磷矿采空区恢复林地土壤养分——以云南昆阳磷矿为实例研究

Restoration of Soil Nutrients in Phosphate Mined-Out Areas:A Case Study of the Phosphate Mine in Kunyang,Yunnan

矿山开采引起了矿区生态环境恶化,进行植被恢复是解决矿区生态破坏问题的有效措施。采用野外调查和室内分析相结合,对昆阳磷矿采空区人工恢复林地的土壤养分进行研究。结果表明:恢复林地的土壤呈酸性;10龄及以下的恢复林地间土壤养分含量无显著差异,10龄及以下的恢复林地与25龄恢复林地间差异则达显著水平;25龄以上的林地土壤有机质含量接近原生林水平;与桉树(Eucalyptus spp.)纯林比,旱冬瓜(Alnus nepalensis)-柏树(Cupressus spp.)混交林能更有效地促进氮素积累;自然状态下,土壤磷素和全钾含量随恢复年限的延长逐渐增加;土壤有机质与水解氮、全氮间呈极显著正相关;土壤水解氮与全氮、有效磷与全磷间表现为极显著正相关。总体上,植被恢复区土壤有机质普遍偏低,氮素普遍缺乏,磷素水平较高,钾素含量适中。从而为建立科学的矿区植被恢复模式提供参考。

Phosphate mining has led to the severe deterioration of environment in mining area, while vegetation restoration is an effective measure to solve this problem. In the present study, we investigated the soil nutrients status of restored woodland in phosphate mined-out area in Kunyang by the combination of field investigation and laboratory analysis. The results showed that the pH value of soil in restored woodland was acidic. At the initial stage of restoration （less than 10 years）, woodland ecosystem did not showed significant difference in soil nutrients, but there was a significant difference between the restored woodland at the age of 10 and below and that at the age of 25 years. Besides, the soil organic matter contents in woodland ecosystem after the 25 years of vegetation restoration were close to primary forest. The mixed forest （A lnus nepalensis-Cupressus spp.） soils accumulated more nitrogen （N） contents than the monoculture forest （Eucalyptus spp.）. In natural state, the phosphorus （P） and total potassium （K） contents in soil increased with the extension of vegetation restoration stages. Soil organic matter showed a positive correlation with the available N and total N. In addition, we found significant positive correlations among available N, total N, available P and total P. In general, soil in the mined-out area had lower soil organic matter, nitrogen, but higher phosphorus level, and moderate potassium content. Thus, these findings in this study could provide a reference for the the establishment of a scientific vegetation restoration model in mining areas.