Effects Of Simulated Nitrogen Deposition And Litter Composition On Soil Animal Diversity In Litter Layer Of Cryptomeriafortunei Plantation

Due to the rapid development of the industrialization in China, southern China has become the third largest nitrogen deposition after the USA and Europe and area, and has a growing trend.Continuous nitrogen deposition may change the species composition of forest, influence the diversity of forest litter, which influence the material cycle of forest ecosystem. Litter is an important part of material cycle in forest ecosystems, is an important food source for soil animal. Therefore, the changes in the composition of litter in a certain extent restrict and affect the soil animal species and quantity. However, due to the complexity and heterogeneity of soil ecosystem,at present, increasing nitrogen deposition on animal community remains considerable uncertainty, the nitrogen deposition and litter components change work together in the study of soil animals is rarely reported.Based on this, the study through field simulation test, using thelitter bag method, set the nitrogen deposition, litter composition and the interaction of three treatments, study the simulated nitrogen deposition and litter composition changes on Chinese Cryptomeria litter layer of soil animal community. N deposition setting control (CK), low nitrogen (N5), medium nitrogen (N10) and high nitrogen (N15) four processing; Litter change control (pure Chinese Cryptomeria litter L), Chinese Cryptomeria (mixed with Chinese Fir 1:1 litter (LS), Chinese Cryptomeria and Phoebe Nanmu 1:1 mixed litter (LN) 3 kinds of processing. Through the experiment of 1.5 a, has obtained the following main research results:(1)The amount of soil animal communities detected in Chinese Cryptomeria litter layer of soil animal communities is 6785,belongs 2 gate 9 classes 23 orders,84 families Dominant groups four types, namely, such as Isotomidae、Onychiuridae、Oribatida, Prostigmata, its individual number accounts for 73.12% of the total number of individuals.(2)Chinese Cryptomeria litter after adding exogenous litter, litter layer of soil animal density increased significantly (P<0.05), also increased the number of soil fauna, but the difference was not significant; Shannon-Wiener diversity index, Pielou uniformity index and density-taxa index increased significantly (P<0.05), Simpson dominance index was significantly lower (P<0.05).(3)Chinese Cryptomerialitter after adding Phoebe Nanmu litter, soil fauna density, the number and diversity of taxa than adding a whole Chinese Fir litter. This indicates that coniferous provide a more mixed coniferous litter better living environment for the layer of soil animals.(4)N deposition makes Chinese Cryptomeria litter layer increases the density of soil animals, high nitrogen soil animal density increased significantly (P<0.05), reducing the number of taxa; animal litter layer of soil nitrogen deposition process Shannon-Wiener diversity index lower, lower nitrogen and nitrogen in Pielou evenness index increased nitrogen in the Pielou evenness index decreased, low nitrogen and nitrogen density-taxa index decreased nitrogen density-taxa index increased significantly (P<0.05), while Simpson dominance index reduced.(5)Two-factor analysis of variance showed that nitrogen deposition in the early experiments only the only soil animal density of Chinese Cryptomeria litter was significantly affected(P<0.01), no impact for other index; In the middle and late have varying degrees of influence on the index.(6)Two-factor analysis of variance showed that Chinese Cryptomeria litter after adding exogenous litter, only at the early stage of the experiment of litter layer soil animal density influence significantly (P< 0.05), no impact for other index; In the medium term to have effects on each index; Late only to density-taxa index showed significant effects (P < 0.01), there is no change for other index.(7)Two-factor analysis of variance showed that nitrogen deposition and changes in litter component interaction in the early experiments had no effect on the soil animals index of Chinese Cryptomeria litter layer. In the medium term influential to each index; In the later only to density-taxa index showed significant effects (P< 0.01), there is no change for other index.Comprehensive analysis shows that Chinese Cryptomeria litter in community structure and diversity of soil animals affected by changes in the composition of litter, litter mixed soil animal density and number of taxa were higher than a single layer of litter, and mixed needle than coniferous mixed.Compared with single litter, due to the mixed litter diversity is richer, its composition is more complex, living in the density of soil animal individuals, groups and diversity index were increased, and suggests that soil animal in the mixed forest of litter provides more ideal habitat, a single pure forest and mixed needle is better than coniferous mixed forest.Exogenous increase in nitrogen will change litter layer of soil animal community structure and diversity, reduce the number and diversity of community groups, due to the input of nitrogen deposition to promote a number of groups of individuals, inhibit some groups of individuals, even some populations have not fit to live in this environment, resulting in reducing the number of taxa.When nitrogen deposition on soil animals a year and a half later, the impact on soil fauna weakened.These results not only further evidence of the sensitivity of soil animal communities to environmental change, but also shows that nitrogen deposition and changes in litter components and their interactions have an impact on soil animal community structure, and suggests that under the action of nitrogen deposition and the changes of litter soil animal community to understand the changes in the environment, to reveal its mechanism is of great significance.