Soil moisture dynamics and restoration of self‐sustaining native vegetation ecosystem on an open‐cut coal mine

Abstract

Post-mining landscape reconstruction on open-cut coal mines aims to support restoration of self-sustaining native vegetation ecosystems that in perpetuity require no extra inputs relative to unmined analogs. Little is known about the soil moisture retention capacity of the limited layer of topsoil replaced (often <30 cm deep), impacts of deep ripping of the profile, and the combined impacts of these on plant available water during the mine restoration process. We examined changes in soil moisture parameters (soil water potential, , and soil water content, ) daily using automated soil sensors installed at 30 and 45-65 cm depths on mine restoration sites aged between 3 and 22 years and on adjacent remnant vegetation sites following heavy rainfall events at Meandu mine, southeast Queensland, Australia. Consistent patterns in soil moisture attributes were observed among rehabilitated sites with generally marked differences from remnant sites. Remnant site soil profiles had generally higher after drying than rehabilitated sites and maintained high for extended periods after rain events. There was a relatively rapid decline of on reconstructed soil profiles compared with remnant sites although the times of decline onset varied. This response indicated that vegetation restoration sites released soil moisture more rapidly than remnant sites but the rate of drying decreased with increasing rehabilitation age and increased with increasing tree stem density. The rapid drying of mine rehabilitated sites may threaten the survival of some remnant forest species, limit tree growth, and delay restoration of self-sustaining native ecosystem.

Successional dynamics of soil fungal diversity along a restoration chronosequence post‐coal mining

“…Despite the composite effect, there was no significant difference in the evenness of fungal communities (Simpson's and Shannon's diversity indices) between the mined and the nonmined sites. These findings support the proposition that topsoil management and soil profile reconstruction on excavated mine sites results in a novel substrate with potentially negative implications for the capacity to restore self‐sustaining ecosystems that are comparable with premining analogues (Doley & Audet ; Erskine & Fletcher ; Quideau et al ; Ngugi et al ).…”

“…Soil types within the study area include Arenic and Leptic Rudosols, Grey Chromosols, and Sodosols (Isbell ) and the texture of the topsoil was consistently sandy clay loam to sandy loam. Prior to commencement of mining in 1978, the native vegetation in the area included microphyll to notophyll vine forest and remnant eucalypt woodlands (Ngugi et al ).…”

“…Open‐cut coal mining affects a wide range of soil physical, chemical, and biological properties that influence the success of restoration on mined sites (Ngugi et al ; Ngugi et al ). Standard methods for the assessment and long‐term monitoring of restoration and rehabilitation management success on mine sites have almost exclusively relied on aboveground vegetation and soil physicochemical properties (Ludwig ; Ngugi & Neldner ).…”

Open‐cut mining impacts on soil abiotic and bacterial community properties as shown by restoration chronosequence

“…The hypothesis was largely supported by the initial increase in soil salinity (as indicated by high levels of EC, Cl, and Na), and the decrease in P. Soil salinity is a common problem for soils within the study region. It is likely that the initial increase in soil salinity recorded in the young rehabilitation sites of our study can be associated with topsoil management practices, and especially the mixing of topsoil with underlying horizons during stripping and stockpile storage (Ngugi et al ). In addition, TC, TN, and NO 3 ‐N concentrations on young rehabilitated sites were considerably lower than in the nonmined analogue sites (Fig.…”

Quantification of the inevitable: the influence of soil macrofauna on soil water movement in rehabilitated open-cut mined lands

“…However, soil properties are still markedly different compared to unmined areas, including higher bulk density (Potter et al, 1988), lower soil water content and lower soil water potential (Ngugi et al, 2015). As soil development is integral in various ecosystem functions (e.g.…”