TIMBER VALUATION 



49 



or less pure stands so that the subtypes are easy to distinguish. 

 The reasons for differences in composition are not always clear. 

 Lumbering, however, usually favors the light seeded species like 

 red maple, spruce and balsam at the expense of the cedars. Con- 

 sequently, a cedar swamp seldom comes up to cedar again when 

 the poles and posts have been cut out. 



In spite of the poor growth conditions insects and fungi ordi- 

 narily do very little damage in the swamp type. The most 

 notable exception to this general statement is the damage done 

 to tamarack by the larch sawfly in the early 8o's. Nearly all 

 the larger trees were killed over wide areas. Butt rot — Trametes 

 pini and Polyporus schweinitzii — occurs on all the coniferous 

 spedes found in this typ>e. While fire is very destructive when it 

 does get into the type the wetness of the soil prevents this form 

 of damage except in very dry seasons. But in droughts swamp 

 fires do occasionally occur and are very difficult to extinguish 

 because they bum down into the accumulated duff and peat and 

 may smoulder for days only to break out anew in fresh places. 



The unfavorable growth conditions have already been referred 

 to so that it is merely necessary to add that a swamp cannot be 

 expected to produce more than one-half what the spruce and hard- 

 wood types win yield in the same time and one-fiith the returns 

 from good white pine soil. This is because the trees are shorter 

 and smaller, not because they do not stand close enough together. 

 Average diameter and height growth figures are as follows: 



25 years 



50 years 



75 years 



100 years 



Tamarack 



dbh. 

 2 inches 

 5 inches 



7 inches 



8 inches 



Arbor Vit« 



dbh. 



1 inch 10 feet 



2 inches 15 feet 

 4 inches 23 feet 

 6 inches 32 feet 



Spruce 



dbh. 



I inch 7 feet 



3 inches 14 feet 



4 inches 26 feet 



Timber Valuation. — Estimates of this type present only one 

 difficulty, the swampy ground. Hence winter is the best time 

 to work in them. The small size of the type usually necessitates 

 a high percentage estimate but to offset this the stands are usually 



