16 



THE IMPROVEMENT OF A MATURE DENSE GROVE. 



A large number of groves are merely parts of the old hardwood 

 forest, having a preponderance of sugar maple in the mixture. These 

 trees have their normal forest form a long, smooth stem and compact 

 crown. There is little to be gained in actual sap production by 

 thinning such a stand (p. 14), as it has generally passed the period 

 of vigorous growth and would not develop larger crowns, although 

 the sap season may be brought on earlier by opening up the grove to 

 sunshine. The mixture can be regulated, however, and provision 

 made for a pure growth of maple to succeed the old forest as it passes 

 away. The usual mixture of birch, beech, elm, basswood, and ash 

 may be gradually removed, and the reproduction of maple thereby 

 assured. This thinning should pay for itself in most localities, from 

 the resulting fuel and saw timber. In making such a thinning the 

 following precautions should be observed: 



(1) When the trees to be removed occur in groups, they should not 

 all be cut out immediately, leaving large gaps in the forest cover, 

 since forest-grown sugar maples have a broad, shallow, root system, 

 and are subject to windfall when suddenly exposed. The trees 

 which crowd the best maples should be taken out first; the rest 

 should be removed later, when the sugar trees have become more 

 wind firm. 



(2) Where several maples crowd each other and form a dense cover, 

 those with the smallest crowns, those which are unsound, and those 

 which show signs of bad health or decline should be removed. 



(3) Young maples which show possibilities of good crown develop- 

 ment should be cut free from interference on every side. 



(4) If the grove borders on open land, it should not be thinned for 

 a distance of at least 25 feet from its edge. This is a safeguard 

 against damage by storms, and is particularly important in borders 

 exposed to heavy winds. 



(5) When practicable, the young growth of other species than 

 maple should be removed. 



(6) It is well to accomplish the thinning in a series of years, rather 

 than at once and radically, thus avoiding violent changes. 



(7) It is important to maintain the humus and ground moisture in 

 every maple grove. In localities where natural forests of sugar maple 

 are common the danger of destroying the proper soil conditions by 

 letting in the sunlight is not great, but if a grove of this type lies 

 where the summers are hot the cover must be broken very gradually. 



THE IMPROVEMENT OF A MATURE OPEN GROVE. 



In the more settled and less wooded portions of the maple sugar 

 producing district, it is noticeable that a large proportion of the groves 



252 



