Estimating Western Hemlock Lumber Recovery and Quality from Historical Data
Forest Service product recovery studies have taken tree, log, and product measurements from the harvesting and manufacturing process . The resulting database provides a tool to allow estimation of product recovery in existing stands by pooling data across studies.† Recovery can be estimated in cubic- or board-foot volume or in terms of product quality.† Value-based recovery can be estimated by using current or projected prices.
Six hundred thirty trees from these studies represent western hemlock (Tsuga heterophylla (Raf.) Sarg.) that include a full set of tree, log, and lumber measurements.† These 630 trees have been cut into 3,047 logs, and the output data from those logs represent about 600,000 board feet of lumber.
Information from the database can be sorted and grouped by different forest management strategy scenarios, roundwood purchasing options, or processing decisions within a mill or among an integrated group of mills.† Each scenario represents the description of one or more management actions on a piece of land, timber purchasing decisions, or other activities used to define and select a portion of the data available in the database.† Users can then build models to estimate volume recovery, grade yield, or product value based on these different scenarios to evaluate their relative wood product potential.†
The data used in the following scenario were from USDA Forest Service Forest Inventory and Analysis (FIA) plot data selected in a manner allowing for the re-creation of stands based on the userís scenario criteria.† The stands were then simulated from the recovery study database. Other scenarios using other species and geographic ranges can be created from the database.
Nonindustrial Private Forest Scenario
A nonindustrial private landowner is interested in an overstory removal from a hemlock stand.† Data from FIA nonindustrial plots in Oregon and Washington give a distribution in the 20- to 40-inch diameter classes, which is then mimicked by using the recovery database. The stand table generated from this process results in the following grade distribution: selects and shops--20%, structural--54%, and economy and utility--26%, with a value of $391/MBF.