Relationship Between Yak Grazing,Vegetation,Soil And Body Condition Of The Eastern Margin Of The Qinghai-Tibet Plateau

Grazing plays an important role in the utilization of natural grassland.It is of great significance to study the mechanism of grazing activities on grassland ecosystem.Our objective were to comprehensively evaluate the interaction and change rules between soil,grassland vegetation and yak body conditions in the grazing ecosystem under free grazing mode.We conducted the experiments in summer pastures of four herdsmen in Maqin County,Golog Tibetan Autonomous Prefecture,Qinghai Province in 2017-2019.This study will provide theoretical support for the establishment of reasonable grazing management measures in alpine meadow area.The results are as follows:1.The change of plant community diversity in grazing ecosystem was more affected by temperature than by precipitation,while the change of biomass,nutrient quality and soil carbon,nitrogen and phosphorus content is more affected by precipitation,but less related to temperature.2.Grazing intensity was negatively correlated with AGB,Pielou evenness index,Simpson dominance index and forage CP content,and positively correlated with BGB,GTC,C/N ratio of forage,soil compactness and SOC.With the increase of grazing intensity,AGB decreased,BGB increased,forage CP and EE content increased first and then decreased.3.With the increase of grazing intensity,GTP content first decreased and then increased,and it was the highest under stocking intensity of 2.16 yaks·hm"2·a-1.The soil compactness of 4.91 yaks·hm-2·a-1 was significantly higher than other grazing intensities.The contents of SM,STC,STN and STP were higher than other grazing intensities when grazing intensity was 3.86 yaks·hm-2·a-1.SOC content was higher than other grazing intensities when grazing intensity was 3.29 yaks·hm-2·a-1 and 3.86 yaks·hm-2·a-1.4.BCS reached the maximum value when the grazing intensity was 3.86 yaks·hm-2·a-1.Grazing intensity directly affects AGB and community diversity,and indirectly affects BGB and forage nutrition quality by affecting soil physical and chemical properties,and finally affects yak body condition.In a word,in the grazing ecosystem,the soil,grassland and livestock interact with each other,and the grazing intensity is the main influencing factor.The herdsmen should strictly control the grazing intensity and optimize the grazing management according to the climatic conditions.In Maqin County,when the grazing intensity is under 3.86 yaks·hm-2·a-1,it has a good effect on the material circulation of vegetation and soil and the condition of yak,which has a positive effect on the economic income and growth of herdsmen,and achieves the balance of economic and ecological benefits.