Particle 



Volume 

 (Percent) 



Surface area 

 (Percent) 



Branches 51.2 26.4 



Cones 21.4 4.3 



Cone scales 11.4 25.1 



Bark 8.0 13.2 



Staminate flowers ^ 4.9 4.4 



Leaves \ 2.4 19.6 



Grass . 7 7 . 



100.0 . 100.0 



In cheatgrass, stalks comprised almost two-thirds of the volume but only one- 

 third of the surface area. The panicles (spikelets, glumes, and peduncles) comprised 

 only a small portion of the total volume but a little over one-third of the surface 

 area as shown in the following tabulation: 



Plant part Volume Surface area 



(Percent) (Percent) 



Stalks 61 ■ 32 



Leaves 25 29 



Panicles: • 14 .39 



Spikelets 9 19 



Glumes 3 . 15 



Peduncles 2 5 



100 ■ 100 



Randomness of Particle Orientation 



Forest and range fuels are composed of particles oriented in many directions. How 

 ever, apparently no studies have been conducted that analytically define the randomness 

 of particle orientation or the type of predominant orientation. Particle orientation 

 should be taken into account when designing and using sampling methods for measuring 

 fuel properties in the field. 



Pine needles were randomly oriented (at the 0.01 confidence level) in the hori- 

 zontal plane for all stands combined as well as for 12 of the 13 stands individually. 

 In the one stand, the tip of a branch fell across the sampling plane on one plot so 

 that a large number of needles attached to the branch lay in one direction. Such 

 situations can be expected to occur sporadically in the forest. All stands grew on 

 flat to moderately sloping terrain. Whether or not the generally random orientation 

 of needles would hold on steep slopes is conjecture. 



All six kinds of cheatgrass particles were nonrandomly oriented in the vertical 

 plane. Except for glumes, the other particles were oriented predominantly within 30° 

 of true vertical. A considerably greater number of glumes than expected under a ran- 

 dom assumption were oriented within 30° of true horizontal. 



Relationships Between Properties 



Relationships between fuel properties were examined to see whether or not some 

 fuel properties may be replaced by or estimated from other fuel properties or from 

 sample data on number of particle intersections. The relationships between the three 

 properties describing porosity are shown by the correlations in figure 8. 



12 



