A NATIONAL PLAN FOE AMERICAN FORESTRY 1457 



England, for example, that in young mixed stands of the almost 

 worthless gray birch and the valuable northern white pine the latter 

 is suppressed unless the birch is cut out, and that the benefits to the 

 stand justify the expense in the long run. Similarly, weeding of young 

 stands of spruce and fir in the Northeast to reduce the competition 

 from worthless fire cherry, red maple, moosewood, etc., may sub- 

 stantially shorten the period required for the softwood species to reach 

 merchantable size. 



The mixed hardwood stands which come in so generally on clear- 

 cut areas throughout the northern hardwood and oak-chestnut regions 

 tend to be dominated by the least desirable species and can usually 

 be greatly benefited by a judicious weeding when from 5 to 7 years 

 of age. In the mixed forests of central New England, in fact, such 

 weeding offers prospect of yielding a greater return on the investment 

 required than almost any other single measure. 



In the spruce-northern hardwoods region of the Northeast, culling 

 of the more valuable softwoods in the past has left large areas occupied 

 by overmature hardwoods which usually have large, spreading crowns 

 and are often defective or otherwise unmerchantable. These worth- 

 less hardwoods occupy space which might be utilized by valuable 

 trees and often overtop or suppress saplings or reproduction of de- 

 sirable species. Girdling these worthless or low-value hardwood trees 

 may immediately increase the current growth of a spruce and fir 

 understory as much as fivefold. Such girdling operations cost not 

 more than $2 per acre, and this investment will usually be amply 

 returned by increased growth within a few years. Girdling of worth- 

 less hardwoods competing for space in the mixed stands will also 

 stimulate the growth of spruce and fir of merchantable size; indeed, 

 the increased growth on such trees is sufficient to warrant systematic 

 girdling operations about 10 years in advance of logging in much of 

 the spruce-northern hardwood region. 



The outstanding example of the commercial application of girdling 

 is to be found on a pulp wood operation near Glens Falls, N.Y. Sys- 

 tematic girdling of worthless hardwoods on lands cut over during the 

 past 15 years and on areas scheduled to be cut in the next 8 to 15 

 years has been under way since 1926. Prior to January 1929, more 

 than 5,000 acres had been covered at a total cost of about $10,000. 

 In an experiment started at Corbin Park, N.H., in 1905, an understory 

 of spruce and fir is showing a very remarkable response to release 

 through girdling of overtopping hardwoods. Growth on the girdled 

 area has been at least five times that on the ungirdled area. Here, 

 twenty-five years after treatment, the girdled plot shows a stand 

 of about 12 cords per acre of merchantable pulpwood with a current 

 rate of increase ol about 1 cord per acre per year, while the ungirdled 

 plot shows a stand of less than 2 cords per acre. An experiment 

 started in 1919 by the Eastern Manufacturing Co. in Maine demon- 

 strates that girdling to release merchantable-sized spruce and fir may 

 yield a profit of $2 per acre per year. In this experiment the girdling 

 of all hardwoods down to a 2-inch diameter released 40 softwood trees 

 per acre averaging 8 inches in diameter and having a volume of 272 

 cubic feet. After 11 years there were 160 merchantable trees per 

 acre with a volume of 1,050 cubic feet, and the annual growth rate 

 had increased from one seventh to three fourths cord per acre per year. 



