黄土丘陵区沙棘群落天然化发育过程中植物物种多样性研究

Species Diversity Change during the Natural Development Process of Hippophae reamnoides L. Community in the Hilly Loess Regions

运用空间代替时间的方法,对黄土丘陵沟壑区不同发育阶段(3 a、8 a、15 a、25 a)的沙棘人工林群落内植物的种类、盖度、密度等进行调查,并分析了沙棘人工林群落天然化发育过程中物种多样性动态变化。结果表明:1.沙棘人工林群落天然化发育过程中主要以菊科、禾本科、豆科植物为主。其生活型变化为:一年生草本群落→多年生草本群落→半灌丛群落→灌丛群落。2.不同发育阶段沙棘群落灌木层物种丰富度呈增加趋势,草本层的物种丰富度呈先减少后增加的趋势;灌木层和草本层的S impson指数和Shannon-W iener指数在不同阶段沙棘群落中表现出大致相同的趋势,即草本层>灌木层。同一层次的物种多样性指数D和H′虽然数值不同,但在不同发育阶段有基本一致的趋势。草本层多样性指数在荒草地阶段较高,其他阶段的沙棘群落随发育时间的增加而减少;灌木层物种多样性指数随发育时间的增加而呈波动性增加。3.随着群落发育,群落相似性增加。总体上,随着沙棘群落的发育,不同科属的植物种类在增加,群落生态优势度增加,到15 a时群落趋向稳定。

The plant species, coverage and density in the Hippophae reamnoides L community for different growth phases in the hilly loess regions were investigated using the method of temporal and spatial substitution, and the dynamic changes of species diversity during the natural development process of H. reamnoides community were also studied. The results showed that： 1 ） The H. reamnoides community was mainly dominated by the Compositae, Gramineae and Leguminosae families during its natural development process, and its life-form varied in the following order： annual herbaceous community → perennial herbaceous community → half-shrub community→ shrub community. 2） The species richness of the shrub layer increased as the growth phase prolonged, but it decreased first and then increased for the shrub layer. The Simpson index and Shannon-Wiener index of shrub layer and herbaceous layer in different growth phases had similar varying trends, that is, herbaceous layer 〉 shrub layer. Though the diversity indices D and H＇ had different values in the same layer, they varied consistently in different growth phases. The diversity index of the herbaceous layer was relatively higher in the phase of deserted grassland, and the amounts of H. reamnoides community in other phases decreased but the diversity index of the shrub layer increased fluctuant as the closuring time prolonged. 3） The community similarity was more distinct as the closuring time prolonged. In general, plant species of different families and genera increased and the ecological predominance of community increased as the closuring time prolonged and the community became stable after 15 years.