Distance from the Forest Edge Influences Soil Fungal Communities Colonizing a Reclaimed Soil Borrow Site in Boreal Mixedwood Forest

Abstract

Soil fungi are important components of boreal forest ecosystems; for example, saprotrophic fungi regulate nutrient cycling, and mycorrhizal species facilitate nutrient uptake by plants. This study aimed to assess soil fungal communities in a reclaimed area and an adjacent natural mixedwood forest and to identify the distribution of taxa available for seedling colonization. Soil fungal microbiomes were assessed along three transects (from 10 m inside the interior of the undisturbed forest to 40 m inside the reclaimed area) and in the roots of small aspen within the natural forest. Using high-throughput deoxyribonucleic acid (DNA) sequencing of internal transcribed spacer amplicons, a total of 2796 unique fungal taxa were detected across fine roots, forest floor, and mineral soils collected along the transects, whereas 166 taxa were detected in the aspen roots from the natural forest. Within the interior of the forest, ectomycorrhizal fungi were more common, whereas in the reclaimed areas, arbuscular mycorrhizae and saprophytes were more common. This survey showed that natural areas of adjacent undisturbed forest can act as a source of ectomycorrhizal fungi for dispersal into reclaimed areas. Notably, soil fungal taxa colonizing the root systems of small aspen included species that are specifically associated with soils from the undisturbed forest (primarily ectomycorrhizae) or the reclaimed clearing (saprotrophs and plant pathogens).

Impact of soil stockpiling on ericoid mycorrhizal colonization and growth of velvetleaf blueberry (Vaccinium myrtilloides) and Labrador tea (Ledum groenlandicum)

“…Soil storage for 3 years was reported to reduce colonization percentage of corn roots with arbuscular mycorrhizal fungi (AM) from 85% to 12% compared to undisturbed soil (Gould & Liberta 1981). A significant decrease in the abundance of ericoid mycorrhizae was also reported for the reclaimed site where soil was replaced after a period of stockpiling compared to undisturbed forest soil adjacent to the reclaimed site (Ramsfield et al 2020).…”

“…In this study, the impact of soil stockpiling on ericoid mycorrhizal colonization and growth of two species of the boreal forest understory shrubs was examined. Earlier studies showed that soil stockpiling resulted in the reduction of diversity of soil microorganisms including ericoid mycorrhizal fungi (Williamson & Johnson 1990; Ramsfield et al 2020), damaged soil structure, and reduced plant growth (Hunter & Currie 1956; Sheoran et al 2010). The present study demonstrated that the total P concentrations in forest soil that was stockpiled for 1 year were almost 200% and Ca concentration were about 370% higher compared to the fresh soil.…”

Soil mycobiomes in native European aspen forests and hybrid aspen plantations have a similar fungal richness but different compositions, mainly driven by edaphic and floristic factors

“…Spatial distribution analysis ( Ramsfield et al, 2020 ) has shown that undisturbed forests contribute EcM fungi to reclaimed areas via dispersal. Moreover, the study showed that fungal richness could be even greater than that in adjacent undisturbed forests within 10–20 m from the forest edge.…”

Contrasted root trait responses between saplings of an arbuscular and an ectomycorrhizal tree species in open field compared to forest conditions

“…This is especially true when trees at forest margins colonize adjacent open fields (Dickie et al, 2013; Nuñez & Dickie, 2014; Reinhart & Callaway, 2006). In general, in such cases, ECM colonization tends to decrease with distance from the forest edge (Dickie & Reich, 2005; Grove et al, 2019; Ramsfield et al, 2020). Such a context suggests a need for plastic responses, where in the absence of sufficient mycorrhizal symbiont populations, plants might display autonomous foraging strategies, while leaning towards cooperation when symbionts are more available (Lee et al, 2014; Wiseman & Wells, 2009).…”