家庭牧场构成对高寒草甸草地健康的影响及其机制研究

Household pasture is the basic unit of management, protection and utilization of alpine grassland on the Qinghai-Tibetan Plateau (QTP). Pasture health plays a key role in the sustainable development of ecosystem on the QTP, which is characterized by vulnerability and sensitivity to external disturbance. However, due to lack of efficient and accurate monitoring methods, studies on systematic assessment system of grassland health are inadequate, hindering studies of mechanisms of households structure on health of grassland ecosystem. In this research, single- and multi-household of grazing strategies will be focused in the typical alpine meadow of Maqu county, Gansu province. Based on field sampling, unmanned aerial vehicle monitoring and aerial photographs processing, our specific objectives are 1) to quantify grazing pressure and spatial and temporal variation of herds; 2) to improve comprehensive model for alpine grassland health evaluation, by utilizing pika population density, fragmentation index and heterogeneous index as additional parameters; and 3) to explore the effects and potential mechanism of household structure on ecosystem health. This research will contribute to sustainable management of alpine meadow and establishment of sophisticated assessment system at household scale.

家庭牧场是青藏高原草地管理、保护和利用的基本单元。家庭牧场草地健康与否对青藏高原生态系统可持续发展起到关键作用，但目前缺少系统的家庭牧场草地健康评价体系和高效、准确的监测方法，阻碍了家庭牧场管理方式对草地健康影响机制的研究。本项目选取甘肃玛曲县典型高寒草甸区的单户和联户家庭牧场为对象，利用地面取样、无人机航拍和样品室内分析方法：1)定量刻画家畜对草地利用强度的时空分布特征；2）引入高原鼠兔种群密度、草地破碎化以及异质性程度指标，完善该尺度草地健康综合评价体系；3)探讨家庭牧场构成对高寒草甸健康的影响及机制。本项目的目的是完善家庭牧场尺度草地监测方法和草地健康评价体系，提高家庭牧场管理方式对草地健康影响的定量认识，为家庭牧场管理提供系统的理论基础和科学依据。

本项目综合利用无人机航拍、野外观测和统计分析等手段，开展了家庭牧场家畜放牧强度时空分布格局对高寒草地健康的影响研究。研究结果表明：1）基于无人机跟踪监测及后续信息自动提取和统计方法能够刻画出家畜放牧强的时空分布格局，其中暖季牧场的最高强度随着生长季逐步由畜圈向边界推进的趋势，即家畜自发采用“轮牧”的方式进行草地的利用；2）牦牛畜群的分散度在一天内呈先下降后上升的趋势，且从6月份到9月份家畜分散指数在早晚呈下降趋势而中午无显著变化，这一指数可应用于指示牧草品质和供给情况；3）草地健康指数随着放牧强度的增加呈幂函数降低的趋势，即随着放牧强度增加草地的耐牧性增强。本项目可以为生态模式研究提供基础资料，同时为高寒草地生态系统保护和退化草地生态恢复提供科学依据。但本研究实现的放牧强度量化及健康评价指标转化如何大尺度推广尚不明确。因此，在将来的研究中需要进一步开展基于大尺度、长期定点工作，推动研究成果的应用和大尺度上解析环境与放牧对草地健康影响的耦合作用。