NITROGEN CONCENTRATION IN FOLIAGE OF PINUS RADIATA AS AFFECTED BY NITROGEN NUTRITION, THINNING, NEEDLE AGE, AND POSITION IN CROWN

Foliar nitrogen concentrations were sampled at four positions on three Pinus radiata D. Don trees in each treatment of a 7-year-old replicated thinning X nutrition experiment. Nitrogen concentration decreased with needle age and from top to bottom of the crown, but was unaffected by thinning treatment. In 1-year-old foliage the decrease in foliar nitrogen from top to lower middle of the crown was similar over the range of nitrogen states examined. As needles aged, differences in needle nitrogen among nutritional treatments decreased.