Effects Of Simulated Warming On Soil Greenhouse Gas Flux And Litter Decomposition Of Pinus Tabulaeformis Plantation In Daqing Mountains

This thesis takes Pinus tabulaeformis carr.in Daqing Mountain,Inner Mongolia as an example Taking the plantation as the research object,the effects of litter decomposition and litter removal on soil physical and chemical properties and soil greenhouse gases under simulated warming were studied.The experiments were carried out in the growth seasons of 2020 and 2021.Four treatments were set up:control（CK）,warming（W）,litter removal（NL）and warming+litter removal（WNL）to study soil nutrients and soil CO₂The response law of three greenhouse gas fluxes such as CH₄and N₂O to warming and removal of litter and the mechanism of litter decomposition in response to climate change.The results show that:1.After simulated warming treatment,the ambient temperature increased by 1.0℃compared with the control.Simulated warming,litter removal and warming+litter removal are conducive to the increase of soil temperature in the range of 0～20 cm soil layer,but different treatments make the increase of soil temperature different;Different treatments reduced the soil water content in the range of 0～20 cm soil layer.2.Different treatments significantly reduced the contents of soil ammonium nitrogen and nitrate nitrogen（P<0.05）,but had no significant effect on soil p H,organic carbon SOC and total nitrogen TN（P>0.05）.The SOC content of soil organic carbon decreased with the increase of soil depth,and the TN content of soil total nitrogen decreased with the deepening of soil depth,and the difference among soil layers was significant（P<0.05）;Different experimental treatments significantly affected the content of soil ammonium nitrogen and nitrate nitrogen.Compared with the control,warming,litter removal and warming+litter removal treatments reduced the content of ammonium nitrogen and nitrate nitrogen in each soil layer,and the content of ammonium nitrogen and nitrate nitrogen decreased with the increase of soil depth.3.In 2020 and 2021,under the four treatments of Pinus tabulaeformis Plantation in Daqing Mountain（natural state,simulated warming,litter removal,simulated warming+litter removal）,the soil in the growing season shows the emission source of CO₂and N₂O and the absorption sink of CH₄.Warming inhibits the emission of soil CO₂and N₂O gas flux and promotes the emission of soil CH₄gas flux.Environmental temperature,environmental humidity,soil temperature and soil humidity are the main limiting factors of soil CO₂flux in the growing season.4.Under simulated warming control treatment,there was a very significant negative correlation between soil CO₂and soil total nitrogen（10 cm）（P<0.01）,and a significant negative correlation with soil total nitrogen（20 cm）（P<0.05）;There was a significant positive correlation between soil CH₄flux and soil nitrate nitrogen content（10 cm,20 cm）under warming,litter removal and warming+litter removal treatments（P<0.05）;There was a significant negative correlation between soil N₂O flux and soil total nitrogen（10 cm,20 cm）under warming and warming+litter removal treatment（P<0.05）.5.In 2020,the total GWP of the four treatments is 39.730 t·hm^-2.In 2021,the total GWP is 21.979 t·hm^-2.The soil GWP decreased under different treatments,and the litter removal GWP was the smallest.6.The decomposition process of litter in Pinus tabulaeformis Plantation Ecosystem in Daqing Mountain,Inner Mongolia has an obvious response to the simulated warming at the level of 1.1℃,and the warming accelerates the decomposition of litter to a certain extent.Compared with natural decomposition conditions,there were significant differences in nutrient contents of N,P,C/N,C/P and lignin/N of litter under warming（P<0.05）.