Benefit-cost analysis of a white spruce clonal seed orchard in New Brunswick, Canada

摘要

Tree improvement for important species is over 30 years old in the province of New Brunswick, Canada, and enough data have been accumulated to perform an economic analysis. In this study, we conducted a benefit-cost analysis of an ongoing, first generation, 6.5 ha white spruce clonal seed orchard, established in 1985-1987 in Lower Queensbury, New Brunswick. This seed orchard has provided seed for reforestation on Crown lands in the province since 1993. The analysis was undertaken by evaluating the present values of relative costs, benefits, and benefit/cost ratios (BCRs) associated with a plantation management strategy that uses the Lower Queensbury clonal seed orchard (LQ_CSO) versus one that uses wild stand (unselected) seeds. Cash flows were based on actual costs for the LQ_CSO (including orchard establishment and management, progeny test establishment and maintenance, and data analysis), and projected revenue increases from the genetic gains associated with the LQ_CSO relative to the unselected seedlot. Genetic gains at rotation ages were predicted using a growth and yield model that used 20-year old data collected from a realized gain test, and considered two rotation ages (40 and 50 years) along with two management scenarios (with vs. without commercial thinning). A number of discount rates (from 4 to 8 %) were also assessed. Findings indicated that the BCRs ranged from 12.5 to 0.4, depending on the scenario considered, with a majority being > 1. BCRs increased when commercial thinning was applied, but declined marginally when the rotation age was extended from 40 to 50 years. Overall, the results demonstrated that the establishment of the LQ_CSO was an excellent investment for all scenarios when the discount rate was < 6 %.