Study On The Interaction Between Soil Substrate And Litter Decomposition

Litter decomposition is the key component of nutrient cycling and energy flowing in forest ecosystem. Litter decomposition deciding the provision of soil available nutrients. At the same time, soil can influence litter decomposition from affecting soil organisms and enzyme activity as the carrier of litter. So, the interaction between litter and soil substrate has great significance on nutrients flowing and cycling in forest ecosystem. Three Gorges Reservoir area is the sensitive area of ecology in our county. There has few research of the interaction between litter decomposition and soil substrate in this area. The coniferous forest, broad-leaved forest and conifer-broadleaved forest are the most representative forest type in this area. Researching the interaction between litter decomposition and soil substrate can provide scientific evidence to study the soil carbon and carbon cycling in Three Gorges Reservoir area, and can provide the basic parameter to calculate soil cabon in this area.This study take three different nutrients of soil as decomposing substrate and take three different litter as the research object. Researching the decomposition of pine, cork oak and mixed litter on different soil substrate and find the key factor that impacting the decomposition. State the affectting mechanism to litter decomposition from different soil nutrients. At the same time, we analyze the influence to soil substrate from different litter to discuss the interaction between litter decomposition and soil nutrients. The results as follows:1. One year later of decomposition, the remaining ratio of pine、cork oak and mixed litter was72.37%,66.53%and64.56%on high nutrient substrate. On middle nutrient substrate, the remaining ratio was73.2%,67.46%and65.58%, and75.19%,68.44%,65.66%on low nutrient substrate. The litter decomposing rate are all expressed as mixed litter> cork oak> pine on three soil substrate.2. The decomposing coefficient one year of pine is0.33,0.319and0.292respectively on high nutrient substrate, middle nutrient substrste and low nutrient substrate. The time that pine decomposing50%and95%is2.089a、9.067a、2.16a、 9.379a、2.351a、10.237a respectively. The decomposing coefficient one year of cork oak is0.418、0.396and0.386, and the time that cork oak decomposing50%and95%is1.669a、7.177a、1.759a、7.574a、1.811a.7.776a respectively. The decomposing coefficient one year of mixed litter is0.457、0.435and0.425, and the time that mixed litter decomposing50%and95%is1.521a、6.559a、1.596a、6.889a、1.643a、7.061a.3. The decomposing coefficient of pine、cork oak and mixed litter has positively correlation with the original soil organic matter、total N and total K. Organic matter has positively correlation with pine litter decomposing rate on high nutrient soil substrate, and soil total N and total P has positively correlation with litter decomposing rate. There has positively correlation between decomposing rate of pine、mixed litter and total N、total P on middle nutrient soil substrate. Soil organic matter has positively correlation with ping decomposing rate on low nutrient soil substrate, and total N、total P have positively correlation with decomposing rate of cork oak.4. One year later of decomposition, the organic matter that under pine、cork oak、mixed litter increased1.4g/kg (1.41%)、0.83g/kg (0.83%) and1.06g/kg (1.07%) than controlled group on high nutrient soil substrate, and increased2.11g/kg (3.4%),0.89g/kg (1.43%)�'�1.78g/kg (2.87%) on middle nutrient soil substrate,and1.2g/kg (5.24%)、0.83g/kg (3.62%)�'�0.75g/kg(3.27%)on low nutrient soil substrate. The organic matter under pine litter increased higher than all of them.5. Sucrase and cellulose have significant positively correlation with soil organic matter、total N and total K, and peroxidase has significantly negatively correlation with soil organic matter、total N and total K. There has no correlation between polyphenol oxidase、urease and soil nutrient. Soil urease has negatively correlation with litter decomposing rate. There has a binomial regression relationship between litter decomposing and polyphenol oxidase、peroxidase、sucrase、cellulase.6. Microbial biomass carbon and nitrogen have significant positively correlation with soil organic matter、total N、total P、polyphenol oxidase、sucrase. cellulase、urease, and have significant negatively correlation with peroxidase. One year later of decomposition, content of microbial biomass carbon expressed as pine>mixed litter>cork oak>controlled group on high and middle nutrient soil substrate, and expressed as mixed litter>pine>cork oak>controlled group on low nutrient soil substrate. Content of microbial biomass nitrogen expressed as cork oak>mixed litter>pine>controlled group on high and low nutrient soil substrate, and expressed as pine>cork oak>mixed litter>controlled group on middle nutrient soil substrate.7. There has significant correlation between total response of PLFA and soil organic matter、total N、total P、soil enzyme、microbial biomass carbon and nitrogen. One year later of decomposition, quantity of total reaction and bacteria expressed as pine>mixed litter>cork oak>controlled group on high and middle nutrient soil substrate, and expressed as cork oak>pine>mixed litter>controlled group. The quantity of actinomycetes and fungi assumed diversity on differert soil substrate due to different treatment.In conclution, soil organic matter、total N and total K are the key factor that affecting litter decomposition and the higher of the nutrient content, the faster of the litter decomposition. The increasing of soil organic matter has more prominent influence on the litter that decomposing slow such as pine than the litter that decomposing fast such as mixed litter. The quality of litter itself is the dominant factor that affectting litter decomposition when the soil organic matter content was low. But the discrepancy between different litter becoming small as the improving of soil organic matter.