Abstract:
Analysis of import trade since 1976 shows that forests of the Pacific Northwest provide
Japan with the largest share of pine mushrooms (Tricholoma spp.) outside of East Asia.
To determine whether North American pine mushrooms (Tricholoma magnivelare (Peck)
Redhead) merit more intensive management in the southern Cascade Range, a major
center of commercial harvesting, the bioeconomic model MUSHROOM has been
developed. The model links annual pine mushroom crops to joint production of other
timber and non-timber forest products at the Diamond Lake pine mushroom management
area in the Umpqua National Forest, Oregon. Experimental silvicultural regimes
emphasize growth of major tree species hosting pine mushrooms plus the major timber
species, western white pine (Pinus monticola Dougl. ex D. Don), for creating mixed-species,
uneven-aged forests with old-growth retention trees. Silvicultural scenarios are
evaluated for feasibility on the basis of statistical distributions of financial returns from
forest products during a 25-year planning period.
Early partial timber harvests offset costs of management designed to promote larger pine
mushroom crops. Stands with numerous, large Shasta red firs (Abies magnfica A. Murr.
var. shastensis Lemmon) are most likely to produce highest incomes from pine mushroom
management initially. Conversion of young stands with few tall overstory trees or of stands dominated by Pacific silver fir (Abies arnabilis Dougl. ex Forbes) incur the greatest
costs for stand conversion to create pine mushroom colonies. Bough pruning to reduce
stand leaf area is designed to improve the understory environment for pine mushrooms,
but commercial conifer bough sales from pruned boughs may not compensate for pruning
costs. Cones of pine species contribute more to stand income than do pine mushrooms in
stands having few true fir or mountain hemlock (Tsuga mertensiana (Bong.) Carr)
overstory trees. A survey of new directions for research, modeling capability, and
management points to the need for better understanding of links between weather events
and mushroom production, for better data about transfers of water and energy through
tree canopies and through ash and pumice soils, and for a labor force trained to monitor
and tend pine mushroom colonies.
