The Preliminary Research Of Caragana Shrub Nabkhas In The Inner Mongolia Plateau

In this study, we explored the morphology of shrubs and nabkhas, sand-fixing capability and soil resource spatial heterogeneity of five dominant Caragana species(C. microphylla, C. korshinskii, C. stenophylla, C. roborovskyi and C. tibetica)) in the diffirent zone; finally, the mutual raletionship of the thicketization mechanism of steppe and thicketization-steppe function was discussed. The main results were as follows:1. The morphology of shrubs and nabkhas and sand-fixing capability of plants had a good adaption with their habitats, and they were largely effected by their habitats2. Within each of the four Caragana species in the typical desert, the nabkha volume, morphology and sand-fixing capacity were probably determined by shrubs’ aboveground biomass. Among the four Caragana species, the difference of nabkha morphology, development characteristics, and shrubs’ sand-fixing capability were probably caused by the interspecific differences in morphology and development strategies.3. Shrub nabkhas, formed by C. stenophylla and C. microphylla in the desert steppe, could induce spatial heterogeneity of soil resource, which enhanced increasingly as the shrub nabkha expanded; the plant species, soil depth and development stage probably determined the spatial heterogeneity of soil resource.4. Spatial heterogeneity of soil resource were caused not only by shrub nabkha development stage, but also effected by landform, soil parent material.5. The soil resource of C. tibetica distributed newly in the process of degeneration of C. tibetica. This phenomenon was related to the shrub morphology, development state and drought resistance mechanism.6. Caragana could induce soil spatial heterogeneity of the Inner Mongolia Plateau; for all soil depths of three Caragana, along the horizontal direction from the inside to the edge and to the outside of nabkha, soil resource of three Caragana tended to decrease; for the inside and edge of shrub nabkha, along the vertical direction from0-10cm to10-20cm and to20-40cm soil depth, soil resource presented different trends among three Caragana.7. In the arid and semi-arid grasslands ecosystem, which the coverage of shrubs should be no more than20%is advisable. On the one hand, the ecological environment of the composite community is better than a single community; on the other hand, the density of shrubs not only avails the development of the herb layer, but also avoids the resources losses of ecological system caused by soil erosion.