Increased interest in the seventies prompted us to resurrect the data and summarize them 

 in a form that we feel both takes advantage of the strengths of the data and puts them in 

 usable form. As suggested by some of the earlier workers, we extracted the earliest, latest, 

 and average dates, plus standard errors, of the phenological events. Because not all stations 

 were read for the whole study period, not all events were recorded every year for each station, 

 and because some stations were added and some dropped, a uniform data base was not available. 

 So that at least some data could be summarized for nearly every event for every species, it 

 was necessary to combine data. We chose to combine data from those stations east of the 

 Continental Divide and the same for those west of the Divide. 



RESULTS 



Included in the results are 50 different species--13 conifers, 22 shrubs and hardwoods, 

 and 15 herbaceous species. Of these, 7 conifers, 17 shrubs and hardwoods, and 7 herbs were 

 conmion to and were measured on both sides of the Continental Divide. Of course, some species 

 occur only west or east of the Divide. 



The number of observations for a given species, east or west of the Divide, and in a given 

 phenological event, was essentially a function of species abundance and distributions. Numbers 

 ranged as high as 82 observations for starting date of lodgepole pine shoot elongation east of 

 the Divide, to only one observation for several event -species-area combinations. 



Two main geographic areas (east and west of the Continental Divide) , and three plant 

 classes [conifers, hardwood trees and shrubs, and herbs) are used to stratify the data. Figure 

 7 illustrates the sequence of phenological events for two common forest species of the Northern 

 Rockies. Tables 1-b document the average, earliest, and latest dates and the standard error 

 for all 50 species. 



4^" 



^ ^ <,o^ 



^ ^ .o^ o<> 



Larix occidentalis 



4: 



II 





1 





II II 



1 





APR. 



IVIAY 



JUNE 



JULY 



AUG. 



SEPT. 



OCT. 



Acer glabrum 



<<< 



^ ^ ^ ^ 



ft'' 





1 1 1 



1 





1 1 





1 



APR. 



AAAY 



JUNE 



JULY 



AUG. 



SEPT. 



OCT. 



Figure 7. --An example of the time sequence of phenological events for two species west of the 



Continental Divide. 



7 



