Study On Soil Respiration In The Freeze-thaw Erosion Area Of Alpine Marsh Meadows On The Qinghai

Soil respiration is a process in which soil releases CO₂ into the atmosphere,and it is one of the important links in the global carbon cycle.Its subtle changes will affect atmospheric CO₂ concentration and global climate change,which is a hot issue of carbon trade assessment in the current climate negotiation table..Alpine marsh meadow is one of the widely distributed grassland types on the Qinghai-Tibet plateau,with an area of about 0.49×10⁵ km² and a soil organic carbon reserve of 19.8×10²Pg,which plays a very important role in the study of soil respiration in alpine ecosystem.In recent years,with the global climate warming,the distribution pattern of permafrost in the high-altitude permafrost areas has gradually begun to deteriorate.In the process of degradation,the surface collapses,resulting in great changes in topography,and developing the landform of freeze-thaw erosion such as thermokarst.In the freeze-thaw erosion area,soil and vegetation have undergone has changed greatly,and the ecological succession has occurred over time,which has changed the soil carbon balance.However,the study on soil respiration in the freeze-thaw erosion area of alpine marsh meadow in Qinghai-Tibet plateau has not been reported.Therefore,we based on the previous research on the definition of the freeze-thaw erosion area,chosen three the freeze-thaw erosion area and three places of the no freeze-thaw erosion area in the Qinghai lake basin located in the northeast of Qinghai-Tibet plateau permafrost regions.Soil respiration,soil temperature at 5 cm depth,soil moisture content at 5 cm depth,air temperature and relative humidity were monitored in May 2019-September.Vegetation profile was monitored in August and soil nutrient status was determined.The results show that:?1?The daily and seasonal changes of the soil respiration of in the freeze-thaw erosion area of the alpine swamp meadow has a single peak dynamic change characteristic similar to the natural control area.The rate is generally lower than that of the natural control area of no freeze-thaw erosion area?the following no freeze-thaw erosion area are called the natural control areas?,and the seasonal change of soil respiration in the freeze-thaw erosion area is smaller than that of natural control area;?2?The relative humidity of the air in the freeze-thaw erosion area,the soil moisture content at 5 cm depth,the above-ground and below-ground biomass and the seasonal changes of the above elements are all smaller than that of the natural control area;?3?Analysis of the reasons for changes in soil respiration,combined with the parameters of air temperature and humidity,soil temperature and moisture content,plant biomass,and soil nutrient content monitored in the freeze-thaw erosion area,shows that air temperature has a good positive linear function relationship with soil respiration.Relative humidity has a significant negative linear function relationship with soil respiration;soil temperature at 5 cm depth has an exponential function relationship with soil respiration,and Q₁₀0 in the freeze-thaw erosion area decreases by19.34%;soil water content at 5 cm depth has a negative linear function relationship with soil respiration,Aboveground-underground plant biomass has a positive linear correlation with soil respiration;the nitrate nitrogen,ammonium nitrogen,total nitrogen,and total carbon content in the soil do not change significantly.the correlation between other factors and soil respiration are not obvious except for the linear correlation between total nitrogen and soil respiration.It,however,should be pointed out that soil respiration is an ecological process influenced by the interaction of multiple factors.The soil respiration in the freeze-thaw erosion area is lower than that in the natural control area,not only due to the changes in environmental-biological factors.The change in the interaction process between the factors the freeze-thaw erosion area is the main research direction in the future,which helps accurately estimating the amount of carbon exchange between the soil and the atmosphere of alpine marsh meadows.It can provide an accurate and scientific theoretical understanding of the effects of the freeze-thaw erosion on soil respiration under global climate change.