The effects of nitrogen （N） availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh lit...The effects of nitrogen （N） availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh litter samples including needle litter （Pinus koraiensis） and two types of broadleaf litters （Quercus mongolica and Tilia amurensis） were collected from a broadleaf-korean pine mixed forest in the northern slope of Changbai Mountain （China）. Different doses of N （equal to 0, 30 and 50 kg.ha^-1yr^-1, respectively, as NH4NO3） were added to litter during the experiment period. The litter decomposition rate expressed as mass loss and respiration rate increased significantly with increasing N availability. The mass loss and cumulative CO2-C emission were higher in leaf litter compared to that in needle litter. The dis- solved organic Carbon （DOC） concentrations in litter leachate varied widely between the species, but were not greatly affected by N treatments. Regardless of the N addition rate, both N treatments and species had no significant effect on dissolved organic N （DON） concentrations in litter leachate. About 52-78% of added N was retained in the litter. The percentage of N retention was positively correlated （R^2=0.9 1, p〈0.05） with the litter mass loss. This suggested that a forest floor with easily decomposed litter might have higher potential N sink strength than that with more slowly decomposed litter.展开更多
基金Foundation project： This work was supported by the Knowledge Innova- tion Project of the Chinese Academy of Sciences （KZCX2-YW-416） and the National Natural Science Foundation （90411020）
文摘The effects of nitrogen （N） availability and tree species on the dynamics of carbon and nitrogen at early stage of decomposition of forest litter were studied in a 13-week laboratory incubation experiment. Fresh litter samples including needle litter （Pinus koraiensis） and two types of broadleaf litters （Quercus mongolica and Tilia amurensis） were collected from a broadleaf-korean pine mixed forest in the northern slope of Changbai Mountain （China）. Different doses of N （equal to 0, 30 and 50 kg.ha^-1yr^-1, respectively, as NH4NO3） were added to litter during the experiment period. The litter decomposition rate expressed as mass loss and respiration rate increased significantly with increasing N availability. The mass loss and cumulative CO2-C emission were higher in leaf litter compared to that in needle litter. The dis- solved organic Carbon （DOC） concentrations in litter leachate varied widely between the species, but were not greatly affected by N treatments. Regardless of the N addition rate, both N treatments and species had no significant effect on dissolved organic N （DON） concentrations in litter leachate. About 52-78% of added N was retained in the litter. The percentage of N retention was positively correlated （R^2=0.9 1, p〈0.05） with the litter mass loss. This suggested that a forest floor with easily decomposed litter might have higher potential N sink strength than that with more slowly decomposed litter.
