锰尾矿区有机菌肥-速生树种的生态修复效应

在锰尾矿区建立了4.5hm²生态修复工程区,以速生树种泡桐（Paulownia tomentosa）和栾树（Koelreuteriapaniclata）作为建群植物,采用有机菌肥改良其根际环境,利用土壤库存耐性植物种子的自然萌发力来丰富物种多样性.结果表明,工程实施后第6a,有机菌肥处理植物群落干物质生物总量达到33498.7kg/hm²,Mn吸收积累量达到5532.6g/hm²,植物种类数达到51种,分别为无机化肥对照的22.8、2.6和3.4倍;有机菌肥处理的植物群落Pb、Cd、Cu、Zn和Cr的总积累量、根际微生物种类及其数量也显著大于对照.有机菌肥的改良机制可归结于其与植物根系、根际微生物对基质的共同作用.有机菌肥处理区泡桐和栾树的总株数不到该区植物总株数的0.2%,但其干物质生物量、锰吸收量与盖度分别为该区的88%、73%和55.2%.速生树种泡桐和栾树对该区生态修复起到了"主导"作用.

Ecological remediation effect of organic bacterium manure-fast growing tree species on a manganese tailing site

An ecological restoration engineering project of 4.5hm² was implemented at a Mn mine tailing site by coplanting two fast-growing trees (Paulownia fortune and Koelreuteriabipinnata) as the dominant colonization species. An organicbacteri-rich manure was used to amend the rhizospheric area surrounding the coplanted seedlings. Enrichment of the site's biodiversity was counted on natural germination of native metal tolerant plant species based on the soil seed inventory capacity. The experimental data showed that the application of the manure not only enhanced the biomass growth and heavy metal uptake of the plant communities but also enriched its species composition and biodiversity. In the sixth year after the establishment of the remediation site, the total dry biomass quantity, total Mn uptake and total number of plant species of the restored plant community with manure treatment reached 33498.7kg/hm², 5532.6g/hm² and 51, respectively, which were approximately 22.8, 2.6 and 3.4 times higher than those in the control plot amended with chemical fertilizers. The total uptake of metals (Pb, Cd, Cu, Zn and Cr) by species and the number of species and quantities of rhizospheric microbial communities were also significantly greater in the manure-treated plot. The remediation effect of the organic manure can be attributed to its interaction with plant roots, microorganisms and substrates, forming an integrated system in reduction of the metal toxicity in the rhizosphere. The transplanted Paulownia fortunei and koelreuteriabipinnata grew very fast with characteristics of high levels of biomass quantity, land coverage and metal uptake. The total number of the two coplanted tree species accounted for less than 0.2% of that of the entire plant community in the treatmentplot, however, their dry biomass quantity, Mn uptake, and land coverage contributed to 88%, 73% and 55.2% of the restored ecosystem, respectively. Paulownia fortunei and Koelreuteriabipinnata played important roles as keystone species in the ecological restoration of the manganese tailing site.