青藏高原载畜能力及草畜平衡状况研究

Livestock Carrying Capacity and Balance Between Carrying Capacity of Grassland with Added Forage and Actual Livestock in the Qinghai-Tibet Plateau

青藏高原草地植被和牲畜是影响该地区生态环境的主要影响因素,因此,研究此两项因素及其之间的关系,对于保护青藏高原生态环境、促进经济发展具有重要的意义。为此,论文利用2003—2004年青藏高原天然草地产草量观测资料,经过GPS定位,与NOAA/AVHRR植被指数建立了天然草地产草量反演模型及不同区域尺度天然草地年最大产草量、载畜量估算模型;同时,利用粮食、油菜、青饲料等农业产量和林地面积等资料,估算了青藏高原精、粗饲料的载畜能力,分别建立了天然草地以及考虑补饲后的草畜平衡监测模型,分析了青藏高原及其县、地、省等不同区域天然草地以及区域总体牲畜承载能力和草畜平衡状况。结果表明:青海和西藏在天然草地和农业等其它补饲共同承载下,2003—2004年年平均最大载畜能力分别为3 140×104、2 865×104只标准羊单位,超载率分别为16%、78%,两省平均超载率为45%。分地州来看,两省除青海的果洛州和玉树州实际牲畜数量没有超过当地的最大承载能力、青海海西州和西藏林芝地区草畜基本平衡以外,其余地州均有不同程度的超载,其中果洛州和玉树州天然草地牲畜超载率分别为-11%-、26%,利于“三江源”地区天然草地植被的恢复和生态环境的改善;青海黄南州、海北州、海南州、西宁市、海东地区和西藏昌都、那曲、阿里地区牲畜超载率为45%～97%,西藏拉萨市、日喀则、山南地区达115%～153%,这些地区应适当降低牲畜数量或加大补饲力度,以减轻对当地生态承载的压力。青海牲畜超载的县主要位于东部,西藏超载的县主要位于西部和南部大部地区。

Grassland and livestock are the main factors affecting eco-environment of the Qinghai-Tibet Plateau.It is thus very important to study them and their relation for protecting eco- environment and promoting economic development.According to the measurement data of grass yield from 2003 to 2004 positioned by GPS,grass yield estimating models have been built with normalized vegetation of NOAA/AVHRR,and the estimating models for the maximum annual total grass production and carrying capacity on different regional scales have been built.Livestock carrying capacity of added forage from food,rape,succulence,forest,etc has been estimated.The models of balance between carrying capacity of grassland or added forage and actual number of livestocks have been built.Carrying capacity and balance state of county,prefectural and provincial level have been analyzed.The results are as follows.The maximum annual livestock carrying capacity of grassland with added forage for Qinghai and Tibet are 3140×10^4 and 2865 ×10^4 standard sheep/y,but the actual livestock numbers have exceeded the maximum livestock carrying capacity.The overgrazing rate is 16% for Qinghai and 78% for Tibet,with average of both being 45%.Overgrazing exists of different degrees in other many administrative regions of Qinghai and Tibet,except for Guoluozhou and Yushuzhou of Qinghai whose actual number of livestocks does not exceed the local maximum carrying capacity, being -11% and -26% separately, it is advantageous to restore grassland and protect eco-environment of ＂Sanjiangyuan＂ area of the Qinghai-Tibet Plateau.The balance between livestock carrying capacity and actual number of livestocks is found in Haixizhou of Qinghai and Nyingtri of Tibet.Overgrazing with a rate of 45%-97% is found in Haibeizhou,Huangnanzhou,Hainanzhou,Haidong,Xining of Qinghai and Chamdo,Nakchu,Ngari of Tibet;and 115%-153% in Lhasa,Shigatse,Lhoka of Tibet.It is necessary to decrease livestock number or provide more forage in order to solve the contradiction between carrying capacity and feed demands of livestock.Counties of Qinghai experiencing overgrazing are mainly located in the eastern part of the province and a majority in the western and southern part of Tibet.