Plantation development and colonization of woody species in response to post-mining spoil preparation methods

Abstract

Rising mineral and fossil fuel demand have accelerated the global prevalence of surface mining, resulting in adverse impacts to many forest ecosystems. Post-mining reclamation techniques, specifically spoil preparation methods, can influence reforestation success and the trajectory of future stand dynamics. Compaction is a common post-mining spoil stabilization technique but consequently creates high-density rooting media unconducive to forest succession. In the eastern USA, mine operators have traditionally attempted mine reforestation in compacted soils, achieving little success. In 1996–1997, a series of reforestation plots were created on a reclaimed surface mine in eastern Kentucky, USA, to evaluate the impacts of post-mining spoil preparation on plantation development of six native tree species. We conducted follow-up inventories 19 years after planting to elucidate the effect of three spoil preparation methods on tree growth, stand structure, and natural regeneration during the initial period of the stem exclusion stage of stand development. Low compaction reclamation techniques prior to tree planting generally resulted in higher survival and larger trees of all species nearly two decades after establishment when compared with compacted spoil. Natural recruitment and relative percentage of native colonizing species were also inversely correlated with level of grading treatment. Height and biomass growth of plantations in low-compaction treatments approximated those of naturally regenerating stands in unmined forests during similar periods. Study findings indicate that choice of spoil preparation technique during initial stages of reclamation guides forest dynamics up to two decades after planting and that loose-dump and strike-off treatments each promote favorable long-term growth trajectories.