Decomposition Of Logging Residues And Effects Of Logging Residues On Surface Soil Biochemical Properties And Enzymatic Activity

Logging residue is an important part of forest productivity and plays an important role in regulating energy flow and nutrient balance,which is the main nutrient source of plant and microorganism.Forest surface soil and material are the most basic resources ecosystem and important nutrition libraries for plant,All kinds of business activities must be conditioned on maintaining the sustainable use of forest surface material,which is an non-renewable physical component.Therefore,Gaining a clear idea of decomposition of logging residue after deforestation and its influence on surface soil is of great significance to fully understand the function of ecosystem.From April 2012 to April 2013,changes of surface soil properties,dissolved organic matter and decomposition of logging residue for one year were studied in different logging residue treatments in a clear-cut 35-year-old secondary Castanopsis carlesii forest.Logging residue treatments included residue burned(LB)and residue remained(LR).The research results showed that:(1)The standing crops of logging residue treatments in a clear-cut secondary Castanopsis carlesii forest are about 73.09 t/ha,which is similar to subtropical area but more than the Temperate Continental Monsoon Climate area.Different logging residue treatments result in different standing crops of logging residue.(2)Rate of weight loss showed exponential relationship with time for logging residue.The higher decay rate of logging residue was found for foliage.The highest decay rate of nutrients was found for K and the lowest for N.During decomposition,there were significant net releases of C,K,while N was firstly released and then accumulated.Foliage of logging residue for P was firstly released and then accumulated and then released.Twigs of logging residue for P was significant net released.It was concluded that the greater amount of N,P,K contained in foliage of logging residue than twigs of logging residue except for C.Twigs of logging residue had higher C/N and C/P,which indicated slower logging residue decomposition rates.(3)After six months,in comparing with LB,soil dissolved organic C,dissolved organic N and microbial biomass C contents in the LR increased by 92%,105%and 39%respectively.Soil acid phosphatase,?-1,4-glucosidase and cellobiohydrolase activities increased by 3.3,2.8 and 2.1 times.But soil available P content and metabolic quotient in the LR decreased by 42%and 68%.Phenol oxidase activity decreased by 34%(P<0.05).One year later,soil enzyme activities significantly increased in the LB treatment except?-1,4-glucosidase.Contents of soil total organic C,total N,dissolved organic C,dissolved organic N,available P,C mineralization rate in the LB treatment decreased significantly compared with six-month values,especially dissolved organic C and metabolic quotient decreased by nearly 80%and 68%.Soil available P(1.71 ± 0.12mg/kg)content in the LB was also significantly higher than in the LR,while dissolved organic C,dissolved organic N and soil C mineralization rate in the LR were much higher(P<0.05).(4)After six months,compared with the LB,soil aromaticity index(4.99 ± 2.39)was much lower and humification index(1.72 ± 0.01)much higher in the LR.However,there were no significant differences in soil aromaticity index and humification index between the two treatments(P>0.05).One year after treatment,soil aromaticity index(10.58 ±0.34)in the LR increased significantly.These results suggested that logging residue input and decomposition strongly influenced contents and properties of DOM in soil,resulting in enhancement of higher-molecular components and aromatic compounds,and a decline in bio availability of DOM.Difference of DOM contents among logging residue treatments differed with further logging residue decay,logging residue input and decomposition strongly increased aromatic compounds in soil humus,surface soil humus quality variation after residue burned,the activation degree was weaking,which is bad for the ability to maintain forest soil structure.In conclusion,surface soil properties will be influenced by different treatments of logging residue.Logging residues remained will be benefit to improve forest hydrothermal conditions,nutrient cycling of the ecosystems and helpful for soil quality maintenance.