• Piene, Harold
  

Intact healthy needles from young Balsam fir trees (Abies balsamera L. Mill) with various defoliation histories showed increased weights and concentrations of nitrogen; phosphorus, potassium, calcium, and magnesium compared to similar needles from shoots that were not defoliated. During the first year of defoliation of the Current year's foliage, a concomitant reduction in Volume growth occurred. A loss of two age classes of needles resulted in about 50 percent reduction of the project stem volume growth.