Mechanism relating cambial electrical resistance to periodic growth rate of balsam fir

Abstract

Cambial electrical resistance (CER) and periodic growth rate (PGR) of canopy balsam fir (Abiesbalsamea L.) trees were determined on 26 sites in Maine, New Hampshire, and Vermont, U.S.A., varying in level of spruce budworm defoliation. Determinations of water and potassium concentrations were made of the bark, wood, and vascular cambial zone (VCZ). Low CER was associated with high PGR and vice versa. A decline in PGR on all 26 sites was detected during early 1970's to late 1970's. It was not associated with, but may have been exacerbated by, spruce budworm defoliation. The most probable mechanism relating CER to PGR in balsam fir was variation in the thickness of VCZ and its correlation with potassium content. Thicker VCZ of faster growing trees released more potassium into the solution contacting electrodes than thinner VCZ of slower growing trees.