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<br />15 percent increase in precipitation, Workshop I reached the follow~ <br />ing conclusions regarding potential impacts on the forest: <br /> <br />"In normal years, cloud seeding will probably result in: <br />(1) soil moisture equal to or greater than that in unaugmented <br />years, (2) snowpacks of" longer duration, and (3) a total <br />increase in precipitation that is very small compared to the <br />total for the area over any decade. <br /> <br />"Forest ecosystems at upper elevations are already adapted to <br />handle more 'normal I wet winters than would presumably occur <br />during weather modification. Therefore, an increased snowpack <br />during 'dry' years probably will not induce 'abnormal I changes <br />and might even result in an overall net benefit to forest <br />stands. <br /> <br />"However, special circumstances should also be considered. <br />Subnormal precipitation years serve to 'weed out' root diseased <br />trees, suppressed trees, and trees marginally adapted to given <br />sites. If the periodic 'thinning' function resulting from <br />subnormal precipitation years is eliminated, overstock and <br />insect/disease problems associated with overstocking or with <br />drought might occur. However, localized sites which are under- <br />stocked because of shallow, rocky soils may be benefited by an <br />increase in stock. <br /> <br />"Some major specific effects can be expected to materialize. <br />However, because of the complex nature of the environmental <br />matrix of soils, moisture, vegetation, yearly climate, cycles of <br />climatic change, and pathogens and insects, it is not expected <br />that conclusive data will be developed from a 5- to 7-year pilot <br />program. The effects are: <br /> <br />"1. Since trees grow faster with a plentiful water supply, <br />it is expected that less severe attacks and less mortality <br />from pathogens such a.s dwarf mi st 1 etoe and cytospora canker <br />will occur under augmented conditions than under drought <br />cond it ions. <br /> <br />"2. For the same reason, root and butt decay (F. annosus) in <br />fir will have less impact because fir growth will keep ahead <br />of the pathogen. <br /> <br />"3. Tipmoth on eastside pine would be less severe due to <br />increased growth of the pine. <br /> <br />"4. Under augmented water supplies, a decrease in losses <br />from the pine reproduction weevil, Cy1indro10pturus eatoni, <br />may be expected as a result of the lessened drought stress. <br /> <br />liThe workshop group believes the normal insect and disease <br />monitoring will serve little purpose, since so many factors <br />other than precipitation augmentation can influence the success <br /> <br />15 <br />