Performance of a canopy light interception model for conifer shoots, trees and stands

Area of Science:

• Forestry Science
• Ecological Modeling
• Plant Physiology

Background:

• Accurate modeling of canopy light interception is crucial for understanding forest dynamics and productivity.
• Previous models often simplify complex shoot and crown structures, leading to potential inaccuracies.

Purpose of the Study:

• To evaluate a hierarchical canopy light interception model at shoot, crown, and stand levels.
• To assess the accuracy of submodels for predicting light interception in lodgepole pine and Engelmann spruce stands.

Main Methods:

• Calculated mean silhouette areas and silhouette to total leaf area ratio (STAR) for individual shoots.
• Modeled crown shadow areas using random and regular shoot dispersion assumptions.
• Estimated mean canopy transmission using spatial distribution models for trees.

Main Results:

• Shoot silhouette area calculations agreed well with measurements; STAR values showed reasonable agreement.
• Crown shadow areas were underestimated, with regular shoot dispersion showing better results than random.
• Leaf area estimations from sapwood area were consistently underestimated.
• Canopy transmission was well-estimated by random models for Engelmann spruce and regular models for lodgepole pine.

Conclusions:

• The individual crown transmission submodel was the weakest component, potentially due to leaf area estimation issues.
• Further research is needed to determine optimal shoot distribution models (random vs. regular) for crown interception.
• Refined leaf area estimation methods are essential for improving canopy light interception models.