Substrate conditions, root and arbuscular mycorrhizal colonisation of landforms rehabilitated after coal mining, sub-tropical Queensland

Authors: Spain, AV; Tibbett, M Download Paper

DOI https://doi.org/10.36487/ACG_rep/1152_22_Spain

Cite As:
Spain, AV & Tibbett, M 2011, 'Substrate conditions, root and arbuscular mycorrhizal colonisation of landforms rehabilitated after coal mining, sub-tropical Queensland', in AB Fourie, M Tibbett & A Beersing (eds), Mine Closure 2011: Proceedings of the Sixth International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 199-208, https://doi.org/10.36487/ACG_rep/1152_22_Spain



Abstract:
The abilities of roots and their mycorrhizal symbionts to colonise often unfavourable materials are critical to successful ecosystem development after mining, both for long-term sustainability and for more immediate erosion control. In this study we examined the capacities of grass roots and their mycorrhizas to colonise successfully a range of soils and post-mining wastes following rehabilitation of landforms constructed after coal mining. Mean soil pH was slightly acidic and within the normal range for soils (pH(H2O) range ca 5–8) while the wastes were predominantly alkaline and more widely variable (pH(H2O) range ca 4–10). Soils were non-saline or slightly saline while most wastes were saline or highly saline. Both soils and waste materials were variably sodic. The depth distributions of fine roots and incidences of arbuscular mycorrhizal (AM) colonisation were assessed in the dominant perennial grasses and herbaceous plants in sites rehabilitated for periods ranging from ca 0.3 to 9.4 years. The concentrations of spores of AM fungi in the post mining materials were also assessed. No major barriers to root penetration were apparent in any of the minesoils examined and roots had colonised a range of materials, including some substrates putatively hostile to plant growth. Furthermore, significant mycorrhizal activity was measured in all landforms assessed, despite their lack of inoculation with AM fungi. Arbuscular mycorrhizal spore concentrations were unusually high in some surface soils but declined markedly with depth in the profile. Both AM spores and root colonisation regularly occurred to depths of 1.0 m or more but the highest concentrations occurred at less than 0.40 m. The consistent colonisation by roots and mycorrhizas of an eclectic range of post-mining soils and wastes demonstrated the innate capacity of (at least) the gross components of the plant-soil system to develop rapidly and extensively in favourable and unfavourable post-mining substrates. Of particular interest was the comprehensive and relatively-rapid natural colonisation by AM fungi of the biologically sterile, and sometimes chemically-hostile mine wastes.

References: