森林群落物种组成对凋落物组成的影响

在海南铜鼓岭山麓灌木林和季雨矮林固定大样地的基础上,通过收集凋落物,比较两林型的凋落物数量及其器官组成、凋落叶物种组成,探讨森林群落物种组成与凋落物组成的关系。结果表明:(1)两林型的凋落物总量及其器官组成不同,山麓灌木林(6.227 t/hm~2)比季雨矮林的年凋落量大(5.636 t/hm~2);凋落叶是凋落物的主要组成部分,能反映凋落物的凋落情况。(2)山麓灌木林凋落物优势种和主要物种为贡甲、林仔竹、橄树等15个物种,凋落叶总量占77.72%;季雨矮林的凋落物优势种和主要物种为方枝蒲桃、肖蒲桃、贡甲等17个物种,凋落叶总量占71.84%;山麓灌木林中凋落物优势种和主要物种的叶凋落量与其组成物种的株数、总断面积、树冠面积极显著正相关而季雨矮林的凋落物优势种和主要物种的叶凋落量与其组成物种的株数极显著正相关。山麓灌木林中两者的Jaccard相似性系数为20%,季雨矮林为25.93%,两林型的群落物种组成与凋落叶物种组成不一致,热带森林群落优势种不一定是凋落物优势种。

Impact of forest community species composition on litter species composition

Based on fixed sample plot data form the shrub and monsoon elfin forests in Tongguling on Hainan Island, we selected two permanent plots and set up litter traps to compare litter production, its organ composition, and leaf litter species compositions between the two forest types, as well as to assess the relationships between forest community and litter species composition. The results were as follows: (1) Some differences were noted between the two forest types in total litter and its organ composition. The annual litter amount obtained from shrub forest(6.227 t/hm²) was larger than that from monsoon elfin forests (5.636 t/hm²). Leaf litter was the main component of the litter in both the shrub and monsoon elfin forests, and it is reflective of the litter condition. (2) In the shrub forest, 15 dominant and main leaf litter species were noted, including Acronychia oligophlebia, Oligostachyum nuspiculum, and Aporosa yunnanensis; the leaf litter amount of these species accounted for 77.72% of the total litter. In the monsoon elfin forests, 17 dominant and main leaf litter species were noted, including Syzygium tephrodes, S.acuminatissima, and A.oligophlebia; these species accounted for 71.84% of the total litter. Thus, we showed that the dominant and main species of leaf litter greatly contribute to the total leaf litter in both forests. Relativity analysis of the leaf litter amount and stand characteristic indexes of the dominant and main species in the shrub forest showed significantly positive correlations between the leaf litter amount of both species and their individual numbers, total basal areas, and crown areas. However, in monsoon elfin forests, the leaf litter amount of the dominant and main species showed significant positive correlations with the number of individuals of the tree species. A comparison between community species composition and leaf litter composition showed that, in the shrub forest, the Jaccard similarity coefficient was 20%, while that in the monsoon elfin forests was 25.93%. The similarity coefficients of the two forest types were not high, suggesting that the species composition was not consistent between the community and leaf litter in either forest type. In other words, community species composition has little influence on the leaf litter species composition, showing that the dominant forest species may not be the same as the dominant litter species.