The study plots, ranging from 5 to 50 percent in steepness, were located on 

 south- or west-facing slopes lying between 3,000 and 3,900 feet elevation. Although 

 ponderosa pine was dominant, Douglas-fir, its chief associate, was climax for these 

 areas. The habitat types (Daubenmire and Daubenmire 1968) on each of the study plots 

 were as follows (in order of decreasing moisture) : 



Bluesky - Pseudotsuga menziesii - Physoaarpos malvaceus (moistest) 



Warland - Pseudotsuga menziesii - Calamagrostis rubesaens s Arctostccphylos uva-ursi 



phase (includes Symphoricarpos albus and Spirea betuli folia) 

 Jackson and Dunn - Pseudotsuga menziesii - Calamagrostis rubesaens , Aratostaphylos 



uva-ursi phase (includes Spirea betuli folia') 

 Butler - Pseudotsuga menziesii - Calamagrostis rubesaens (driest) 



The soils developed in glacial till deposits. Silty volcanic ash mixed with local 

 colluvial materials in the upper horizons while the horizons below 8 to 15 inches were 

 of older colluvium. The soils were classified as Typic Cryandept at Bluesky and 

 Warland, Mollic Cryandept at Jackson, and Typic Cryoboralf at Dunn and Butler. All 

 were silty and loamy. Site quality class averaged IV or V for ponderosa pine by 

 Meyer's (1938) classification. 



Because there were studies on eight areas, the methods and results are presented 

 in the natural sequence of events under the five main headings: (1) cone production; 

 (2) cone stimulation; (3) seed dissemination; (4) seed survival; and (5) seedling 

 establishment . 



CONE PRODUCTION 



Roeser (1941) studied ponderosa pine seed development, in central Colorado, from 

 flowers to the mature cones. He found that an average of only about 1/4 of the pistil J 

 late flowers ultimately developed into mature cones; most of the mortality occurred in 

 the first season of cone development. Further studies on development of ponderosa pine 

 cones from the initial ovulate bud were made in western Montana to identify these 

 factors that limit cone production and are reported here. 



Methods 



Eight sample trees, at least 16 inches d.b.h., were randomly selected for study 

 in a partially cutover ponderosa pine stand at Bluesky (fig. 1). A total of 100 

 branches in the upper portion of the crowns of the trees (10 to 15 branches per tree) 

 were systematically selected. Losses of buds, conelets, and mature cones were de- 

 scribed by total number and apparent cause on each individually-marked branch; this 

 description was made for each stage of cone development. The trees were climbed and 

 data recorded four to seven times during the two-year cone-development periods for 

 each of the cone crops that matured in 1953 through 1956. 



In addition, a banding experiment was conducted to measure the effects of squirrels 

 on seed production. To prevent squirrels from climbing the cone-bearing trees on the 

 study plot at Dunn, all trees were protected in 1953 by 20-inch-wide aluminum bands. 

 Stands used as check plots were not banded on the nearby Butler study area. In late 

 1953 four banded and four unhanded trees were climbed and the effectiveness of bands 

 evaluated. Differences in seedfall at Dunn and Butler were measured by 20 seed traps 

 on each of these two areas. 



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