Study On Dynamic Soil Nitrogen In Different Vegetaion Restorations In Guangyuan City

Nitrogen is one of the main compositions made of organism protein and nuclei acid , at the same time , it is also one of the necessary nutritious elements during the course of vegetation growth. Only with plenteous nitrogen, can vegetation grow healthy.Howere, most of nitrogen exists in organic form, which form is different from the inorganic and can't be absorbed and utilized by vegetation. How to make forest utilize the limited nitrogen resource? It is a challenge in front of us .So, on this background, it is very imperative to comprehend the mechanism about nitrogen cycling in order to increase efficiency of nitrogen in the forest ecosystem. We research five vegetation restoration types and compare the following facts to exceeding a degeneration soil: nitrogen input , transition , return; the relationship between nitrogen and other elements; the relationship between nitrogen and microorganism; the relationship between nitrogen and special diversity.The results indicate that:(1)Compare with the comparion, the soil physics character are improved after vegetation restortion , the soil unit weight in cyclobalanopsis glauca, Pinus elliottii, Robinia pseudoacacia , mixed forest and fire slash shrub separatly are 1.525g/cm~3, 1.426 g/cm~3, 1.625 g/cm~3, 1.482 g/cm~3, 1.423 g/cm~3. We can find the soil unit weight in other forest all bigger than the comparion (1.580 g/cm~3) except Robinia pseudoacacia .All these mean forest soil is looser and better capacity for aerated and dank.(2) The total soil nitrogen content is teady and no obvious change during all the season.There is nearly the same season trends as organism and microorganism. The total nitrogen begins to reduce in spring(april) and reach the minimal in July. After July, it again increase and reach the maximum in October going with temperature decreases. Thetotal soil nitrogen is positive relativity (relativity index is 0.722**), which is inosculated with the foregoing conclusion.(3)There is positive .relativity between the total soil nitrogen and nitration nitrogen(relativity index is 0.510**), no correlationship between ammonium nitrogen. The content of nitration nitrogen under 0.159~8.45mg/kg and the absoluted quantity is smaller than ammonium nitrogen. These indicate the basal resource of minal nitrogen is ammonium nitrogen and the function of nitration nitrogen is tiny. In view of nitration nitrogen and ammonium nitrogen, there is obvious difference between different forests (F=2.037, Sig .F=0.122; F=1.649, Sig .F=0.198) .Other nutritious elements also add with the vegetation restoration.(4) Forest litter is the adjuster between forest water cycling and nutrient cycling .Litter has following functions: overcasting the earth's surface > decasing velocity of runoff> conservating the soil and water, depositeding nutrient substance, and so on, but the last function is the most important. The litter reserves in different forestes in following order: Pinus elliottii average index > richness index andsoil fertilities factors(espically the relativity of soil nitrogen).The results shows : there is a obvious relativity among the biodiversity index(Shannon-Wiene index ) -. effective phosphor and hydrolyzed nitrogen(the relativity respectively is 0.960** and 0.996**);the relativity of the Simpson index -. effective phosphor and hydrolyzed nitrogen respectively is 0.934*, *0.991**; the relativity of the margalef index and nitration nitrogen respectively is 0.890*; the relativity of menhinck index> effective phosphor> hydrolyzed nitrogen respectively is 0.945*, *0887**.Therefore, we can draw the conclusion that the biodiversity relay on the contents of soil hydrolyzed nitrogen and effective phosphor.