Effects of different fallow and wetting methods on soil and vegetation properties in the middle reaches of the Heihe River: a case study of Zhangye National Wetland Park

Wetland is one of the most biologically diverse ecological landscapes in nature and the environment for the survival and development of human society. It is of great significance for the maintenance of ecosystem function and regional ecological security. The purpose of this study was to clarify the impacts of different wetland restoration methods on the physical and chemical properties of the soil and the vegetation characteristics. Inaddition, the application of different wetland restoration methods in arid areas was studied. We used Zhangye National Wetland Park, which is in the middle of the Heihe River, as the research object. Vegetation surveys and soil sampling were conducted in the summer of 2017 on three typical restoration modes in the main area of Zhangye National Wetland Park: natural restoration mode, restoration protection mode, and restoration and utilization mode. The size and road distribution of the area was such that 3-14 samples of 1 m~2 were used. A total of 25 samples were investigated and it was attempted to ensure that they were evenly distributed within the sample plot. The number and height of individual species were also recorded, and specimens of the individual species were brought back to the laboratory for identification. The soil samples from 0-10, 10-20, and 20-40 cm depth were collected from the center of the sample square by using the ring knife method; these were loaded into aluminum boxes and the fresh weight was measured. Another soil sample was taken from each sampling area and brought back to the laboratory. The litter and roots were collected and dried naturally. To determine the physical and chemical properties of the soil samples collected, they were passed through sieves with diameters of 1 mm, 0.25 mm, and 0.15 mm. The plant diversity, plant growth status, soil pH, soil temperature, and soil temperature under natural restoration, restoration utilization, and restoration protection were compared and analyzed. The variation in the characteristics of salinity, bulk density, water content, organic carbon, total nitrogen, total phosphorus, available nitrogen, and available phosphorus were also studied. The results showed that the soil total phosphorus, soil available nitrogen, and species diversity of each layer of wetland were the highest after natural restoration, which indicated that natural restoration could lead to soil phosphorus fixation in arid areas and that appropriate interference may be an effective method