Analysis Of The Spatial Structure And Seasonal Variations Of The Isolated Wetland Soil Carton, Nitrogen And Phosphorus In Sanjiang Plain

Sanjiang Plain is one of the largest freshwater wetland area in China. In recentdecades, under the influences of human activities and natural factors, wetland areawas reduced rapidly, a serious of landscapes fragmented seriously, and Wetlandlandscape structure fragmentation produced a large number of isolated wetlands. Thispaper was concerned about relatively isolated and smaller isolated wetlands after theloss of landscape fragmentation and took samples of soil accdording to plant tractswhich was taken from the center farmland to the surround. Using the method ofmathematical statistics analysis of soil carbon, nitrogen and phosphorus spacestructure, seasonal changes and influencing factors of the Sanjiang Plain isolatedwetland.Research results show that:From the point on the vertical direction, every sample point of total nitrogen inthe soil from May to September was mainly distributed in the upper soil. Everysample point of nitrate content declined with the increase of soil depth in May to Aug,then with the increase of soil depth showed a trend of decrease after the first increasein September. Every sample point of ammonia and nitrogen contents declinedgradually with the increase of soil depth from May to Aug, but except farmland.Except the centre of isolated wetlands in September, the rest of the sample pointspresented "V" shape trend that increased first and then declined with the increase ofsoil depth. On the horizontal direction, soil total nitrogen and ammonia nitrogencontent by isolated wetland center to the surrounding farmland were increased afterdecreased first inverted "V" word, the nitrate nitrogen content were increased after thefirst reduce "V" rule.Soil organic carbon content declined with the increase of soil depth in wholeaspect, and was evident in the growth season of plants. Organic carbon content inisolated wetland was higher than fields. From May to September averages, by isolated wetland center to the surrounding farmland soil organic carbon content declined afterthe first increase as the rule of "V" word, maximum point appeared in Mao Guo mossgrass.Spatial distribution of total phosphorus was more complicated, and seasonaldifferences was clear. Every point of total phosphorus content have been increasedafter decreased inverted "V" shape trend with the increase of the depth of soil in May.Every point of total phosphorus content overall showed a trend of decrease withthe increase of soil depth in July and August. After September it reduced thenincreased as the trend of "V" type. Soil available P content was more obvious in Mayand July, while the underlying concentration was more obvious in August andSeptember. On the spatial distribution of it, isolated wetland center to the surroundingfarmland soil available P content showed a trend of decline.Interference by human activities, spatial and temporal variations of soil carbonand nitrogen and phosphorus content was larger than that under the condition of thestate of nature. Lobular chapter community soil pH and organic carbon werenegatively related and every sample point was not significant correlation between soilpH and total nitrogen, but it was significant in carex pseudocurica-reed grass. Soil carbon,nitrogen and phosphorus contents rised with the increase of the isolated wetlandsurface temperature and shallow soil temperature.This paper has significant influences on uncovering the ecological function ofwetland and assessing environmental effect of wetland.