Effects Of Different Disturbance Types On Vegetation And Soil In Jartai Saline Lake Area

In this paper,the artificial management,grazing prohibition and free grazing disturbance plots in Jilantai Salt Lake area were taken as the research objects.The field sampling and indoor analysis were used to investigate the characteristics of typical plant communities and soil physicochemical properties in this area.The succession law of vegetation under different disturbance modes was analyzed,and the regulation mechanism of human disturbance on land desertification was revealed,and the desert in Northwest China was discussed.The suitable utilization and management mode of Jilantai Salt Lake provides scientific basis for rational utilization and effective management of Jilantai Salt Lake Area.The main conclusions are as follows:(1)By investigating three kinds of plots,there are 35 species of plants in 11 families,including 12 Chenopodiaceae,9 Poaceae and 7 Asteraceae,accounting for more than 60%of the total.The species composition showed as follows:artificial management>grazing prohibition>free grazing.Artificial management can significantly increase vegetation height,coverage,Shannon—Wiener diversity,Simpson dominance,Margalef richness and aboveground biomass.From artificial management to grazing prohibition to free grazing,the dominant species succession sequence was Artemisia ordosica+Sphaerophysa salsula+Thermopsislupinoides+Tamarix chinensis?Nitraria tangutorum+Agriophyllum squarrosum+Sophora alopecuroides ? Agriophyllum squarrosum+Phragmites australlis.The species succession degree of artificial management and grazing prohibition was relatively low,the habitat heterogeneity was small,and the community similarity was high.In addition,the European distances from the three sample plots to the stable point in the study area are quite different,which indicates that the vegetation community structure in Jartai Saline Lake area is extremely unstable.(2)The distribution of soil particles in the study area was relatively dispersed,in which fine sand and medium sand were dominant,with average contents of 52.99%and 39.11%.After the measures of enclosure and protection are implemented,the fine matter accumulates continuously,and the order of fractal dimension from big to small is:artificial management(2.46)>grazing prohibition(2.33)>free grazing(2.27).The frequency distribution curves of soil particles in grazing prohibition and free grazing are bimodal,while the frequency distribution curves of soil particles in artificial management are single-peak and narrow-peak,and the range of easily eroded particles in three different disturbance modes is 58.9—111um.The contents of organic matter,alkaline hydrolyzable nitrogen,total nitrogen,available potassium and total potassium in the 0-30cm soil layer of different disturbance modes in the study area all showed the disturbance modes of artificial management>grazing prohibition>free grazing.In the study area,K+and Na+are the main cations,Cl-and SO42-are the main anions,and most of them increase with the increase of soil depth,which has certain characteristics of bottom concentration distribution.(3)Through correlation analysis and principal component analysis,the main factors affecting vegetation growth are soil mechanical composition,soil water content,total nitrogen,organic matter and available phosphorus content,and artificial management can significantly promote vegetation restoration and soil improvement.