铅锌矿渣场植被自然演替与基质的交互效应

Interactions between natural vegetation succession and waste residue in lead-zinc tailings deposited sites

矿业废弃地生态系统自然恢复的植被演替过程与机理是生态恢复研究的重要内容之一.以空间代替时间的方法,选择立地条件基本一致的4个不同自然恢复年限铅锌矿区为对象,研究黔西北土法炼锌渣场废弃地植被自然演替与矿渣基质理化性质的交互效应.结果表明:随着堆置时间的增加,矿渣基质的营养条件明显得到改善,全氮、全磷和全钾含量极显著增加,pH上升,电导率下降,容重降低,有效铅和镉显著降低.同时,随着恢复时间的增长,植物群落的物种丰富度、多样性指数和均匀度也相应提高.植物群落组成以多年生草本植物为主,植物群落演替在前20年较为缓慢,30年后植被群落盖度可达到53%,超过40年盖度可达87%.矿渣理化性质与物种多样性显著相关,典型变量分别是全氮、全磷和全钾;物种多样性指数与有效铅和镉呈显著负相关.土法炼锌渣场废弃地植被自然演替过程在30年后速度加快,植被生长的限制因子是营养供给不足和重金属的有效性高.

Natural vegetation succession process and related mechanism is one of the important research contents in ecological restoration of abandoned mining land. Taking 4 lead-zinc tailings deposited sites with the recovery time being about 10 years,20 years,30 years,and over 40 years under similar site conditions in northwest Guizhou Province as study areas,this paper studied the interactions between the natural vegetation succession and the physicochemical properties of waste residue. The results showed that with the increasing dumping time of the waste residue,the nutritional conditions of base material improved significantly,the total N,P,and K contents and the pH value increased,while the EC,bulk density,and especially,available lead and cadmium contents decreased. Meanwhile,the plant community species richness （ S） ,diversity index （ H） ,and evenness （ J） increased correspondingly with increasing recovery time. The composition of plant communities was dominated by perennial herbaceous. In the first 20 years of recovery,the vegetation succession process was very slow,but after 30-and 40-year recovery,the vegetation coverage reached 53% and 87% ,respectively. Canonical correlation analysis showed that there were significant correlations between base material properties and species diversity,and the canonical variables were the total N,P, and K contents of base material. The species diversity index was significantly negatively correlated with the available Pb and Cd contents of base material. The natural vegetation succession process in the study areas accelerated after 30 years of recovery,and the limiting factors of vegetation recovery were the nutrient deficiency and the high availability of Pb and Cd in base material.