草原区矿产开发对景观格局和初级生产力的影响——以黑岱沟露天煤矿为例

煤炭是我国的主要能源,大型露天煤矿的开发推动了地区经济与社会的发展,但同时也引发了区域生态环境问题。因此,探讨矿产开发对区域景观格局的影响,并阐明景观格局动态与生态系统初级生产力的关系,对生态环境的保护具有重要意义。以内蒙古草原区的黑岱沟露天煤矿为例,利用3S(RS、GIS和GPS)技术,在野外实地调查的基础上,分析了1987年以来矿产开发导致的土地利用/覆盖变化、景观格局动态及其与生态系统初级生产力之间的关系,主要结果如下:(1)提出了界定最适研究区范围的方法,认为沿矿区边界向外建立10 km的缓冲区是该研究最适研究区域的大小;(2)草地和耕地是研究区主要的土地利用/覆盖类型,但是在过去20多年间其面积在逐渐减少,而工矿仓储用地及住宅用地面积在急剧增加;(3)矿产开发导致景观格局发生变化,并且在两种不同的空间尺度(研究区和矿区)上表现出总体变化趋势的一致性,但在后期有较大差异;(4)初级生产力变化呈现下降趋势,并且矿区的降低更为突出;(5)以生长季降水量为控制因子的偏相关分析表明,景观配置(平均斑块周长面积比、景观形状指数)与初级生产力呈正相关关系,在研究区尺度上尤其显著,但在矿区尺度上,景观结构组成(斑块密度、均匀度指数和多样性指数)更为重要,与初级生产力呈显著负相关;(6)受复垦规模和演替进程的影响,局限在矿区排土场上的植被重建尚不能改变研究区尺度景观-生态系统初级生产力之间的关系。可见,景观格局的变化以及景观格局与生态系统初级生产力之间的关系均存在尺度依赖性。

Impacts of mining on landscape pattern and primary productivity in the grassland of Inner Mongolia: a case study of Heidaigou open pit coal mining

Coal has been the primary energy resource that made rapid economic and social development in China possible. Yet, its extraction in the form of open-field mining operations changed landscape patterns considerably and created a suite of environmental and ecological problems. Therefore, it is very important to understand these landscape pattern dynamics and their effects on ecosystem processes. While open pit coal mining is one of the fast growing human modifications of the Earth's surface which transforms landscapes and ecological functioning, studies in applied ecology and restoration ecology examining the effects of this human activities have been lacking. We conducted a field study in the 10 km buffer around the landscape of Zhungger Heidaigou in Inner Mongolia where large open mine operations are presently underway. Within this landscape land use/land cover changed substantially between 1987 and 2010. We related these human transformed landscape patterns to primary productivity and found the relationship to be highly scale dependent. Our results are summarized as follows. First, the 10 km buffer was found to be the optimum size of this study area, although we seek expanding the scale domain of our study because the size of the mining area is expected to increase. Second, grassland and agricultural areas, the two main land uses that preceded coal mining, have both decreased in the past 20 years. Grassland area decreased from 71.18% (45 199.73 hm²) in 1987 to 60.71% (38 550.76 hm²) in 2010,while agricultural area decreased from 25.76% (16 360.24 hm²) in 1987 to 20.48% (13 002.40 hm²) in 2010. On the other hand, industrial and residentia lareas increased between 1987 and 2010. Particularly, mining operations occupied only 0.01% (3.12 hm²) in 1987, but increased to 3.16% (2 007.04 hm²) in 2000, which corresponds to 10.05% (6 385.04 hm²) in 2010, respectively. Third, although landscape structure in the area has experienced overall consistent trend of change dynamics of landscape pattern at later stages were very different at two spatial scales-the scale of the mining area and the whole landscape. The number of introduced and disturbance patches increased at the expense of dominant resource patches, which resulted in severe landscape fragmentation. At the fine scale, previously dominant grassland patches characterized by higher pattern complexity and irregular shapes were replaced by simpler and more regular patches of coal mining operations and accompanying infrastructures.Fourth, primary productivity in the landscape as a whole and mining area in particular decreased with time since mining operations started. Areas affected by mining experienced more significant decrease of primary productivity. Partial correlation analysis of landscape patterns and primary productivity, with growing season precipitation as the controlling factor, showed that primary productivity was positively correlated with landscape configuration landscape pattern indices(perimeter-area ratio average, PARA; landscape shape index, LSI),especially at the whole landscape level. Primary productivity was negatively correlated with landscape composition indices (patch density, PD; shannon-weaver diversity index, SHDI; and shannon evenness index, SHEI) in the mining area. We conclude that vegetation restoration cannot change the relationship between landscape patterns and primary productivity at the large scale because of current limitations of available potential habitat areas and long term successions.We believe the success of restoration of damaged ecosystems in the study area is heavily dependent upon the realization of the importance of natural ecosystems.