Soil Respiration Characteristics And Its Relationship With Soil Temperature And Moisture In Desert Shrub Grassland In The Southern Margin Of Junggar Basin

Arid and semi-arid areas have typical characteristics of overground vegetation cover and special plant root mechanism.The study of soil inorganic carbon process was still controversial.In this experiment,the soil respiration of desert grassland in hutubi county was studied by means of field observation.Soil respiration was measured by li-8100 automatic soil CO2 flow observation system.HOBO was used to record soil temperature and humidity data.The characteristics of soil temperature and humidity,soil respiration and their influencing factors at different depths were analyzed.Design the simulated rainfall experiment,discuss the change characteristics of soil respiration in short time after rain,and master the change rules.It was important to evaluate the carbon budget of terrestrial ecosystem accurately.The conclusions was as follows:(1)Soil temperature has obvious monthly change,and the lag time of soil temperature increases with depth.Soil moisture is mainly affected by snow melt and rainfall,Soil moisture changes the most in spring.Only 5 cm of soil moisture fluctuated significantly in summer,and there is little change in autumn and winter.Soil temperature is positively correlated with 0 cm ground temperature,air temperature and evaporation.The correlation coefficients is as high as 0.955,0.942 and 0.823(P<0.01).The correlation between soil temperature and meteorological factors is better than that of soil moisture.In addition,due to less precipitation,short duration and strong soil evaporation in arid areas,there is no obvious correlation between soil temperature and humidity and daily precipitation.(2)Soil respiration has a "bimodal" curve during the day.Soil respiration rate was negatively correlated with soil temperature and moisture and a positive correlation at night.The respiration rate of grassland soil is about four times that of bare land,Bare land shows a carbon sequestration process at night.(3)During the growing season,soil moisture has a greater effect on soil respiration rate.The effects of soil temperature and humidity on soil respiration at night is smaller than those in the daytime.In particular,the effect of soil moisture is significantly lower than that of daytime.(4)Rainfall increases soil respiration,under different simulated rainfall treatment,the average soil respiration rate is A:0.637 B:1.020 C:1.111 D:1.962 E:2.701 F:1.626(μmol·m-2·s-1).Compare with A,the soil respiration rate increased under different treatments.The soil respiration rate of E is 4.2 times that of the control group,and B is 1.6 times.(5)In the process of soil respiration,the influence of soil temperature on soil respiration gradually increases with the increase of soil moisture.The relationship between total soil respiration and treatment is quadratic,and the R2 value is 0.97,P<0.01.With the increase of rainfall,soil respiration volume increase first and then decrease.