Canadian Forest Service Publications

Temporal composition and structure of post-beetle lodgepole pine stands: Regeneration, growth, economics, and harvest implications. 2009. Runzer, K.; Hassegawa, M.; Balliet, N.; Bittencourt, E.; Hawkins, C. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, BC. Mountain Pine Beetle Working Paper 2008-23. 68 p.

Year: 2009

Available from: Pacific Forestry Centre

Catalog ID: 29223

Language: English

Series: Mountain Pine Beetle Working Paper (PFC - Victoria)

CFS Availability: Order paper copy (free), PDF (download)

Abstract

A recent survey of mountain pine beetle (MPB) attack in mature and immature pine leading stands indicated that attack rate was a function of tree size, age and stand density. However, the temporal dynamics of MPB attack in mature and immature stands, as well as the release of the regeneration layer or secondary structure under a dying canopy, are poorly understood. The primary objectives of this study were to i) investigate temporal and spatial aspects of MPB attack, ii) investigate regeneration dynamics (mortality and growth) of post-beetle attack, iii) model growth and yield with actual mortality and regeneration metrics, iv) describe economic opportunities of harvest scheduling with respect to post-MPB stand structure and v) develop improved management and regeneration options. The results have shown that attack rates are higher than anticipated and originally assumed by timber supply analysts, with attack rates in immature stands (except age class 1) ranging from 40% to 60% and exceeding 80% in mature stands. Almost all the pine were killed in mature stands. Although at the landscape level stands have considerable secondary structure, there is a need to quantify the release of secondary structure and competing shrubs in these stands. An accurate inventory of post-MPB stand attributes is also required to determine which stands could benefit from restoration activities. The forest simulator model SORTIE-ND was used to project the outcome of four management scenarios: 1) the base case - stand development without MPB attack (Base), 2) the result of MPB attack - attacked trees proportionally removed by 2 cm diameter at breast height (DBH) classes (MPB), 3) underplant the MPB attacked stand and allow the residual tree layer and secondary structure to develop (UPlant), and 4) clearcut the tree layer and replant with 800 sph of spruce and 800 sph of pine (Clear-Plant). The base case was modelled for comparison purposes. Concerns with the no treatment option (MPB) are fire hazard, species composition, rate of release of the secondary structure and stand density. Concerns with underplanting (UPlant) is that it is costly and has historically been unsuccessful due to abiotic and biotic agents. Concerns with the clear cut (Clear-Plant) scenario are that the stands will not contribute to mid-term timber supply and that structural and species diversity will be reduced. The scenarios and the modelling highlighted that the use of secondary stand structure may be the best option for designing cost-effective and environmentally sound management/restoration strategies/activities.

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