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

Abstract

Recolonisation of soil by macrofauna (especially ants, termites and earthworms) in rehabilitated open-cut mine sites is inevitable and, in terms of habitat restoration and function, typically of great value. In these highly disturbed landscapes, soil invertebrates play a major role in soil development (macropore configuration, nutrient cycling, bioturbation, etc.) and can influence hydrological processes such as infiltration, seepage, runoff generation and soil erosion. Understanding and quantifying these ecosystem processes is important in rehabilitation design, establishment and subsequent management to ensure progress to the desired end goal, especially in waste cover systems designed to prevent water reaching and transporting underlying hazardous waste materials. However, the soil macrofauna is typically overlooked during hydrological modelling, possibly due to uncertainties on the extent of their influence, which can lead to failure of waste cover systems or rehabilitation activities. We propose that scientific experiments under controlled conditions and field trials on post-mining lands are required to quantify (i) macrofauna-soil structure interactions, (ii) functional dynamics of macrofauna taxa, and (iii) their effects on macrofauna and soil development over time. Such knowledge would provide crucial information for soil water models, which would increase confidence in mine waste cover design recommendations and eventually lead to higher likelihood of rehabilitation success of open-cut mining land.

SOIL, 2, 4148, 2016 www.soil-journal.net/2/41/2016/ doi:10.5194/soil-2-41-2016 Author(s) 2016. CC Attribution 3.0 License.

S. Arnold1 and E. R. Williams2,3

1Centre for Water in the Minerals Industry, Sustainable Minerals Institute, The University of Queensland,St. Lucia, 4072, QLD, Australia

2Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland,St. Lucia, 4072, QLD, Australia

3Agri-Science Queensland, Department of Agriculture and Fisheries, Kingaroy 4610, QLD, Australia Correspondence to: S. Arnold ([email protected])

Received: 23 July 2015 Published in SOIL Discuss.: 14 August 2015 Revised: 8 December 2015 Accepted: 3 January 2016 Published: 21 January 2016

Abstract. Recolonisation of soil by macrofauna (especially ants, termites and earthworms) in rehabilitated open-cut mine sites is inevitable and, in terms of habitat restoration and function, typically of great value. In these highly disturbed landscapes, soil invertebrates play a major role in soil development (macropore congu-ration, nutrient cycling, bioturbation, etc.) and can inuence hydrological processes such as inltration, seepage, runoff generation and soil erosion. Understanding and quantifying these ecosystem processes is important in rehabilitation design, establishment and subsequent management to ensure progress to the desired end goal, especially in waste cover systems designed to prevent water reaching and transporting underlying hazardous waste materials. However, the soil macrofauna is typically overlooked during hydrological modelling, possibly due to uncertainties on the extent of their inuence, which can lead to failure of waste cover systems or rehabilitation activities. We propose that scientic experiments under controlled conditions and eld trials on post-mining lands are required to quantify (i) macrofaunasoil structure interactions, (ii) functional dynamics of macrofauna taxa, and (iii) their effects on macrofauna and soil development over time. Such knowledge would provide crucial information for soil water models, which would increase condence in mine waste cover design recommendations and eventually lead to higher likelihood of rehabilitation success of open-cut mining land.

1 Introduction

In land restoration, practitioners are principally concerned with the residual physical properties of reconstructed landscape components and their assembly to either resemble the original congurations or develop novel designs that achieve acceptable functional outcomes (sensu lato ecological engineering by Mitsch and Jorgensen, 1989). Typically, the impact of macrofauna (e.g. ants, termites, earthworms) on soil structure is scarcely recognised by these ecological engineers and soil scientists, despite recognition by soil ecologists and entomologists that the soil macrofauna signicantly contributes to ecosystem services such as soil forma-

SOIL

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

tion, water availability for vegetation, or ood and erosion control (Lavelle et al., 2006; Cerd et al., 2009; Cerda andJurgensen 2011), and soil development and fertility (Oo et al., 2013; Bottinelli et al., 2015). This omission of macro-fauna from landscape design may in part be due to the current lack of quantitative knowledge of their role in the nature and timing of signicant alterations to soil physical properties (e.g. the formation of macropores and soil aggregates) at the landscape scale, and their temporal evolution (Bottinelli et al., 2015). Such information is crucial for soil restoration and ongoing ecosystem productivity in degraded lands (Blouin et al., 2013; Jouquet et al., 2014; Frouz and Kuraz, 2013), where biodiversity and materialenergy cycles are in-

Published by Copernicus Publications on behalf of the European Geosciences Union.

42 S. Arnold and E. R. Williams : Quantication of the inevitable

Figure 1. Relation between land use intensity/disturbance impact and soil biodiversity of natural ecosystems, conventional agriculture, and open-cut mining lands (modied after Bottinelli et al., 2015; Doley and Audet, 2013). While the transition from conventional agriculture to natural ecosystems mainly requires restoration of biotic soil components, the transition of open-cut mining land to novel (Perring et al., 2014), agricultural or native ecosystems (if possible) requires rehabilitation of both biotic and abiotic soil components. Feedbacks between different macrofauna taxa, as well as between macrofauna and soil structure, might be critical drivers of the temporal transition of open-cut mining land to novel or agricultural ecosystems.

terrupted and mainly driven by disturbances and land management history (e.g. for agriculture, the history of tillage and pesticide application; Bottinelli et al., 2015; Doley and Audet, 2013). The perturbation of normal soil-forming processes is exacerbated in open-cut mining lands, where topo-graphical and geological ecosystem elements are disrupted at the landscape-scale (Fig. 1). In this regard, and throughout this article, we refer to ecosystem rehabilitation as the process of attempting to reinstate ecosystem functions and services (Seastedt et al., 2008; Audet et al., 2013; Doley and Audet, 2013; Aronson et al., 1993) as opposed to ecosystem restoration, which aims to reinstate the structure, functioning, and dynamics of historical (pristine) ecosystems (Aronson et al., 1993; Hobbs et al., 2006).

Numerical models of environmental processes are a critical component of any planning scheme for the management of human-impacted ecosystems (Arnold et al., 2014, 2012b) or for the design and construction of facilities aiming to protect ecosystems and local communities from hazardous materials such as mine waste (Arnold et al., 2015; Gwenzi et al., 2013; OKane and Wels, 2003). For example, modelling of soil water dynamics is essential at the early design stage

of mine waste rock storage facilities. However, if model assumptions about material properties are based on their initial state rather than after their temporal evolution, such facilities may fail to attain their long-term design objectives (Taylor et al., 2003). On the other hand, a sensible balance between the complexity and uncertainty of numerical models is required to use them as exploratory or management tools (Arnold et al., 2012a). We acknowledge the effects of plant roots on soil hydraulic properties and preferential ow, as well as the progress in numerical modelling of root system architecture and root water uptake in recent years (Bargus Tobella et al., 2014; Carminati et al., 2011; Javaux et al., 2008; Schrder et al., 2008). However, we believe that macrofaunasoil structure interactions rather than rootsoil interactions play a critical role in the soil water distribution at the early stage of soil reconstruction, particularly if plant available water is the predominant abiotic stressor (Arnold et al., 2013).

While the recent review article of Bottinelli et al. (2015) advocates collaboration between soil ecologists and physicists in order to increase understanding of soilplant water relations, their review is limited to natural and agricultural ecosystems subjected to low or moderate levels of disturbance. As an extension of their work, we propose that interactions between soil fauna and soil structure dynamics are even more critical for severely disturbed ecosystems such as in open-cut mining lands. Therefore, in this short communication article, we (i) consider the impact of macrofauna on the rehabilitation of open-cut mine lands, specically the effects of ants/termites and mine waste facilities, and (ii) indicate how further research on feedbacks between macrofauna and soil structure may help to reduce uncertainties in the prediction of soil water movement in rehabilitated mine environments, especially toxic waste covers.

2 Socio-ecological impacts of open-cut mining

Both biotic (e.g. fauna, vegetation, microbes) and abiotic (e.g. water, soil material, meteorological variables) ecosystem components are fundamental drivers of material and energy cycles, and thereby govern ecosystem structure and function. During open-cut mining, many ecosystem components, including these material and energy cycles, undergo signicant physical and chemical disturbances and may be irreversibly disrupted to at least some extent (Fig. 1).

After mining activities are complete, the topography and physical soil properties are reconstructed in an attempt to establish the foundation of a self-sustaining ecosystem. 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. carbon, nutrient and water cycles, and vegetation establishment; Pallavini et al., 2015;Smith et al., 2015), these alterations have long-lasting effects

SOIL, 2, 4148, 2016 www.soil-journal.net/2/41/2016/

S. Arnold and E. R. Williams : Quantication of the inevitable 43

on successful ecosystem rehabilitation. At this initial stage and at the landscape scale, soil biodiversity is reduced and/or disrupted to an extent that could almost be referred to as sterile (Rives et al., 1980; Miller et al., 2011). In addition to this initial sterile conditions, open-cut mining often results in the generation of hazardous wastes in the form of either coarse-grained waste rock that is separated before mineral processing or ne-grained processing wastes (tailings) (Lottermoser, 2010). These waste materials are then deposited at the mine site and require rehabilitation. One form of rehabilitation that is increasingly accepted for closure of mining waste facilities is the use of vegetated mine waste cover systems (Arnold et al., 2014b; Gwenzi et al., 2013). These evapotranspiration cover systems are also referred to as monolithic alternative covers (Albright et al., 2004), phytocaps (Venkatraman and Ashwath, 2010), or store and release covers (Fourie and Tibbett, 2007; Wilson et al., 2003). Their design aims to minimise drainage into underlying hazardous wastes. Contrary to conventional covers made of compacted clay, geosynthetic clay liners, or polyvinyl chloride (Othman et al., 1994; Benson, 2000; Levin and Hammod, 1990), phytocaps serve two purposes: (1) to maximise rainfall interception by vegetation and, if required, a compacted soil layer, and (2) to remove soil water through plant transpiration and evaporation from bare soil (Salt et al., 2011). Through successive rainfall events, the loss of stored soil water through evapotranspiration decreases net percolation through the soil (Hauser et al., 2001; Rock, 2010) and reduces surface runoff and erosion.

Regardless of the rehabilitation design, the soil macro-fauna is particularly important in this initial stage of rehabilitation (Frouz and Kuraz, 2013), due to their rapid recolonisation, particularly by generalist taxa that have long-distance dispersal strategies. For example, the typical dispersal strategy for many ant species is by nuptial ights (Peeters and Molet, 2009), where copulation occurs in the air after specic climatic cues and queens y from 100 m to 10 km from their originating nest to nd suitable habitat before dropping their wings and establishing a new nest (Hlldobler and Wilson, 1990). Initially, a limited number of individuals are produced from newly laid eggs and colony survival depends on food resources, which for ants (omnivores) include seeds (e.g. from topsoil spreading or revegetation activities), other fauna (invertebrates or vertebrates and their products) or other organic matter (Blthgen and Feldhaar, 2009). As these newly established colonies are small, not much food is required for survival until further resources become available. Thus, colony foundation at rehabilitated mine sites can occur within weeks (Williams, personal observation) and prior to vegetation establishment from seeds.

However, deterioration in cover performance and even failure can be caused by increased soil permeability resulting from (i) the formation of shrinkage cracks and (ii) macro-pores associated with root channels or (iii) ant and termite galleries (Taylor et al., 2003) or (iv) burrowing macrofauna

such as earthworms (Edwards et al., 1990; Frouz and Kuraz, 2013). While the importance of the rst two causes has been accepted by soil scientists (e.g. Bengough et al., 2011, 2006;Czarnes et al., 2000; Hinsinger et al., 2009; Ranatunga et al., 2008), the contribution of soil macrofauna to waste cover failure has been largely overlooked (Taylor et al., 2003). For example, in their report about the deterioration in performance of a waste rock cover facility in tropical Australia, Taylor et al. (2003) concluded that, amongst (i) and (ii), the formation of termite galleries played a critical role.

3 The price to pay for negligence

At post-mining sites, the type of mineral processing initially determines the soil properties, as well as the depth of overburden and topsoil materials removed from mine pits (Gould, 2012; Erskine and Fletcher, 2013). Likewise, the method and equipment used to reconstruct topsoil affects soil hydraulic properties (Fourie and Tibbett, 2007). However, within weeks after topsoil establishment, the rst colonisers such as soil-nesting ants (e.g. Iridomyrmex species in Australia) build underground galleries, thereby initiating changes in soil properties (Lee and Foster, 1991). This macrofauna alters the local soil structure and prole characteristics (Jones et al., 1994; De Bruyn and Conacher, 1994); inuence soil aggregate stability (Cammeraat and Risch, 2008; Lavelle et al., 2006), water inltration and mechanical strength (Eldridge, 1994; Frouz and Kuraz, 2013); and increase the eld capacity through the formation of holo-organic and organo-mineral aggregates (Frouz and Kuraz, 2013). That is, soil macrofauna introduces or increases heterogeneity of soil properties. Mound-building ants, for example, excavate soil material and thereby increase the number of macropores, which leads to a lower bulk density (Dostl et al., 2005; Cammeraat and Risch, 2008; Jones et al., 1994). These changes in soil features lead to increasing inltration rates under wet conditions (Cammeraat et al., 2002). Some ant species bring soil material from deep soil horizons to the surface (Folgarait, 1998) or damage geotextiles, which can have negative impacts on the functionality of compacted barrier layers through the creation of preferential ow paths (Manassero et al., 2013; OKane Consultants Inc., 2003). Later during ecosystem rehabilitation, burrowing macrofauna such as earthworms affect the soil structure and prole characteristics in a similar manner by modifying the pore and aggregate size distribution, the soil bulk density, and soil organic matter, eventually affecting the soil water-holding capacity and inltration rates (Blouin et al., 2013; Jouquet et al., 2014;Frouz and Kuraz, 2013). The qualitative and quantitative impact of macrofauna on hydrological variables (e.g. inltration) depends on the taxa and species involved, the soil type, the successional stage of the ecosystem, and the initial soil water conditions (Cammeraat and Risch, 2008; Cammeraat et al., 2002).

www.soil-journal.net/2/41/2016/ SOIL, 2, 4148, 2016

44 S. Arnold and E. R. Williams : Quantication of the inevitable

Table 1. Proposed approaches to collect empirical data in relation to antsoil interactions.

Glasshouse/laboratory Post-mining land

Methodology Controlled/manipulative experiments Field trials with control site Investigative scale Small Medium

Knowledge gap Quantity and conditions of colonisation ratesEffects on soil hydraulics

Inter-specic interactions Succession of colonisation Long-term water availability for plants

Arnold et al. (2013)

Additional uncertainties with respect to soil properties arise during ecosystem development. Specically, unlike static engineered structures such as bridges, water levees, or dam walls, the reconstruction of soil for the purpose of ecosystem rehabilitation or waste cover systems must allow for structural and functional changes. The temporal evolution of soils on post-mining lands is affected by various biotic taxa during recolonisation and compositional changes over time, including vegetation and soil macrofauna such as ants and termites (Taylor et al., 2003).

Numerical models of the one-dimensional water movement through a vertical unsaturated soil column are typically based on the Richards equation (Richards, 1931), which requires knowledge of the effective soil hydraulic properties. A range of hydraulic models are suitable to describe unimodal soil water retention curves (Brooks and Corey, 1964; Kosugi, 1996; van Genuchten, 1980; Vogel et al., 1991); however, in open-cut mining lands where the formation of secondary pore systems is common (e.g. in waste rock materials), multimodal soil water retention curves are an appropriate means to describe soil moisture and hydraulic conductivity characteristics in relation to soil water pressure conditions (Durner, 1994). Hence, at the early stage of soil reconstruction, model uncertainty is relatively low (Fig. 2) because the models include well-quantied soil parameters, and in reality, macro-fauna contributes minimally to the hydraulic soil properties. However, even at a low level of complexity, these models tend to lose their predictive power over time due to pedological processes that may be ignored in the initial soil water model but which later lead to signicant material changes such as increasing saturated hydraulic conductivities (Fourie and Tibbett, 2007), particularly in layers of low permeability (Taylor et al., 2003). Even more critical is the lack of quantitative knowledge about the role of macrofauna processes for soil hydraulic properties at subsequent stages of soil reconstruction. Any empirical data, be it in the form of manipulative experiments under controlled conditions or in situ eld trials, would make a signicant contribution to integrate the temporal impact of macrofauna on soil development into numerical soil water models.

Although this integration increases model complexity and thereby model uncertainty, it can result in more predictive power and condence if these interactions are well quantied

Figure 2. Conceptual scheme of predictive power of soil water models at different levels of complexity. While uncertainty in hydrological variables such as deep drainage or plant available water is lowest for traditional models that only consider abiotic soil components, these models may also have low predictive power due to omission of critical macrofaunasoil structure interactions. Integration of biotic components and feedbacks between macrofauna taxa, as well as between macrofauna and soil development, increases model complexity and thereby uncertainty. However, quantication of macrofaunasoil interactions by controlled scientic experiments reduces these uncertainties, thereby increasing the predictive power to a level acceptable to assess the risk of potential failure of post-mining land rehabilitation.

(Arnold et al., 2012a). In this regard, more complex models provide the opportunity to include the temporal changes in soil material properties due to pedological and biological processes. For example, while some ant species increase inltration rates (De Bruyn and Conacher, 1990; Eldridge, 1993; Cerd and Jurgensen, 2008), other species may have a contrary impact on inltration (Sarr et al., 2001; Navarro and Jaffe, 1985). Inltration rates may vary between different locations or stages of ecosystem development, thereby affecting several aspects of the soil water balance and the availability of plant material for faunal consumption, and in turn the colonisation of the site by different ant species (Williams, 2011). Likewise, while feedbacks between the temporal evo-

SOIL, 2, 4148, 2016 www.soil-journal.net/2/41/2016/

S. Arnold and E. R. Williams : Quantication of the inevitable 45

lution of macrofauna and soil structure increase model complexity and uncertainty, they could play a critical role in predicting the long-term performance and hence the design of waste cover facilities (Taylor et al., 2003) or post-mining lands (Frouz et al., 2006), which ultimately leads to a higher probability of rehabilitation success and the construction of self-sustaining post-mining landscapes.

4 Conclusions and further directions

Soil colonisation by macrofauna such as ants and termites on post-mining rehabilitation sites is inevitable. Due to the signicant effects of these macrofauna on soil structure, we conclude that macrofauna needs to be considered by ecological engineers when designing and reconstructing lands after open-cut mining. In this regard, rehabilitation plans should include numerical soil water models that consider the temporal evolution of (i) macrofaunasoil structure interactions, and (ii) feedbacks between macrofauna taxa, as well as between macrofauna and soil development, over time.

We suggest two alternative approaches to collect empirical data (Table 1) that can be used to initially quantify these interactions and eventually to reduce uncertainty in modelled hydrological variables such as deep drainage, inltration, or plant available water (Lonard et al., 2004). For example, manipulative experiments under controlled conditions are effective means to assess the impact of early colonisers on the soil water dynamics. A soil chamber or column (Joschko et al., 1989, 1992) can be used as a formicarium (Wang et al., 1995), where an ant nest is transplanted (including queen and workers) and food, water and nesting resources provided.Predened water regimes could then be administered to simulate rainfall events, while the temporal dynamics of soil water potential and content are monitored across the soil prole.Similarly, these small-scale experiments are suitable for assessing the colonisation rates and environmental conditions (e.g. pH, temperature, humidity, soil water content) required to colonise soils by ants. At a larger investigative scale (Table 1), eld trials in combination with untreated control or reference sites are effective means to assess the impact of macrofauna on soil structure and inter-specic fauna interactions (feedbacks) in relation to soil biodiversity and soil development (Cammeraat et al., 2002). In this regard, open-cut mining lands may provide ideal environments, because the physical properties of reconstructed soils are fundamentally different (and less complex) from those of degraded but physically intact soils.

Acknowledgements. The authors would like to thank David Doley for critical discussions and encouragement to publish this paper, as well as the three anonymous reviewers for constructive comments.

Edited by: E. Nadal Romero

References

Albright, W. H., Benson, C. H., Gee, G. W., Roesler, A. C., Abi-chou, T., Apiwantragoon, P., Lyles, B. F., and Rock, S. A.: Field water balance of landll nal covers, J. Environ. Qual., 33, 2317 2332, 2004.

Arnold, S., Lechner, A., and Baumgartl, T.: Merging modelling and experimental approaches to advance ecohydrological system understanding., in: Revisiting experimental catchment studies in forest hydrology, edited by: Webb, A. A., Bonell, M., Bren, L., Lane, P. N. J., McGuire, D., Neary, D. G., Nettles, J., Scott, D.F., Stednick, J. D., and Wang, Y., IAHS Publications, 117124, 2012a.

Arnold, S., Thornton, C., and Baumgartl, T.: Ecohydrological feedback as a land restoration tool in the semi-arid Brigalow Belt, QLD, Australia, Agriculture, Ecosyst. Environ., 163, 6171, doi:http://dx.doi.org/10.1016/j.agee.2012.05.020

Web End =10.1016/j.agee.2012.05.020 http://dx.doi.org/10.1016/j.agee.2012.05.020

Web End = , 2012b.

Arnold, S., Audet, P., Doley, D., and Baumgartl, T.: Hydropedology and Ecohydrology of the Brigalow Belt, Australia: Opportunities for Ecosystem Rehabilitation in Semiarid Environments, gsvad-zone, 12, doi:http://dx.doi.org/10.2136/vzj2013.03.0052

Web End =10.2136/vzj2013.03.0052 http://dx.doi.org/10.2136/vzj2013.03.0052

Web End = , 2013.

Arnold, S., Attinger, S., Frank, K., Baxter, P., Possingham, H., and Hildebrandt, A.: Ecosystem management along ephemeral rivers: Trading off socio-economic water supply and vegetation conservation under ood regime uncertainty, River Res. Appl., doi:http://dx.doi.org/10.1002/rra.2853

Web End =10.1002/rra.2853 http://dx.doi.org/10.1002/rra.2853

Web End = , 2014.

Arnold, S., Schneider, A., Doley, D., and Baumgartl, T.: The limited impact of vegetation on the water balance of mine waste cover systems in semi-arid Australia, Ecohydrology, 8, 355367, doi:http://dx.doi.org/10.1002/eco.1485

Web End =10.1002/eco.1485 http://dx.doi.org/10.1002/eco.1485

Web End = , 2015.

Aronson, J., Floret, C., Le Floch, E., Ovalle, C., and Pontanier, R.:

Restoration and Rehabilitation of Degraded Ecosystems in Arid and Semi-Arid Lands. I. A View from the South, Restor. Ecol., 1, 817, doi:http://dx.doi.org/10.1111/j.1526-100X.1993.tb00004.x

Web End =10.1111/j.1526-100X.1993.tb00004.x http://dx.doi.org/10.1111/j.1526-100X.1993.tb00004.x

Web End = , 1993.Audet, P., Gravina, A., Glenn, V., McKenna, P., Vickers, H., Gillespie, M., and Mulligan, D.: Structure of vegetation development on rehabilitated North Stradbroke Island: above/belowground feedback may facilitate alternative ecological outcomes, Ecol.Process, 2, p. 20, 2013.

Bargus Tobella, A., Reese, H., Almaw, A., Bayala, J., Malmer,A., Laudon, H., and Ilstedt, U.: The effect of trees on preferential ow and soil inltrability in an agroforestry parkland in semiarid Burkina Faso, Water Resour. Res., 50, 33423354, doi:http://dx.doi.org/10.1002/2013wr015197

Web End =10.1002/2013wr015197 http://dx.doi.org/10.1002/2013wr015197

Web End = , 2014.

Bengough, A. G., Bransby, M. F., Hans, J., McKenna, S. J., Roberts,T. J., and Valentine, T. A.: Root responses to soil physical conditions; growth dynamics from eld to cell, J. Exp. Bot., 57, 437 447, doi:http://dx.doi.org/10.1093/jxb/erj003

Web End =10.1093/jxb/erj003 http://dx.doi.org/10.1093/jxb/erj003

Web End = , 2006.

Bengough, A. G., McKenzie, B. M., Hallett, P. D., and Valentine,T. A.: Root elongation, water stress, and mechanical impedance: a review of limiting stresses and benecial root tip traits, J. Exp.Bot., 62, 5968, doi:http://dx.doi.org/10.1093/jxb/erq350

Web End =10.1093/jxb/erq350 http://dx.doi.org/10.1093/jxb/erq350

Web End = , 2011.

Benson, C. H.: Liners and covers for waste containment, 4th KansaiInternational Geotechnical Forum, Japan, 140, 2000.

Blouin, M., Hodson, M. E., Delgado, E. A., Baker, G., Brussaard,L., Butt, K. R., Dai, J., Dendooven, L., Peres, G., Tondoh, J. E., Cluzeau, D., and Brun, J. J.: A review of earthworm impact on soil function and ecosystem services, Eur. J. Soil Sci., 64, 161 182, 2013.

www.soil-journal.net/2/41/2016/ SOIL, 2, 4148, 2016

46 S. Arnold and E. R. Williams : Quantication of the inevitable

Blthgen, N. and Feldhaar, H.: Food and shelter: How resources inuence ant ecology, in: Ant ecology, edited by: Lach, L., Parr,C., and Abbott, K., Oxford University Press, Oxford, 2009.

Bottinelli, N., Jouquet, P., Capowiez, Y., Podwojewski, P., Grimaldi,M., and Peng, X.: Why is the inuence of soil macrofauna on soil structure only considered by soil ecologists?, Soil Till. Res., 146, 118124, doi:http://dx.doi.org/10.1016/j.still.2014.01.007

Web End =10.1016/j.still.2014.01.007 http://dx.doi.org/10.1016/j.still.2014.01.007

Web End = , 2015.

Brooks, R. H. and Corey, A. T.: Hydraulic properties of porous media, Hydrol. Paper No. 3, Colorado State University, Fort Collins, CO, 1964.

Cammeraat, E. L. H. and Risch, A. C.: The impact of ants on mineral soil properties and processes at different spatial scales, J. Appl. Entomol., 132, 285294, doi:http://dx.doi.org/10.1111/j.1439-0418.2008.01281.x

Web End =10.1111/j.1439- http://dx.doi.org/10.1111/j.1439-0418.2008.01281.x

Web End =0418.2008.01281.x , 2008.

Cammeraat, E. L. H., Willott, S. J., Compton, S. G., and Incoll, L.D.: The effects of ants nests on the physical, chemical and hydrological properties of a rangeland soil in semi-arid Spain, Geoderma, 105, 120, doi:http://dx.doi.org/10.1016/S0016-7061(01)00085-4

Web End =10.1016/S0016-7061(01)00085-4 http://dx.doi.org/10.1016/S0016-7061(01)00085-4

Web End = , 2002.Carminati, A., Schneider, C. L., Moradi, A. B., Zarebanadkouki,M., Vetterlein, D., Vogel, H.-J., Hildebrandt, A., Weller, U., Schler, L., and Oswald, S. E.: How the Rhizosphere May Favor Water Availability to Roots, gsvadzone, 10, 988998, doi:http://dx.doi.org/10.2136/vzj2010.0113

Web End =10.2136/vzj2010.0113 http://dx.doi.org/10.2136/vzj2010.0113

Web End = , 2011.

Cerd, A. and Jurgensen, M. F.: The inuence of ants on soil and water losses from an orange orchard in eastern Spain, J. Appl. Entomol., 132, 306314, doi:http://dx.doi.org/10.1111/j.1439-0418.2008.01267.x

Web End =10.1111/j.1439- http://dx.doi.org/10.1111/j.1439-0418.2008.01267.x

Web End =0418.2008.01267.x , 2008.

Cerd, A., Jurgensen, M. F., and Bodi, M. B.: Effects of ants on water and soil losses from organically-managed citrus orchards in eastern Spain, Biologia, 3, 527531, doi:http://dx.doi.org/10.2478/s11756-009-0114-7

Web End =10.2478/s11756-009- http://dx.doi.org/10.2478/s11756-009-0114-7

Web End =0114-7 , 2009.

Czarnes, S., Hallett, P. D., Bengough, A. G., and Young, I. M.: Root-and microbial-derived mucilages affect soil structure and water transport, Eur. J. Soil Sci., 51, 435443, doi:http://dx.doi.org/10.1046/j.1365-2389.2000.00327.x

Web End =10.1046/j.1365- http://dx.doi.org/10.1046/j.1365-2389.2000.00327.x

Web End =2389.2000.00327.x , 2000.

De Bruyn, L. and Conacher, A.: The role of termites and ants in soil modication a review, Soil Res., 28, 5593, doi:http://dx.doi.org/10.1071/SR9900055

Web End =10.1071/SR9900055 http://dx.doi.org/10.1071/SR9900055

Web End = , 1990.

De Bruyn, L. and Conacher, A.: The bioturbation activity of ants in agricultural and naturally vegetated habitats in semiarid environments, Soil Res., 32, 555570, doi:http://dx.doi.org/10.1071/SR9940555

Web End =10.1071/SR9940555 http://dx.doi.org/10.1071/SR9940555

Web End = , 1994.Doley, D. and Audet, P.: Adopting novel ecosystems as suitable rehabilitation alternatives for former mine sites, Ecol. Process., 2, doi:http://dx.doi.org/10.1186/2192-1709-2-33

Web End =10.1186/2192-1709-2-33 http://dx.doi.org/10.1186/2192-1709-2-33

Web End = , 2013.

Dostl, P., Beznov, M., Kozlkov, V., Herben, T., and Kov, P.: Ant-induced soil modication and its effect on plant below-ground biomass, Pedobiologia, 49, 127137, doi:http://dx.doi.org/10.1016/j.pedobi.2004.09.004

Web End =10.1016/j.pedobi.2004.09.004 http://dx.doi.org/10.1016/j.pedobi.2004.09.004

Web End = , 2005.

Durner, W.: Hydraulic conductivity estimation for soils with heterogeneous pore structure, Water Resour. Res., 30, 211223, doi:http://dx.doi.org/10.1029/93wr02676

Web End =10.1029/93wr02676 http://dx.doi.org/10.1029/93wr02676

Web End = , 1994.

Edwards, W. M., Shipitalo, M. J., Owens, L. B., and Norton, L. D.: Effect of Lumbricus terrestris L. burrows on hydrology of continuous no-till corn elds, Geoderma, 46, 7384, doi:http://dx.doi.org/10.1016/0016-7061(90)90008-W

Web End =10.1016/0016- http://dx.doi.org/10.1016/0016-7061(90)90008-W

Web End =7061(90)90008-W , 1990.

Eldridge, D.: Effect of ants on sandy soils in semi-arid eastern Australia Local distribution of nest entrances and their effect on inltration of water, Soil Res., 31, 509518, doi:http://dx.doi.org/10.1071/SR9930509

Web End =10.1071/SR9930509 http://dx.doi.org/10.1071/SR9930509

Web End = , 1993.

Eldridge, D. J.: Nests of ants and termites inuence inltration in a semiarid woodland, Pedobiologia, 38, 481492, 1994.

Erskine, P. and Fletcher, A.: Novel ecosystems created by coal mines in central Queenslands Bowen Basin, Ecol. Process., 2, 965981, 2013.

Folgarait, P.: Ant biodiversity and its relationship to ecosystem functioning: a review, Biodivers. Conserv., 7, 12211244, doi:http://dx.doi.org/10.1023/a:1008891901953

Web End =10.1023/a:1008891901953 http://dx.doi.org/10.1023/a:1008891901953

Web End = , 1998.

Fourie, A. and Tibbett, M.: Post-mining landforms engineering a biological system, Mine Closure Santiago, Chile, 2007.

Frouz, J. and Kuraz, V.: Soil fauna and soil physical properties, in:

Soil Biota and Ecosystem Development in Post Mining Sites, edited by: Frouz, J., CRC Press, Boca Raton, 265278, 2013. Frouz, J., Elhottov, D., Kur, V., and ourkov, M.: Effects of soil macrofauna on other soil biota and soil formation in reclaimed and unreclaimed post mining sites: Results of a eld microcosm experiment, Appl. Soil Ecol., 33, 308320, doi:http://dx.doi.org/10.1016/j.apsoil.2005.11.001

Web End =10.1016/j.apsoil.2005.11.001 http://dx.doi.org/10.1016/j.apsoil.2005.11.001

Web End = , 2006.

Gould, S. F.: Comparison of Post-mining Rehabilitation with Reference Ecosystems in Monsoonal Eucalypt Woodlands, Northern Australia, Restoration Ecol., 20, 250259, doi:http://dx.doi.org/10.1111/j.1526-100X.2010.00757.x

Web End =10.1111/j.1526- http://dx.doi.org/10.1111/j.1526-100X.2010.00757.x

Web End =100X.2010.00757.x , 2012.

Gwenzi, W., Hinz, C., Bleby, T. M., and Veneklaas, E. J.: Transpiration and water relations of evergreen shrub species on an articial landform for mine waste storage versus an adjacent natural site in semi-arid Western Australia, Ecohydrology, 7, 965981, doi:http://dx.doi.org/10.1002/eco.1422

Web End =10.1002/eco.1422 http://dx.doi.org/10.1002/eco.1422

Web End = , 2013.

Hauser, V., Weand, B., and Gill, M.: Natural Covers for Land-lls and Buried Waste, J. Environ. Eng., 127, 768775, doi:http://dx.doi.org/10.1061/(asce)0733-9372(2001)127:9(768)

Web End =10.1061/(asce)0733-9372(2001)127:9(768) http://dx.doi.org/10.1061/(asce)0733-9372(2001)127:9(768)

Web End = , 2001. Hinsinger, P., Bengough, A. G., Vetterlein, D., and Young, I.:

Rhizosphere: biophysics, biogeochemistry and ecological relevance, Plant Soil, 321, 117152, doi:http://dx.doi.org/10.1007/s11104-008-9885-9

Web End =10.1007/s11104-008-9885- http://dx.doi.org/10.1007/s11104-008-9885-9

Web End =9 , 2009.

Hobbs, R. J., Arico, S., Aronson, J., Baron, J. S., Bridgewater, P., Cramer, V. A., Epstein, P. R., Ewel, J. J., Klink, C. A., Lugo,A. E., Norton, D., Ojima, D., Richardson, D. M., Sanderson,E. W., Valladares, F., Vil, M., Zamora, R., and Zobel, M.: Novel ecosystems: theoretical and management aspects of the new ecological world order, Global Ecol. Biogeogr., 15, 17, doi:http://dx.doi.org/10.1111/j.1466-822X.2006.00212.x

Web End =10.1111/j.1466-822X.2006.00212.x http://dx.doi.org/10.1111/j.1466-822X.2006.00212.x

Web End = , 2006.

Hlldobler, B. and Wilson, E.: The Ants, Harvard University Press,Cambridge, 1990.

Javaux, M., Schrder, T., Vanderborght, J., and Vereecken, H.: Use of a Three-Dimensional Detailed Modeling Approach for Predicting Root Water Uptake, Vadose Zone J., 7, 10791088, doi:http://dx.doi.org/10.2136/vzj2007.0115

Web End =10.2136/vzj2007.0115 http://dx.doi.org/10.2136/vzj2007.0115

Web End = , 2008.

Jones, C. G., Lawton, J. H., and Shachak, M.: Organisms as ecosystem engineers, Oikos, 69, 373386, 1994.

Joschko, M., Diestel, H., and Larink, O.: Assessment of earthworm burrowing efciency in compacted soil with a combination of morphological and soil physical measurements, Biol. Fert. Soils, 8, 191196, doi:http://dx.doi.org/10.1007/BF00266478

Web End =10.1007/BF00266478 http://dx.doi.org/10.1007/BF00266478

Web End = , 1989.

Joschko, M., Schtig, W., and Larink, O.: Functional relationship between earthworm burrows and soil water movement in column experiments, Soil Biol. Biochem., 24, 15451547, doi:http://dx.doi.org/10.1016/0038-0717(92)90148-Q

Web End =10.1016/0038-0717(92)90148-Q http://dx.doi.org/10.1016/0038-0717(92)90148-Q

Web End = , 1992.

SOIL, 2, 4148, 2016 www.soil-journal.net/2/41/2016/

S. Arnold and E. R. Williams : Quantication of the inevitable 47

Jouquet, P., Blanchart, E., and Capowiez, Y.: Utilization of earthworms and termites for the restoration of ecosystem functioning, Appl. Soil Ecol., 73, 3440, 2014.

Kosugi, K. I.: Lognormal Distribution Model for Unsaturated Soil Hydraulic Properties, Water Resour. Res., 32, 26972703, doi:http://dx.doi.org/10.1029/96wr01776

Web End =10.1029/96wr01776 http://dx.doi.org/10.1029/96wr01776

Web End = , 1996.

Lavelle, P., Decans, T., Aubert, M., Barot, S., Blouin, M., Bureau, F., Margerie, P., Mora, P., and Rossi, J. P.: Soil invertebrates and ecosystem services, Eur. J. Soil Biol., 42, S3S15, doi:http://dx.doi.org/10.1016/j.ejsobi.2006.10.002

Web End =10.1016/j.ejsobi.2006.10.002 http://dx.doi.org/10.1016/j.ejsobi.2006.10.002

Web End = , 2006.

Lee, K. and Foster, R.: Soil fauna and soil structure, Soil Res., 29,745775, doi:http://dx.doi.org/10.1071/SR9910745

Web End =10.1071/SR9910745 http://dx.doi.org/10.1071/SR9910745

Web End = , 1991.

Lonard, J., Perrier, E., and Rajot, J. L.: Biological macropores effect on runoff and inltration: a combined experimental and modelling approach, Agriculture, Ecosyst. Environ., 104, 277 285, doi:http://dx.doi.org/10.1016/j.agee.2003.11.015

Web End =10.1016/j.agee.2003.11.015 http://dx.doi.org/10.1016/j.agee.2003.11.015

Web End = , 2004.

Levin, S. and Hammod, M.: Application of PVC in a Top Cap application in: Geosynthetic Testing for Waste Containment Applications, edited by: Robert, M., American Society for Testing and Materials, Philadelphia, PA, 1990.

Lottermoser, B.: Mine Wastes: Characterization, Treatment and Environmental Impacts, 3rd Edn., Springer, Berlin Heidelberg, 400 pp., 2010.

Manassero, M., Dominijanni, A., Foti, S., and Musso, G.: Coupled phenomena in environmental geotechnics, CRC Press, 2013.Miller, C., Franklin, J., and Buckley, D.: Effects of soil amendment treatments on American chestnut performance and physiology on an East Tennessee surface mine, National Meeting of the American Society of Mining and Reclamation, Bismarck, ND, 2011.Mitsch, W. J. and Jorgensen, S. E.: Introduction to Ecological Engineering, in: Ecological Engineering: An Introduction to Ecotechnology, edited by: Mitsch, W. J. and Jorgensen, S. E., John Wiley & Sons, New York, 312, 1989.

Navarro, J. G. and Jaffe, K.: On the Adaptive Value of Nest Features in the Grass-Cutting Ant Acromyrmex landolti, Biotropica, 17, 347348, doi:http://dx.doi.org/10.2307/2388602

Web End =10.2307/2388602 http://dx.doi.org/10.2307/2388602

Web End = , 1985.

Ngugi, M. R., Neldner, V. J., Doley, D., Kusy, B., Moore, D., and Richter, C.: Soil moisture dynamics and restoration of self-sustaining native vegetation ecosystem on an open-cut coal mine, Restor. Ecol., 23, 615624, doi:http://dx.doi.org/10.1111/rec.12221

Web End =10.1111/rec.12221 http://dx.doi.org/10.1111/rec.12221

Web End = , 2015.OKane, M. and Wels, C.: Mine waste cover system design linking predicted performance to groundwater and surface water impacts, 6th International Conference on Acid Rock Drainage (ICARD), Cairns, 2003.

OKane Consultants Inc.: Evaluation of the long-term performance of dry cover systems Phase 2 Final Report, 2003.

Oo, A. N., Iwai, C. B., and Saenjan, P.: Soil properties and maize growth in saline and nonsaline soils using cassava-industrial waste compost and vermicompost with or without earthworms, Land Degrad. Dev., 26, 300310, doi:http://dx.doi.org/10.1002/ldr.2208

Web End =10.1002/ldr.2208 http://dx.doi.org/10.1002/ldr.2208

Web End = , 2013.Othman, M., Benson, C., Chamberlain, E., and Zimmie, T.: Laboratory testing to evaluate changes in hydraulic conductivity caused by freeze thaw: state of the art, in: Hydraulic Conductivity and Waste Containment Transport in Soils, edited by: Trautwein, S. and Daniel, D., 227254, 1994.

Pallavicini, Y., Alday, J. G., and Martnez-Ruiz, C.: Factors affecting herbaceous richness and biomass accumulation patterns of reclaimed coal mines, Land Degrad. Dev., 26, 211217, doi:http://dx.doi.org/10.1002/ldr.2198

Web End =10.1002/ldr.2198 http://dx.doi.org/10.1002/ldr.2198

Web End = , 2015.

Peeters, C. and Molet, M.: Colonial reproduction and life histories, in: Ant ecology, edited by: Lach, L., Parr, C., and Abbott, K., Oxford University Press, Oxford, 2009.

Perring, M., Audet, P., and Lamb, D.: Novel ecosystems in ecological restoration and rehabilitation: Innovative planning or lowering the bar?, Ecol. Process., 3, doi:http://dx.doi.org/10.1186/2192-1709-3-8

Web End =10.1186/2192-1709-3-8 http://dx.doi.org/10.1186/2192-1709-3-8

Web End = , 2014.

Potter, K. N., Carter, F. S., and Doll, E. C.: Physical properties of constructed and undisturbed soils, Soil Sci. Soc. Am. J., 52, 14351438, 1988.

Ranatunga, K., Nation, E. R., and Barratt, D. G.: Review of soil water models and their applications in Australia, Environ. Model.Softw., 23, 11821206, doi:http://dx.doi.org/10.1016/j.envsoft.2008.02.003

Web End =10.1016/j.envsoft.2008.02.003 http://dx.doi.org/10.1016/j.envsoft.2008.02.003

Web End = , 2008.

Richards, L. A.: Capillary conduction of liquids through porous mediums, J. Appl. Phys., 1, 318333, doi:http://dx.doi.org/10.1063/1.1745010

Web End =10.1063/1.1745010 http://dx.doi.org/10.1063/1.1745010

Web End = , 1931.

Rives, C., Bajwa, M., Liberta, A., and Miller, R.: Effect of topsoil storage during surface mining on the viability of VA Mycorrhiza, Soil Sci., 129, 253257, 1980.

Rock, S.: Evapotranspiration covers for landlls, in: Application of

Phytotechnologies for Cleanup of Industrial, Agricultural, and Wastewater Contamination, edited by: Kulakow, P., and Pidlisnyuk, V., Springer, Dordrecht, 189198, 2010.

Salt, M., Lightbody, P., Stuart, R., Albright, W., and Yeates,R.: Guidelines for the assessment, design, construction and maintenance of phytocaps as nal covers for landlls, United States Environmental Protection Agency report number, REF No. 20100260RA3F, 2011.

Sarr, M., Agbogba, C., Russell-Smith, A., and Masse, D.: Effects of soil faunal activity and woody shrubs on water inltration rates in a semi-arid fallow of Senegal, Appl. Soil Ecol., 16, 283290, doi:http://dx.doi.org/10.1016/S0929-1393(00)00126-8

Web End =10.1016/S0929-1393(00)00126-8 http://dx.doi.org/10.1016/S0929-1393(00)00126-8

Web End = , 2001.

Schrder, T., Javaux, M., Vanderborght, J., Krfgen, B., and

Vereecken, H.: Effect of Local Soil Hydraulic Conductivity Drop Using a Three-Dimensional Root Water Uptake Model, Vadose Zone J., 7, 10891098, doi:http://dx.doi.org/10.2136/vzj2007.0114

Web End =10.2136/vzj2007.0114 http://dx.doi.org/10.2136/vzj2007.0114

Web End = , 2008.Seastedt, T. R., Hobbs, R. J., and Suding, K. N.: Management of novel ecosystems: are novel approaches required?, Front. Ecol.Environ., 6, 547553, doi:http://dx.doi.org/10.1890/070046

Web End =10.1890/070046 http://dx.doi.org/10.1890/070046

Web End = , 2008.

Smith, P., Cotrufo, M. F., Rumpel, C., Paustian, K., Kuikman, P. J.,

Elliott, J. A., McDowell, R., Grifths, R. I., Asakawa, S., Bustamante, M., House, J. I., Sobock, J., Harper, R., Pan, G., West,P. C., Gerber, J. S., Clark, J. M., Adhya, T., Scholes, R. J., and Scholes, M. C.: Biogeochemical cycles and biodiversity as key drivers of ecosystem services provided by soils, SOIL, 1, 665 685, doi:http://dx.doi.org/10.5194/soil-1-665-2015

Web End =10.5194/soil-1-665-2015 http://dx.doi.org/10.5194/soil-1-665-2015

Web End = , 2015.

Taylor, G., Spain, A., Neodovas, A., Timms, G., Kuznetsov, V., and Bennet, J.: Determination of the reasons for deterioration of the Rum Jungle waste rock cover, Brisbane, Australian Centre for Mining Environmental Research, 2003.van Genuchten, M. T.: A Closed-form Equation for

Predicting the Hydraulic Conductivity of Unsatu-rated Soils, Soil Sci. Soc. Am. J., 44, 892898, doi:http://dx.doi.org/10.2136/sssaj1980.03615995004400050002x

Web End =10.2136/sssaj1980.03615995004400050002x http://dx.doi.org/10.2136/sssaj1980.03615995004400050002x

Web End = , 1980.Venkatraman, K. and Ashwath, N.: Field performance of a phytocap at Lakes Creek landll, Rockhampton, Australia, Management of Environmental Quality: An International Journal, 21, 237252, doi:http://dx.doi.org/10.1108/14777831011025571

Web End =10.1108/14777831011025571 http://dx.doi.org/10.1108/14777831011025571

Web End = , 2010.

www.soil-journal.net/2/41/2016/ SOIL, 2, 4148, 2016

48 S. Arnold and E. R. Williams : Quantication of the inevitable

Vogel, T., Cislerova, M., and Hopmans, J. W.: Porous Media With Linearly Variable Hydraulic Properties, Water Resour. Res., 27, 27352741, doi:http://dx.doi.org/10.1029/91wr01676

Web End =10.1029/91wr01676 http://dx.doi.org/10.1029/91wr01676

Web End = , 1991.

Wang, D., McSweeney, K., Lowery, B., and Norman, J. M.: Nest structure of ant Lasius neoniger Emery and its implications to soil modication, Geoderma, 66, 259272, doi:http://dx.doi.org/10.1016/0016-7061(94)00082-L

Web End =10.1016/0016- http://dx.doi.org/10.1016/0016-7061(94)00082-L

Web End =7061(94)00082-L , 1995.

Williams, E.: Ant community response to management practices on rehabilitated mine sites, Doctorate of Philosophy Thesis, The University of Queensland, 2011.

Wilson, G. W., Williams, D. G., and Rykaart, E. M.: Integrity on Cover Systems An Update, 6th International Conference on Acid Rock Drainage, Cairns, Australia, available at: https://www.ausimm.com.au/publications/epublication.aspx?ID=1031

Web End =https://www.ausimm.com.au/publications/epublication.aspx? https://www.ausimm.com.au/publications/epublication.aspx?ID=1031

Web End =ID=1031 (last access: 6 January 2016), 2003.

SOIL, 2, 4148, 2016 www.soil-journal.net/2/41/2016/