川西高山林线三种灌木凋落叶分解中的无脊椎动物多样性

以无脊椎动物为主体的土壤动物是影响凋落物分解的重要生物因素,对维持陆地生态系统物质循环和能量流动具有重要作用。高山林线交错带是高山植被垂直带谱中重要的过渡区域,拥有比相邻生态系统更高的生境复杂性和物种多样性。林线上温度波动和冻融循环频率显著高于针叶林,为了了解林线交错带上环境差异对凋落物分解过程中的土壤动物群落结构和多样性的影响,采用凋落物分解袋的方法,于高山生态系统的两个主要时期,即雪被末期和生长季末期,研究了林线主要代表性灌木——高山柳(Salix cupularis)、高山杜鹃(Rhododendron lapponicum)和红毛花楸(Sorbus rufopilosa)凋落叶分解的土壤动物多样性特征。结果表明:凋落物中的无脊椎动物群落多样性及个体、类群密度随物种、海拔梯度和季节而变化,且季节差异对无脊椎动物多样性的影响比物种和海拔梯度更显著。3个因子的交互作用不仅影响土壤动物群落多样性和均匀度,而且影响群落个体密度和类群密度。雪被末期,凋落物中的无脊椎动物多样性指数H、均匀度指数J及丰富度指数D以针叶林最高,优势度指数C以林线最高;生长季节末期的无脊椎动物类群密度和个体密度显著高于雪被末期。总体上,凋落物中的无脊椎动物群落丰富度以生长季末期最高,林线较针叶林丰富。这意味着,未来气候变暖情景下,灌丛密度增加,凋落物输入量增大,可能导致无脊椎动物多样性增加。

Invertebrate diversity in foliar litter of three shrubs in the alpine timberline of western Sichuan

Invertebrate fauna as the main soil fauna is one of the important biological factors affecting litter decomposition, which plays an essential role in maintaining material circulation and energy flow of terrestrial ecosystems. Alpine timberline ecotone is an important transition region of mountain vegetation vertical band with more habitat complexity and species diversity than the adjacent ecosystems. Temperature fluctuation and freeze-thaw cycle frequency in timberline was significantly higher than that in coniferous forest, in order to understand the environmental difference in timberline ecotone on the influence of invertebrate community structure and diversity in the process of litter decomposition, a field experiment using litterbag method was carried out at the end of two main periods (snow cover season and growing season), the invertebrate community structure and diversity was studied in the foliar litter of Salix cupularis, Rhododendron lapponicum and Sorbus rufopilosa, three representative shrubs in the alpine timberline ecotone. The results showed that the invertebrate community diversity and density of individual and groups varied with the altitude, seasons and litter species, and invertebrate diversity influenced by seasonal variation was more significant than the altitude and litter species. The interaction of three factors(altitude, seasons and litter species) affected not only the invertebrate community diversity and evenness, but also the individual density and group density. At the end of snow cover season, Shannon index H, Pielou index J and Margalef index D was highest in the coniferous forest, and Simpson index C was highest in the timberline, while group density and individual density at the end of growing season was significant higher than that of snow cover season. In general, invertebrate fauna was the most abundant at the end of growing season, and relatively rich in timberline than in coniferous forest. This means that with increasing of shrub density and litter input quantity, invertebrate diversity is likely to increase in the future climate change scenarios.