. A case study of a Douglas-fir tussock moth outbreak and stand conditions 10 years later. Douglas-fir tussock moth; Tree declines California; Trees Diseases and pests California. the base oftreesfor 2 years following defolia- tion. Height growth was also measured on seven additional small trees in heavy defolia- tion class (50-percent or more defoliated) and seven small trees in the light class (less than 50-percent defoliated). These measurements are shown in figure 5 and follow a pattern similar to radial growth except growth reduc- tion started in 1964 at a pronounced rate and recovery was
. A case study of a Douglas-fir tussock moth outbreak and stand conditions 10 years later. Douglas-fir tussock moth; Tree declines California; Trees Diseases and pests California. the base oftreesfor 2 years following defolia- tion. Height growth was also measured on seven additional small trees in heavy defolia- tion class (50-percent or more defoliated) and seven small trees in the light class (less than 50-percent defoliated). These measurements are shown in figure 5 and follow a pattern similar to radial growth except growth reduc- tion started in 1964 at a pronounced rate and recovery was a year earlier than for radial growth. The data presented are based on such small samples that it is useful only as an illustration of patterns of growth reduction immediately after defoliation. These patterns are similar to those studied previously (Wickman 1963). Light Heavy. V 0 1 1 1 1 1 1 1 1 1 1959 60 61 62 63 64 65 66 67 1968 YEARS Figure 5.—Average annual height growth for 12 heavily and 7 lightly defoliated white fir, Stowe Reservoir. 2. Ten-year postoutbreak growth patterns. — Growth patterns for the 10-year postoutbreak period were obtained from the following sets of trees: defoliated white fir on the plots, 116 trees; nonhost pine on the plots, 36 trees; defoliated white fir from two plots thinned in 1960, 35 trees—thinned areas were and acres (.49 ha and .24 ha) and spacing was irregular, but averaged 25 by 25 ft ( m); and nondefoliated white fir, 35 trees. Average radial growth for the period 1946-1974 from each of the four sets of trees is shown in figure 6. The annual precipitation from the station in Cedarville, California, about 15 miles (24 km) east is plotted at the top of the figure. The normal 13 inches (33 cm) per year is the average from 1940 to 1971. The values for 1956 and 1957 were estimated, because of unavailable data, from values at Alturas, California, the next closest station. Data on the nondefoliated white fir and the pine tre
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