New volume model

Developing and adopting a new timber volume model

Consultations with university forestry experts identified potential improvements to DNR’s timber cruising methods and software system. It was suggested that switching to a “taper model” could more accurately calculate the volume of wood in a tree. A taper model can be used to predict the diameter of a tree at any point along the stem and can be used to estimate the volume of wood up to that point. 

The DNR collected data and tested the taper model, working to fine-tune it for local conditions. This resulted in the 2019 development of the Michigan variant of the Clark, Souter and Schlaegel (CSS) taper model, called the CSS-M, as modified by Dr. MacFarlane of Michigan State University.

The Michigan taper model is based on analysis of approximately 3,000 trees with a modeling error of about 2%. Volumes are calculated in cubic volume and are then converted to cords and board footages.

For further information, please view: New Models for a New Michigan DNR Timber Volume Inventory System, by Dr. MacFarlane. 

Refer to the volume tables document for details on the new system.