A leaf area – sapwood area ratio developed to rate loblolly pine tree vigor

Abstract

Stem cross-sectional sapwood area was linearly related to leaf area in loblolly pine. A better relationship was obtained using cross-sectional sapwood area taken at crown base than at breast height. The relationship was affected by time of sampling, with time of maximum needle biomass giving the best correlation. Specific leaf area (area in square centimetres per gram dry weight) was variable, but the mean of 95.32 cm2/g is comparable to reported values for other species. The leaf area-sapwood area ratio at breast height varies only slightly among individual trees so that a mean ratio of 0.29 can be utilized to accurately predict leaf area. The ratio between current-year or previous-year sapwood production and leaf area (grams per square metre of foliage) was used as an indicator of tree vigor. Tree vigor values varied greatly (21-180 g/m2), but were normally distributed within this range.