祁连山北坡“毒杂草”型退化草地群落生态位特征

Niche characteristics of ‘noxious and miscellaneous grass type'degraded grassland on northern slope of Qilian Mountains,China

采用生态位相关理论,分析了祁连山北坡阿尔泰针茅草原放牧干扰下"毒杂草"型退化草地群落生态位特征。结果表明:在"毒杂草"型退化草地,建群种阿尔泰针茅(Stipa krylovii)与狼毒(Stellera chamaejasme)和甘肃臭草(Melica przewalskyi)等伴生物种的重要值相似,均有较高重要值;阿尔泰针茅的生态位宽度小于赖草(Aneurolepidium dasystachys)和狼毒等伴生物种,赖草和狼毒的生态位宽度分别为0.925、0.922,阿尔泰针茅仅为0.669;草地群落中植物物种之间生态位重叠较高,生态位重叠值大于0.050的种对有207对。"毒杂草"型退化草地群落生态位特征具有一定的特殊性,不同于其他草地退化类型,这与过度放牧引起的群落微环境改变以及植物种群抵御群落环境改变的策略和种群自身的适应能力相关,反映了"毒杂草"型退化草地植物种群应对放牧干扰的更新途径。

By using niche theory, this paper analyzed the niche characteristics of ＇noxious and miscellaneous grass type＇ degraded grassland on the northern slopes of the Qilian Mountains under the grazing disturbance of Stipa krylovii grassland. In the degraded grassland of ＇noxious and miscellaneous grass type＇, the constructive species （S. krylovii） and the main accompanying species （Stellera chamaejasme and Melica przewalskyi） had the similar higher importance value. The niche breadth of Aneurolepidium dasystachys and S. chamaejasme was 0.925 and 0.922, respectively, being greater than that of the other species, while the niche breadth of S. krylovii was only 0.669. There were 207 species pairs having the niche overlapping index over 0.05, indicating a lower niche polarization of the populations. The niche of the degraded grassland had some special characters different from other degraded grassland types, which could be related to the changes of community microenvironment, the resistance strategies of the populations against the microenvironment changes, and the populations themselves adaptability, reflecting the adaptive approaches of the populations to the regeneration under grazing disturbance.