Content area
Full Text
Introduction
Rehabilitation of a mine site after closure is an important component of modern mine planning, and there are strong expectations from the surrounding population that this be done promptly and completely (Cristescu et al. 2012; Vymazal and Sklenicka 2012). There is a long history of mine sites left unremediated, and these have had a negative impact on public perception of mining, to the detriment of the industry at large (Bradshaw and Hüttl 2001; Cooke and Johnson 2002). As part of mine site rehabilitation, revegetation of the today’s mine excavations and waste rock piles is now typical. To this end, modern mines usually stockpile topsoil for later redistribution to allow rapid plant establishment (Bell 2001; Boyer et al. 2011; Bradshaw and Hüttl 2001). This approach limits erosion of bare rock piles, and generally yields a uniform vegetation cover with a predictable flora component that can be engineered to fit the perceived needs of the end use of the post-mining landscape (Hodačová and Prach 2003; Holmes 2001; Prach and Hobbs 2008; Voeller et al. 1998).
Rehabilitation of abandoned mine sites is more difficult because of the lack of stockpiled topsoil with which to establish revegetation, unless very expensive importation of topsoil is undertaken. Instead, plant establishment must occur in the various substrates left after the mining process, and this can present challenges if the substrates have low nutrient contents or contain components that are toxic for incoming flora (Prach and Hobbs 2008). In these cases, revegetation results can be incomplete and patchy unless appropriate tolerant species or substrate treatments are used (Craw et al. 2007; dos Santos et al. 2008; Lottermoser et al. 2011). A further complication is the degree to which natural plant colonization can be relied on, instead of direct planting of imported species. Natural colonization can be effective at providing revegetation by suitable and tolerant local species, provided sufficient nearby seed sources exist, and is a lower cost option than direct planting (Borden and Black 2005; Hodacová and Prach 2003; Novák and Konvicka 2006; Valente et al. 2012). However, natural colonisation takes longer than direct planting, leaving bare ground exposed to erosional processes, with associated undesirable visual and water quality issues (Bradshaw 2000; Prach and Hobbs 2008).
Mine site revegetation is an approach...