Mountaintop mining legacies constrain ecological, hydrological and biogeochemical recovery trajectories

Abstract

Mountaintop mining, like all forms of surface mining, fundamentally alters the landscape to extract resources that lie 10–100 ms below the land surface. Despite these deep, critical zone alterations, post-mining landscapes are required by United States law to be restored to ecosystems of equal or greater value than the ones they replace. Yet, remote sensing of vegetation across more than 1000 km2 of reclaimed surface mines in WV, USA reveals little evidence that these habitats are returning to the diverse Appalachian forests that were removed by mining. Instead, even decades after reclamation, mined landscapes are dominated by shorter and sparser trees. Based on detailed field studies and literature synthesis, we suggest that part of these widespread failures in re-establishing native forest result from the fundamental changes in critical zone processes on the post-mining landscape. Former surface mines have substantially altered topography, hydrology and chemistry. In these post-mining, synthetic landscapes, water moves more slowly through piles of exploded bedrock, changing the system from one dominated by stormflow in unmined catchments, to one dominated by baseflow after mining. This slow-moving water, travelling through high surface-area debris and pyrite-rich bedrock, creates ideal conditions for highly elevated weathering in mines both old and new. These foundational changes to the critical zone set ecosystem recovery along a novel trajectory, in which the legacy of past disturbance is likely to constrain the establishment of native forest for many decades.

Closing pit lakes as aquatic ecosystems: Risk, reality, and future uses

“…If most mine voids cannot be re-filled, and pre-mining conditions can never be replicated (Ross et al, 2021), pit lakes will continue to be created. Pit lakes are a mining legacy in the landscape for thousands of years, and planning for their future uses can mitigate negative effects and improve outcomes.…”

“…Overburden may have naturally rehabilitated into native forest ecosystems after many decades (Figure 3) to become valued by communities (Campbell, 2016; van der Plank et al, 2016). Further, re‐establishing a pre‐mining environment will never be truly possible due to irreversible changes in physico‐chemical conditions (Cooke & Johnson, 2002; Gwenzi, 2021; Hobbs et al, 2009; Ross et al, 2021).…”

The salmonid and the subsurface: Hillslope storage capacity determines the quality and distribution of fish habitat

“…This is an active research area. Subsurface CZ properties may also be altered over shorter timescales by disturbance events (which may be caused or exacerbated by human activity), such as soil-altering wildfire events (e.g., Moody et al, 2013) or mining (Ross et al, 2021). Watershed hydrologic behavior arises from the collected dynamics of individual hillslopes, whose subsurface capacity to produce recharge and transmit flow downslope dictates the spatial extent of runoff generation and flow recession behavior (Duan & Miller, 1997).…”

Research on geological environment protection and geological disasters control countermeasures in China

“…Especially on abandoned mines around urban areas and within the visual range along important traffic arteries, the resulting destruction of vegetation, exposed hills and land damage have a bad impact on the city image and ecological environment [15][16][17][18][19]. Mine geological hazards have become a hot issue of public concern and social attention, and gradually evolved into a major obstacle to social and economic development, making the prevention of geological hazards and ecological environment restoration and management increasingly a common demand [20][21][22].…”