Primary Study on the Community Characterisfics of Vegetative Restoration in the Gully Area of the Hilly Loess Region

Hilly Loess Region is the most fragile and underdeveloped area of the Loess Plateau and vegetative restoration and reconstruction is the first task of ecological enviroment construction in this region.The policy of returning farmland to grassland,grazing ban,and hillside enclosure and so on has been allaround implemented in the northwestern China.Realizing the community characteristics after enclosing hillsides for vegetative restoration in the gully area would help to analyze the direction of vegetative succession in this area and make sure of the mission and objective of vegetative restoration.Investigations were conducted on plant species abundance,species frequency,and species similarity coefficient in plots of two gullies which located in the typical Hilly Loess Region of Ansai County,northern Shaanxi Province.Based on the investigation,81 species belonging to 31 families were found and the families of Gramineae,Compositae,and Leguminoseae accounted for 19.75 %,16.05 %,and 14.81 %,respectively.After 20-year hillside enclosure,vegetative succession has expressed a better succession trend with high abundances and diversity.Herbage was the major community life form,especially perennial herbage,while shrub and arbor also had importance positions.Shrub and arbor showed significant influence on the diversity and structure of plant communities and so on.Patch pattern of vegetative distribution was prominent in the gullies.Differenceswere found in the construction pattern of importance values of shrub and arbor between different direction gullies.We also found that the south-north gully was more even than the west-east gully.There were some differences in species similarity between different gully directions;however,these differences were mainly affected by some coexistence species and unusual species.