Effects Of N Fertilization On C:N:P Ecological Stoichiometry Of Chinese Fir In Huitong

Chinese fir is unique and famous fast-growing timber species in China. The quality of Chinese fir plantation forest declines would effect the long-term productivity. From state of development of our country’s Chinese fir plantation forest, we had some necessary management measures to help plantations, of which fertilization was a quick and effective way to increase soil nutrient. In this paper, the author has chosen the Chinese fir forest which in Huitong Hunan as the object of study to conduct the one-year experiment though different fertilizer. The author measured the C, N, P content and stoichiometric ratio of soil, root, leaf and litter under different fertilizer treatments and different times with the ecological metrology method. The research analyzed the influence of C, N, P content and ecological stoichiometry of Chinese fir forest through applying N fertilizer. And the research also analyzed the seasonally dynamical change rule of the same index above by applying N fertilizer. It discussed the relationship of C, N, P content and stoichiometric ratio between the different organs and soil. It also discussed seasonal dynamic comparison and relationship of C, N, P content and stoichiometric ratio among the different organs. The research revealed the important effect on the growth of Chinese fir forest with applying N fertilizer. It provided theoretical basis for the healthy and rapid development of Huitong Chinese fir forest. The main research results are as follows:（1） N fertilizer can increase the N, P content of leaf, inside applying N fertilizer 5 g.m^-2 effects better than applying N fertilizer 15 g.m^-2 and 25 g.m^-2 to increase N content of leaf. And the correlation analysis showed that N content of leaf and soil had significant positive correlation after applying N fertilizer 5 g.m^-2. The study shows that applying low N fertilizer helps the growing of plants in this study area.（2） Applying N fertilizer 15 g.m^-2 and 25 g.m^-2 increases the C:N ratio of leaf, inside applying N fertilizer 15 g.m"2 effects better than applying N fertilizer 25 g.m^-2, which shows that fertilizer reached into the certain number, the C:N ratio of leaf will reduce with the increasing of N fertilizer. N fertilizer can increase the C:N, C:P ratio of litter, and applying N fertilizer 5 g.m^-2 and 25 g.m^-2 increases the N:P ratio of litter. The study shows that applying N fertilizer helps the growing of Chinese fir forest. From here we can see that only the scientific and reasonable fertilization measures can effectively promote the rapid development of Chinese fir forest in health.（3） The C content of Chinese fir forest decreased from autumn to winter, increased from winter to spring, decreased from spring to summer. The C content of root, leaf and litter reached the maximum in April after applying N fertilizer. The N content of Chinese fir forest was in a decreasing trend, inside the N content of root was relatively low in July. But after N fertilizer the N content of leaf was relatively high in autumn. The P content of Chinese fir forest reached the minimum in April. Inside the P content of leaf was the highest among that of all the organs. The P content of litter was the lowest among the P content of other organs from April to July. The analysis of seasonal dynamic shows the demand of N for plant is larger in spring.（4） The C:N ratio of soil was significantly increased from autumn to winter. The C:N ratio of root has been higher than that of other organs from autumn to winter. And the C:N ratio of leaf in all the organs was the lowest. The C:N ratio of litter was relatively low in autumn and winter. The C:P ratio of soil and root reached the maximum in the spring. The C:P ratio of litter was gradually increased from January to April. N:P ratio of soil decreased significantly from April to July. N:P ratio of leaf was higher than the N:P ratio of root and litter in January. It shows that the demand for N fertilizer is small in autumn and winter. N:P ratio of leaf was higher than the N:P ratio of root under applying N fertilizer 5 g.m^-2. The study shows that the application of N fertilizer 5 g.m^-2 was more beneficial to the growth of Chinese fir forest.（5） The C:N ratio of leaf and litter was significantly positively correlated with no fertilization and applying N fertilizer 25 g.m^-2. The C.P ratio of root and litter was significantly positively correlated with applying N fertilizer 15 g.m^-2. The N:P ratio of root and litter was significantly positively correlated with no fertilization. The research shows that under the condition of no fertilizer and high nitrogen, the conversion rate of nutrients is high among leaf, root and litter, which is not good for plants to grow. In sum, the Chinese fir forest management needs to fertilise quantitatively according to the actual situation.