Document: SCO-3-35-28

Family effects on leaf area predictive equations for Pinus taeda.

ROBERTS, S.D.* ¹ and T.J.DEAN ²

Mississippi State University, Mississippi State, MS 84321 USA ¹
Louisiana State University, Baton Rouge, LA 70803 USA ²

Abstract:
Accurate estimation of leaf area index (LAI) is crucial for investigations into the production ecology of forested systems. One means of estimating LAI is through the use of allometric relationships between individual-tree leaf area (LA) and either breast-height stem diameter (DBH) or sapwood cross-sectional area. These relationships, once thought to be universal for a given species, have more recently been shown been shown to vary by site. Modern plantation forestry uses a variety of genotypes which can vary in LAI. To better understand how individual trees accumulate LA in plantations, predictive equations are needed that account for possible genetic effects on the allometric relationships. Our objective was to determine if genetic differences exist in the relationship between LA and DBH in Pinus taeda. We destructively sampled 15-year-old trees of eight families selected to represent either "fast" or "slow" growing genotypes. The regression between logarithm of LA and logarithm of DBH was highly significant (r² = 0.81, p < 0.0001). In addition, the relationship was significantly influenced by family (p = 0.0045). When analyzed separately, r² values for individual families ranged from 0.69 to 0.98, with a mean value of 0.86. When the fast growing families were grouped and compared against the slow growing families, growth rate was not found to significantly influence the relationship (p = 0.28). There was greater variability in the slope of the relationship for the faster growing families, but the mean regression relationship did not show any differences between the two groups. Our results clearly indicate that LA-DBH relationships can differ between families, but these differences do not appear to be related to inherent growth rate.

Keywords: leaf area index, allometric relations, genetic differences

This abstract is being presented at: 9:00 AM in session:
Oral Session #1: Plant Carbon Allocation.