Reconnaissance Data and Marking Timber 459 



IV. Dense. — (31-28 trees per acre.) Humid slope type mixed 

 with White fir, also cedar, Douglas fir, Sugar pine and Lodgepole 

 pine. Soil : rich, sandy loam with gravel and disintegrated shales 

 and slates in mixture. Elevation 4500 to 5800 feet. 



V. Very dense. — (Over 28 trees per acre.) Humid slope type 

 like above, usually about 5500 feet. 



Having determined these density classes, the next step was to 

 ascertain the relation of these classes to the diameter groups 

 spoken of before. Accordingly, the average number of trees 

 per acre for each class and each diameter group was determined 

 and compiled into the following table : 



TABLE 2 

 Average Number of Trees per Acre 



Max- 

 Diameter Very Very Aver- imum 

 Groups Open Open Medium Dense Dense age^ Acre 



6-lOinches 0.63 3.0 3.4 5.3 9.2 2.8 48 



11-20 0.9 3.8 4.6 8.0 11.2 3.7 15 



21-30 1.2 2.7 5.3 8.4 13.5 3.8 15 



31-40 2.4 3.1 3.3 3.5 4.7 3.0 1 



Over40 1.7 1.8 1.3 0.9 1.1 1.5 1 



Totals 6.8 14.4 17.9 26.1 39.7 14.8 80 



Probably the most striking result of this table is that the aver- 

 age number of trees per acre above 5 inches D.B.H. is only 14.8. 

 The maximum acre given above is the acre in Class V that had 

 the greatest number of trees on it. It is interesting to note 

 here how the average compares with the best we have. Another 

 feature of this table is the poor representation of the lower 

 diameter groups and the large percentage of trees over 20 inches 

 in diameter. It is likewise interesting to note that as the density 

 of the stands increases, the lower diameter groups are better, 

 and the upper diameter groups more poorly represented. 



Density of Stands 

 It is by no means an easy matter to obtain figures on the 

 density of all-aged stands. Considerable time was spent in try- 

 ing to arrive at a method of determining this factor. It was of 

 no avail to try to compare our stands with German stands of 

 Scots pine, principally because of the great difference in sizes 

 and age of the two species and on account of the fact that stand 

 and yield tables are in most cases made for even-aged stands 

 under careful management. It was concluded that all the litera- 

 ture written would not be of as much use as a few hours spent in 

 * Properly weighted on basis of acreage. 



