Native Seedling Colonization on Stockpiled Mine Soils Is Constrained by Site Conditions and Competition with Exotic Species

Abstract

Sites disturbed through mining practices can be challenging to restore with native vegetation, as the path of ecological succession is often unknown and hard to predict. We conducted an establishment study that explored restoration strategies to increase native vegetation on a newly formed stockpile of soil at New Gold’s New Afton Mine in British Columbia, Canada. Establishment of native species in semi-arid grasslands is often constrained by seed and seedling microsite limitations, so treatments were imposed to assist in reducing these limitations. We established a fully factorial design with a native seed treatment (seeded and unseeded) and four soil preparations: raking, hydroseed slurry, a combination of raking and hydroseed slurry, and no preparation. Raking assisted in increasing total seedling establishment, regardless of whether the site was seeded or not. Raking and seeding increased the number of native seedlings and resulted in the greatest species richness, suggesting that native seedling establishment is primarily seed-limited, but that microclimate is also important for the establishment of some native seeds. We found that exotic species were able to capitalize on the disturbance and outcompeted the native species, but reducing seed-limitations by sowing more native seeds and increasing available microclimates by raking or tilling may increase native species’ success at the establishment phase.

Revegetation of degraded ecosystems into grasslands using biosolids as an organic amendment: A meta‐analysis

“…Reclamation methods for revegetation of degraded land should find a balance between the short‐term needs like soil stabilization and erosion control and long‐term objectives, such as increasing native biodiversity or establishing woody vegetation. Site preparation and seeding may assist in reducing the negative environmental conditions that often constrain establishment, like poor soil quality, limitations in the number of microclimates suitable for growth and establishment of different species, and propagule pressure by exotic species (Zobel et al, 2000; Martin and Wilsey, 2006; Baethke et al, 2020). Unfortunately, we were unable to assess plant‐functional groups or exotic species, but the relatively rapid cover provided by seeding may aid in reducing the probability of establishment of invasive plants (Jessop and Anderson, 2007).…”

“…The increased cover on seeded sites to which biosolids have been applied may be a result of increased nitrogen and phosphorus availability (Meyer et al, 2002; You et al, 2017). Agronomic species are often used to revegetate severely disturbed sites, which are able to take rapid advantage of increases in nutrient availability and provide rapid cover (Carrick and Krüger, 2007; Bochet et al, 2010; Baethke et al, 2020). Research remains limited on the use of native seed mixes when reclaiming severely degraded lands (Alday et al, 2011; Baethke et al, 2020), but it will be important to select plant species that are able to compete in this nutrient‐rich environment.…”

Grassland reclamation of a copper mine tailings facility: Long‐term effects of biosolids on plant community responses

“…However, the fact that non‐native/naturalized grasses benefit more from nutrient addition show that this is still a challenge to overcome (Huang et al, 2018). Restoring with native seedlings may be an alternative and contribute to increase native species’ success (Baethke et al, 2020).…”

“…Since bringing back mining sites to a state close to the historical ecosystem can be challenging, restoration efforts often lead to the creation of a novel ecosystem with different species, interactions, and functions than the original site (Hobbs et al, 2009). Novel ecosystems can be valuable natural assets, but there is an increasing desire to re‐establish near‐natural ecosystems to sustain biodiversity and improve resilience in a changing climate (Baethke et al, 2020; Salgueiro et al, 2020).…”

Editorial for Special Issue “Sustainable Use of Abandoned Mines”

“…In the geo-ecological regeneration of disturbed areas, a systematic approach to revegetate the area with native vegetation to foster positive natural ecological processes is an attractive approach. Baethke et al reported efforts conducted in semi-arid grasslands in British Columbia, Canada [13]. They found that native seedling establishment is primarily seed-limited, and that proper raking and tilling help keep incursion of exotic species at bay.…”