Extractives 



During both summers, Douglas-fir needles showed much more change in extractive 

 content than did ponderosa pine. In 1968 fir needles gained in extractives until mid- 

 August, at which time they decreased (fig. 9). This trend was statistically significant 

 at the .05 level (fig. 10) (Appendix E) . Pine showed a similar trend of lower magnitude 

 in 1968, but it was not significant (Appendix F) . Pine showed little or no change dur- 

 ing 1969, but fir had a significant increase from 4-1/2 to 8 percent during the 1969 

 fire season (figs. 11 and 12) (Appendixes G and H) . 



An interesting aspect of these trends is the difference between 1968 and 1969. The 

 mid-summer decrease in 1968 coincided with the onset of precipitation, while during the 

 dry year the gain in extractives continued through to September. Pine seemed to main- 

 tain a high extractive content (8-9 percent) during both fire seasons, but a dip did 

 occur in 1968 in early August. Tukey's test (1956) showed this dip to be statistically 

 insignificant . 



12 I- 



11 



10 



O New 

 • 1 Yr. 



5 



JUNE 



JULY 



AUG 



SEPT 



OCT 



Figure 9. — The ether extractive aontent of Douglas- fir needles 

 during the 1968 fire season. 



9 



