Preliminary Study On The Distribution Trend Of Relative Grazing Intensity By UAV Technical Monitoring

Grazing intensity,as the most direct impact factor of grazing livestock affecting grassland,is an important indicator of our research on grassland health level and economic benefits of pastoral areas.This study observed the activities of yak grazing on a summer pasture in Jiangqian Township,Gande County,Golo Tibetan Autonomous Prefecture,Sanjiangyuan District,Qinghai-Tibet Plateau.By using UAV technology,the trends of livestock activities were tracked and photographed,and then the monthly and overall relative grazing intensity distribution trend in the use period of summer pasture was calculated and drawn.The indicators of vegetation biomass,community characteristics,nutrient values of forage and soil physical and chemical properties were determined monthly by forage and soil randomly sampled in summer pasture.The correlation analysis was carried out between the cumulative value of relative grazing intensity at sampling time points,and forage and soil indicators.The main results were shown as follows.1)In July,the relative grazing intensity of herd mainly close to the X-axis(ranch southern fence)was gradually increased from zero to the near-far.Analyzing the relative grazing intensity trend map in August,the herd's range of activity was mainly close to the eastern fenced area of the pasture,which was at the diagonal point of the coordinate zero.The main areas of herd activity in September was mainly concentrated on the diagonal point of the zero point to the northern fenced area of the pasture,and gradually moved to western part,that was the lower grazing intensity area of herd at early,but the main area was still within the area of X>200 and Y>500).On the whole,the regional rational grazing was obviously observed under free grazing conditions.2)The grass biomass in July,August and September slowly increased and then tended to stabilize with the increase of relative grazing intensity.3)The relative grazing intensity had significant effects on the EE,N,C and P contents of grassland vegetation,but the effect on grass fiber content was not obvious.4)Excepting the soil moisture for 0-10 cm,all indicators of soil physical and chemical properties were increased when the relative grazing intensity increase,while the response of indicators for 10-20 cm soil layer to the relative grazing intensity was not obviously observed.5)There was a significant correlation between the normalized vegetation index(NDVI)and the relative grazing intensity distribution results observed,which could contribute to the study of the establishment of mesoscale grassland monitoring methods by drone technology.