Plant Functional Type And Its Functional Dynamic In Degraded Stages Of Three Type Of Steppe In Inner Mongolia

This study focused on three types of steppe ecosystem and their grazing degradation succession serious in Inner Mongolia, including meadow steppe, typical steppe, desert steppe. On the basis of determination of plant caloric values, the classification system of energy functional group in Inner Mongolia steppe was built. The purpose is to reveal steppe degradation mechanism in energy perspective and to provide theory to utilize and to protect grassland in reasonable way. The results were as follow : (1) The value of plant caloric in meadow steppe, typical steppe and desert steppe was small change under grazing disturbance, and no difference existed among different grazing gradients, which showed the stabilization of plant caloric.(2) 128 species of Inner Mongolia steppe were classified in to three energy functional type(high, medium, low)according to plant caloric value by FASTCLUST method. The high energy functional group comprised many grasses and some shrubs. Short grasses and many perennial forbs belonged to the main components of the medium energy functional type. Most of the annual forbs and some perennial forbs composed the low energy functional group. (3) Cover, average height, biomass of high and medium energy functional types decreased, while low energy functional type increased in the heavy grazing areas. The variation of structure caused the change of function. With the degradation increased, the dominance of high and medium functional group were replaced by the low energy functional group. (4)The indices of grassland community were high including species, cover, average height, density, biomass, average caloric values, energy, during the primary of degradation succession. With the degradation increased, especially in late of degradation succession, the function and structure were worse, which were caused by the change of energy functional type. (5) The liner regression model between community energy and energy functional type biomass was built through mathematics method.