Effects Of Simulated Warming On Soil CO₂ Flux Of Pinus Tabulaeformis Plantation In Daqing Mountains

Climate warming is an important issue in the study of global change,and soil CO₂flux is one of the most important factors of global climate change.Arid and semi-arid region is an important part of terrestrial ecosystem,and its ecological type is extremely fragile,which plays an important role in global climate change.Located in the middle part of Yinshan Mountains,Daqing Mountains is an arid and semi-arid region,belonging to a complex ecosystem of montane forest,shrub and grassland.Pinus tabulaeformis,as the main afforestation species and main forest type in the front mountain of Daqing Mountains,is an important ecological barrier in this region.In the context of global warming,climate,in order to further clear arid and the relative changes of soil respiration to temperature response in arid areas,this thesis adopts the Open Top increase greenhouse(Open Top Chamber,OTC)from June to September in 2020 observed by simulation heating in Daqing Mountains of pinus tabulaeformis plantation soil CO₂flux change,reveal the changing trends of Daqing Mountains pinus tabulaeformis plantation soil respiration and the relationship between various factors.The results are as follows:1.The OTC heating device increases the annual atmospheric temperature by0.72?and humidifies by 0.39%;The average annual temperature of soil at 5 cm,10 cm and 20 cm increased by 1.01?,1.24?and 1.07?,respectively,and the average annual temperature at 40 cm increased by 0.55?.Soil moisture at 5 cm,10 cm and 20cm decreased by 3.58%,0.96%and 7.94%,respectively,and increased by 1.28%at 40cm.2.Soil CO₂fluxes showed obvious seasonal variation under both control and warming treatments,and the highest values in August were 557.46 mg·m^-2·h^-1and 473.96mg·m^-2·h^-1,respectively.Compared with the control,soil CO₂emission was significantly reduced by 15.2%on average during the whole growing season.Soil CO₂flux was affected by both temperature and humidity.3.The soil CO₂flux of Pinus tabulaeformis plantation in Daqing Mountains showed a significant diurnal variation pattern,showing a single peak trend,and the peak time of soil CO₂flux was lagging behind that of temperature.The diurnal variation of soil CO₂flux was significantly related to atmospheric temperature and soil temperature of 5 cm,and the soil CO₂flux under warming condition was lower than that under control condition.4.The temperature sensitivity of soil respiration increased with the deepening of soil layer,and the Q₁₀value of soil 40 cm>20 cm>10 cm>5 cm.Temperature increase increased the temperature sensitivity of soil respiration in Pinus tabulaeformis plantation in Daqing Mountains.The temperature increase state of Q₁₀values in different soil layers ranged from 2.81 to 6.67,and that of the control layer ranged from 2.50 to 5.58.5.Soil carbon and nitrogen content(except ammonium nitrogen in 0?10 cm soil layer and C/N content in 10?20 cm soil layer)had no significant effect on CO₂flux.Soil carbon and nitrogen contents(denitration nitrogen and ammonium nitrogen in 10?20 cm soil layer)decreased in the growing season with increasing temperature,but they were not significant.10?20 cm soil nitrate nitrogen content of warming than control increased,soil carbon and nitrogen content had no significant effect on CO₂flux.