江河源区草地生态建设构想

江河源区是青藏高原的主要组成部分,面积仅占全球陆地面积的0.24%,占全球土壤碳库的1.06%～1.20%左右,生态价值巨大.江河源区1986-2000年,土地植被盖度下降了2.252%,土壤有机碳含量下降了11.454%,土壤CO2年释放量仅下降了9.165%,表现了土壤从碳汇转化为碳源的趋势.而草地面积减少是使土壤从碳汇转化为碳源的主体因素.特别是过度放牧引起的高寒类型草地面积减少559.03 km2,致使土壤有机碳含量减少了750 070万t,占14年来(1986-2000)土壤有机碳含量下降总量的39.03%,是使土壤有机碳流失的主因.从维护全国乃至全球生态安全的角度看,江河源区草地生态建设意义重大.建议在江河源地区建立特色草地农业生态耦合系统,将江河源区分为4个功能区,即自然保护核心功能区、自然保护过渡区(狩猎采集保护区)、自然保护生态-生产功能区、常规居民区.以自然保护区为核心,把这4个功能区与草地农业系统的4个生产层理论相衔接,构建2个层次的系统耦合,即江河源区内部4个功能区之间的系统耦合;江河源区与外区的系统耦合.通过2个层次的系统耦合,将实现江河源头的生态服务功能与下游受益地区的物质与能流的合理交换,以取得经济、生态和社会的巨大效益.

Assumed plan on grassland ecological reconstruction in the source region of Yangtse River, Yellow River and Lantsang River

The source region of Yangtse River,Yellow River and Lantsang River is main part of Tibet plateau, covering only 0.24% of the global terrestrial sphere, but its soil carbon pool accounts for 1.06%-1.20% of the global soil carbon pool with great ecological values. The canopy of plant decreased 2.252%; soil organic carbon reservoir fell down 11.454% from 1986 to 2000 in this region, while the annual carbon dioxide emission dropped only 9.165% in the same period. It indicates the tendency that soil is transforming the carbon pool into carbon emission source and the reduced grassland is the key factor for this tendency. Particularly, the loss of the high-cold steppe and meadow by over-grazing is the leading cause for the loss of the soil organic carbon. There were 559.03 km~2 diminished for that reason, resulted in the loss of 750.07 millions ton of the soil organic carbon that equals 39.03% of the total loss of the soil organic carbon in the period (1986-2000). So it is of great importance to strengthen the ecological settings of the alpine meadow and alpine steppe in the area in order to safeguard the national as well as global ecological situation. Authors proposed a special grassland agricultural coupling ecosystem in this region by dividing the region into four function areas: the core area of the natural reserve, transitional area of the natural reserve (for hunting and collecting), ecological-production area of natural reserve and ordinary residence area. The theory of four production levels in grassland agro-ecosystem is applied correspondingly into the four function areas based on the natural reserve in order to form a coupling system with two levels: the internal coupling system among the four function areas in the region and the external coupling system between the region and its surrounding areas. In doing so, the economic, ecological and social potentials would be developed effectively through rational exchange of ecological functional services at the headstream areas with materials and energy flows in the benefited lower reaches.