Measuring tree-ring increments on tree bole sections with a video-based robotic positioner

Area of Science:

• Dendrochronology
• Forestry Science
• Image Analysis

Background:

• Traditional tree-ring measurement using microscopes is time-consuming.
• Accurate radial increment data is crucial for understanding tree volume growth and stand dynamics.
• Old-growth ponderosa pine stands require efficient methods for assessing long-term growth patterns.

Purpose of the Study:

• To develop and evaluate a system that accelerates the measurement of radial tree-ring increments.
• To automate the process of measuring and recording annual growth from tree stem disks.
• To enable faster acquisition of growth data from numerous samples for volume growth determination.

Main Methods:

• A video imaging system integrated with a personal computer and a 3-axis positioning system replaced traditional microscopy.
• Operators used a computer-driven mouse to select tree rings on a monitor, with the computer measuring and recording distances.
• Menu-driven software facilitated task selection, data formatting, checking, and organization.

Main Results:

• The system achieved measurement resolutions of 0.026 mm, with potential for finer resolution.
• Measurement variability tests showed standard errors of 0.006 mm or less for individual operators.
• Low correlation coefficients (as low as 0.66) among radii suggest single-radius measurements may not fully represent radial growth in older trees.

Conclusions:

• The developed system significantly speeds up tree-ring width measurement compared to traditional methods.
• Automated measurement and recording enhance efficiency in dendrochronological studies.
• The system's potential for automatic ring detection offers further advancements in tree growth analysis.