Effects Of DOM And N Additions On Soil Organic Matter Mineralization And Microorganisms In Subtropical Forests

Here long-term(120 day)incubation experiment was conducted to measure the mineralization of soil organic matter and microbial community structure caused by additions of nitrogen and dissolved organic matter(DOM)from fresh leaf of Castanopsis carlesii and Cunninghamia lanceolata.Castanopsis carlesii and Cunninghamia lanceolata fresh leaf DOM and interactive processing have significant effects on organic matter mineralization in subtropical forest soils.In terms of mineralization amount,N addition inhibited the mineralization rate of soil organic carbon compared with the control,addition of fresh leaves DOM and fresh leaves DOM and N interaction significantly increased soil organic carbon mineralization rate compared with the control.The interaction of N and fresh leaves DOM additions on soil organic carbon pool was more intense,and the deep soil was more affected than the surface soil.The priming effects of exogenous DOM and DOM with N interaction on soil organic carbon in the deep soil were stronger than those on the surface soil.Compared with the soil of Cunninghamia lanceolata,more strong priming effects were occurred in Castanopsis carlesii forest soil.Addition of fresh leaves DOM significantly increased total microbial PLFAs in Cunninghamia lanceolata soil.Total PLFAs in surface soil of Cunninghamia lanceolata increased with the increase of nitrogen level.Also,PLFAs in surface soils were significantly higher than those in deep soils.The GP:GN ratio in surface Cunninghamia lanceolata soil in each treatment was significantly higher than that in deep soil.There were no significant differences in GP:GN ratio among N addition treatments.Effects of DOM and N additions on soil F:B ratio were different between surface and deep soils.In the deep soil of Castanopsis carlesii,Cunninghamia lanceolata fresh leaves DOM and Castanopsis carlesii fresh leaves DOM with N interaction,the deep soil F:B ratio was significantly lower than surface soil F:B ratio.