Relationship Between Tree Age and Sapwood/Heartwood Width in Populus Tremuloides Michx.

K. C. Yang, G. Hazenberg


Populus tremuloides Michx. has become a major commercial species within the last decade. The proportion of sapwood and heartwood has a significant impact on various uses. The relationship between tree age and sapwood/heartwood width was studied using 101 trees of Populus tremuloides Michx. The sample trees were grown at various stand densities in the Lakehead University woodlot, Thunder Bay, Ontario. The ages of the trees ranged from 5 to 90 years at breast height. The boundary of sapwood and heartwood was delineated with the IKI technique. Sapwood and heartwood widths were expressed by ring count and by linear measurement. The sapwood basal area was calculated and expressed as the difference between stem basal area and heartwood basal area. It was found that sapwood width (ring count basis) increases with increasing tree age. A curvilinear relation between sapwood width and tree age was found. Sapwood basal area increased linearly with increasing tree age. Heartwood width, both in ring count and linear measurement, showed a positive relationship with tree age. Heartwood started to be formed at age 5. The average rates of sapwood and heartwood expansion were found to be 0.40 and 0.60 ring per year, respectively. It is concluded that tree age is an important factor that affects sapwood/heartwood width and sapwood basal area in P. tremuloides.


Sapwood/heartwood width;tree age;basal area;Populus tremuloides

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