Plant And Soil Characteristics Of Different Vegetation Types And Their Relationship With Soil Organic Carbon In The Middle Reaches Of Heihe Wetland

Wetlands are one of the most important carbon reservoirs in the world,accounting for about 35% of the carbon reserves of terrestrial ecosystems and playing a crucial role in the global carbon cycle.For a long time,due to the increase of population and rapid economic development,the wetland area is shrinking,and its function is declining or even disappearing.The degradation and disappearance of wetland will cause the changes of plant community characteristics and soil physical and chemical properties,thus affecting the storage and release of wetland carbon,and appropriately improving plant and soil conditions.Therefore,the study of different vegetation types,soil characteristics and their relationship with soil organic carbon has important practical significance and theoretical guidance for carbon sequestration and carbon loss reduction in Heihe and other arid wetlands.Based on the field investigation to obtain data of vegetation,soil and soil samples based on the experimental data,comparison of different vegetation types of plant community characteristics,the indicators of soil physical and chemical properties,using the variance analysis,correlation analysis and structural equation model method,studied the heihe river middle reaches the growth condition of wetland plant community composition,and various vegetation types,the difference of soil physical and chemical properties,soil organic carbon and soil organic carbon change path,eventually clear vegetation types in favour of soil organic carbon accumulation.The main research results show that:(1)Natural trees are good at maintaining species diversity and plant community structure.Artificial management of grassland effectively promotes plant growth and development,while returning cultivated land to wetland,natural grassland and natural shrubs are better than artificial management of grassland in maintaining species diversity and plant community structure,and inferior to natural trees.(2)Compared with the natural state,soil physical and chemical properties can be better improved.Under artificial management,the soil moisture content was the highest,soil bulk density and pH were the lowest,and soil salinity was low.Artificial fertilization has great influence on soil nutrient,and the influence of artificial fertilization on soil nutrient is difficult to be eliminated in a short time.The conversion time of farmland to wetland was relatively short,so the soil available nitrogen,total soil phosphorus and available soil phosphorus were significantly higher than that of artificially managed grassland,natural grassland,natural shrub and natural tree(P<0.05).(3)Artificial management of grassland is more conducive to the accumulation of soil organic carbon.Soil organic carbon of different vegetation types is different,showing the law of artificial management of grassland > to return farmland to wetland > natural grassland > natural shrub > natural trees,soil organic carbon density distribution law in each vegetation type is basically consistent with that of soil organic carbon.(4)Artificial management can mask the process of soil organic carbon change.Artificial management such as water diversion fertilization methods can improve the growth condition of plant community,soil physical and chemical properties change dominated the affecting factor on the changes of soil organic carbon,in the presence of path analysis simpler paths,but essentially the change process is not simple,and is likely due to the addition of human factors become more complex.