Rebecca Ralston, Joseph Buongiorno, Jeremy S. Fried. (2004). Potential yield, return, and tree diversity of managed, uneven-aged Douglas-fir stands. Silva Fennica vol. 38 no. 1 article id 435. https://doi.org/10.14214/sf.435

Keywords: diversity; simulation; uneven-aged management; Douglas-fir; WestPro; economics

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The effects of different management regimes on uneven-aged Douglas-fir stands in the Pacific Northwest of the United States were predicted with a simulation model. Management alternatives were defined by residual stand structure and cutting cycle. The residual stand structure was set by basal area–diameter-q-ratio (BDq) distributions, diameter-limit cuts (assuming concurrent stand improvement), or the current diameter distribution. Cutting cycles of 10 or 20 years were applied for 200 years. The current diameter distribution was defined as the average of the uneven-aged Douglas-fir stands sampled in the most recent Forest Inventory and Analysis conducted in Oregon and Washington. Simulation results were compared in terms of financial returns, timber productivity, species group diversity (hardwoods vs softwoods), size class diversity, and stand structure. Other things being equal, there was little difference between 10- and 20-year cutting cycles. The highest financial returns were obtained with either a 58.4 cm diameter-limit cut, or a BDq distribution with 8.4 m2 of residual basal area, a 71.1 cm maximum diameter, and a q-ratio of 1.2. Using the current stand state as the residual distribution was the best way to obtain high tree size diversity, and high species group diversity. Several uneven-aged regimes gave net present values comparable to that obtained by converting the initial, uneven-aged stand to an even-aged, commercially thinned, plantation.

Ralston, Dept of Forest Ecology and Management, University of Wisconsin, Madison, WI 53706, USA E-mail: rr@nn.us
Buongiorno, Dept of Forest Ecology and Management, University of Wisconsin, Madison, WI 53706, USA E-mail: jbuongio@facstaff.wisc.edu
Fried, USDA Forest Service, Pacific Northwest Forest Experiment Station, Forest Inventory and Analysis Program, P.O. Box 3890, Portland, OR 97208, USA E-mail: jsf@nn.us

article id 627, category Research article

Joseph Buongiorno, Audra Kolbe, Mike Vasievich. (2000). Economic and ecological effects of diameter-limit and BDq management regimes: simulation results for northern hardwoods. Silva Fennica vol. 34 no. 3 article id 627. https://doi.org/10.14214/sf.627

Keywords: diversity; hardwoods; simulation; uneven-aged management; economics; mixed-species stands

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The long-term financial and ecological effects of diameter-limit regimes and basal-area-diameter-q-ratio (BDq) regimes were compared by simulation in the case of northern hardwood forests. Varying the cutting cycle between 10 and 20 years had little effect on returns or stand structure. A 28-cm diameter-limit cut gave the highest production and financial returns, and the highest species diversity, but considerably lower size diversity. A 38-cm diameter-limit cut and a heavy BDq selection harvest gave high returns, while maintaining high levels of diversity. On lands of equal site quality, Michigan’s stands were more productive than Wisconsin’s. The results suggest that it is possible to manage northern hardwood stands sustainably with diameter-limit cuts, combined with removal of poorly performing understory trees. Adjusting the diameter limit gave rise to stands similar in productivity and structure to those obtained by BDq cutting regimes. Given their simplicity of implementation and monitoring, more attention should be given to diameter-limit cutting regimes, with attendant stand improvement measures, as a practical means for uneven-aged management of northern hardwoods.

Buongiorno, Department of Forest Ecology and Management, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53705, USA E-mail: Jbuongio@facstaff.wisc.edu
Kolbe, Department of Forest Ecology and Management, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53705, USA E-mail: ak@nn.us
Vasievich, USDA Forest Service, North Central Forest Experiment Station, 1407 S. Harrison Road, Suite 220, East Lansing, MI 48823, USA E-mail: mv@nn.us

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