For use by qualified professionals in conjunction with the 10th Edition of the Guide for Plant Appraisal published by the International Society of Arboriculture. As of July 2019 the Appraisal Factors for Illinois have been updated. These factors will be updated by the Regional Plant Appraisal Committee every 4-5 years, or as needed.
Updated Illinois Appraisal Factors
The Plant Appraisal Committee has updated the Appraisal Factors for use in plant appraisals in Illinois. Below are links to the Illinois Regional Map and updated appraisal factors for each region in Illinois. In past surveys only a handful of species were surveyed. In the 2019 data collection a total of 60 deciduous and evergreen plants were surveyed and calculated based on the following criteria:
- Caliper of the largest commonly available tree
- Wholesale purchase price of the largest commonly available tree
- Cross–sectional area
- Unit Cost of the largest commonly available tree
The Regional Map has also been redrawn in order to better reflect the areas where regional grower markets exist. Please use this map to determine which set of regional replacement tree data to consult while performing your appraisals.
The 10th Edition of the Guide has brought a few changes to the appraisal process. Below are a few them:
- Trunk Area of trees 30” DBH and greater is no longer adjusted
- Species Rating has been removed and replaced
- The three new depreciation factors are:
- Condition: Physical deterioration. The components of Condition are health, structural integrity, and form.
- Functional Limitations: Factors associated with the interaction of a tree and its planting site and will affect plant condition, limit development, or reduce utility of the plant within the foreseeable future. These factors include site conditions, placement, and genetic limitations.
- External Limitations: Factors that are outside of the property, out of the control of the property owner, and that will affect plant condition, limit development, or reduce plant utility within the foreseeable future. These factors include legal restrictions that limit the development of the plant and environmental factors that affect long-term health and life expectancy of the plant.
Plant Appraisal Committee Members:
Aaron Schulz, Chair