The recovery of soil N-cycling and P-cycling following reforestation in a degraded tropical limestone mine

Restoration of mined out lands by reforestation can mitigate the worst impacts of industrial mining. However, the speed of restoration and the rapid recovery of biogeochemical cycling and ecosystem function remain a challenge. We present a novel approach for technical reclamation and rapid restoration using a 0.2 km2 extremely degraded tropical limestone post-mining site by using the initial forest soil that was removed by mining as the substrate, and by planting grown saplings of eight non-native fast-growing tree species. By comparing the belowground attributes in the restored site with that of undisturbed tropical forest and the mined unplanted soil, we deduced that our reforestation could recover soil N-cycling and P-cycling communities and associated soil N-cycling and P-cycling processes, root biomass, and key root functional traits to the levels found in forest soils within four years. The reforestation could also mitigate mining induced soil degradation such as soil alkalization, soil nutrient (organic matter, and N) deficiency and soil metal (cadmium, plumbum, copper, zinc, and mercury) pollution. Based on these findings, we recommend that using non-native fast growing tree species for planting with top-soil built using the initial soil can rapidly restore (<10 years) above-ground biomass, biogeochemical cycling soil microbial communities, and facilitate the recovery of native biodiversity.