露天矿排土场边坡自然恢复规律及其环境解释

Effects of soil properties on vegetation restoration on dump slopes of opencast coalmine

露天矿排土场边坡水土流失严重,易发生地质灾害,急需开展生态恢复和土地复垦研究。为了解排土场边坡植物群落演替规律以及植物对生境因子的响应关系,本研究以阜新露天矿不同恢复年限排土场边坡为对象,调查不同坡向和坡位的植物组成、数量、高度和盖度,采用双向指示种法(TWINSPAN)对植物群落进行分类;同时分析边坡土壤物理、化学和生物学性质,采用去趋势典范对应分析(DCCA)方法研究群落分布格局与环境因子的关系。结果表明,排土场边坡共出现27种植物,物种数量小于平台。植物群落在阴坡和阳坡呈现出不同的演替格局,阴坡演替顺序为狗尾草(Setaira viridis)+茵陈蒿(Artemisia capillaries)+铁杆蒿(Artemisia sacrorum)→狗尾草+铁杆蒿+白蒿(Artemisia anethoides)→铁杆蒿+狗尾草;恢复10 a后,铁杆蒿在中上坡位占据优势地位,植物种类和数量下降,植物群落呈逆向演替。阳坡演替顺序为蒺藜(Tribulus terrestris)+旱稗(Echinochloa hispidula)+狗尾草→狗尾草+蒺藜+白蒿→狗尾草+页蒿(Carum carvi)+白蒿,植被演替进程缓慢。DCCA排序表明,第一轴主要反映植物群落随坡位、土壤水分、氮元素有效性和周转的变化规律,其与土壤pH值和脲酶紧密相关;第二轴主要反映植物群落随着恢复年限和土壤磷素有效性的梯度变化,其与土壤容重、速效磷、蔗糖酶和碱性磷酸酶紧密相关。排土场边坡必须采取人工恢复措施,土壤酶活性对植物群落分布影响较大。

It is necessary to carry out the research about ecological restoration and land reclamation on dump slopes of opencast coalmine, for where there remain great risks of soil and water loss and geological hazards. In order to understand the plant community succession patterns and find out relationships between vegetation and environmental factors on dump slopes, we carried out an investigation on plant communities within different successional stages on several dump slopes of opencast coalmine in Fuxin, Liaoning. Plant species composition, density, height, and coverage of different slope aspects and slope position were recorded during the survey. Soil characteristics of physics, chemistry and biology were measured also. Two-way indicators species analysis （TWINSPAN） method was used for cluster analysis of plant communities. Detrended canonical correspondence analysis （DCCA） method was employed to identify relationships between distribution patterns of plant communities and environmental factors. The results showed that richness of plant species on dump slopes （27 species totally） less than platform. Different succession patterns occurred on the slopes. The successional series on the shady slope were Setaira viridis ＋ Artemisia capillaries ＋ Artemisia sacrorum→S. viridis ＋ A. sacrorum＋ Artemisia anethoides→A. sacrorum ＋ S. viridis.A. capillaries became the dominant species at the upper and middle part after 10 years’ recovery, which lead to the plant species and richness decline and regressive succession of plant communities. The succession series on the sunny slope wereTribulus terrestris ＋ Echinochloa hispidula ＋S. viridis→S. viridis＋T. terrestris＋ A. anethoides→S. viridis ＋ Carum carvi ＋ A. anethoides. It suggested that the succession processes were slow. The first axis of DCCA ordination represented the slope position, soil water content, available N and its turnover gradients. And it was correlated with soil pH value and urease. The second axis of DCCA ordination reflected restoration years and gradients of soil available P. And it was related to soil bulk density, available P, invertase and alkaline phosphatase. Our results implied that artificial rehabilitation is essential for the restoration of dump slopes. The soil enzyme activity could explain most variations of species composition in communities.