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Since the 1970s, the forest ecosystem carbon cycle by the profound impact of the global nitrogen deposition, nitrogen deposition changed the terrestrial ecosystem productivity and biomass accumulation. In this thesis, the four levels of nitrogen deposition (N0, N1, N2 and N3) 18a-born Chinese fir plantation soil organic carbon pool, active organic carbon pool and participate in the carbon cycle and soil activity, N settlement order 0,60,120,240 kg N · hm-2 · a-1, each treatment was repeated three times. The main results are: (1) the increase in the amount of nitrogen deposition total organic carbon content of soil organic carbon density had no significant impact of increased total nitrogen content of the soil surface, resulting in soil C / N ratio decreased. (2) The impact of nitrogen deposition on soil soil active organic carbon component content differences, no significant effect on MBC and POC content HWC content showed significant inhibition; - low nitrogen deposition (N1, N2) DOC content, Nitrogen Deposition (N3) of the DOC content. (3) different levels of nitrogen deposition, four kinds of soil active organic carbon accounted for soil organic carbon ratio was 45.08%, which POC / TOC (16.23% ~ 40.02%), followed by MBC / TOC (2.58% to 3.39%) and HWC / TOC (0.45% ~ 1.12%), DOC / TOC (0.36% ~ 0.55%) minimum. (4) the topsoil, TOC and MBC, POC, HWC was a significant positive correlation with DOC showed a significant negative correlation; activated carbon each component also exists a certain correlation between DOC and MBC, POC, HWC was a significant negative correlation, MBC and POC, HWC was a significant positive correlation. (5) through 28 d of culture found that the average daily soil organic carbon mineralization with the incubation time. Downward trend, while the organic carbon cumulative mineralization gradually increase. Overall trend in cumulative mineralization of different nitrogen deposition process under various soil organic carbon performance: With the increase in the amount of nitrogen deposition and reduced average daily amounts of mineralized reduction N1 largest, followed by NO and N2, N3 smallest decline. (6) of nitrogen deposition on soil activity differences, with the promotion of the role of cellulase and polyphenol oxidase, amylase and peroxidase showed some inhibition; - low nitrogen deposition (N1, N2), sucrase no effect, while having a promoting effect on the β-glucosidase enzyme, a high nitrogen deposition (N3) to promote sucrase, but inhibited the β-glucosidase activity. Topsoil, the accumulation of soil organic carbon mineralization with soil cellulase, beta-glucosidase, peroxidase activity was a significant positive correlation. (7) in the topsoil, the cumulative amounts of mineralized soil cellulase, beta-glucosidase, peroxidase activity was significantly positively related to soil organic carbon; invertase, cellulase, amylase, peroxidase with DOC, POC, HWC was significantly related; beta-glucosidase and polyphenol oxidase MBC was a significant positive correlation.
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