放牧梯度下甘南土壤碳氮储量的时空动态及环境协同效应OA

90%of grassland carbon and nitrogen are stored in the soil,and grazing is the main production and utilization mode.Understanding the changes of soil carbon storage under different intensity of grazing disturbance and environmental factors in Gannan alpine meadow is conducive to maintaining grassland ecological balance and implementing grazing management reasonably.The Daycent model was used to study the interannual changes of soil organic carbon and nitrogen storage in the alpine meadow of Gannan Prefecture in the past 50 years,and principal component analysis was used to reduce the dimension of climate,environment and nitrogen,and the relationship between the comprehensive factors and soil organic carbon storage was analyzed by Co-kriging interpolation to predict its spatial distribution.The results were as follows:(1)The long-term grazing of 50 years resulted in the decrease of soil total organic carbon storage.However,within a ten-year period,the soil carbon and nitrogen storage increased,and the short-term light grazing was the most suitable for carbon and nitrogen storage.(2)The main factors affecting organic carbon storage were altitude,temperature,precipitation,bulk density,pH,etc.The highest values of soil carbon storage in Gannan grassland were found in high altitude and low temperature areas.(3)In the horizontal spatial distribution,soil organic carbon storage exhibited a gradual decline from the southwest to the northeast.In the vertical direction,except for Maqu County,the decrease of carbon storage decreased with the increase of soil depth.Soil organic carbon in 0-10 cm soil layer was more sensitive to grazing.Soil organic carbon storage decreased the most under heavy grazing,with an average decrease of 8.56 Mg·hm-2.However,the organic carbon storage in the 20-30 cm soil layer in Maqu County was higher than that in the upper soil layer,and was 76.53 Mg·hm-2 under no grazing and 65.73 Mg·hm-2 under heavy grazing,which was relatively stable.