Advanced mine restoration protocols facilitate early recovery of soil microbial biomass, activity and functional diversity

Abstract

Many ecosystem restoration programmes can take over 15 years to achieve ecosystem functioning comparable to that of an unmodified ecosystem, therefore a reliable shorter-term method of assessing and monitoring ecosystem recovery is needed to ensure that recovery is following an appropriate trajectory. Soil microbes respond to environmental change relatively quickly, and shifts in microbial communities can reflect the current status of their environment. As well as potentially acting as 'indicator communities', microbes play an integral role in restoring ecosystem functions. On an active opencast mine on New Zealand's West Coast, three main restoration methods are used, differing in cost and restoration effort. They range from most expensive (1) vegetation direct transfer (VDT), to (2) biosolids-amended stockpiles that are spread and replanted, and (3) untreated stockpiles that are spread and replanted. We assessed the impacts of these methods on soil microbial communities by measuring microbial biomass, dehydrogenase activity, community level physiological profile (CLPP) and functional diversity as measured by carbon substrate utilisation, where restored sites were 5 years old or less. These measures were compared to an unmodified reference ecosystem in the same location. Microbial activity and biomass were highest in pristine habitats, followed by VDT and biosolidsamended soils, then untreated stockpile soil. When compared to all other treatments untreated stockpiled soils had significantly different CLPPs and significantly reduced microbial biomass and activity; microbial biomass was an order of magnitude lower than in pristine soils. Functional diversity and richness did not differ between pristine, VDT and biosolids-amended soils, but were higher than in untreated stockpiled soils. CLPPs did not differ between pristine habitat soil and VDT soil but biosolidsamended and untreated stockpiled soils were significantly different to pristine soil. This study has shown that soil microbial communities are a valuable tool to assess restoration progress, and that ecosystem restoration can begin in a relatively short time following investment in appropriate restoration strategy, ultimately benefiting recolonisation by plants and animals. ZusammenfassungViele Ökosystem-Renaturierungsprogramme können mehr als 15 Jahre benötigen, bevor eine Ökosystemfunktion, die mit der eines nicht modifizierten Ökosystems vergleichbar ist, erreicht wird. Darum wird eine verlässliche, früher einsetzbare Methode zur Bewertung und Überwachung der Regeneration des Ökosystems benötigt, um sicherzustellen, dass die Regeneration einen geeigneten Verlauf nimmt. Bodenmikroorganismen reagieren relativ schnell auf Umweltänderungen, und Änderungen der Mikroben-Gemeinschaften können den aktuellen Status ihrer Umwelt widerspiegeln. So wie sie potentiell B.R. Waterhouse et al. / Basic and Applied Ecology 15 (2014) 599-606 als "Indikator-Gemeinschaften" fungieren, spielen Mikroben auch eine zentrale Rolle bei der Wiederherstellung von Ökosystemfunktione...

Examining assumptions of soil microbial ecology in the monitoring of ecological restoration

“…When the microbial community is inoculated into each well, cell respiration results in a colour change within the well that can be read photometrically (Weber and Legge 2010). This method for assessing soil functionality is coarse (Waterhouse, Adair, & Boyer, 2014) and is limited to carbon‐degrading microbes. It would be a good technique to use when attempting to assess basic nutrient cycling in previously devastated soils, but does not provide any information on taxonomy or genes present.…”

Developing Diverse, Effective, and Permanent Plant Communities on Reclaimed Surface Coal Mines: Restoring Ecosystem Function

“…Mycorrhiza is the most widespread association between microorganisms and higher plants resulting in the increase in below-ground surface area (roots and mycorrhizal hyphae) for acquisition of nutrients. Results from a study by Li-ping et al, (2009) However, soil microbial communities can be important for successful reclamation in many ecosystems as post-mined soils typically have low microbial diversity, biomass, and enzymatic activity (Waterhouse et al, 2014;Dorr de Quadros et al, 2016;Thavamani et al, 2017).…”

Lateritic Plateaus in the Northern Western Ghats, India; a Review of Bauxite Mining Restoration Practices

“…Ecological details for almost all ferricrete specialists are absent from the literature. Waterhouse, et al, (2014) found that soil microbial communities are sensitive to restoration process and the only way of preserving them was to remove, carefully store and replace the top 300mm of topsoil at the same time limiting the depth of storage piles. This process was also suggested for the conservation of soil invertebrates by Majer et al, (2013).…”