干旱砾漠区露天采煤对草地植物群落特征及其稳定性影响

露天煤炭开采对区域地形地貌、水文循环和土壤植被等生态环境因子产生了较大干扰,但干旱砾漠区露天开采对周边植物群落及其稳定性的影响范围和程度仍有待深入研究,这个问题的探明才能为矿区植被恢复的精准施策提供科学依据。该文通过定量比较距露天开采区不同距离植物群落组成、多样性、生产力和稳定性变化特征,分析干旱砾漠区露天采煤对植物群落的影响范围和程度,并结合土壤性状和微气象因子的测量,探究影响干旱矿区植物群落特征的主导因子。结果表明:(1)干旱砾漠区露天开采排土场原始植被消失殆尽,开采区外围0~500 m范围内原优势物种重要值降低,伴生物种重要值增加,500 m后随着距开采区距离的增加优势植物重要值逐渐增加,至开采区800 m外植物群落组成趋于稳定;(2)开采区外围0~500 m范围内植物群落地上生物量、多样性和群落稳定性较5000 m处分别平均下降了53%、70%和37%,开采区500 m以外上述群落指标整体上变化不明显,而植被覆盖度在开采区外围不同距离并未表现出显著变化趋势;(3)土壤水分、有机质、有效氮磷钾、可溶性盐与植物群落地上生物量、多样性和稳定性呈正相关关系,而土壤pH、光照强度和地表温度与上述植物群落指标呈负相关关系。因此干旱砾漠区露天开采排土场及开采区外围0~500 m范围是矿区生态修复过程中重点考虑区域,同时研究表明干旱砾漠区植被主要分布在砾漠戈壁浅沟和季节性河道等生境相对良好的凹陷微地形条件下,综合可得出干旱砾漠区植被修复过程中可通过微地形塑造、土壤改良和乡土物种繁殖促进,以实现干旱矿区生态系统的稳定和可持续发展。

Effect of Open-pit Coal Mining on Grassland Plant Community Characteristics and Stability in Arid Gravel Desert Area

The influencing degree and scope of open-pit coal mining on plant communities were analyzed in arid gravel desert areas by quantitative comparing the composition, diversity, productivity and stability of plant communities at different distances from the mining area, and the leading factors affecting the characteristics of plant communities were explored in combination with the measurement of soil and micrometeorological factors. The results showed that: (1) the original vegetation in dump sites disappeared completely, the important value (IV) of dominant species decreased within 0~500m around the mining area, but the IV of companion species increased. The IV of dominant plants gradually increases with the increasing distance from mining area, and the composition of plant community tended to be stable 800 m away from the mining area. (2) The aboveground biomass, diversity and stability of plant communities within the range of 0~500 m around the mining area decreased by 53%, 70% and 37% averagely compared with 5000 m areas, respectively. The above plant community indicators did not changing significantly beyond 500 m of the mining area as a whole, while the vegetation coverage did not showing a significant change at different distances around the mining area. (3) Soil water content, organic matter, available nitrogen, phosphorus, potassium and soluble salt were positively correlated with aboveground biomass, diversity and stability of plant communities, while soil pH, light intensity and surface temperature were negatively correlated with these plant community indicators. (4) In arid gravel desert areas, the dump sites and range of 0 ~ 500 m around mining area is the key area to be considered in the ecological restoration process of the open-pit coal mining area. Vegetation is mainly distributed in the micro-canyon topography, shallow ditches and seasonal rivers in the study area. Therefore, it is necessary to reshape micro-terrain, improve soil quality, and use local species with strong adaptability and good reproductive capacity in the process of vegetation restoration. In these ways, a stable and sustainable ecosystem can be realized in the arid coal mining area.