Contrast Study On The Community Dynamics Of Sophora Davidii And Robinia Pseudoacacia In Hilly-gully Region Of Loess Plateau

Erosion of water and soil was serious, ecology environment was weak, diversity was decreased in hilly-gully region of Loess plateau, which affect production and living of people's. Natural community of Sophora davidii and Robinia pseudoacacia in different stage of aged and different slope in hilly-gully region of Loess plateau, age structure of community of Sophora davidii and Robinia pseudoacacia, community diversity, effect of water and nutrition, effect of environment factors were studied systematical, evaluated system of community stability was set up, stability of community of Sophora davidii and Robinia pseudoacacia in different conditions was evaluated, fit habitat of Robinia pseudoacacia community was decided, in which theory were supplied standard for vegetable restore and rebuild in hilly-gully region of Loess plateau.1. Age structure of community of Sophora davidii,effect of water and nutrition in community, community diversity and effect of environment factors were analysis: Sophora davidii can natural renew well in semi-sunny slope and sunny slope, individuals of middle aged were many, Sophora dvidii population in loess hilly region was a developing one, Sophora davidii population can survived for long in different habitat in hilly-gully region of Loess plateau. Diversity was high, community was stability more and more, water and nutrition was better in both semi-sunny slope and sunny slope. community was more stability by studying age structure, community diversity and effect of water and nutrition in different restore stage in the same habitat, with development of time. So recovery condition of Sophora davidii population was better after sealing, manifeting the efficiency of sealing measure.2. Age structure of population of Robinia pseudoacacia effect of water and nutrition in community, community diversity and effect of environment factors were analysis: Robinia pseudoacacia population in different habitat of the same aged stage had renewed seeding in the semi-sunny slope, semi-cloudy slope, gully and valley, otherwise has not renewed seeding in the mao slope and sunny slope, Robinia pseudoacacia population in loess hilly region was a recession one, that is not stability population, will recession with the development of time, but is fitter basically in the semi-cloudy and gully and valley. Diversity was high in the semi-sunny slope, semi-cloudy slope, gully and valley. Water was serious shortage in mao slope and sunny slope, which affect grow of Robinia pseudoacacia, although nutrition was improved, was low more than Sophora davidii, water and nutrition did not supplied for stability development of community. Community was not stability by studying age structure, community diversity and effect of water and nutrition in different restore stage in the same habitat, with development of time. So Robinia pseudoacacia was planted in semi-cloudy and gully and valley slope with better water condition, and effect foster measure was made. 3. Environment factors were analyzed: it was showed that water factor was the importantest in different stage and different habitat, and affect stability of community. Therefore water factor was adjusted in management in order to enable sustainable living of community and gain ecology goal of water and soil conversation. 4. Local trees should be considered in priority in order to restore vegetable beneficial as soon as possible in recovering and rebuilding vegetable in the future in hilly-gully region of Loess plateau; Natural community should be sealed and enabled coverage to raise gradually, at the same time, plants in herb layer should be not disturbed and promoted to develop ecology benefit. Man-made forest should be remade in order to emerge recession of community and forestation failure.