THE NORTHERN HARDWOODS REGION 



281 



others. Of course only a very young stand can be economically 

 thinned in this way. 



Frequently the owner of a sugar grove considers it desirable 

 to keep down reproduction and undergrowth with the idea of 

 making the interior of the stand as open as possible, — because 

 then men and teams can get around and collect the sap more 

 easily. Grazing animals are sometimes turned in to accompHsh 



Fig. 98. — A pure bland uf yuung hard nuiple in which a hr^l thinning has been made, 

 reducing the number of trees per acre from 4000 to 2000. The product of the thinning 

 was too small to be merchantable. 



this purpose. Such an opening up of the stand is a mistake and 

 true forest conditions should be maintained for two reasons, 

 first, because sugar maple needs forest conditions, especially 

 a thick, moist leaf litter underneath, for thrifty development, 

 and second, because for the longest and largest yield of sap the 

 ground should be protected from sudden thaws and kept frozen 

 as long as possible and this is best accomplished by the thick leaf 

 litter and heavy undergrowth. Reproduction should be encour- 

 aged in all openings and allowed to develop. Later on it may be 

 needed to replace some older trees which have been injured. 



