Tree Health level assignment
Some trees in a Pittsfield Township conservation easement were identified as fair to poor. Can you tell me how such a rating would be determined and what categories there are?
Washtenaw County Michigan
First any ratings should be done by a trained expert. In the field of Urban Forestry tree evaluation is taught as part of the curriculum. Trees are evaluated by their species, then by physical factors (number of limbs dying or dead, structure, growth, injuries to roots or stems). It also depends on their location based on their species (if the site is conducive to their health), whether they are nuisance trees (cause root problems, disease and insect prone, and brittle wood). All of these factors can also help determine if trees are a hazard. These are just a few things that go into an evaluation. Urban tree evaluation is based on a list with different categories that look at specific questions about each tree. Usually an expert trained in tree evaluation is hired to provide this evaluation. It should be done by an experienced arborist (usually certified arborists) or someone with a degree in Urban Forestry. The International Society of Arboriculture provides a risk assessment form which helps to make the evaluation objective. You can see a copy of this form at: https://www.isa-arbor.com/Portals/0/Assets/PDF/Certification-Applications/ISA-Basic-Tree-Risk-Assessment-Form-Instructions.pdf