Canadian Forest Service Publications
Genetic by environment interactions of two North American Salix species assessed for coppice yield and components of growth on three sites of varying quality. 2014. Mosseler, A.; Major, J.E.; Labrecque, M. Trees: Structure and Function 28(5): 1401–1411.
Issued by: Atlantic Forestry Centre
Catalog ID: 35728
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Coppice yield and components of growth were quantified in eight clones of two widely distributed North American willows, Salix discolor (DIS) and S. eriocephala (ERI), in common-garden field tests on three sites of varying quality. Both species and clones within species varied significantly across different sites and interacted with site for plant yield and components of growth traits. At the species level, ERI was significantly more productive than DIS on the two most productive sites (85 and 57% greater, respectively), but on the poorest site, a shale coal mine overburden, species ranking was reversed, with DIS showing a 60% greater biomass yield than ERI. These sites had similar mean temperature, growing degree days, and seasonal precipitation. Site quality differences were thus most probably driven by soil nutrients, physical traits, and water-holding capacity quantified by 13 soil properties, 12 of which were significantly different and showed fairly consistent ranking among sites. At the clonal level, growth trends and differences were mostly consistent among clones across the three test sites, with the exception of one clone of DIS and to a lesser extent a clone of ERI, which showed abnormally strong clone by site interaction for specific growth traits. Productivity reached as high as 6.0 kg green mass in 2-year-old coppices for a clone from each of DIS and ERI on the most productive site. The strong expression of genetic by environment interactions at both the species and clonal levels suggests that biomass production can be optimized by taking advantage of such interactions and highlights the need for testing not only different species, but also a number of clones within a species before selecting clones for biomass production on different site types. Our results highlight variation in coppice form and the potential for genetic selection both among and within species.
Plain Language Summary
This study used former coal mine sites in New Brunswick to field test large numbers of clones of seven native willow (Salix) species collected from natural populations originating from central and eastern Canada. The aim was to identify a series clones from the most promising native willows for reclamation (rapid re-vegetation) of highly disturbed areas such as mine sites for eventual restoration of high forest cover by using the willows as a nurse crop for natural or artificial succession to higher value conifers. Significant differences were apparent among species in growth performance, survival, and plant growth form. Following establishment of unrooted stem cuttings, the best clones of Salix eriocephala and S. interior had over 95% survival and produced 5-6 Mt ha-1 of fresh biomass 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, S. discolor, and S. humilis, several clones of these species also showed good survival and growth, and further selection for these traits is warranted. Selected clones of these species are now being used for reclamation activities on base metals mine sites in Ontario, on gold mine sites in Quebec, and could also be used to re-vegetate and restore forest cover on oil sands and oil and gas exploration sites in Alberta.