The relationship between community species diversity and degradation degree of Leymus chinensis meadow steppe in the Hulunbeier

chinois. 对不同退化程度下呼伦贝尔羊草草甸草原植物多样性进行了研究.结果表明：随草原退化程度加重,植物种数目逐渐减少,其中禾本科植物物种明显下降,而豆科、菊科、莎草科植物物种数目变化不大;生活型内多年生草本植物和半灌木类植物种逐渐减少,而一、二年生草本则呈现“低-高-低”的波动变化;中生植物物种数目在群落中所占比例明显下降,而中旱生和旱生植物所占比例逐渐上升;在草原退化过程中,植物群落发生了羊草＋杂类草草原-羊草＋寸草苔-寸草苔的逆向演替;随草原退化加剧,群落α-多样性明显下降,其中重度退化草地的物种丰富度、多样性、均匀度分别比轻度退化草地下降了27%、62%、61%;β-多样性指数表明,轻度退化草地与中度、重度退化草地的群落结构相似性较低,中度与重度退化草地之间相似性较高.[著者文摘]

anglais. The community species diversity tion degrees in Hulunbeier was studied 1） Along with the degradation degree, on the b of Leymus chinensis meadow steppe in different degradaasis of sample plot survey. The results showed as follows： the species number of plants in different families varied as well, number of plants gradually decreased,and the species among which the species number of plant in Gramineae decreased, the species number of plants in three families including Leguminosae, Compositae and Cyperaceae had no significant variation, while the species number of plants in the genus Potentilla L. of Rosaceae with a kind of indicative significance for grassland degradation significantly increased. 2） Along with degradation succession, species number of herbaceo degraded us plants the species composition of plants in different life forms had changed. Among which, the perennial herbaceous plants and semi-shrubs gradually decreased. As to annual-biennial ,the species number showed a changing trend of single peak curve（low-high-low） with succession. As to the change dynamics of ecological types with succession process, the proportion of the species number of the mesophytes both the intermediate xerophytes and xe gradually decreased,while the proportion of the specie rophytes increased. 3） Along with the grassland degra s number of dation gradients,the grassland communities showed a serie to the Leymus＋Carex duriuscula meadow,and munities significantly decreased with serious de s of regressive succession from the Leymus＋orbs meadow to the Carex duriuscula meadow. 4） The α-diversity of communities significantly decreased with serious degradation of grassland,in which three indexes such as species richness,diversity and evenness decreased by 27 % ,62% ,and 60.7 % respectively compared with the light degradation. 5）The β-diversity indexes in community gradient showed that the similarity in community structure of light degradated communities to others was lower, while the moderate degraded communities was more similar to the heavy degraded communities.