THE RELATION OF GRAY BIRCH TO THE REGENERATION 



OF WHITE PINE 



r>Y J. W. TOUMKY 



Professor of Forestry, Yale University 



During the months of July and August, 1918, the writer made a 

 series of field studies on the natural regeneration of white pine near 

 Keene, in southern New Hampshire. The primary object of these 

 studies was to ascertain so far as possible the effect of gray birch of 

 varying ages and densities on white pine reproduction and on its rate 

 of height growth. The studies were made for the most part on the 

 forest owned by the Yale School of Forestry some two miles south of 

 Keene. Some of the studies, however, were on privately owned for- 

 ests west of Keene. All of the areas where studies were made are 

 in or adjacent to the sand plain of the Ashuelot River. The under- 

 lying rock formation is granite, which appears at the surface only in 

 a few places adjacent to the sand plain. A deep mantle of sand for 

 the most part covers the rock formation. The surface soil where the 

 studies were made is for the most part relatively free from stones, a*nd 

 is light, loamy sand, much better adapted for forest crops than for 

 agriculture. It is better suited for white pine and red pine than for 

 hardwoods. The writer knows no general locality better suited by 

 nature for the growth of white pine, where natural reproduction can 

 be more easily attained and where the young trees suffer less from 

 competition with hardwoods. 



Most of the lots near Keene owned by the School of Forestry are 

 more or less completely stocked with white pine from natural repro- 

 duction. Until recently most of the young reproduction was over- 

 topped by gray birch of varying ages and varying degrees of density. 

 Approximately ten years ago improvement work was begun in remov- 

 ing the gray birch and thus exposing the pine to the light and air. The 

 hardwood has been removed from considerable areas during the past 

 four years; thus, during the past winter some 500 cords were cut, 

 mostly gray birch from two to six inches in diameter and from 20 to 30 

 feet tall. These hardwoods formed a more or less complete canopy 

 over the pine, or else when sufficiently open some of the pines reached 

 into the hardwood canopy, where their tops were broken or badly 

 whipped by the birch, due to wind action. 



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