The Study On Degradation Characteristics Of Ammopiptanthus Mongolicus Community In West Ordos Region

In recent years, the Ammopiptanthus mongolicus community had begun to degrade in the West Ordos district. In order to understand the degrade processes, and investigate the reason causes such degrade and in particular the evolution trends of the physical and chemical properties of the soil within the community, we proposean approach to investigate and analyse the community structure of s community, quantitative characteristic, structure of Ammopiptanthus mongolicus group and spatial distribution and made the measurement the physical and chemical properties of the soil within the community for the Ammopiptanthus mongolicus community in different degeneration stages. The research provides scientific basis for the reasonable protection of Ammopiptanthus mongolicus and the regulation and control of artificial community in Ammopiptanthus mongolicus community. The following conclusions were drawn from the preliminary study:(1) The species composition, species quantity and diversity of species for the Ammopiptanthus mongolicus community in different degeneration degree have changed. With increasing degree of degradation, the number of the plant species decreased first and then increased, biological diversity index increased, and annual species proportionincreased. Replacement took place amongplant species in each degradation stageswith the reduction of above-ground biomass and coverage in the bush fallow and the increase of herbaceous above-ground biomass and coverage.(2) Through the analysis on the age class of constructive species, it can be obtained that the Ammopiptanthus mongolicus community lacked of seedlings and young plants in the West Ordos district with slow natural reproduction and the seeding only updated in severe degradation stage. The reasons for the degradation may be caused by the natural update when growing up to the summit or other undiscovered external reasons.(3) Soil nutrients may not be the reason that leads to Ammopiptanthus mongolicus degradation, and the soil could not be used to judge the degree of degeneration for Ammopiptanthus mongolicus community due to the hysteresis quality of the soil nutrient degeneration and self recovery quality of the community degeneration in short time.(4) With the advance of degraded communities, the soil moisture within the community began to decrease with the reduction of soil bulk density and soil clay grain and the increase of soil porosity at the same time.Soil moisture may one of the main reasons lead to the Ammopiptanthus mongolicus degradation.