高寒牧区村域生态足迹——以甘南州合作市为例

高寒牧区是一类特殊的地域,其生态环境本底和压力明显区别于其它地域类型。从自然本底上讲,"高寒"特征造成生态系统结构单一、节律缓慢、功能稳定性差,因此,脆弱性强,而修复难度大;从压力上讲,"高寒"又一定程度上屏蔽了外界要素的过分介入,导致人口分布的高度离散性和稀疏性,人地矛盾转化为更直观的草畜矛盾。论文结合高寒牧区的特质,对生态足迹模型和生态承载力模型进行了修正,强调了高寒牧区生态承载力的主控因素———牲畜特征、人口特征、生境特征和地域特征,以甘南州合作市为案例,具体测算和分析了41个行政单元的生态足迹和生态承载力。结果表明:(1)人口生态足迹和牲畜生态足迹分布格局大致呈反向态势,说明在高寒牧区,人口与牲畜对环境造成的压力存在着显著的空间差异。(2)从人口生态足迹和牲畜生态足迹对总生态足迹的贡献度上看,总生态足迹的高低主要取决于牲畜生态足迹,说明牲畜是主控因素。(3)从地均生态承载力分布态势看,低承载区主要分布于北部海拔较高的广大牧区,这里生态结构非常单一,主要以高寒草甸草原和沼泽草原生态类型为主,寒冻风化作用异常强烈,生物有效生长期非常短。而高承载区分布在市区周围和南部洮河谷地沿岸,生态系统除草地生态系统外,还有森林生态系统。从而说明人为条件的改善、自然生态系统结构的复杂程度和自然环境的严酷程度是决定高寒牧区承载力高低的主要因素。(4)从生态盈余与赤字的空间分布态势看,赤字区域主要集中分布在广大的纯牧区,超载过牧是生态状况的关键性致因。因此提高生态承载力、减少生态赤字的关键集结于草畜关系上。有鉴于此,需要采取以下措施:一是根据天然草场的承载能力,建立适宜的草畜平衡关系,将超载的牲畜转移出去;二是科学合理的提高草场的生产能力和承载能力,这就需要加强草原生态保护建设;三是调整经济结构,减少社会经济发展对天然放牧业的高度依赖性,推进传统草地畜牧业向现代畜牧业转型。

The ecological footprint of alpine pastures at the village-level: a case study of Hezuo in Gannan Autonomous Prefecture, China

Alpine pasture is a unique plant community with an ecological set of conditions and environmental pressures which are significantly different from other areas. This simple ecosystem has a naturally slow rhythm. Its functional instability is caused by the cold, alpine pasture environment which makes it vulnerable to disturbance and difficult to repair once damages occurred. To a certain extent, external forces and influences are limited in this cold climate because of its isolation from human activities. This leads to alpine pasture having a highly localized and sparse human population, so that human conflicts only tend to arise over grass-livestock conflicts. Based on characteristics of alpine pastures, the authors have revised the ecological footprint model and ecological carrying capacity model of this unique habitat placing strong emphasis on the key factors controlling ecological carrying capacity. These factors include the numbers and types of livestock, human population, local habitat conditions and regional characteristics. Following the methods of Hezuo, the authors then measured and analyzed the ecological footprint and ecological carrying capacity of 41 administrative units. The results show: 1) The distribution patterns and ecological footprints of the human population and their livestock are very different and roughly the opposite of each other, which indicates there are significant spatial differences between the environmental pressure on alpine pastures coming from the human population and pressures from livestock. 2) The combined ecological footprint of humans and livestock is mainly determined by the location of the livestock ecological footprint, so we can conclude the impact of livestock is the main factor in the formation of the combined ecological footprint. 3) Looking at the distribution of the ecological carrying capacity per unit area, the areas with a low carrying capacity are mainly located in the northern expansive pastoral areas at higher altitudes where the structure of the ecosystem is fairly simple, and main ecological types are alpine meadows and hydric grassland. Also, in these high altitude areas, frost weathering is quite strong, and the effective growing season is very short. Unlike these low carrying capacity and high altitude areas, the areas with high carrying capacity are mainly located around urban areas and along the Taohe River, with both grassland ecosystems and forested ecosystems present.In summary, we can conclude the main factor determining the ecological carrying capacity is our ability to improve anthropogenic factors, while dealing with the complex structure of natural ecological systems and harsh natural environment. 4) When we consider the nature of the spatial distribution of ecological surpluses and deficits, ecological deficit areas are mainly concentrated in pure pastoral areas, and overgrazing is the key cause for the ecological damage. So, the key to increasing the ecological carrying capacity and reducing ecological impact is focusing our attention on the relationships between grasses and livestock. We should take several measures to improve the situation. First, maintaining the balance between forage and livestock and avoiding overgrazing is required. Stocking levels need to be based on the carrying capacity of native pasture. Second, we can improve productivity and carrying capacity of pastoral areas using scientific and reasonable methods, and in this way strengthen protection for grassland ecosystems. Finally, we need to adjust the economic structure, by decreasing human dependence on grassland farming and by promoting the transition from traditional grassland husbandry into modern animal husbandry.