Utilization of Beetle-Killed Southern Pine

George Woodson – Prepared under contract with the Forest Service, U.S. Dpearment of Agriculture Forestry Associate Professor, Wood Utilization, School of Forestry, Louisiana Tech University, Ruston, LA.

United States Department of Agriculture, Forest Service, General Technical Report WO-47.

SAMTAM Utilization Guidelines

Increasing costs for personnel, material, and equipment have placed increased emphasis on more efficient processing in the sawmill. A sawmill manager must be aware of the profit or loss received from processing logs of various grades and diameters. This is important in day-to-day operation, but becomes incresingly so during beetle outbreaks when there is an abundance of large-diameter, low-cost raw material. To increase the utilization of beetle-killed timber, it is important to know how the profit or loss is affected by processing material at various stages of deterioration. Sawmill analysis models for green and beetle-killed timber developed at Texas A&M (known by their acronyms SAMTAM and SAMTAM II) (Massey et. al. 1983) provide information to help a mill manager determine whether it is profitable to process logs of different grades, sizes, and (in the case of beetle-killed timber) kill class (time since death). SAMTAM is the model for green logs only, SAMTAM II for both green and beetle-killed logs.

Both models provide two quality control checks (sawing variation and log overlength), three recovery efficiencies (LRF, overrun, and product percentages), and two profit or loss analysis (actual log data and smoothed predictions).

The models are designed to provide the following information:

1. Average rough green size for each lumber size class. The standard deviation and the range (which will include 95 percent of the measurements) are determined for each size class.
2. A prediction equation for log sawing time.
3. Data on:
1. The dollar value of sawdust, chips, shavings, bark, and lumber by individual log.
2. The percentage of green log cubic volume in sawdust, chips, shavings, dry lumber, and green lumber by individual log.
3. The board foot recovery, log scale, overrun, cubic volume, and LRF for each log.
4. The log grade, scaling diameter, length, total volume, total cost, and profit or loss for each log.
4. Tables giving the value, cost, and profit or loss for each diameter and log length by USDA Forest Service log grade for SAMTAM and by kill class for SAMTAM II.

A schematic of the input/output for SAMTAM II is illustrated in figure 8. The information given by SAMTAM II should be more appropriate to conditions in the mid-South because the residue volumes are based on the actual lumber sawn, the density value is assigned from a distribution function based on data collected in east Texas sawmills, and the kill classes and their respective moisture contents and bark volumes are based on trees from east Texas.

Figure 8 – Schematic of input/output for Texas A&M sawmill analysis model (SAMTAM II).

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