Surface mines show little progress towards native species forest restoration following 35 years of passive management after initial reclamation

Abstract

Restoration techniques using passive management rely on natural plant community succession after reclamation to return disturbed areas to native ecosystems. This approach is often used in areas affected by mining activity, but effectiveness is variable and depends on the ability of native plants to establish in highly degraded soil and outcompete invasive species. We evaluated the restoration progress of three former surface mines where activity had exposed alkaline glacial till parent material. The mines underwent reclamation (grading, soil compaction, and planting fast‐growing herbaceous species) followed by passive management for 7, 28, and 35 years. At the time of initial restoration planning in the 1980s, native woody species were expected to recolonize the site within 10–20 years. Treating the sites as a chronosequence, we observed that woody vegetation increased inconsistently over this 35‐year timespan. Most of the woody plants present today are invasive species (Elaeagnus umbellata and Rhamnus frangula) that are counterproductive to reestablishment of native forest. However, results were not entirely negative, with increased overall native species and decreased exotic species in the older sites, and plant community composition changing somewhat consistently over time. This suggests that succession has been slowed rather than completely arrested, and native herbaceous plants are establishing. The progression of restoration appears to be far slower than expectations during initial planning. Furthermore, native woody plants struggle to establish, whereas invasive woody plants are thriving, raising doubts that passively managed succession can lead to the desired outcome of a native species forest in this significantly degraded habitat.

Reintroduction of native plants indicates the return of ecosystem services after iron mining at the Urucum Massif

“…Despite the positive developments in the analyzed sites, the presence of three alien invasive grass species at high coverage rates presents a potential stumbling block to rehabilitation success (e.g., Ruggles et al 2021). The negative correlations between invasive species coverage and species richness or phylogenetic diversity observed in this study indicate that invasions reduce the taxonomic and phylogenetic diversity of reinstated communities, confirming previous findings (e.g., Vojík and Boublík 2018, Kiełtyk and Delimat 2019, Adams et al 2020.…”

Characteristics and gaps in the assessment of progress in mine restoration: insights from five decades of published literature relating to native ecosystem restoration after mining

“…An assessment of multiple restored Appalachian coal mines that used satellite imagery to explore plant community structural similarity over large scales and long time frames similarly highlighted the potential for poor overall outcomes, which may be less apparent at smaller scales (e.g. Ruggles et al 2021). Both examples highlight the critical importance of monitoring that is able to demonstrate success at appropriate spatial scales.…”

Soil microbes-mediated enzymes promoted the secondary succession in post-mining plantations on the Loess Plateau, China

“…Soil enzyme activities were determined as described earlier. In brief, dehydrogenase activity (DHA) was measured using the triphenyl tetrazolium chloride method (TTC) (Ruggles et al, 2021). Urease (URE) activity was measured using the sodium phenolate-sodium hypochlorite colorimetric method (Nannipieri et al, 2012).…”