METHODS 



Two sites in western Montana with mixed ponderosa pine and Douglas-fir, 

 approximately 1 acre each, were used for this study. In 1968 the moisture content, 

 ether extractive, and energy data were collected from a stand at 3,500 feet, southwest 

 exposure, and 58-percent slope. The ponderosa pine averaged 24 feet high and 4.9 inches 

 d.b.h. The Douglas-fir averaged 31 feet high and 5.2 inches d.b.h. Physiological 

 changes that might result from the large amount of foliage sampling required in this 

 study necessitated a change of site in 1969. The 1969 site was at 3,840 feet, south- 

 west exposure, and less than 10-percent slope. On this site, the pine averaged 39 feet 

 high and 10.9 inches d.b.h., and Douglas-fir averaged 38 feet high and 8.5 inches d.b.h. 

 All trees were dominant or codominant. 



Twelve trees of each species were randomly tagged on each site. Three trees of 

 each species were randomly chosen for sampling on a given date. All sampling occurred 

 between 1300 and 1600 hours to minimize the effect of diurnal variation.^ Two branches 

 from each tree were cut from the middle one-third of the south side of the crown. A 

 portion of the needles of each age class (new, 1 year, and 2 years) was immediately 

 sealed in a tared 500 ml. flask. These flasks were placed in an insulated container in 

 the field and the same flasks were used for moisture determination by solvent distilla- 

 tion (fig. 2). The foliage for extractive and energy determinations was placed in an 

 insulated chest and frozen with dry ice. The frozen samples were separated by age class 

 and placed on a freeze dryer for 14 hours. They were then ground in a Wiley mill and 

 sifted to 40-60 mesh. Ether extractives (AOAC 1965) and heat content (ASTM 1967) were 

 determined by standard methods. Energy content of untreated and ether extracted 1-year- 

 old foliage samples was determined. All extractive and energy data were reduced to a 

 dry weight basis by Karl Fischer titration (ASTM 1962). 



Precipitation, temperature, and humidity were measured at a nearby fire-weather 

 station and the buildup index was computed (USDA Forest Service 1964). The moisture 

 and extractive content data were statistically analyzed using Tukey's test (Snedecor 

 1956). 



12 TREES PER SPEOES 



3 T5EES PICKED AT RANDOM 

 ON A GIVEN SAMPLE DATE 



F-igure 2. — The foliage sampling 

 scheme used for ponderosa pine 

 and Douglas- fir 



NEEDLES PICKED BT AGE QASS 



^Philpot, op. cit. 



2 BRANCHES CUT 



ROM THE MID -THIRD OF EACH TREE 



4 



