Plant Community Structure within a Reclamation Field Trial and Forested Reference Sites in a Post-Mine Environment

Abstract

Early successional plant community assemblage within a reclamation field trial at the Detour Lake Mine in northeastern Ontario is assessed, and compared with reference forested and historically reclaimed sites. The reclamation field trial examines eight amendment treatment combinations that include treatments with a winter kill cover crop of oats, fertilizer, biosolids, peat, and combinations thereof. The objectives of this study are to: (1) Investigate how soil amendments influence plant functional group establishment and growth in mine overburden; and (2) Explore the amendment properties that best support the establishment and growth of a plant community that resembles the baseline reference sites. Currently, the presence of non-native species and a dominant woody plant community explains the largest proportion of variance between the forested upland and lowland reference sites and all reclaimed sites. Similar to non-native species, graminoids were absent from the upland forested reference sites. The difference in the graminoid community explains much of the variance between the forested reference sites and all reclaimed sites. The cumulative additions of fertilizer and peat increased alpha diversity of non-native and graminoid plants within the amendment treatments, which had greater alpha diversity of these plant functional groups than the forested reference sites. Within the amendment treatments, non-native and graminoid alpha diversity was initially greater in the nutrient treatments, but by 2019 there was no significant difference in non-native or graminoid alpha diversity between amendment treatments. The results indicate that applications of nutrients through fertilizer or biosolids may increase graminoid alpha diversity and abundance within reclamation units in year 1. The results also confirm that the vascular plant community composition present within the historically reclaimed sites and amendment treatments does not resemble the forested reference sites. The plant community present within the amendment treatment sites is best described as early successional, with the presence of non-native herbaceous legumes dominating the historically reclaimed sites. Despite this, the results indicate that fertilizer and biosolids-based treatments have developed a vascular plant community, excluding woody species that is more similar to the forested reference sites than the peat-based treatments. Further research and long-term monitoring are needed to determine which amendment treatment will best support a plant community that resembles the forested reference sites. In addition, future studies of this nature might consider including wildfire affected and post-harvested forest stands as additional reference sites, to better capture possible plant community trajectories of a severely disturbed environment.

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

“…Based on previous research, stockpiling of topsoil may increase graminoid species abundance after reclamation of boreal sites as some of the graminoids can still maintain their viability at greater depths during stockpiling (Alberta Environment & Water, 2012; Dhar et al, 2019). Although reclaimed sites have been reported to have a higher proportion of graminoids than undisturbed natural forests (Rapai et al, 2021; Rowland et al, 2009), we anticipate these graminoids to decline as the dominance of trees and shrubs increases and propagules from neighboring areas establish (Dhar, Comeau, Naeth, Pinno, & Vassov, 2020a). However, there is evidence that graminoids may persist for up to 24 years on reclaimed sites (Dhar, Comeau, Naeth, Pinno, & Vassov, 2020a; Norman et al, 2006).…”

“…As a result, they suppress the growth of desirable woody plants and delay the successional progression of ecosystem recovery. On the other hand, their canopy and roots can reduce soil erosion and contribute to soil formation processes (Dhar et al, 2018; Rapai et al, 2021). The decrease in non‐native canopy cover and richness and dominance of native species 5 years after reclamation translates to a dissipation in competition of non‐native species for available resources as desirable perennial native species became more established (Dhar, Comeau, Naeth, Pinno, & Vassov, 2020a; Pinno & Hawkes, 2015; Rowland et al, 2009).…”

“…Based on previous research, stockpiling of topsoil may increase graminoid species abundance after reclamation of boreal sites as some of the graminoids can still maintain their viability at greater depths during stockpiling (Alberta Environment & Water, 2012;Dhar et al, 2019). Although reclaimed sites have been reported to have a higher proportion of graminoids than undisturbed natural forests (Rapai et al, 2021;Rowland et al, 2009), we anticipate these graminoids to decline as the T A B L E 3 Soil properties responses to topsoil replacement depth and organic amendments treatments across 5 years. Means within a column followed by the same letter are not significantly different at α = 0.05 according to the Tukey multiple comparison procedure.…”