川西亚高山五种主要森林类型凋落物组成及动态

利用连续收获法研究了川西亚高山老龄林(VF)、桦木林(BF)、次生针阔混交林(MF)、人工云杉林(AF)及高山栎灌丛(AO) 5种主要森林类型的凋落物组成及其动态,目的在于探索不同恢复途径对森林凋落物组成和产量的影响。结果表明,5种森林类型的全年凋落产量大小依次为VF(4.32 t/hm~2)、MF(4.10 t/hm~2)、BF(3.52 t/hm~2)、AO(3.01 t/hm~2)、AF(2.34 t/hm~2)。AF全年凋落量显著小于其他3种乔木森林类型(VF,BF,MF)(P 0. 05)。各森林类型的叶片年凋落量占总量比例均超过70%。VF、AF、AO均在生长前期(前一年10月至当年5月)达到最大凋落量2.41,1.29,1.63 t/hm~2; BF、MF凋落产量在生长季后期(当年7月至10月)到达最大值,分别为1.34,1.80 t/hm~2。常绿针叶树为主的VF、AF叶片凋落物样地间变异显著高于落叶阔叶树为主的BF、MF,表明其对立地条件的响应更为敏感。林分密度与胸高断面积组合因子更能反映凋落物特征。

Litter composition and its dynamic in five main forest types in subalpine areas of west Sichuan, China

Litter composition was investigated for a whole year in five representative forest types:virgin forest (VF), secondary birch forest (BF), secondary coniferous and broad-leaved mixed forest (MF), artificial spruce forest (AF), and alpine oak (AO), in west Sichuan, in order to understand the litter dynamic and spatial variation among different restoration approaches. The annual litter production for VF, MF, BF, AO, and AF was 4.32, 4.10, 3.52, 3.01, and 2.34 t/hm², respectively. Litter production was significantly lower in AF than that in the other three forest types (VF, BF, and MF). More than 70% of annual litter was leaf in all forest types. Litter production of VF, AF, and AO reached its peak value (2.41, 1.29, and 1.63 t/hm², respectively) in the pre-growing season (previous October-May), while that for BF and MF achieved their maximum (1.34 and 1.80 t/hm², respectively) in the late growing season (July-October). Spatial variation of leaf litter for VF and AF, both composed of evergreen coniferous species, was significantly greater than that for BF and MF, with more deciduous species. Spatial variation analysis indicated that sensitivity of litter production to stand condition was higher for evergreen coniferous forest (VF, AF) than that for deciduous forest. The combination of stand density and area at breast height was advantageous in evaluating litter production.