Evaluating biological properties of topsoil for post‐mining ecological restoration: different assessment methods give different results

Abstract

Salvaged native topsoil is a scarce, highly valuable resource in post-mining restoration, being the main source of organic matter and nutrients and a major repository of plant propagules and soil microbes. During the mining process, topsoil is often stockpiled, and factors such as stockpile depth, season of stripping, and storage time can adversely affect topsoil functionality. We aimed to determine if soil functionality differs between undisturbed native reference topsoils and stockpiled topsoils of various age and origin, and whether measures of soil microbial community composition, soil respiration, and plant growth provide comparable assessments of soil functionality. We investigated this using select biological assessments of undisturbed native reference topsoils and stockpiled topsoils collected from seven mine sites representing a range of climate, soil, commodity, and vegetation types across the major mining province of Western Australia. Biotic properties of stored topsoil were idiosyncratic and variable across mine sites, and results differed based on the biotic measure being assessed. Biomass was generally lower for plants grown in stockpiled topsoils than for plants grown in native reference topsoils across mine sites. However, no single biotic measure provided an accurate assessment of soil functionality as reflected in plant growth responses. Overall, stockpiling adversely affected soil functionality and further research is needed to improve topsoil management procedures that may be site-and biome-specific.

Limited efficacy of a commercial microbial inoculant for improving growth and physiological performance of native plant species

“…The selected inoculant was used under the assumption that it contained live, viable beneficial microorganisms as stated. The bacterial composition of the GOGO Juice inoculant was verified using 16S rRNA sequencing following the method described in D'Agui et al. (2022) ; Supplementary Table S1 ).…”

Ten principles for restoring campo rupestre, a threatened tropical, megadiverse, nutrient‐impoverished montane grassland

“…Seed‐based strategies are widely used as a relatively low‐cost, large‐scale grassland restoration (D'Agui et al 2022; Gerrits et al 2023) and post‐mining sites (Dalziell et al 2022). However, seed‐based strategies often show low success for campo rupestre (Le Stradic et al 2014; Figueiredo et al 2021), as indicated by low seedling emergence, and the prevalence of invasive species in the initial years of restoration.…”

Advances in mining restoration

“…Native topsoil is a scarce, highly valuable resource in post‐mining restoration; however, handling and storage during the mining process can adversely affect its functionality. D'Agui et al (2022) report that when taken in isolation, commonly employed measures of soil microbial community composition and activity are poor indicators of soil functionality as reflected in plant growth. Customized approaches to topsoil management should be considered for individual sites to maintain soil functionality.…”