Abstract
Intensive plantation forestry is a potent strategy for forest managers to increase wood production on a smaller forest land acreage, especially with the use of genetically improved reforestation stock. The main drawback with conventional conifer improvement is the several decades it takes before stock deployment, which is particularly acute in the context of climate change and evolving wood markets. Use of genomic selection allows to drastically shorten breeding cycles, resulting in more flexibility and potentially increasing benefits. This study compares the financial performance of five white spruce (Picea glauca) breeding and deployment scenarios, from conventional breeding to genomic selection in conjunction with top-grafting or the use of somatic embryogenesis, in the context of plantations established by the Quebec government on public lands with banned herbicide use. We estimated the land expectation value (LEV) for the five scenarios applied to eight site productivity indices, and considered costs and revenues from breeding, plantation establishment, silviculture, and harvest. LEVs at 4% discount rate were positive for all scenarios on all site indices, and varied from $197 to $2015 ha−1 assuming mechanical brushing of the plantations. The scenarios integrating genomic selection resulted in the highest LEVs, which increased with site index. We also conducted sensitivity analyses with 3% and 5% discount rates, with a range of costs and benefits, and with herbicide control of competing vegetation. These results should help orientate public investment decisions regarding the integration of genomic selection at the operational level in tree breeding and reforestation programs on public lands.
Highlights
In Canada and in the province of Quebec in particular, genetically improved seeds from first-generation and secondgeneration seed orchards are available for reforestation for many conifers, including several spruce species
Our results indicate that an increase in site index means an increase in land expectation value (LEV)
The drop in LEV at site index 9 and the slow recovery on higher site indices can be explained by the fact that no mechanical control of the competing vegetation is required on low-productivity sites
Summary
In Canada and in the province of Quebec in particular, genetically improved seeds from first-generation and secondgeneration seed orchards are available for reforestation for many conifers, including several spruce species. Genomic selection is a method proposed by Meuwissen et al (2001) to estimate the breeding and genetic values of individuals for any quantitative trait such as growth or wood quality using their genomic profiles The assumption of these authors was that with genome-wide distributed markers, it is possible to capture all the variation in a given trait from effects of each gene involved in the control of this trait. The first studies on the development and application of GS in spruces were for growth and wood traits in white spruce (Picea glauca [Moench] Voss) (Beaulieu et al 2014a, 2014b), interior spruce (Picea engelmannii ×glauca complex) (Gamal El-Dien et al 2015), black spruce (Picea mariana [Mill.] B.S.P.) (Lenz et al 2017), and Norway spruce (Picea abies [L.] Karst.) (Chen et al 2018; Lenz et al 2019) These studies demonstrated that GS was highly efficient in small populations such as the breeding populations developed and maintained by tree breeders. They showed that the breeding and genetic values of individuals can be predicted at the seed or seedling stage, making it possible to select superior parents or individuals for the traits of interest at a very early age and without having to resort to long-lasting field testing, at least for the current generation
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