© 1995 Heron Publishing—Victoria, Canada
Canopy dynamics and the morphological development of Abies balsamea: effects of foliage age on specific leaf area and secondary vascular development
D. W. Gilmore (1), R. S. Seymour (1), W. A. Halteman (2) and M. S. Greenwood (1)
1. Department of Forest Ecosystem Science, College of Natural Resources, Forestry and Agriculture, University of Maine, Orono,
ME 04469-5755, USA / 2. Department of Mathematics and Statistics, College of Sciences, University of Maine, Orono, ME 04469-5752, USA / Received April 12, 1994
Summary
Data were collected from two branches from each whorl of nine open-grown Abies balsamea (L.) Miller trees to test the hypothesis that specific leaf area (SLA, m2 projected fresh leaf area kg–1 oven-dry foliage) is constant among five foliage age classes (current-year, 1-year-old, 2-year-old, 3-year-old and 4-year-old-plus).
Between-tree variation in SLA was greater than within-tree variation. Differences in SLA among the foliage age classes were
small, but statistically significant, showing a trend of decreasing SLA with increasing foliage age. Using data from two previous
biomass studies, we found that three different methods of calculating SLA of individual trees produced the same projected
leaf area estimates.
To test the hypothesis that foliage mass increases with foliage age as a result of secondary xylem or phloem development,
we examined the secondary vascular development of foliage collected from five age classes and three crown sections in an open-grown
A. balsamea. The number of rows of xylem cells was not constant among foliage age classes, but the differences were small and showed
no consistent pattern of change with foliage age. Total number of rows of phloem cells increased, number of living rows of
phloem cells decreased, and the number of rows of nonliving crushed phloem cells increased with foliage age.
Keywords:
balsam fir, needle shrinkage, nested analysis of variance, projected leaf area, secondary phloem development, xylem.
