Study On Desertification Of Typical Steppe In Inner Mongolia

By lacustrine deposits of Arshut as the research object, analyzed the variation of physico-chemical properties of soil to show the influence of grassland ecology caused by dryed up lake. Main results are as follows:1. Profile organic matter, total potassium content: primary vegetation area> the center of Lake>Northwest coast of lake; Total phosphorus content: the center of Lake>Northwest coast of lake>native vegetation area; Vertical distribution of total nitrogen in different area, Profile were very similar to that of correspondingly organic matter. Available potassium content of profile: the center of lake>northwest coast of lake>native vegetation area. PH value, total salt content, salinity and conductivity: the center of lake>Northwest Coast of Lake. Display generally that: salinization degree of lacustrine deposits became heavier, pH value became higher and lacustrine were drying rapid. Vegetation succession falled behind and then accelerated desertification.2. The analyses of particle in profile deposits showed that when diameter of particle1-0.05 mm the grain content were the highest, it took second place when diameter of particle<0.001 mm,the diameter of particle1-0.05 mm, which in 0~30cm.particles content reached 52%,with plentiful sand source. Bare lacustrine deposits is one of the important reasons for grassland desertification, sand storm, saline-Alkaline dust storm.3. Analysis of horizontal differentiation showed that: the differentiation of organic matter, nitrogen, total phosphorus, available potassium and available nitrogen in surface layer tended to be uniform. tendency of increase first and reduction afterwards, from the center of lake to outer margin, accumulated in junctional area and Southeast Region of the lake. The horizontal distribution pattern of total potassium was less evident. Available potassium in the southeast Region were higher then that of northwest region. The accumulation of Saline-Alkaline in southeast region of lake were more under the action of wind-blown desert region. The horizontal distribution pattern of conductivity were similar to that of salinity and the highest value were in bare region; pH value took bare region as boundary, increased with depth in Southeast Region of the lake and decreased in northwest region. In general, they were higher in Southeast region of the lake than that of northwest Region. Horizontal differentiation salinity, conductivity and total salt content showed that the center region higher then edge and increased in grass weeds. The practical of sediment showed that the content of diameter of particle1-0.05 mm were higher in centre than edge. The distribution of diameter of particle<0.001 mm was opposite.4 The vegetation changed seriously due to drying up of Arshut lake. When it dried up, drawing into new sand-tolerant, salt-tolerant plants, such as Messerschmidia sibirica and Suaeda salsa L., Saussurea runcinata DC, etc. With distance from the lake, the Arshut lake vegetation and terrain, vegetation changes regularly and variety of vegetation was from Messerschmidia sibirica and Suaeda salsa L.to Leymus chinensis, L. chinensis (Trin.) and Stipa grandis .