. Effects of defoliation by Douglas-fir tussock moth on timing and quantity of streamflow . Annual runoff, Mill Creek (cm) Figure 3.—Annual runoff from the Umatilla River compared to annual runoff from Mill Creek. The number beside each solid dot is the year of measurement for that point. prediction should be restricted to the range of data used to compute the regression. Although runoff in 1974 was greater than the upper end point of the 95-percent confidence band, the uncertainty associated with the confidence band location prevents a definitive statement about the effects of defoliation on
. Effects of defoliation by Douglas-fir tussock moth on timing and quantity of streamflow . Annual runoff, Mill Creek (cm) Figure 3.—Annual runoff from the Umatilla River compared to annual runoff from Mill Creek. The number beside each solid dot is the year of measurement for that point. prediction should be restricted to the range of data used to compute the regression. Although runoff in 1974 was greater than the upper end point of the 95-percent confidence band, the uncertainty associated with the confidence band location prevents a definitive statement about the effects of defoliation on runoff in 1974. In 1975 and 1976 when precipitation was slightly above average, runoff from the Umatilla River was near the predicted value. If the increase in 1974 was due to decreased evapotranspiration resulting from defoliation, it seems that increased runoff would have continued into 1975 and 1976. It could be that tree recovery from the initial defoliation (greenup) was sufficient to restore transpiration losses to a level which approximated natural conditions. The next step in the analysis was to test for seasonal changes in runoff from the Umatilla River associated with the defoliation. Tests 8
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Keywords: ., bookcentury1900, booksubjectstreammeasurements, booksubjecttrees
