Abstract: Through greenhouse cultivation and field investigation, the major constraints on plant colonization at Fankou Pb/Zn mine tailings are analysed.The results show that total Pb, Zn, Cu and Cd contents in the tailings are 34300,36500,215 and 82.6 mg·kg^-1 ,while their available contents are 1.5, 1963,0.71 and 8.03 mg·kg^-1 respectively.Greenhouse cultivation reveals that the toxicity of heavy metals significantly inhibits the root vitality of Stylosanthes guianensis, prevents plant from absorbing inorganic nutrient, and leads to evident chlorosis, which significantly affects grass growth. Both greenhouse cultivation and field investigation demonstrate that available Zn and Cd contents in tailings are negatively correlated with plant growth.Heavy metal toxicity, especially the toxicity of available Zn and Cd is the major constraint on plant colonization at Fankou Pb/Zn mine tailings, and the extreme infertility is another major constraint on plant growth.

Key words: Pb/Zn tailings, Vegetation resconstruction, Major constraints, Heavy metals, Populus simonii, stable carbon isotope, tree rings, land use type, intrinsic water-use efficiency