Impact Of Short Term Simulated Nitrogen Deposition On Carbon And Nitrogen Dynamics Of The In Three Types Of Forest Soils In Changbai Mountain

There are typical temperature, rainfall and nitrogen deposition gradients in temperateforest along the north slope of Changbai Mountain. It’s also one of the most sensitive regionsof climate change in the world, which provides an ideal platform for the experimental studyon the dynamic interaction between carbon and nitrogen in the temperate forest soils underthe circumstance of climate change.This study analyzed the effects of simulated nitrogen deposition on soil carbon andnitrogen dynamics in the three typical forests (mixed coniferous broad leaved forest,spruce-abies forest, birch forest) of the vertical sample zones in the north slope of ChangbaiMountain. The available nitrogen, total dissolved nitrogen, dissolved organic nitrogen, soilmicrobial biomass nitrogen, total carbon, dissolved organic carbon and soil microbial biomasscarbon, soil pH values and soil electric conductivity (EC) were analyzed. The main resultsare as follows:（1）After the application of nitrogen, the pH values of the soils under three types offorests presented a downward trend, with evident decrease in the profile of0～10cm soillayers than in the10～50cm soil layers. The soil pH values decreased evidently in thespruce-fir forest than in the mixed coniferous broad leaved forest, and birch forest. Theelectric conductivity maintains a general increase trend among the three forest types.（2）Nitrogen application caused an increase trend in the contents of NH4+-N and totaldissolved nitrogen in the soil of mixed coniferous broad leaved forest, spruce-fir forest andbirch forest, and a decrease trend in the contents of dissolved organic nitrogen. The dissolvedorganic nitrogen presentd a decreased trend in the0～20cm soil layer of the three types offorest, which decreased more evidently in the0～10cm soil layer than those of the10～20cm soil layer. As a whole, nitrogen application exerted an increase in spruce-fir forest andbirch forest, but caused no obvious effects on soil microbial biomass nitrogen in mixedconiferous broad leaved forest.（3）The contents of total carbon presented a downward trend in the0～10cm soil layerin the three types of forest. The dissolved organic carbon in the0～50cm soil layer in mixedconiferous broad leaved forest presented a increase trend while spruce-fir forest and birchforest presented a downward trend. No obvious change of microbial biomass carbon has beendetected in the three types of forest after nitrogen application in the growing season. （4）Most of the analysed carbon and nitrogen indices were more sensitive in the0～10cm soil layers than that of10～20cm soil layer.