## 1 Introduction  
Given their high metal content, metal-based tailings are widely considered to have a serious environmental impact [1; 2]. China has a considerable number of metal mines that produce extensive waste byproducts, and consequently result in severe environmental pollution [3; 4]. Mining activities have also caused considerable damage to the eco-environment. The Zhongtiao Mountains copper mine is the largest underground copper mine in China [3; 5]. The mine has an annual output of greater than four million tons of ore [6]. This mine predominately produces copper (Cu) ore, but it also produces other metals, such as iron (Fe), lead (Pb), zinc (Zn), and cadmium (Cd) [7]. During metal mineral resource development, a large amount of heavy metals is directly deposited into the soil with waste rocks, tailings, and other mineral dust in mining districts and their surrounding areas, which then become the primary source of environmental pollution [5]. Phytoremediation is regarded as one of the most effective methods in reducing the environmental risk from tailings [8]. This remediation approach either removes pollutants or degrades them into less harmful constituents by using the metabolic activities of plants. On the other hand, it employs plant unique tolerance or accumulation abilities to existent contaminants, and actuating root absorption and the transformation of pollutants, subsequently both reducing the pollutant concentrations and pollutants altogether [9]. At the present time, the phytoremediation method typically selects plants that are resistant to poor soil and heavy metals, such as _Isocoma veneta_ ([PERSON]) [PERSON], _Teloxys graveolens_ ([PERSON].) [PERSON] [10], _Bidens humilis_[11], _Atriplex lentiiformis_ ([PERSON].) [PERSON]. [12], _Lygeum spartum_ [PERSON], and _Piptatherum miliaceum_ (L) [PERSON] [13], which can grow normally on lead-zinc deposits and copper tailings from mine extraction. _Thlasi calaminare_, a recognized hyperaccumulator, has a strong Zn and Cd heavy metal absorption capacity [11]. In recent years, plant-microbial remediation has gradually gained considerable attention [14; 15; 16]. The mutualistic symbiosis between microorganisms and plants do not only stimulate plant growth, it promotes water and nutrient absorption capacities, increases plant biomass, strengthens plant tolerance to heavy metals, and enhances the plant absorption capacities of heavy metals, thus improving the overall ability of the phytoremediation method [17]. Both plants and soil microbes are capable of remediating heavy metals; therefore, the combination of microbe and plant remediation has a tremendous application potential in improving the absorption and transformation efficiency of heavy metals in the soil profile [2; 7]. On the one hand, soil microbial community remediation is one of the primary means of ecosystem rehabilitation and sustainability within mining areas, because most of these areas are subject to contamination [18]. Soil microorganisms, which are involved in many biochemical processes, such as the promotion of ecosystem material circulation, energy flow, organic matter decomposition, and soil nutrient transportation, are the repository of soil nutrients and a source of available nutrients for plant growth. They can also be used as key performance indicators for biological effectiveness of soil fertility and nutrient resources. Soil microbial activity and structure vary under the different rehabilitation methods and their respective time allotments [19; 20; 21]. Moreover, different reclamation scenarios have been reported to play a role in determining soil microbial abundance, diversity, and composition [22]. [PERSON] et al. found that forest types are significantly affected by soil microbial properties due to differences in soil physicochemical features [23].