高寒沙地不同林龄乌柳林下植物物种多样性

Species diversity of understory plants of different age Salix cheilophila in alpine sandy land

以共和盆地乌柳人工林为对象,调查了不同发育阶段(4、11、25和37年生)乌柳林下植物物种组成及物种多样性变化。结果表明,菊科、藜科、豆科和禾本科为各阶段乌柳林下植被的优势科。4个林龄乌柳林下植被重要值较大的物种不尽相同,赖草在各林龄乌柳林下植被中均为优势种。演替各阶段多年生植物种数占绝对优势且基本保持稳定,其单种重要值明显大于一年生植物。随着林龄的增加,在流动、半流动沙地中出现的一年生植物逐渐消失,小、半灌木开始出现在林下植被中。林下植被的地上生物量和盖度均表现为先增加、后降低、再增加的趋势。物种丰富度、物种多样性、均匀度、生态优势度指数均表现为逐渐增加的趋势。随演替进展,林下植被群落结构趋于复杂、稳定,物种多样性达到了较高的水平,植被群落得到了较好的恢复。

Salix cheilophila sand-fixing plantations at different development stages（4, 11, 25, and 37 years old） were used to study the understory plant species composition and species diversity in alpine sandy land of Gonghe basin. The results showed that compositae, chenopodiaceae, leguminosae and gramineae were dominant understory vegetation of the four stands. The import value species were different in the understory vegetation of four stand ages of S. cheilophila. Leymus decalinus was the dominant species in the understory vegetation of different stand ages of S. cheilophila. In all succession stages, the number of perennials occupied dominant status and almost remained stable. The important value of individual perennial species was significantly higher than that of annuals. With the increase of plantation age, some annual indicator species in drifting or semi-drifting sandy land gradually disappeared, and undershrub and subshrub began to appear in the understory vegetation. Both aboveground biomass and coverage of the understory vegetation presented an increasing-decreasing-increasing trend, simultaneously. The species richness, species diversity, evenness and ecological dominance indexes of the understory vegetation community increased gradually with the increasing age of the plantation. Community structure of the understory vegetation tended to be complex and stable and the species diversity reached a high level with the process of succession, suggesting that the understory vegetation community got better restoration.