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TIMBER STAND VOLUME CLASS: 

 Critical to Understanding Tongass Timber Issues 



The Importance of Volume Class 



For decades the Forest Service has used the net timber volume per acre of given timber stands 

 as the key characteristic of the Tongass timber inventory. 



High volume of timber on an acre of old growth forest on the Tongass is generally an 

 indication that the stand contains the very large, 200-600 year old Sitka spruce and western 

 hemlock that are the most valuable wood products in Alaska. Similarly, high volume old 

 growth stands usually have fewer trees relative to the volume of the stand; this means fewer 

 logs need to handled to recover a given amount of wood. 



Research on deer habitat shows that timber stand volume class is the best indicator of deer 

 winter habitat quality. The same big trees that are found in high volume old growth stands 

 create optimal winter habitat for Sitka black-tailed deer. The canopies of the large trees 

 intercept snow, allowing deer more mobility during periods of heavy snowfall. The uneven 

 canopy of the forest still allows enough light penetration for luxuriant deer browse to grow. In 

 contrast, low volume stands intercept less snow and have less browse. Second growth stands 

 grow in dense thickets that have no understory browse. 



Classificat ion of Volume Class 



The Forest Service classifies timber stand volume class according to the units "thousands of 

 board feet per acre", or mbf/a. The agency also numbers different volume classes. For 

 example, the highest volume class stands are called "Volume Class (VC) 7", and have more than 

 50 mbf/a. The Forest Service classification scheme is summarized in the table below. 



OLD GROWTH TIMBER STAND VOLUME CLASSES 

 Tongass National Forest 



Volume Class Volume/Acre (mbf/a) 



3 0-8 



4 8-20 



5 20-30 



6 30-50 



7 50+ 



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