基于两种收益目标的西藏境内不同地区草畜平衡

Effect of income objective on the forage-livestock balance of sheep production in the Tibet autonomous region

草畜平衡是西藏畜牧业持续发展和草地生态系统维持稳定的基础。本研究以“一江两河”地区的南木林县和藏北高原的申扎县为对象,以牧户饲养家畜获取经济收益和不获取经济收益为基准,评估了两个空间上毗邻县的草畜平衡状况,提出了实现草畜平衡的最优技术方案。结果表明,若牧户饲养家畜的主要目标为获取经济效益,则会增加家畜数量,若牧户饲养家畜的主要目标不是获取经济效益,则家畜数量处于波动稳定状态。无论是以获取经济收益为主要目标,还是以不获取经济收益为主要目标,南木林县和申扎县在2015–2017年均处于饲草料供给匮缺状态,其中以不获取经济收益为主要目标时两个县分别匮缺14.05万~16.65万和7.39万~9.67万t,以获取经济收益为主要目标时两个县则分别匮缺29.35万~32.89万和22.67万~25.70万t。以青贮玉米(Zea mays)、燕麦(Avena sativa)和紫花苜蓿(Medicago sativa)为例,从两个县农牧空间互补角度提出实现草畜平衡的12种技术方案,其中最优方案为南木林县以获取经济收益为主要目标、申扎县以不获取经济收益为主要目标,分别需要减畜6.97万~11.60万和12.80万~16.75万羊单位,或分别外调紫花苜蓿5.34万~8.88万和7.39万~9.67万t。

Forage-livestock balance is the basis for the sustainability of animal husbandry and for the health of grassland ecosystems in the Tibet autonomous region.Thus,the present study used two economic income objectives for raising livestock to estimate the forage-livestock balance between two neighboring counties(Namling County,in the YNL River Region,and Shenza County,in the northern Tibetan Plateau)and to propose optimal feasibility plan for achieving foragelivestock balance in the Tibet autonomous region.The results indicated that livestock number will increase if the objective of husbandry is economic gain and will,otherwise,remain stable.Meanwhile,regardless of objective,both counties experienced a shortage in forage supplies from 2015 to 2017.Indeed,Namling and Shenza County experienced forage supply shortages of 140500~166500 tons and 73900~96700 tons,respectively,when maintaining livestock number and shortages of 293500~328900 tons and 226700~257000 tons,respectively,when maximizing economic income.The feasibility plan proposed for balancing forage supply and livestock demand involves the establishment of pasture silage maize(Zea mays),oat(Avena sativa),and alfalfa(Medicago sativa).To maximize economic income in Namling County and to maintain livestock number in Shenza County,the counties should reduce sheep number by 69700~116000 and 128000~167500,respectively,or increase alfalfa production by 53400~88800 tons and 73900~96700 tons.