|Abstract or Summary
- Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) ranging
from 9.6 to 14.3 inches diameter breast height were treated with
the organic arsenicals, monosodium methanearsonate (MSMA) and
cacodylic acid. Treatments were applied at monthly intervals from
February, 1967 to October, 1968, to ten to 25 trees each month.
Treated trees were sampled in September, 1967 and September,
1968. The time lapse from treatment to harvest ranged from five
to 19 months, during which time the trees were left standing in the
forest to air-dry. Untreated control trees were cut in February,
1967 and at both of the September cutting dates. Treatments consisted
of boring holes, one for each three inches of diameter at
breast height and pouring ten to 20 milliliters of the herbicide in
each hole. Wafer samples were cut from the ends of each log at the time
the trees were cut. The respective diameters and moisture contents
of the bark, sapwood and heartwood were recorded. Tree and log
measurements were taken in the field. Individual logs were weighed
after skidding to the landing for each harvest made in September.
A model tree was constructed mathematically, based on measurements
from the samples and field data, for a standard comparison
of the moisture profiles of each treatment. The moisture profiles
were determined by multiple linear stepwise regression analysis of
the moisture contents of the sample components (bark, sapwood
and heartwood) and data characterizing each sample. Weights of
these components and the total tree for each treatment were determined
by integration of the moisture profiles over the model tree.
Percentage weight reductions range from negative values to
values greater than 2O percent. Weight losses were a result of
drying in the bark and sapwood and loss of bark. MSMA treated
trees were consistently drier than trees treated with cacodylic acid.
The moisture content of the heartwood was unaffected by the treatments. Bark loss was more apparent and breakage tended to occur
more frequently with long drying periods. The data suggest that
treating in mid-summer after the major insect flights created trees
unattractive to certain insects during the second year.
The summer of 1967 was abnormally hot and dry and the summer of 1968 was abnormally wet. Thus, weather had an important
bearing on results, particularly in reducing the drying exposure
of trees treated in September and October, 1967.
The economic implications and potentials of the results are
discussed for various aspects of the forest industry and forest practices.
Visual observations made of the treated trees being cut into
lumber and veneer indicated that utilization processes were not adversely
affected. Drying times longer than those tested appear to
be possible without degrade. The drier wood enables more uniform
kiln drying and reduces the time required for air drying by nearly
25 percent. This feature should be applicable to all types of drying
of various products. This is especially important for products requiring
very long drying periods such as poles and pilings. Benefits
of field drying carry through logging, shipping, manufacturing, and
handling. Drying was adequate to permit faster drying of sapwood
veneer. At the moisture contents obtained there was no effect on the
veneer process nor on pulping quality. The loss of weight was adequate
for an appreciable increase of the volume per truck load for
hauling, and for an increase in the efficiency of present logging
equipment while making less expensive equipment more practical.
This type of treatment permits more intensive management of
timber stands, enabling the land manager to accomplish many objectives
at one time and has the potential of reducing the diameter of the marginal tree. Storage of the wood fiber on the stump by continuous
thinnings is a logical outgrowth of the above findings. This
practice would keep the stand at optimum stocking for maximum
growth while maintaining the killed trees in salvagable condition.
The combined silvicultural benefits of insect and disease control,
along with slash reduction and reduction of operating costs in logging
and manufacturing, provide a tool of broad utility to forest managers.