Effects Of Simulated Warming And Nitrogen Deposition On Soil Respiration And DOM In Soil Solution

Deep soil organic carbon storage accounted for more than 50% of the total soil organic carbon. Under the background of global climate change, for example, warming and nitrogen deposition, there are important significant effects on global carbon cycle from the soil carbon dynamics of terrestrial ecosystem deep soil. It has attracted more and more attention recent years. In order to reveal the responses of soil respiration in vertical profile at different depth to global warming and nitrogen deposition, especially the underlying soil respiration. Our study was started in situ observation vertical profiles in different depth of soil respiration from May 2014 to August 2015 in Sanming Fujian forest ecosystem and global change research station of Chinese fir seedlings warming ?2 m*2 m?. There were six kinds of treatments, control ?CT?, low nitrogen ?LN? and high nitrogen ?HN?, temperature ?W?, the warming and low nitrogen ?WLN? and warming with high nitrogen ?WHN?, each treatment with 5 replicates.This study focused on the soil temperature, soil water content, soil nutrient content, soil organic matter amount, microbial biomass and soil solution of dissolved organic matter ?DOM? quantity and spectral characteristics and preliminary to investigate the mechanism of soil respiration to warming and nitrogen addition in soil vertical profile. Results showed:Warming intensified the seasonal variation of soil moisture vertical differentiation and soil CO₂ flux, soil temperature and moisture can work together to explain 62%-87% of the differences of soil CO₂ fluxes and seasonal variation, and regression coefficient R2 of the warming treatment increased. Warming significantly increased soil CO₂ flux in deep soil ?P<0.05?, the CO₂ flux was about 3 times of CT. HN can significantly reduce the deep soil CO₂ flux and CO₂ flux in deep soil was increased significantly under WHN treament; In addition, deep soil basal respiration F10 and soil temperature sensitivity index Q10 were raised to W, WLN and WHN significantly, and there was no significant effect on soil F10 and Q10 under nitrogen treatment, indicating that the influences were greater on deep soil microbial activity under the warming treatment than the inhibition in deep soil carbon emissions under nitrogen addition treatment.Warming deduced nitrogen soil solution doc quantity, soil solution DOM structure complex, namely the proportion of relatively complex aromatic compounds increased relatively that after short-term warming, organic matter decomposition rate of increase is a result of soil labile organic carbon storage decreased, reduce DOM concentration in the soil solution, a significant increase in deep soil CO₂ flux which is warming is another important reason; nitrogen through such as nitrification solution ionic strength and the degree of acidification resulted in growth way change solution environment, and microbial activity in soil mineralization activity decreased, DOM induced decomposition rate decreased.