SURVIVAL 

 PERCENT 



100 



CONE AND 

 SEED EVENTS 



MONTHS 



Ovulate 

 buds form 

 I Aug I 



LEGEND: 



Bud failures 

 Abortions 



b^^^S^^ Squirrels, birds, and 



possibly insects 

 t-:-:-:-:-:l Mice, chipmunks, birds, and 



possibly some invertebrates 



F lowering 

 (May) 



Conelets begin Cones mature 

 second season and disperse seed 

 (May) (Aug Sept.) 

 I I l_ 



Seeds 

 germinate 

 (May) 

 I 



12 



15 



18 



21 



24 



27 



30 



33 



Figure l.--Cone and seed development sequence of ponderosa pine and the most important 

 factors affecting their survival during a 33-month period. Survival percent 

 based on the potential seed crop present in the initial ovulate buds. 



Figure 2. — Factors affecting the 

 survival of ponderosa pine 

 cones during their first year 



of development. FIRST-YEAR DEVELOPMENT 



5 



