云南松林与常绿阔叶林中枯落叶分解研究

Decomposition of Leaf Litter in Pinus yunnanensis Forest and Evergreen Broad-Leaved Forest in Central Yunnan

采用分解袋的方法 ,研究了云南松、滇青冈和元江栲枯叶在针、阔叶林两种生境下的分解及养分动态变化规律。结果表明 ,滇青冈和元江栲枯叶分解速率高于云南松针叶。在阔叶林下这些枯叶的分解系数 (0 55～ 0 6 1a- 1 )要比在云南松林下的 (0 50～ 0 53a- 1 )高。在分解过程中 3种枯叶的N、Al、Fe、Zn元素含量表现出分解前期富积 ,后期释放的特征 ,P、Ca元素在阔叶林地的分解中也有富积过程。而Mg、K元素的浓度与绝对量在分解初期迅速降低后呈缓慢变化的情况。分解中两种阔叶的养分迁移率均高于云南松针叶 ,在阔叶林生境中 3种枯叶的大多数养分元素的富积时间缩短 ,下降幅度和分解速度加快 ,说明阔叶林生境有利于枯落叶的分解和养分元素的循环。

The decomposition and its nutrient dynamics of leaf litters of Pinus yunnanensis, Cyclobanopsis glaucoides and Castanopsis orthacantha in pine forest stand and evergreen broad-leaved forest stand in central Yunnan had been investigated by using the litterbag method in a duration of 868 days. It was found that the decomposition rates of both broad-leaved leaf litters are greater than that of pine needles. There are obvious differences between pine forest stand and evergreen broad-leaved forest stand in decomposed mass loss of leaf litters of three species. The decomposition coefficients were 0 55～0 6 1a -1 for three leaf litters in evergreen broad-leaved forest, and in pine forest they were 0 50～0 53 a -1 . The removal rates of nutrient elements in litter change with the quality of leaf litter and decomposing site. During decomposition process the N, Al, Fe and Zn release of three leaf litters in both forest stands showed increase in the first period in content, and thereafter showed decrease over rest of this trial. P and Ca in decomposing leaf litters had also immobilization in evergreen broad-leaved forest stand. Mg and K exhibited a relatively rapid initial loss in the light of concentration and content, thereafter followed a steady decrease. The removal rates of nutrients in decomposing pine needles were lower than that of the other two broadleaf litters. The time and range of most elements immobilization of leaf litters in evergreen broad-leaved forest stand were cut down, and the decomposition speed of leaf litter increased, which indicates evergreen broad-leaved forest stand was beneficial to the decomposition of leaf litter and nutrients cycling in comparison with pine forest stand.