坡度对香根草护坡植物群落早期特征的影响

对不同坡度的相邻两边坡上香根草(Vetiveria zizanioides)护坡植物群落早期阶段连续2年的调查与分析,结果显示:(1)菊科(Compositae)、禾本科(Gramineae)、豆科(Lentil)3类物种最早在群落中定居,3类物种数占物种总数比例为56.00%～84.62%。(2)香根草种植两年后两坡面上植物群落开始出现分化。其中,1#坡面(坡度小)有利于香根草种群的发展,但也有利于乡土植物种在其中定居,植物群落保水效果也较好。(3)秋季植物群落特征规律明显,表现为:1#坡面(坡度小)植物群落丰富度指数R、多样性指数H′、均匀度指数J′随时间上升,植物群落优势度指数C′则呈现随时间下降;而2#坡面(坡度大)表现规律则相反。(4)植物群落丰富度指数R与群落中香根草物种优势度呈显著线性负相关;多样性指数H′和均匀度指数J′与群落中香根草物种优势度呈极显著线性负相关;优势度指数C′均与群落中香根草物种优势度呈极显著线性负相关。

Impacts of slope gradient on the characteristics of Vetiveria zizanioides community in early-stage

The impacts of slope gradient on the community characteristics of Vetiveria zizanioides in early-stage were studied through 2-year investigation with fixed plots from June 2005 to October 2006.The results showed that in the earliest period,the main plants settled on the slope-protection land were from Composite,Gramineousness and Leguminosae,which accounted for 56.00% to 84.62% of the total.The characteristics of the communities in 2 plots with different slope gradients began to vary since the second year.V.zizanioides population in Plot 1（low slope gradient）developed better,and the native plants grown well.The effect of plant community on soil moisture conservation was satisfied.The plant community characteristics showed obvious pattern in autumn compared with that in spring.The richness index,diversity index and evenness index increased and the dominance index decreased along with the time in Plot 1,but that was reverse in Plot 2（high slope gradient）.Species dominance of V.zizanioides population was negatively correlated with the richness index,diversity index,evenness index and dominance index of the plant community.