Growth response of native shrubs to acid mine spoil and to proposed soil amendments

Successful reclamation of acid mine sites may be enhanced by revegetating with species that are tolerant to acid mine spoil conditions. This study was conducted to assess the response of four native shrub species, Amelanchier alnifolia Nutt., Symphoricarpos albus (L.) Blake, Berberis repens Lindl., and Ceanothus sanguineus Pursh, to 1) pyritic acid mine spoil amended with various levels of lime and composted sewage sludge with added ammonium nitrate (CSS+N) and 2) acidified granitic spoil, with and without CSS+N. Species responded to soil acidity and nutrient supply similarly in both spoil materials. Berberis and Amelanchier exhibited acid soil tolerance, Symphoricarpos grew poorly in acidic soils but had low mortality, and Ceanothus responded to low pH with very poor growth, high mortality, or both. Amelanchier was conservative in growth and did not respond to either soil pH or nutrient supply with significant differences in biomass accumulation. Symphoricarpos varied in response to CSS+N but was most productive at neutral or higher pH. Berberis responded to nutrient availability with substantial increases in biomass production, including significant growth in strongly acidic spoil. Ceanothus responded to nutrient availability with large increases in biomass and was most productive with added CSS+N at neutral or higher pH. Nitrogen fixing nodules developed on the roots of Ceanothus plants grown in granitic spoil without CSS+N. The results indicated that these species differ significantly in acid soil tolerance and in their potential for growth, stress tolerance, and resource acquisition.