RESULTS AND DISCUSSION 



Several biological and physical factors drastically reduced the potential number 

 of seeds available for animals, and they in turn further reduced the number available 

 for germination. To illustrate this reduction of the seed crop, the results are pre- 

 sented in a time sequence, starting at the time of initial ovulate bud formation and 

 ending just before seed germination. This 33-month period is diagramed to identify and 

 show how the most important factors affected cone and seed survival throughout the se- 

 quence (fig- The two important time segments emphasized in these discussions are: 



(a) before seed dispersal when red squirrels were the most important predator; and 



(b) after seed dispersal when ground-dwelling rodents were most important. 



Effects of Animals on Cones 



During the 4 cone years studied, only about one- fourth of the potential cones 

 survived the first year of development (fig. 2). First-year cone survival ranged as 

 high as 48 percent for the prospective 1956 crop and as low as 3 percent for the 1955 

 crop. Animals had little to do with this high mortality; abortions were primarily 

 responsible, reducing the potential cone crop nearly two-thirds. Abortion rates ranged 

 as high as 73 percent for the 1954 cone crop and as low as 21 percent for the 1956 crop. 

 The causes of these extremely large and variable abortion rates were not determined. 



4 



