112 Forest Club Annual 



The difficulty of accurately determining a cover type in this 

 region can be seen from these various mixtures. In some cases 

 it is almost impossible to determine where such a type begins and 

 where it ends. It means that a reconnaissance crew before start- 

 ing on this work must have some standard to go by. For instance 

 the white pine hemlock cover type might be so designated that 

 it should contain forty per cent hemlock or over by volume, with 

 a corresponding amount of white pine. The white pine cedar 

 hemlock type might be standarized by saying that it should contain 

 25 per cent or more of each species by volume. The above per 

 cents are simply taken to show the principle and are not meant 

 to indicate a correct figure. The impossibility of mapping these 

 types in the field before the percentage by volume of each species 

 is determined is readily seen. 



The above list of cover types might be added to almost in- 

 definitely, determined by the varying mixtures and the fineness 

 of detail wanted. As yet no standard rule has been adopted for 

 such a classification of cover types by percentage of species in 

 mixture and the reconnaissance man is often confronted with a 

 hopeless problem. The cover types thus obtained are really 

 not types at all but an attempt to show the principal species of 

 timber and their location on a given area. A forest type is the 

 result of the effect of similar site conditions. Therefore it would 

 hardly seem proper, within the confines of such conditions, to 

 indicate as a new type all the slight variations in composition, 

 especially if such a type is determined arbitrarily by a certain 

 increased percentage of one species or another. Such a division 

 of the forest into cover types is however a most valuable one ; and 

 it is more needed at the present time, probably, than a division 

 into management types, especially in showing timbered areas to 

 a prospective purchaser. A map made from such a division of 

 the forest is purely a stand map and should not be confused with 

 a type map. The stand map is of present value only, while the 

 type map shows the potential value of the forest under manage- 

 ment. 



CAUSE OF THE FOREST TYPES. 



What might be termed the indirect cause for the formation 

 of the above described types is quite apparent, though the direct 

 cause is not so easily determined. The indirect cause is the aspect 

 or slope direction, which in turn determines the amount and angle 

 of insolation received, and the velocity and amount of wind. 

 These factors determine the rate of evaporation, the humidity of 

 the air, and the rapidity of snow melting, or, summed up, the 



