Vegetation Dynamics And Soil Characteristics During Grassland Succession Process In Abandoned Land

Vegetation dynamics and soil characteristics of different period abandoned land was conducted in typical steppe at Xilinguole League and meadow steppe at Hulunbeier League, Inner Mongolia. The results showed:The function community of annual plants, perennial rhizornatous grasses and perennial rosette grasses were appeared at different succession stage of abandoned land in typical steppe and meadow steppe. With the increase of abandoned time, perennial plants increased, the function communities were richer, P diversity index in two communities reduced with abandoned interval, but the vegetation restoration was slow, the land abandoned for 30 years have not got to climax community. The average of Shannon-Wiener diversity index was 1.5481 in typical steppe abandoned land, which was only 55% of natural grassland, while it was 1.3492 in meadow steppe abandoned steppe.The organic matter, total N, hydrolytic N were increased, then reduced with the increase of abandoned time. The loss of organic C got up to 59.4% in abandoned land. In 0-20cm, the sand content of 0.25-0.05mm was increased gradually, the average content of sand in the abandoned land was up to 76.84%, the sand contents of silt and sand was gradually reduced, the soil mechanic compose became coarse. The soil reclamation has different effect upon soil unit weight and water.In the long run, the economy beneficial of grassland claim is lower. The soil nutrition lose, mechanic compose become crude, vegetation restore is slow, the drought resisted ability is poor. Therefore, it is not worth to claim grassland both from economy and ecology point of view.