Physio-ecological Responses Of Leymus Chinensis To Overgrazing And Clipping

Grazing is the most important way for grassland utilization. Partial or entire defoliation of grass by herbivores is a common phenomenon in natural grassland. At the individual level, defoliation by herbivores has various consequences on grass growth and biomass allocation. As an important arid and semiarid grassland ecosystem in north of China, Inner Mongolia grassland has endured severe degradation and desertification due to overgrazing in past several decades. Overgrazing has resulted in reduction of vegetation coverage and leanness of soil. The deteriorated habitat in turn affected the physioecological fuctions of local plants, such as lowering their photosynthetic rates, restraining plant growth, and eventually decreasing their biomass. In the context of the relationshipes among livestock, plants and soil, this study investigated the possible effects of overgrazing and clipping on morphological and physiological characteristics of Leymus chinensis, and the physio-ecological responses of this dominant grass species to overgrazing and clipping. The main results were summarized as followed:1. Overgrazing resulted in significant decrease in the soil water content, organic carbon content and total nitrogen content, especially in the surface layer. Overgrazing also resulted in reduction of leaf biomass and the number of rhizome tillers per plant, shortening of shoot internodes, and increase of SLA (special leaf area). More biomass was allocated to belowground and little biomass was allocated to reproductive tissues under overgrazing conditions. The height, density, plant coverage and biomass...