Study On Effects Of Litter On The Soil Fertility Properties Of Different Plantation Forests In Karst Mount Region

The decomposition of forest litters was an important process of nutrient cycling in forest ecosystems and played important role in soil organic matter formation and nutrients released. The nutrition elements released from decomposition in forest litters which was an important material sources to vegetation grow. At the same time, litter layers were main part to keep water and soil.According to the test in the annual litterfall, storage of litter, decomposition rate of litter, water holding capacity of litter, litter nutrients and the physical, chemical and biological properties of forest soil of four different plantations, including C. duclouxiana, E. ulmoides, A. cremastogyne and P. salicina in Karst Mount Region, the methods of principal component and cluster analysis were used to evaluate soil fertility quality. The main results were as follows:(1) The annual litterfall of different plantations varied from 1.39 t·hm-2 to 11.33 t·hm-2. Compared with broad-leaved plantation, the annual litterfall of A. cremastogyne was highest, while the C. duclouxiana was the lowest. And the storage of litter in different plantations varied from 1.81 t·hm-2 to 9.68t·hm-2. Based on the storage of litter sequence, there were A. cremastogyne, E. ulmoides, P. salicina and C. duclouxiana. And its decomposition rate in sequence was A. cremastogyne, P. salicina, C. duclouxiana and E. ulmoides.(2) The natural water content and natural moisture rate of four different plantations were almost same in litters. A. cremastogyne highest, E. ulmoides and P. salicina, C. duclouxiana was lowest. The saturated water capacity of litter of four different plantations was E. ulmoides, A. cremastogyne, P. salicina and C. duclouxiana. While saturation moisture content of litter was A. cremastogyne, E. ulmoides, P. salicina and C. duclouxiana, varied from 1.41 t-hm-2 to 16.29t-hm-2.(3) The integrated property of soil of four different plantations had been improved by the decomposition of litter. Almost each index in the fertility of soil was higher than those of contrast plantations. Only the soil pH was lower than contrast plantations in decomposition progress.(4) The annual litterfall showed negative correlation with the soil pH, polyphenoloidase, catalase and phosphatase, while the positive correlation with other factors. The storage of litter showed positive correlation with soil bulk density, maximum moisture capacity, total porosity, organic matter, total N and so on. And the litter decomposition rate also showed positive correlation with organic matter, maximum moisture capacity, total porosity, total N, total K and soon.(5) On the basis of PCA method, two selected principal components could reflect 87.78% of information which represented by soil fertility indices. The integrated index sequence of soil fertility in different plantations was A. cremastogyne,E. ulmoides,P. salicina and C. duclouxiana.