不同植被对晋陕蒙矿区排土场土壤养分16 a恢复程度的影响

摘要

Shanxi-Shaanxi-Inner Monglia adjacent region is an important coal energy base, and also the most fragile ecological region in China. Recent years, the large-scale opencast mining has heavily destroyed the original landscape and ecosystem, and formed a large number of earth disposal sites. To guaranty the harmonious development of the local society, economy and ecosystem, the rapid artificial vegetation reconstruction in these sites is the key part of the local ecological restoration. To evaluate the effects of different vegetation measures in the process of land reclamation on the recovery of soil nutrient, the east earth disposal site in Heidaigou opencast coal mine located in Jungar Banner, Inner Mongolia was chosen as studying area, where the land reclamation was carried out with 7 different artificial vegetation configuration modes (Astragalus adsurgens, Stipa bungeana, Amorpha fruticosa, Robinia pseudoacacia, Hippophae rhamnoides, PoplarandPinus sylvestris var mongolica Litv) since 1996. The recovery degrees of soil total nitrogen (TN), soil organic carbon (SOC), NO3––N and NH4+–N within 0-40 cm were studied by comparing with the nearby natural soil under 2 vegetation types (natural Stipa bungeanaand natural Hippophae rhamnoides). The results showed that: 1) The content of TN, SOC, NO3––N and NH4+–N declined with the increase of the soil depth within 0-40 cm under different vegetation except thePinus sylvestris var mongolica Litv and Astragalus adsurgens. 2) Within 0-40 cm, the contents of TN and SOC of 7 artificial vegetation types were significantly lower than the 2 natural vegetation types, and there was no significant difference between 7 artificial vegetation types and 2 natural vegetation types in NH4+–N within 0-10 and 20-40 cm. Seven vegetation types improved soil quality at different levels, and the remediationdegree ofRobinia pseudoacacia vegetation was better than other vegetation patterns. Average TN, SOC, NO3––N and NH4+–N within 40 cm soil depth were recovered to 44.15%, 44.65%, 85.33% and 93.77% of naturalStipa bungeana site and 56.85%, 54.82%, 84.66% and 105.70% of naturalHippophae rhamnoides site after nearly 16 years’ recovery. And the remediationeffects ofPoplar andPinus sylvestris var mongolica Litv were no more than 40% of the 2 natural vegetation types. The remediationeffect of NH4+–N was relatively better under 7 vegetation patterns. Average NH4+–N within 40 cm soil depth was recovered to 79.50%-93.77% of naturalStipa bungeana site, and 89.47%-105.7% of naturalHippophae rhamnoides site. However, the remediationdegree of TN, SOC, and NO3––N were relatively lower than NH4+–N. Average TN, SOC, and NO3––N within 40 cm soil depth had recovered to 24.70%–44.15%, 25.09%–44.65%, 47.25%–85.33% of naturalStipa bungeana site, and 33.52%–56.85%, 32.83%–54.82%, 47.18%–84.66% of naturalHippophae rhamnoides site. Although soil nutrients of 7 artificial vegetation modes in land reclamation area have not reach the natural level completely after 16 years’ land reclamation, artificial vegetation is an effective measure to improve soil nutrients’ recovery.Fabaceous plantvegetation (mainlyRobinia pseudoacacia) was better than other vegetation patterns for soil nutrient recovery, soRobinia pseudoacacia, Hippophae rhamnoides andStipa bungeana could be the suitable vegetation for the land reclamation in this area. The research has evaluated the soil nutrient remediation degree of different vegetation measures in the process of land reclamation and provided the theoretical basis for the vegetation measure selection during ecological restoration and land reclamation in the opencast coal mine area.%为评价晋陕蒙矿区排土场土地复垦过程中不同植被措施对土壤肥力的恢复作用及程度，在内蒙古准格尔旗黑岱沟煤矿东排土场，分别选取已恢复16 a的7种不同人工植被（沙打旺、长芒草、紫穗槐+长芒草、刺槐林、沙棘林、杨树林、樟子松），并以周边原地貌条件下两种植被（退耕梯田长芒草、自然坡地沙棘林）为对照，分析了不同植被条件下0～10、>10～20、>20～40 cm土层土壤全氮、有机碳、硝态氮以及铵态氮的含量及其差异。结果表明：1）9种植被配置中除樟子松地和沙打旺草地外，土壤养分含量均随深度增加而递减。2）经过近16 a植被修复后，7种人工植被不同程度地改善了土壤肥力状况，其中刺槐纯林配置的恢复效果最佳，土壤肥力恢复程度接近或超过原地貌条件下植被的50%，沙棘次之。杨树和樟子松两种配置对土壤全氮、有机碳、硝态氮恢复效果相对较差，恢复程度均不超过40%。7种不同植被措施对土壤铵态氮的恢复程度相对较好，分别恢复到自然植被长芒草样地和自然植被沙棘样地的79.50%～93.77%，89.47%～105.70%。土壤全氮、有机碳、硝态氮恢复程度则相对较低，分别恢复到自然植被长芒草样地的24.70%～44.15%、25.09%～44.65%、47.25%～85.33%；分别恢复到自然植被沙棘样地的33.52%～56.85%、32.83%～54.82%、47.18%～84.66%。总之，尽管经过近16 a的复垦，7种人工植被下的土壤养分状况尚未完全恢复到该地区自然水平，但仍可认为该地区进行生态修复时可优先选择以刺槐为主的豆科乔木、以沙棘为主的灌木、以及长芒草等草本植物，并进行适当的套种、间种，以增强复垦效果。