黄土区露天煤矿排土场土壤与地形因子对植被恢复的影响

Effect of soil and topography on vegetation restoration in an opencast coal mine dump in a loess area

在脆弱的生态环境改善和恢复过程中,植被恢复与重建扮演着重要的角色。黄土露天煤矿区生态环境极其脆弱,认识矿区损毁土地植被恢复与地形、土壤因子之间的作用规律对矿区土地复垦与生态恢复改善至关重要。为此,选择山西平朔安太堡露天煤矿南排土场对2条样带27个复垦样地的土壤、地形、植被参数进行了采集与测定,并应用单因素方差分析与CANOCO4.5软件的降趋势对应分析和冗余分析研究了地形与土壤因子对植被恢复的影响。结果表明:植被与土壤变量之间呈显著相关,与地形变量之间相关性不明显;坡度主要影响草本覆盖度,坡向与有机质和速效磷之间具有线性相关性;速效钾对植被的变化起着重要的作用;土壤容重与砾石含量对土壤养分含量具有明显的指示作用;有机质与全氮呈显著正相关,各土壤养分指标之间存在明显的相关关系。为了改善和恢复黄土区露天煤矿排土场脆弱的生态系统,应该考虑植被和土壤的联合演替。在当地的生态环境状况下土地复垦与生态恢复的关键是改善土壤状况和增加人工植被,同时加强对排土场人工和自然植被的保护。

Restoration and reconstruction of vegetation play an important role in improving and restoring the fragile ecological environment in disturbed areas. In opencast coal mine dumps in loess areas,the ecological environment is extremely fragile. Therefore,it is crucial to understand the effects of topography and soil factors on the response of vegetation restoration in order to improve the damaged ecosystems in mining areas. Here,we determined the effects of soil and topography on the response of vegetation to restoration activities at 27 reclamation sample plots（ each with two transects） with different site conditions in the Shanxi Pingshuo Antaibao Opencast Coal Mine in a loess area. We conducted one-way analysis of variance（ ANOVA） tests and pairwise tests of significance with SPSS 20. 0. We performed multivariate techniques,including detrended correspondence analysis（ DCA） and redundancy analysis（ RDA） using the program CANOCO 4. 5.The ANOVA and pairwise tests indicated that environmental factors significantly effected changes in vegetation.Available K（ AK） had the most significant impact on vegetation restoration（ P 0. 01）,followed by total N（ TN） and bulk density（ BD）（ P 0. 05）. However,topography variables did not significantly effect changes in vegetation（ P 0. 05）. Soil nutrients were the main factors affecting the distribution and growth of vegetation during the process of restoration in this opencast coal mine dump in a loess area.The RDA results indicated that vegetation and soil variables were significantly correlated,whereas the correlation between vegetation and topography variables was not significant. There was a strong correlation between vegetation and environmental factors with species-environment correlations of 0. 811 on the first axis and 0. 702 on the second axis. The cumulative percentage of variance in the species occurrence data on the first four axes of the RDA was 59. 9%. The cumulative percentage of variance for the species-environment relationship on the first axis was 75. 3% and on the second axis was 20. 1%. Thus,the first axis and second axis explained 95. 4% of the variation in the relationship between species and the environment. This indicated that the species and the environment axes were highly correlated with the set of variables. The Monte Carlo permutation test indicated that vegetation restoration was not associated with all the environmental factors（ P 0. 05）. AK played an important role in vegetation change. The soil nutrient content correlated with soil bulk density and rock content. Soil organic matter and total nitrogen showed significantly positive correlation. The slope determined the herbage coverage. There was also a linear relationship between slope direction and soil organic matter;a similar relationship was noted between slope direction and rapidly available phosphorus.In order to improve and restore the degraded ecosystems in opencast coal mine dumps in loess areas,the co-evolution of vegetation and soil should be understood and natural succession should be considered. Vegetation restoration is not only an ecological,but also an economic and social problem,and some relevant conservation policies,such as the prohibition of grazing and logging,and conservation of natural vegetation are needed to reduce the human disturbance on these lands. A key strategy for ecological restoration in opencast coal mine dumps in loess areas is to improve soil conditions and increase the area of propagated vegetation; protection of propagated and natural vegetation under local environmental conditions should also be strengthened.