IntensIve sIlvIculture - Forest Science Labs - Research Network ...

289
edges; characteristics which increase susceptibility to wind damage. In this analysis, the
increasing vulnerability factors are mostly compensated for by the reduced rotation lengths
expected in the plantations. The pattern of transition in managed landscapes generates an
associated pattern of vulnerability to wind damage. Homogeneously and heterogeneously aged
landscapes have distinct patterns of vulnerability. These differences could be harnessed to
enhance the particular goals associated with managing individual ownerships.
664. Wilson, J.S. and P.J. Baker. 2001. Flexibility in forest management: managing uncertainty in
Douglas-fir forests of the Pacific Northwest. Forest-Ecology-and-Management 145(3): 219-227.
Keywords: planting operations
thinning
yield
tree morphology
economics
tree/stand health
Abstract: Long planning horizons generate substantial uncertainty in forest management,
making management flexibility, the ability to choose between multiple options or opportunities, a
desirable attribute of managed forests. Flexibility in forest management reflects both the relative
rigidity of intervention requirements and the potential range of development pathways for a stand.
The wind stability of Pacific Northwest Douglas-fir (Pseudotsuga menziesii) plantations is used
to demonstrate the concept of management flexibility. Dense Douglas-fir plantations develop
high height to diameter ratios in the dominant trees making them unstable and prone to wind
damage. The management of these plantations is inflexible, because without early and timely
thinning, the stands do not contain stable trees that could be expected to survive long rotations or
late thinnings. A combination of reduced planting densities and site-specific management reduces
both the necessity and rigidity of intervention requirements (e.g., thinning) and expands the
number of potential developmental pathways for these stands. The cost of greater management
flexibility is reduced efficiency of wood volume production; however, greater adaptability to
changing markets, labour conditions, and management objectives may be more important for
many forest owners. While this approach to management is complex, it frees owners and
managers from rigid management requirements and allows for a wider range of future stand
conditions.
665. Wilson, J.S. and C.D. Oliver. 2000. Stability and density management in Douglas-fir plantations.
Canadian-Journal-of-Forest-Research 30(6): 910-920.
Keywords: planting operations
thinning
tree/stand protection
tree morphology
tree/stand health
Abstract: Limited tree size variation in Douglas fir (Pseudotsuga menziesii) plantations in
coastal Oregon, Washington, and British Columbia makes them susceptible to developing high
height to diameter ratios (H/D) in the dominant trees. The H/D of a tree is a relative measure of
stability under wind and snow loads. Experimental plot data from three large studies were used to
evaluate the impact of initial planting densities and thinning on plantation H/D values. The H/D
predictions from the experimental plot data match spacing trial results closely but are
substantially different from distance-independent growth model predictions. The results suggest