Metal mining generates large volumes of wastes, which can contain sulphide minerals that generate acid when exposed to atmospheric conditions, providing unfavourable conditions for plant establishment. In particular, mining waste rocks are piled on tens of meters, and remain devoid of vegetation, creating a desolated anthropogenic landscape. The use of adapted plants able to grow quickly on waste rocks can help increasing their aesthetical aspect. An experiment was conducted at the Westwood mine in Quebec to evaluate the establishment ability of a fast-growing willow (Salix miyabeana Sx64) on acid-generating waste rocks. The main objective was to identify substrate thickness and composition that maximized willow productivity while limiting water stress exposure and trace metal accumulation. A randomized complete block design was established in June 2014 with five treatments: (1) direct planting in waste rocks, (2) and (3) 20 cm or 40 cm moraine amended with 20% of organic matter (OM) (in volume), (4) 20 cm moraine at 40% of OM, and (5) 20 cm moraine at 20% of OM over 20 cm lime sludge from water treatment. Trees directly planted in waste rocks survived well (75%) but had the lowest aerial productivity, with the lowest height and diameter growth, aerial biomass, and total leaf area, while the treatment richer in OM showed the greatest aerial biomass and total leaf area, and the thicker treatment the greatest height and diameter growth. Willow root development was restricted to cover soils the first year after planting, and foliar δ13C values decreased in thicker soil (40 cm) compared to thin soil (20 cm). Willow accumulation factors in leaves were below one for all investigated trace metals except Zn.
aerial productivity, lime sludge, mine revegetation, phytostabilization, root development, soil cover, trace metals, water stress
 Aubertin, M., Bussière, B. & Bernier, L., Environnement et gestion des rejets miniers, Presses Internationales Polytechnique, 2002.
 Markert, B., Kayser, G., Korhammer, S. & Oehlmann, J., Distribution and effects of trace substances in soils, plants and animals. Trace Elements: Their Distribution and Effects in the Environment, ed. J.P. Vernet, 4th edn., Elsevier: Amsterdam, pp. 3–32, 2000. http://dx.doi.org/10.1016/S0927-5215(00)80004-1
 Tordoff, G.M., Baker, A.J.M. & Willis, A.J., Current approaches to the revegetation and reclamation of metalliferous mine wastes. Chemosphere, 41, pp. 219–228, 2000. http://dx.doi.org/10.1016/S0045-6535(99)00414-2
 Moffat, A.J., Minimum soil depths for the establishment of woodland on disturbed ground. Arboricultural Journal, 19, pp. 19–27, 1995. http://dx.doi.org/10.1080/03071375.1995.9756445
 Emerson, P., Skousen, J. & Ziemkiewicz, P., Survival and growth of hardwoods in brown versus gray sandstone on a surface mine in West Virginia. Journal of Environmental Quality, 38, pp. 1821–1829, 2009. http://dx.doi.org/10.2134/jeq2008.0479
 Maiti, S.K., Bioreclamation of coalmine overburden dumps-with special emphasis on micronutrients and heavy metals accumulation in tree species. Environmental Monitoring and Assessment, 125(1–3), pp. 111–122, 2007. http://dx.doi.org/10.1007/s10661-006-9244-3
 Gibson, D.J., The natural revegetation of lead/zinc mine spoil in northeastern Oklahoma. The Southwestern Naturalist, 27(4), pp. 425–436, 1982. http://dx.doi.org/10.2307/3670717
 Mosseler, A., Major, J.E. & Labrecque, M., Growth and survival of seven native willow species on highly disturbed coal mine sites in eastern Canada. Canadian Journal of Forest Research, 44, pp. 340–349, 2014. http://dx.doi.org/10.1139/cjfr-2013-0447
 Boyter, M.J, Brummer, J.E. & Leininger, W.C., Growth and metal accumulation of geyer and mountain willow grown in topsoil versus amended mine tailings. Water Air Soil Pollution, 198, pp. 17–29, 2009. http://dx.doi.org/10.1007/s11270-008-9822-9
 Mirck, J. & Volk, T.A., Response of three shrub willow varieties (Salix spp.) to storm water treatments with different concentrations of salts. Bioresource Technology, 101, pp. 3484–3492, 2010. http://dx.doi.org/10.1016/j.biortech.2009.12.128
 Hangs, R.D., Schoenau, J.J., Van Rees, K.C.J. & Steppuhn, H., Examining the salt tolerance of willow (Salix spp.) bioenergy species for use on salt-affected agricultural lands. Canadian Journal of Plant Sciences, 91, pp. 509–517, 2011. http://dx.doi.org/10.4141/cjps10135
 Harada, E., Hokura, A., Nakai, I., Terada, Y., Baba, K., Yazaki, K., Shiono, M., Mizuno, N. & Mizuno, T., Assessment of willow (Salix sp.) as a woody heavy metal accumulator: field survey and in vivo X-ray analyses. Metallomics, 3, pp. 1340–1346, 2011. http://dx.doi.org/10.1039/c1mt00102g
 Zhivotosky, O.P., Kuzovkina, J.A., Schulthess, C.P., Morris, T., Pettinelli, D. & Ge, M., Hydroponic screening of willows (Salix L.) for lead tolerance and accumulation. International Journal Phytoremediation, 13, pp. 75–94, 2011. http://dx.doi.org/10.1080/15226511003671361
 Mahar, A., Wang, P., Ali, A., Kumar Awasthi, M., Hussain Lahori, A., Wang, Q., Li, R. & Zhang, Z., Challenges and opportunities in the phytoremediation of heavy metals contaminated soils: a review. Ecotoxicology and Environmental Safety, 126, pp. 111–121, 2016. http://dx.doi.org/10.1016/j.ecoenv.2015.12.023
 Cooke, J.A. & Johnson, M.S., Ecological restoration of land with particular reference to the mining of metals and industrial minerals: a review of theory and practice. Environment Reviews, 10, pp. 41–71, 2002. http://dx.doi.org/10.1139/a01-014
 Larchevêque, M., Desrochers, A., Bussière, B. & Cimon, D., Plantation of trees in soil layers for the reclamation of non-acid generating wastes of a boreal gold mine. Ecoscience, 21(3–4), pp. 217–231, 2014. http://dx.doi.org/10.2980/21-(3-4)-3697
 Larchevêque, M., Desrochers, A., Bussière, B., Cartier, H. & David, J.-S., Revegetation of non acid-generating, thickened tailings with boreal trees: a greenhouse study. Journal of Environmental Quality, 42, pp. 351–360, 2013. http://dx.doi.org/10.2134/jeq2012.0111
 Government of Canada, National climate archives, available at http://climate.weather.gc.ca/
 Government of Quebec. Annexe I: Règlement sur la protection et la réhabilitation des terrains, LQE Chapitre Q2 r.37, available at www2.publicationsduquebec.gouv.qc.ca/dynamicSearch/telecharge.php?type=3&file=/Q_2/Q2R37.htm
 Agriculture and Agri-Food Canada, The Canadian system of soil classification, 3rd ed., available at http://sis.agr.gc.ca/cansis/taxa/cssc3/index.html
 Farquhar, G.D., Ehleringer, J.R. & Hubick, K.T., Carbon isotope discrimination and photosynthesis. Annual Review Plant Physiology Plant Molecular Biology, 40, pp. 503–537, 1989. http://dx.doi.org/10.1146/annurev.pp.40.060189.002443
 Pallardy, S.G., Physiology of Woody Plants, 3rd edn., Academic Press: Burlington, MA, 2008.
 Prasad, M.N. & Strzalka, K., Physiology and biochemistry of metal toxicity and tolerance in plants. Physiological Responses of Vascular Plants to Heavy Metals, Kluwer Academic Publisher, pp. 149–171, 2002. http://dx.doi.org/10.1007/978-94-017-2660-3
 Kabata-Pendias, A. & Pendias, H., Trace Elements in Soil and Plants, 3rd edn., CRC Press: Boca Raton, FL, 2001.