Release of individual trees as a means to stimulate cone production was tested by 

 removing competition within a radius of 12, 20, and 25 feet around immature, mature, 

 and overmature trees (five of each) . These release conditions were established for the 

 immature trees in May 1954 at Lick and for the mature and overmature trees in May and 

 June 1955 at Buck. Response to release was evaluated by pairing each treated tree with 

 a nearby untreated tree. All of these trees were banded with 16-inch-wide metal strips 

 to prevent squirrels from climbing the trees. 



( 



The average ages and sizes for girdled and released trees were 



(Class) 



Age 



(Years) 



D.b.h. 



( Inches) 



Height 

 (Feet) 



Immature 



Mature 



Overmature 



50 

 140 



220 



9 

 18 

 25 



42 

 78 

 98 



Results 



Girdling 



Both wide and narrow girdling of 50-year-old ponderosa pines increased cone 

 production of the first crop formed after treatment (table 3) . Even though the analysis 

 of variance showed a statistically significant (1 percent level) increase overall, 

 about 20 percent of the trees showed no effects of treatment. Trees with either of the 

 girdling treatments produced an average of over 20 cones per tree in 1956 while their 

 untreated counterparts averaged only one cone per tree. In the years following the 

 first crop, there were no significant cone-production differences between treated and 

 untreated trees. 



Wide girdling of 140- and 220-year-old pines prompted no statistically significant 

 increase in cone production, but cone production from about half of the treated trees \ 

 did increase considerably in 1957 which was the first cone crop that could have been 

 affected by the girdling (table 3). Narrow girdling was not tried on these older trees. 



Girdling usually did not change the subsequent appearance of the trees. In 1956, 

 2 years following treatment, two trees had slight yellowing of the foliage, but these 

 improved later. No comparisons were made to see if girdling affected increment. 



Table 3 .--Average cone ■production by age class on girdled and check trees 



before and after treatment 





50-year age class 



.140- and 220-year age 



classes combined 



Year . 











Girdled Check 



Girdled 



Check 



1954 

 1956 

 1957 

 1958 

 1959 



,12 

 zj 22 



2 

 37 

 2 



■Cones per tree 



i/ 



1/ 



1 



28 



2 



124 

 100 

 5/ll8 

 150 

 2 



110 

 70 

 60 

 148 

 1 



8/, 



1 Based on five 50-year-old trees, five 140-year-old trees, and five 220-year-old 



trees. The 140- and 220-year age classes were combined because they did not differ 

 significantly . 



2 First possible cone crop that could have been affected by the girdling treatments 



6 



