两种幼龄乔木修复林下土壤改良及植被多样性研究

Study on soil improvement and vegetation diversity of two kinds of young trees under remediation

以辽宁省抚顺市榆树铁矿和傲牛铁矿植被恢复区为研究对象,两矿山分别选用先锋树种樟子松和刺槐进行单纯乔木层植被修复。通过调查样方植被株高及胸径、测定土壤指标,参照全国第二次土壤普查分级标准分析两矿山已恢复样地土壤肥力状况,再综合香农-维纳多样性指数和德尔菲法确定的指标权重计算植被多样性指数,进而分析恢复初期林下草本层植被多样性及土壤基质变化情况。结果表明:幼龄林恢复期间,樟子松和刺槐的胸径和树高逐年升高,刺槐年均树高增长可达樟子松的1.94-4.43倍,两种乔木均可将酸性土壤改良至中性,但幼龄樟子松林较幼龄刺槐林更易积累贫瘠地中的营养物质;植被多样性调查共出现19种草本植物,隶属于11科16属,植被多样性评价显示刺槐林草本层植被多样性指数均高于樟子松林。综上,推荐抚顺市废弃矿山乔木层混交种植樟子松和刺槐,以共同作用促进草本层自然演替过程,并引入灌木种形成“乔-灌-草”复合系统加快矿山修复进程。

In this paper, Yushu Iron Mine and Aoniu Iron Mine vegetation restoration areas in Fushun City, Liaoning Province, were taken as the research objects. The local pioneer species, Pinus sylvestris and locust were selected for vegetation restoration in tree layer. The soil fertility status of the restored sample plots in the two mines was analyzed by investigating plant height and DBH, determining soil fertility index, and referring to the second national soil census grading standards, then the vegetation diversity index was calculated by combining Shannon-Wiener diversity index and the weight of the index determined by Delphi method. The vegetation diversity and the change of soil matrix in the understory herbaceous layer at the initial stage of restoration were analyzed. The results show that the tree height and DBH of Pinus sylvestris and locust increased year by year during the recovery of young forest;the average annual growth of locust tree height could reach 1.94-4.43 times than that of Pinus sylvestris. Two species of trees could improve the acidic soils to neutral soil. However, the young Pinus sylvestris was more likely to enhance the nutrient content of barren wasteland than the young locus forest. There were 19 herbs in the survey of vegetation diversity, belonging to 11 families of 16 genera. The vegetation diversity evaluation showed that the herb layer vegetation diversity index of Robinia pseudoacacia forest was higher than that of Pinus sylvestris var. mongolica forest. In conclusion, mixed planting of Pinus sylvestris var. mongolica and locust in abandoned mines in Fushun is recommended to promote the natural succession of herbaceous layer and introduce shrub species to form a "tree-shrub-grass" composite repair system to accelerate the process of mine restoration.