Growth and survival of seven native willow species on highly disturbed coal mine sites in eastern Canada

Abstract

Significant differences were apparent in seven native North American willow (Salix) species compared and assessed in common garden field tests for survival, biomass production, and coppice structure on former coal mine sites in New Brunswick, Canada. In most species, percentage survival was relatively constant after the initial establishment phase, allowing good prediction of final survival in the first or second year after establishment. Unrooted dormant stem sections collected from clones of five willow species previously field-tested and selected for survival and growth, survived and grew better on the mine site to be reclaimed than those collected directly from natural populations, demonstrating the ability to rapidly improve survival results based on prior field testing. Survival at ages 5 and 6 improved from an average of 70% to 94% for S. eriocephala Michx. and from 42% to 84% for S. interior Rowlee. The best clones in both species had over 95% survival and had approximately 5–6 t·ha−1 (t = tonne) fresh mass after 2 years of coppice growth. We recommend these two species for use in mine reclamation activities, because they grew best overall and had the highest survival rates. Despite poor average rooting ability in S. bebbiana Sarg., S. discolor Muhl., and S. humilis Marshall, some genotypes of these species showed good survival and growth, and further selection for these traits is warranted.