Vol18 No.5: 1307-1320
【Title】Influences of pika and simulated grazing disturbances on bare patches of alpine meadow in the Yellow River Source Zone
【Author】LI Jie-xia1,2,3; LI Xi-lai1,2*; GAO Jay3*; SHI Yan3; MA Ge-liang4; Ka-zhao-cai-rang4
【Addresses】1 State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China; 2 College of Agriculture and Animal Husbandry, Qinghai University, Xining 810016, China; 3 School of Environment, The University of Auckland, Private Bag 92019, Auckland, New Zealand; 4 Grassland Integrated Professional Team of Mongolian Autonomous County of Henan, Huangnan 811500, China
【Corresponding author】LI Xi-lai; GAO Jay
【Citation】Li JX, Li XL, Gao J et al. (2021) Influences of pika and simulated grazing disturbances on bare patches of alpine meadow in the Yellow River Source Zone. Journal of Mountain Science 18(5). https://doi.org/10.1007/s11629-020-6196-y
【Abstract】Bare patches in alpine meadow are the main manifestation of its degradation. The change of bare patches in an alpine meadow in the Yellow River Source Zone during 2018-2019 was studied in relation to the disturbances caused by plateau pika (Ochotona curzoniae) population and simulated grazing via artificial mowing both independently and interactively. The disturbance was set at three levels of high, medium and no disturbance (control group). Bare patches were mapped by from unmanned aerial vehicle (UAV) images with fine resolution of 1 cm obtained in August 2018 and August 2019 in ArcGIS. The results showed that the total area of bare patches decreased by 112.05 m2 in sub-plots devoid of pika disturbance but increased by 126.37 m2 in other sub-plots. The highest rate of increase is 89.02%. The individual effect of pika exceeds the joint effect of pika and mowing disturbances. The sole effect of mowing is lower than the joint effect of pika disturbance and intensive mowing, but higher than the joint influence of pika disturbance and moderate mowing. Strong pika disturbance (14 per sub-plot) caused the influence of mowing from moderate to intensive to increase by five-fold. The area of bare patches treated with moderate mowing and no pika disturbance decreased at the highest pace (-37.22%). Intensive mowing and medium density pikas (100 pikas/ha) are considered the thresholds at which the bare patches start to expand. Even if the meadow is mowed at the medium and high intensity, the area of bare patches can be significantly reduced if plateau pika population is controlled to a low level. ANOVA analysis and long-term macro-scale satellite-derived results reveal that pika disturbance is more important in causing the bare patches to change than simulated grazing. Therefore, it is more important to control the number of pikas than to reduce grazing intensity to prevent the expansion of bare patches in the degraded alpine meadow in the study area.
【Keywords】Bare patches; simulated grazing; Pika disturbance; Interactive influence; UAV; Yellow River Source Zone