Early ecosystem establishment using forest floor and peat cover soils in oil sands reclamation

Abstract

Early trends of plant community development provide the basis of ecosystem function and reclamation success of oil sand extraction sites. However, few studies have explicitly investigated species-level interactions with different cover soil types, placement depths, and time since reclamation during early plant community development in boreal forests. We investigated effectiveness of forest floor mineral mix (FMM) and peat mineral mix (PMM) cover soils and placement depths (10 and 20 cm) at four research sites 4 to 13 years after reclamation. Outcomes of this study indicate FMM had a more positive influence on woody plant densities, vegetation cover, and species richness than PMM. Species assemblage, composition, dominance, and types (successional stages, habitat types, competitive-stress tolerant-ruderal strategies) also showed FMM cover soil performed better than PMM. Greater vegetation cover and richness on deeper (20 cm) cover soil placements were evident. However, this effect of cover soil depth would likely decrease with time. Dominant and subdominant species on FMM were native and early to late successional, thus trajectory community development on FMM followed typical early succession of boreal forests (from ruderal and annual to perennial communities), while PMM was dominated by non-native and annual forbs which could slow succession and ecosystem recovery.

Revegetation of disturbed land reclaimed with suboptimal topsoil replacement depth and organic amendments

“…This is because thick topsoil layers provide ample space for root development and expansion, while also retaining sufficient nutrients and water to support prompt revegetation (Redente et al, 1997; Schladweiler et al, 2005). Our results corroborate those of Archibald et al (2023), which showed increased vegetation cover in thicker topsoil layers (20 cm) compared to thinner layers in a revegetation study in the oil sands region of Alberta, Canada. Redente et al (1997) and Bowen et al (2005) observed greater vegetation canopy cover at greater depths (40 and 60 cm), although these did not differ significantly from the total canopy cover at shallow depths (15 cm).…”

Reclamation of Hydrocarbon Contaminated Soils Using Soil Amendments and Native Plant Species

“…Organic amendments are typically high in organic matter, have a neutral pH, and contain nutrients in a slow-release form due to slow carbon and nitrogen mineralization [9,19]. Among the most commonly used organic amendments are animal manure, compost, vermicompost, biosolids, sewage sludge, biochar, forest floor material, and peat soil; common inorganic amendments include gypsum, zeolite, pyrite, and fertilizers [20][21][22]. Soil organic amendments can immobilize contaminants to limit their bioavailability and improve soil quality by balancing pH, adding organic matter, increasing water holding capacity, re-establishing microbial communities, and alleviating compaction [22,23].…”

“…Soil organic amendments can immobilize contaminants to limit their bioavailability and improve soil quality by balancing pH, adding organic matter, increasing water holding capacity, re-establishing microbial communities, and alleviating compaction [22,23]. Among the organic amendments, compost is the most commonly and widely used in land reclamation, facilitation disturbed or contaminated sites to be remedied, revegetated, and revitalized [20][21][22][23]. Fertilizers are widely used inorganic amendments as they supply readily available nutrients over a short time which has a priming effect on microbial activity and plant growth [24,25].…”

“…To stimulate microbial activity and therefore contaminant degradation, plant species that develop fibrous root systems and establish rapidly are advantageous [20,29,30]. Vegetation on disturbed sites can stabilize the soil surface, reduce erosion, and contribute to nutrient cycling and soil aeration [21] which directly leads to successful reclamation. However, absence of adequate seed sources can limit establishment of desired plant communities on disturbed or contaminated sites.…”