灌丛化草原物种多样性与生产力的权衡关系

Trade-offs between productivity and biodiversity in a shrub-encroached grassland

针对全球变化背景下内蒙古典型草原小叶锦鸡儿灌丛密度增加对生态系统主要服务功能影响尚不清晰的问题,该文采用野外调查为主的方法,研究小叶锦鸡儿灌丛化对内蒙古典型草原物种多样性和草地生产力的影响,探讨灌丛化过程中二者间是否存在权衡关系。结果表明:随着灌丛高度、盖度、密度和生物量的增加,草地生产力显著增加,从8.55 g/m^(2)增加到21.76 g/m^(2);草本群落的物种多样性指数显著降低,物种丰富度从22种/m^(2)降到12种/m^(2);草地生产力与物种多样性间存在明显权衡关系。结构方程模型证明灌丛化对物种多样性和草地生产力都是直接影响,不存在通过影响土壤养分而间接影响物种多样性或草地生产力。本研究结果为灌丛草原利用与管理提供重要理论依据。

Due to the impact of climate changes and human activities,shrubs have encroached in worldwide temperate grasslands and savanna.However,it’s still unclear that the impact of encroached shrubs on the grass productivity and species diversity of typical steppe in Inner Mongolia.Field investigation and sampling were used to analyse the impact of shrub traits on steppe ecosystem functions and their relationships.The results showed that with the increase of shrub height,cover,density and biomass,the grassland biomass increased significantly,from 8.55 g/m^(2)to 21.76 g/m^(2);but biodiversity indices decreased significantly,and the species richness decreased from 22 to 11 species per square meter.Structural equation model further proved that shrub traits only had direct impacts on steppe productivity and biodiversity,and there was no indirect impact on those through affecting soil nutrients.The results of this study provided an important theoretical basis for the management of shrub encroached grassland.