| Forest litter has the important function of regulating energy flow,nutrient recycling,maintaining soil fertility,and it is also very important for soil and water conservation.The process of material cycling and energy conversion is mainly accomplished by litter decomposition.In terrestrial ecosystems,more than 90%of the above-ground net primary production is returned to the surface soil via litter.Litter decomposition plays a key role in soil physical,chemical properties,fertility and vegetation productivity,and maintains the carbon and nitrogen balance of ecosystem.During litter decomposition,the decomposition rate will change,as well as the nutrient elements.In this study,the decomposition process of Castanea mollissima B1.was investigated in a field study in Castanea mollissima B1.forest of Luhu Village,Hetian Town,Changting County,Fujian Province in central subtropical.The decomposition study was conducted under five artificial promotion treatments:1)control group was placed in the forest shade surface;2)membrane covered design was covered the membrane and placed in the forest shade surface;3)no shade design was placed in the open surface of the open forest;4)buried design was in the soil from the surface of about 5-10cm;5)add bacteria design was diluted with 100 times the double-effect biotin and placed under the shade of the forest surface,and the quality loss rate,nutrient content and nutrient release were analyzed.The experiment was carried out for one year.The monthly dynamic law of mass decomposition rate and nutrient release rate was obtained,and the corresponding model was established and the optimal scheme was selected.The main results were as follows:(1)The mass loss model of leaf litter was divided into two stages:rapid weight loss stage and slow weight loss stage.Changes in the quality loss rate of litter of Castanea mollissima B1.may be affected by three factors:First,litter leaves contained a certain amount of easily decomposed components,so the short-term weight loss changed more obvious.Second,from the spring,the rainfall began to increase,the temperature gradually increased,rainwater and temperature make soil animals and microbes begin to multiply which promote litter decomposition of leaf litter.Third,autumn to winter,the temperature decreases,microbial activity decreased,and leaf litter had a number of substances difficult to decompose,so the decomposition of leaf litter basically in a stagnant state.According to the quality loss rate of time changes could be obtained the Olson model of control group:y=0.887e-0.048x.The Olson model of membrane covered design:y=0.923e-0.039x.The Olson model of no shade design:y=0.857e-0.075x.The Olson model of buried design:y=0.994e-0.137x.The Olson model of add bacteria design:y=0.897e-0.073x.The rate of decomposition of litter were different from large to small:buried design>no shade design>add bacteria design>control group>membrane covered design.According to the decomposition coefficient,the half-life of litter decomposition was estimated,which was consistent with the experimental results.The results showed that the half-life estimated by Olson model was reasonable.(2)The nutrient release characteristics of the deciduous process of the deciduous litter of Castanea mollissima B1.showed obvious enrichment-release and direct release.Carbon and potassium elements for the direct release mode;nitrogen,phosphorus,calcium,magnesium,manganese elements for the first enrichment after the release of the model.The regularity of release from carbon was consistent with the change of decomposition rate.In the decomposition stage were showing a continuous decline,and rapid declined in the early stage,and the rate of decline slowed in the later period.Nitrogen element in the early decomposition of the phenomenon of enrichment,and then decreased.Phosphorus was in a state of fluctuation at the beginning of the experiment,showing a tendency to rise first and then decrease.Potassium first appeared rapid leaching phenomenon,followed by slow release.Calcium content fluctuates up and down,but the trend for the first rise and then decline.Magnesium was enriched during decomposition,fluctuates,and then decreased slowly.Manganese content of the initial low,first enrichment after the release.According to the net release rate of nutrient elements,it could be found that the net release rate of nutrient elements of buried design was almost the highest,and the net release rate of nutrient elements was buried design>no shade design>add bacteria design>control group>membrane covered design.By comparing the 11 kinds of models,to choose the best time of the dynamic model nutrients.The results showed that carbon and nitrogen were mainly released by logarithmic attenuation.The optimal models of phosphorus,potassium,calcium,magnesium and manganese were different under different treatments.There were three or more models,and the difference was greater(3)There was a correlation between nutrient elements in the process of leaf litter decomposition.There was a significant correlation(P<0.01)between the residual rate of carbon and the residual ratio of nitrogen,potassium,calcium and magnesium and C/N.The residual ratio of nitrogen and phosphorus,potassium,calcium residual rate and C/N were significantly correlated with each other.The residual rate of phosphorus and calcium residue rate,C/N were extremely significant correlation.There was a significant correlation between the residual rate of calcium and the residual ratio of magnesium.Magnesium element residual rate and manganese element residual rate were significantly correlated with each other.Indicators of leaf litter decomposition had a significant correlation,and each indicator can influence each other.There was a significant positive correlation between the mass decomposition coefficient and the net release rate of nitrogen,calcium and manganese,and had a significant negative correlation(P<0.05)with the net release rate of phosphorus.Through the comparison of correlation,the decomposition rate of buried design was the fastest,which was consistent with the results of the decomposition coefficient of Olson model.In summary,the design of buried in the soil was the optimal scheme of artificial promotion decomposition of leaf litter of Castanea mollissima B1.Forest.The design of the Castanea mollissima B1.leaves buried in the soil to ensure that the humidity,temperature,and increase the contact surface with the soil.Therefore,the best way of artificial promotion decomposition of leaf litter of Castanea mollissima B1.forest was that to provide a high temperature and humidity environment for litter decomposition,and to ensure that the activity of soil microbes and animals,in order to improve soil fertility technologies. |
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