典型草原合理放牧强度阈值研究

Threshold of Rational Grazing Intensity in Typical Grassland

探寻合理放牧强度及其研判依据,是当前草原监管中最急迫需要解决的理论和技术问题。研究以内蒙古典型草原为例,利用放牧强度实验平台的植被和家畜监测数据,解析了不同放牧强度下草-畜系统重要指标的响应规律,依据成本-效益分析模式,确立了研究区合理放牧强度的阈值,并筛选出7个能够指示草畜平衡的参考指标。主要结论:(1)试验区合理放牧强度为170~340羊单位·d/hm^2/a,下限时生态效益较好,经济效益偏低,上限时生态和经济效益可实现均衡最优。(2)与对照系统相比,牧后剩余率(35%~75%),建群植物高度(50%~95%)、密度(≥85%)、生物量(50%~95%),群落物种多样性(≥100%)和生物量(55%~85%)以及净初级生产力(≥100%)等指标可作为草畜平衡快速评价的重要参考依据。

Exploring the rational grazing intensity and its criterion is the most urgent theoretical and technical problem to solve in the grassland supervision.Taking typical grassland in Inner Mongolia as an example,the response pattern of important indicators of grassland and livestock system were studied under different grazing intensities by monitoring the plant and animal data obtained from the grazing platform.The threshold of rational grazing intensity was established according to the cost-benefit analysis model,in which 7 indicators of grass-livestock balance were screened out.The results were shown in following contents.Firstly,the rational grazing intensity in the present experimental area was 170~340 sheep units·day/hectare/year;The ecological benefit was better in lower grazing intensity (170 sheep units·day/hectare/year) while the economic benefit was under estimation.The ecological and economic benefit can be balanced and optimized in higher grazing intensity (340 sheep units·day/hectare/year).Secondly,compared with the enclosure grassland ecosystem,the residual rate after grazing (35%~75%),the height of constructive plant population (50%~95%),plant density (>85%),plant biomass (50%~95%) and community species diversity (>100%),plant biomass (>55%~85%) and primary productivity (>100%) can be used as important indicators for rapid evaluation of grass-livestock balance.