4种林分凋落叶不同分解阶段化学计量特征

  目的  研究黔西南地区不同林分凋落叶不同分解阶段的化学计量特征，深入了解喀斯特地区不同森林生态系统养分循环规律。  方法  选取黔西南地区4种典型林分类型，包括马尾松Pinus massoniana林、毛竹Phyllostachys edulis林、杉木Cunninghamia lanceolata林，以及以麻栎Quercus acutissima、安顺润楠Machilus cavaleriei和滇青冈Cyclobalanopsis glaucoides为优势种的天然林，采集处于不同分解阶段的森林凋落叶，并测定其全碳、全氮和全磷化学计量特征。  结果  ①毛竹林各分解阶段全碳质量分数均显著低于其余林分(P＜0.05)，马尾松林和杉木林已分解阶段凋落叶全碳质量分数均显著低于未分解和半分解阶段(P＜0.05)；杉木林未分解阶段全氮质量分数显著低于半分解和已分解阶段(P＜0.05)；天然林已分解阶段全磷质量分数显著高于其余林分(P＜0.05)，且其半分解阶段全磷质量分数显著低于未分解和已分解阶段(P＜0.05)。②杉木林已分解阶段碳氮比显著高于毛竹林(P＜0.05)，且其未分解阶段碳氮比显著高于半分解和已分解阶段(P＜0.05)；毛竹林未分解和已分解阶段氮磷比显著高于天然林(P＜0.05)；杉木林和天然林半分解阶段碳磷比均显著低于马尾松林(P＜0.05)，天然林已分解阶段碳磷比显著低于其余林分(P＜0.05)。  结论  林分类型和分解阶段对凋落叶全碳、全氮和全磷质量分数及化学计量特征均有显著影响。图2表2参36

Stoichiometric characteristics of leaf litter at different decomposition stages in 4 forest types

  Objective  This research aims to study the stoichiometric characteristics of leaf litter at different decomposition stages in different stands in southwest Guizhou Province, so as to better understand the nutrient cycling law of different forest ecosystems in karst areas.   Method  4 typical forest types were selected in southwest Guizhou, including Pinus massoniana forest, Phyllostachys edulis forest, Cunninghamia lanceolata forest, and natural forest dominated by Quercus acutissima, Machilus cavaleriei and Cyclobalanopsis glaucoides. Leaf litter at different decomposition stages was collected and stoichiometric characteristics of C, N and P were measured.   Result  (1) The total C content of leaf litter in each decomposition stage of P. edulis forest was significantly lower than that in other stands (P＜0.05), and the total C content of leaf litter at decomposed stage of P. massoniana and C. lanceolata forests was significantly lower than that at undecomposed and semi-decomposed stages (P＜0.05). The total N content of leaf litter in C. lanceolata forest at undecomposed stage was significantly lower than that at semi-decomposed and decomposed stages (P＜0.05). The total P content of leaf litter at decomposed stage of natural forest was significantly higher than that in other stands (P＜ 0.05), and the total P content at semi-decomposed stage of natural forest was significantly lower than that at undecomposed and decomposed stages (P＜ 0.05). (2) The C/N ratio of C. lanceolata forest at decomposed stage was significantly higher than that of Ph. edulis forest (P＜0.05), and the C/N ratio at undecomposed stage was significantly higher than that at semi-decomposed and decomposed stages (P＜0.05). The N/P ratio at undecomposed and decomposed stages of Ph. edulis forest was significantly higher than that of natural forest (P＜0.05). The C/P ratio of leaf litter at semi-decomposed stage of C. lanceolata and natural forests was significantly lower than that of P. massoniana forest (P＜ 0.05), and the C/P ratio at decomposed stage of natural forest was significantly lower than that of other stands (P＜0.05).   Conclusion  Both forest type and decomposition stage have significant effects on contents of total C, N and P, as well as stoichiometric characteristics of leaf litter. Ch, 2 fig. 2 tab. 36 ref.]