Tailings slope aspect influences biomass and nutrient reproductive allocation of restorative plants in an alpine mining area

The biomass and nutrient concentration of propagule, leaves, and stems were measured for three species, Elymus sibiricus, Puccinellia tenuiflora, and Poa crymophila, that are used for restoration of alpine mining areas. The measurements were conducted in three different habitats, that is, sunny slope, summit, and shaded slope. We analyzed the variations in reproductive allocation for biomass and nutrients and determined the effects of tailings slope aspect on reproductive allocation in plants. The results showed that biomass and nutrient reproductive allocation were different among slope aspects, and decreased gradually from the sunny slope to the summit to shaded slope. The interaction between slope aspect and plant species could significantly alter the biomass and nitrogen reproductive allocation, with values being higher in E. sibiricus and P. crymophila than in P. tenuiflora on the sunny slope and summit, whereas P. tenuiflora exhibited higher values than those of the others on the shaded slope. Biomass and nitrogen reproductive allocation were increased with propagule nitrogen concentration and above-ground biomass, and phosphorus reproductive allocation was increased with propagule phosphorus concentration. In addition, reproductive allocation was increased based on individual size of plants. Our results indicated that we need to consider the different responses of vegetative and reproductive allocation to tailing slope aspect, to improve the restoration efficiency of alpine mining areas.