Differentiation Law Of Vegetation Characteristics On Slope Micro-topography Of Semiarid Loess Area In North Shaanxi Province

Loess Plateau is one of the most fragile areas of ecological environment of China, vegetation restoration is an important way of ecological environment construction in this area. When carry artificial vegetation configuration in Loess Plateau, take the slope as unit and ignore the micro-topography and the habitat differences caused by it, resulting in poor growth of vegetation and other issues. Therefore, this paper based on the investigation data of natural recovery herbaceous communities and arbor communities with different restoration years in Wuqi County of north Shaanxi, studied the vegetation characteristics on the five typical micro-topography categories including shallow gully, gully, collapse, platform, and scarp in the loess plateau, and analysis the soil moisture characteristics of micro-topography, which have most influence on vegetation distribution. Then combined with vegetation recovery goals and configuration structure of micro-topography, put forward suitable vegetation configuration scheme.Following conclusions can be drawn in this paper:(1)There existed distinct differences in the species composition, quantitative characteristics, and species diversity of natural recovery herbaceous communities on the five typical micro-topography categories and the undisturbed slope. After twelve years of enclosure recovery, the study area formed herbaceous plant community, with Artemisia sacrorum and Artemisia giraldii as the dominant species. Among the main companion species, shrubs such as Prinsepia uniflora and Caragana korshinskii were found in scarp and gully, and hygrophyte Phragmites australis appeared in platform. The coverage, height, and biomass of the plant communities on most of the micro-topography, especially on the gully and collapse, were larger than those on the undisturbed slope. The Shannon-Wiener index on the micro-topography and undisturbed slope was in the order of scarp> gully> shallow gully> undisturbed slope> platform> collapse. (2) In the natural recovery arbor communities of micro-topography, Populus simonii, Primus armniaca, Robinia pseudoacacia, Ulmus pumila and shrub Caragana korshinskii distributed widely. Vegetation of scarp is mainly arbor-herb and shrub-herb structure, the growth condition of arbor is poor,"small-old" tree is wide distribution and communities have low canopy density and low diversity index. Shrub Caragana korshinskii has the largest importance value in the shallow gully vegetation, arbor, shrub and herb have no competitive advantage in the host level. Vegetation of collapse is arbor-herb structure in shady slope and shrub-herb structure in sunny slope and arbor species have a significant advantage in both of them. Vegetation of platform is arbor-herb structure based, the development of communities is well and the arbor layer is the most significant, trees in a natural distribution and the communities has high stability. Vegetation of gully is arbor-shrub-herb composite structure and no obvious dominant species, the canopy density of communities is high and the diversity index is the highest.(3) The soil moisture of the micro-topography were most larger than those on the undisturbed slope. Platform and gully have largest soil moisture in all of micro-topography. The soil moisture of shallow layer in collapse has a significant advantage, but the deep layer is small. The change of soil moisture in shallow gully and scarp are similar to those on the undisturbed slope, the soil moisture of shallow gully is slightly better than those on the undisturbed slope and the soil moisture of deep layer in scarp is smallar than those on the undisturbed slope.(4) The vegetation configuration mode of the micro-topography as follows:enclosure recovery is the appropriate mode of scarp; shallow gully should be configurated as same as the undisturbed slope; shrub-herb structure suit for the vegetation configuration of collapse; platform should be configured arbor-herb structure of vegetation; the gully’s appropriate vegetation configuration is arbor-shrub-herb structure.