leaf litter. Seed accumulative germination percentage of Castanopsis fargesii was the highest, however, Litoea mollis was the lowest in all six species.(3) The sequence of seedling emergence rate of six canopy trees species was:Cinnamomum camphora> Camptotheca acuminata> Gordonia acuminata> Castanopsis fargesii> Diospyros morrisiana> Litoea mollis. Seedlings that covered by bamboo leaf litter had higher mortality rate, and deciduous trees seedling mortality rate was higher than evergreen trees. Litter types and litter depth had different impacts on the seedling survival rate. The8cm depth of bamboo leaf litter had significantly influence on tree seedling survival rate, while the depth of tree litter had no significant influence. |
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