ONE CORD AN ACRE A YEAR 757 



Example of Crozvth Retarded by Crowding. 



Other experiments and demonstrations of improvement cutting have 

 been made during 1921 on the Stokes State Forest in Sussex County, 

 and on the lands of the East Orange Water Reserve in Essex County. 

 Although only the preliminary cutting and growth measurements have 

 been made, the latter demonstration afifords an excellent example of 

 what happens when thinnings and improvement cuttings are not made 

 in time. 



Two tracts of mixed hardwoods growing side by side on a rich, 

 moist, gravelly, clay-loam soil, too rocky for agriculture, were selected. 

 Both were comparatively even-aged stands, except as reproduction 

 of tolerant species — maple, beech, etc., had cone in from time to time. 

 Both tracts grew from sprout and seedling reproduction following clear 

 cutting, but with this difference, one tract was 25 years old and the 

 other 50. The principal species in the order of their abundance were 

 white oak, red maple, black oak, and red oak, with some hickory, beech, 

 ash, black gum, sassafras, blue beech, and dogwood. As far as can be 

 learned both tracts have grown under similar conditions, the only 

 difference being that of age. 



The 25-year old stand contained 826 trees per acre from 2 to 

 8 inches in diameter with an average diameter of 3.7 inches and a total 

 volume of 1,423 cubic feet, or 17.8 cords per acre. The 50-year-old 

 stand contained 630 trees per acre from 2 to 10 inches in diameter with 

 an average diameter of 4 inches, and a total volume of 1,635 cubic feet, 

 or 20.4 cords per acre. The trees on both tracts showed a marked 

 slowing up of growth at about 20 years of age, which means that 

 the 25-year-old stand is just beginning to show the retarding eft'ects 

 of crowding, whereas the 50-year-old trees have grown slowly for the 

 last 30 years; in the 50-year-old stand there are approximately 200 

 trees per acre less than in the 25-year-old stand, the average diameter 

 is only 0.3 inch larger, and the volume of wood only 2.6 cords per acre 

 greater. Assuming that the 50-year-old tract at 25 years of age wa^ 

 identical with the present 25-year-old tract adjoining, as seems justi- 

 fiable, then it has increased in volume at the rate of 0.1 cord per acre 

 per year for the past 25 years. This figure checks closely with the 

 growth observed in the crowded check plot described above on the 

 Lebanon State Forest, after 7 years of growth. 



Following these preliminary measurements and observations, thin- 

 nings were made in both tracts with check plots left for control. In 



