放牧对草甸草原植物群落结构及多样性的影响

Effects of grazing intensity on species diversity and structure of meadow steppe community

在贝加尔针茅—羊草草甸草原的同一草地地境上,按放牧退化程度,将其划分为轻度退化区、中度退化区及重度退化区,并测定每一样地内植物群落特征及多样性指标。结果表明,随着放牧强度的增加,群落地上总生物量与中旱生植物的生物量变化保持一致,均呈降低趋势;中生植物先呈增加趋势,后下降;旱生植物呈增加趋势;群落优势种贝加尔针茅Stipa baicalensis和羊草Leymus chinensis呈降低趋势;物种丰富度指数先增加,而后降低;多样性指数和均匀度指数均呈增加趋势,优势度指数则相反。

The Stipa baicalensis-Leymus chinensis meadow was classified into light, moderate and heavy degradation plots according to the different degradation degrees caused by grazing. The plant community characteristics and diversity index in each plot were measured. Results showed that along with the increasing of grazing intensity, the total aboveground yield of community and middle-xerophytes kept similar decreasing trend. That of mesophyte increased first and then decreased but xerophyte showed an increasing tendency. S. baicalensis and L. chinensis were the dominant species and showed a decreasing trend. Species richness index increased first and then decreased. The index of diversity and evenness kept increasing, but the dominance index was contrary.