Temporal And Spatial Variation Of Nitrogen In Ecological Protective Forests Soil In The Riparian Of East Lake Taihu

Nowadays, the situation of water pollution situation is getting worse and the eutrophication isgrim. Riparian ecosystem is an important ecological protective barrier that could alleviate theeutrophication of water. The process of soil nitrogen mineralization in the Riparian can furtherelucidate the function of protecting the riparian ecosystem. In this research, compared with Lawn,we selected three typical ecological protective forests in Lake Taihu. We applied lab incubationmethod to incubate primary soil samples and the method of collecting and analyzing soil samplesto study soil nitrogen mineralization and dynamics of soil mineralized nitrogen. The purpose wasthat to under the potential influence caused by the soil nitrogen mineralization in differentecological protective forests and the relevance of various factors in the research area. The resultsshowed:（1）In three typical ecological protective forests of Lake Taihu, total soil nitrogen, availablenitrogen and NO3--N content were higher than Lawn, showed that: Camphor> Magnoliagrandiflora>Poplar> Lawn. The content of NH4⁺-N was obviously higher than Lawn, showed that:Magnolia grandiflora> Camphor> Poplar> Lawn. NH4⁺-N, NO3--N, available nitrogen and totalnitrogen showed a significant seasonal fluctuations in this research, winter> autumn> spring>summer. Among the seasons, temperature is an important factor affecting the level of availablenitrogen in soil. The vertical direction showed that the upper> middle> lower, indicating thatavailable nitrogen is mainly existed in the surface soil, the deeper soil is relatively less.（2） In the condition of ecological protective forests, the soil of different forests was put in theartificial climate chamber of temperature under5,15,25and35°C for30days. The result showedthat no matter Lawn soil or ecological protective forests soil, soil mineral nitrogen, the rate ofnitrification and nitrogen mineralization trend to increase with the temperature. At the sametemperature, the mineral nitrogen, nitrogen mineralization rate of different ecological protectiveforests soil were as follows, Camphor> Magnolia grandiflora> Poplar> Lawn.（3） The seasonal dynamics of different forests soil nitrogen mineralization results showed thefollowing characteristics that the amount of soil ammonification and nitrification of nitrogen,mineral nitrogen content run in the order, summer> autumn> spring> winter, and the maximumappeared in the summer. Soil nitrification rate showed the following characteristics that Camphor> Poplar> Magnolia grandiflora> Lawn. Soil mineralization rate showed the followingcharacteristics that Camphor> Magnolia grandiflora> Poplar> Lawn, following the same regularwhich is summer> autumn> spring> winter. The maximum was the same appeared in the summer. （4）The soil temperature and humidity have significant correlation with the soil NH4+-N andthe mineralized total nitrogen （p<0.05）.The soil TN,TOC and pH have very significant correlationwith NH4⁺-N and the mineralized total nitrogen（p<0.01）,but there were no significant correlationbetween them and the soil NO₃--N（p>0.05）.The NH4⁺-N and the mineralized total nitrogen havevery significant correlation（p<0.01）.