• Paul, Benson H.
  Forest Products Laboratory, Forest Service, U.S. Department of Agriculture, Madison, Wisconsin
  

In work at the Forest Products Laboratory on wood from 11 red pine plantations ranging in age from 14 to 37 years, it was found that wood at the 8-to 12-foot height averaged between 0.317 and 0.372 in specific gravity. In these plantations the increase in specific gravity was not entirely consistent with age, although there was a general tendency to that relationship. The plantation with the heaviest wood, 0.372, was 34 years of age and diameter growth of the trees averaged 12.8 rings per radial inch. The plantation producing wood that was lowest in average specific gravity, 0.317, was 23 years old, and diameter growth averaged 5.7 rings per inch. in these plantations the trees with the highest average specific gravity were of slowest growth, particularly in their outer 10 years.