Effects Of Simulated Warming On Soil Respiration In Larix Gmelini Forests In Da Xing'an Mountains

Global warming is an indisputable fact.As the most important terrestrial ecosystem,forest ecosystems play an important role in mitigating global climate change.In the carbon cycle of forest ecosystems,soil respiration is an important part of soil carbon emissions.Soil carbon emissions from Larix gmelinii forests in the Greater Khingan Mountains under the background of global warming are crucial for the accurate calculation of regional carbon budgets.In this thesis,the Open-Top Chamber(OTC)is used to simulate the warming of Larix olgensis forests in the Greater Khingan Mountains to study the influence of temperature rise on the seasonal,monthly,and diurnal changes of soil respiration.At the same time,the effects of environmental factors are measured simultaneously.Change,analyze the mechanism of soil respiration changes caused by warming.the result shows:1.In the warming treatment,the average annual temperature increase is 1.2?,the atmospheric humidity decreases by 2.5%,the soil temperature increases by 0.5?for 5 cm,the soil temperature increases by 1.1?for 10 cm,the soil temperature decreases by 0.08?for 20 cm,and the humidity of each layer of soil decreases by 2.9%,4.9%,8.8%.The increase in temperature and the monthly average value of soil temperature in each soil layer showed a single peak trend,reaching the peak temperature in July and August,and the soil moisture in the growing season also showed a gradual increase trend.Increasing temperature reduced the soil moisture.There is a significant correlation between soil temperature and soil respiration,and a negative correlation between soil moisture and soil respiration,and the correlation is not significant.2.Increasing temperature treatment reduced the content of soil chemical properties,the pH value of soil 0?10 cm decreased by 0.03,and the organic carbon content,total nitrogen content,and ammonium nitrogen content decreased by 5.8 g/kg,0.13 g/kg,and 0.73 mg/L.The nitrate nitrogen content increased by 0.07 mg/L.The soil pH value of 10?20 cm decreased by 0.19,the organic carbon content,total nitrogen content,and ammonium nitrogen content decreased by 29.42 g/kg,1.77 g/kg,0.02 mg/L,respectively,and the nitrate nitrogen content increased by 0.02 mg/L.3.The variation range of CO₂flux in the growing season warming plot was(45.9±12.8?476.8±158.2)mg·m^-2·h^-1,and the variation range of CO₂flux in the control plot was(27.3±12.2?356.3±131.1))mg·m^-2·h^-1.The warming treatment increased the soil respiration rate during the growing season by 5.76 mg·m^-2·h^-1on average.During the growing season,the change in soil respiration emissions under the warming treatment in August compared with the control treatment was the highest at 23.9 mg·m^-2·h^-1.The seasonal change is characterized by the low CO₂emission rate in June.As the surface temperature rises,the soil respiration emission rate begins to increase gradually in July.During the growing season,the soil respiration rate reaches its peak at the end of July and the beginning of August,and the maintenance time is longer short.4.The CO₂emission rate increases with the increase of soil depth,and the sensitivity to temperature is increasing,which is expressed as Q₁₀(10 cm)<Q₁₀(5 cm)<Q₁₀(20 cm).During the study period,the sensitivity of soil respiration and temperature persists.The difference in scale and soil depth during the entire study period was 4.02,Q₁₀(10 cm)4.00 and Q₁₀(20 cm)4.66 in soil respiration of the control plots.The overall temperature of the sample plots was significantly greater than that of the control plots.The same Q₁₀values are 5.91,5.41 and 6.67.