Dynamic Monitoring And Evaluation Of Grassland Rocky Desertification In Karst Region In The Southwest

Rocky desertification of karst area in the southwest of China are the extreme form of degradation of karst ecosystems, which has severely hampered the healthy social and economic development in those regions, and has attracted wide attention domestic and overseas. Grassland is an important part of the natural ecosystem. With a significant karst features grassland resources mainly composed of the secondary growth of natural grass and shrub after the destruction of native forest vegetation in the southwest regions, also as an important class of Rocky desertification of karst area.In this study, evaluation index system of rocky desertification of grassland in the southwest karst area was established using slope, rock exposure rate, grassland vegetation cover rate, grassland vegetation types and biomass aboveground. Weighting of each index was confirmed using analysis hierarchy process and the extent of rocky desertification of grassland was quantitatively estimated according to the rocky Index. The extent of rocky desertification of grassland was divided into five scales, including none, potential, mild, moderate and severe.In case of Qinglong County, Southwest of Guizhou Province, rocky desertification of grassland was systematically researched.Research on vegetation characters and community sorting in rocky desertification of grassland area proved that with more and more serious rocky desertification of grassland, community structure and plant bio-diversities decreased, grass height, grassland vegetation cover rate and biomass aboveground did so to different extent. Slop image, bare rock ratio diagram, grassland type diagram, grassland vegetation coverage map, distribution map of biomass on the ground in the research area were obtained by remote sensing. Current distribution map in the years of1988,1998and2010were obtained by spatial overlaying the raster data.Dynamic monitoring on rocky desertification of grassland showed that area and degree of mild, moderate and severe type were increasing, with a serious situation of rocky desertification of grassland.Space transformation of different scales of rocky desertification of grassland from1988to1998and that from1998to2010was characterized by the trend of main stable degree of desertification, and greater degraded degree than improved degree. However, only a slight improvement but a serious deterioration was found predominantly in above degrees of rocky desertification.Rocky desertification of grassland from different degrees in2050was simulated with Markov process simulation. Results showed that the area of none, potential, mild and moderate degree of rocky desertification of grassland would decline year by year. While, that of sever degree of rocky desertification of grassland would remain unchanged. The total situation of rocky desertification of grassland would be improved.Constructing evaluation index system on driving force in rocky desertification of grassland was also performed based on ten index of lithology, geomorphology, altitude, annual average rainfall, maximum daily rainfall, vegetation index, population density, land reclamation rate, the proportion of dry land are, and the proportion of animal husbandry output value in the total output value of agriculture. And the main force included human factor including land reclamation rate and the proportion of animal husbandry output value in the total output value of agriculture, lithology, annual average rainfall and altitude.According to the spatial principal component analysis results, the grassland rocky desertification vulnerability is divided into5levels:Micro fragile, vulnerable, fragile, mild moderate and severe vulnerable, and the township of Qinglong County, grassland desertification vulnerability zoning evaluation.