Effect of Douglas - fir Seed Supply 



Douglas-fir seeds, when available, also constitute an important segment of the 

 pine squirrel's diet. In 1954, squirrels left many more cones on the trees than in 

 1953 or 1956, most likely because a fair number of ponderosa pine cones were available 

 and Douglas-fir produced a bumper seed crop that supplemented the food supply. In 

 1956, all but one pine cone was harvested before the seed could be dispersed. This was 

 probably due to the absence of Douglas-fir cones. 



Squirrel Cutting 



The tree-banding experiment provided additional information about squirrel effects 

 on seed production. Four trees with aluminum bands at Dunn produced 84 cones that 

 shed seed. Three shoots were cut before the bands were installed. The unhanded trees 

 at Butler still retained 58 cones at the time of seedfall, but careful examination 

 revealed that 16 cones and 39 shoots were cut by squirrels. 



Seed production from trees that had been banded in the Dunn area was more than 

 three times greater in 1953 (9,300 seeds per acre) than it was in 1951 (2,800 seeds per 

 acre), before these trees had been banded. Seed production from trees that had not 

 been banded in the Butler and Bluesky areas, however, remained about the same: in the 

 Butler area, it was 1,600 in 1951 and 1,700 in 1953; in the Bluesky area, it was 10,300 

 in 1951 and 10,400 in 1953. 



Cone Crop Forecasting 



At times it is desirable to forecast cone crops for purposes of timing seedbed 

 preparation or scheduling seed tree removal. This can be done by examining branches 

 in the upper half of the crown 2 years before a ponderosa pine seed crop will be 

 disseminated. Data from this study indicate that when the number of ovulate buds 

 average one or less per branch, few conelets will survive the period between bud 

 formation and first-year cone development. Any that do survive are highly vulnerable 

 to squirrels that are faced with a short food supply during the second year of cone 

 development. The poor seed crops of 1953 and 1956 resulted from three or less ovulate 

 buds per branch. The fair cone crop in 1954 was initiated by an average of six to 

 seven ovulate buds per branch. It is likely that 10 or more ovulate buds are required 

 per branch to produce a good ponderosa pine seed crop. 



If management planning can be delayed until 1 year prior to seed release, then 

 the observer, by counting the first -year conelets, can make a more accurate estimate 

 of the potential seed crop. This study showed that when less than one conelet remained 

 per branch after one year, a poor seed crop resulted. Fair seed crops resulted when 

 more than one conelet remained at the end of the first year of development. 



The number of Douglas-fir cones maturing at the same time as the ponderosa pine 

 cones probably influences the number of pine cones taken by squirrels. A good Douglas- 

 fir crop provides a readily available source of food for squirrels. Apparently, the 

 squirrels respond by feeding less heavily on the pine and a fair cone crop of pine may 

 mature. When an alternate source of food is not available, the squirrels usually feed 

 heavily on pine and reduce its production. 



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