The Impact Of Temperature And Acidity On Decomposition And Dissolved Organic Carbon Release From Leaf Litter In Greater Xingan Mountains

Soil organic carbon?SOC?is one of the most important carbon pools in the earth.A small increase or decrease of SOC will significantly affect the concentration of CO₂ in the atmosphere.Dissolved organic carbon?DOC?is an important source of SOC.DOC is a moving and reactive part of SOC.which affects the activities of soil animals and the biogeochemical process of soil.Leaf litter decomposition is the main source of forest DOC.Global warming and acid rain is a severe environmental problem for human survival at present.It also affects the decomposition of litter leaves and the release of DOC.In this study.DOC release from leaf litter was analyzed with laboratory experiment.Leaf litter of eight forest species was collected from Genhe Forestry Bureau of Greater Xingan Mountain.The eight species includes Sophora japonica L..Populus davidiana L..Populus vaccinium vitis-idaea L..Ledum palustre L..and Vaccinium uliginosum.L..Sabina davurica Antoine.Salix babylonica L..and Betula platyphylla Suk.We studied the effects of the original chemical composition.temperature and acidity on the decomposition and release of dissolved organic carbon from litter leaves.The mathematical model is used to simulate the process of litter decomposition and release of dissolved organic carbon.The main results of this paper are as follows:?1?The decomposition rate of litter leaves of 8 tree species was significantly positively correlated with the initial N.P.K and cellulose content.And there was a significant negative correlation between the decomposition rate and thecontent of ash.C.Si.Lignin.C/N.Lignin/N the early leaf litters.?2?Under different temperature and acidity.the doc released from the leaves of the eight species increased at the early stage?30 days before?.then decreased.and finally tended to decline steadily.?3?The response of different tree species to acid stress was different.The concentration of DOC was the highest at pH 5.0.followed by pH 7.0 and lowest at pH3.5 for Sophora japonica L.?Populus davidiana L.?Vacciniumvitis-idaea L.?Ledum palustre L.?Sabina davurica Antoine.The DOC concentration of Salix babylonica L.?Vaccinium uliginosum L.and Betula platyphylla Suk.reached the highest at pH 5.0.followed by pH 3.5 and pH 7.0.?4?When the temperature was constant.acid could inhibit the decomposition of litter leaves.and with the increase of acidity.the inhibition was more obvious.?5?When the acidity was constant.temperature promoted the decomposition of litter leaves.and the DOC release increased with the increase of temperature.The increase of temperature will accelerate the decomposition of litter leaves.thus the weight loss rate and decomposition rate will increase.?6?The FLDOCM model of Sophora japonica L.and Vacciniumvitis-idaea L.leaf litter decomposition and release of DOC has a better fitting established in this study.followed by Ledum palustre L..Vaccinium uliginosum L..Sabina davurica Antoine.Salix babylonica L..Betula platyphylla Suk..Populus davidiana L.leaf litter.The correlation coefficient of DOC content of 8 tree species simulated by the model was from 0.744 to0.948.