Reclamation of copper mine wastes with shrubs in the southwestern U.S.A

Experiments were conducted in Arizona to study seed germination, seedling establishment, and growth of five species of shrubs in copper mine wastes. Four soil materials associated with copper mining wastes were involved in the research: (1) desert soil, (2) overburden, (3) overburden plus tailings, and (4) tailings. A smooth, loose seedbed was prepared in each soil material using a ‘sidewinder’ and a ‘sheepfoot roller’. Five species of shrubs were grown in each of the four soil materials: (1) fourwing saltbush (Atriplex canescens (Pursh.) Nutt.), (2) quailbush (Atriplex lentiformis (Torr.) Wats.), (3) Australian saltbush (Atriplex semibaccata R. Br.), (4) creosote bush (Larrea tridentata (DC.) Cov.), and (5) desert broom (Baccharis sarothroides Gray). Plant growth data indicated that desert soil had the highest fertility level, followed by overburden, overburden plus tailings, and tailings, in decreasing order. All species of shrubs produced taller plants, more vegetation, and more ground cover during their second year of growth than they did during the first year. The establishment of the five species of shrubs together provided the most desirable revegetation on the disturbed areas. The planting of a variety of adapted shrubs on copper mine wastes in the southwestern U.S.A. is believed to be the most effective way to revegetate these disturbed areas and blend them into the surrounding environment.