Tree inventory approaches
Each tree is mapped, identified to species, its size is measured and it is evaluated for condition, hazard potential and any maintenance that is required. This type of inventory is conducted by trained and experienced staff, or professional consultants. A full inventory can be confined to street trees, or include park trees as well. This approach is ideal since it will help with planning for emerald ash borer (EAB), routine tree maintenance, and new invasive insects or pathogens.
Ash only inventory:
Measure and evaluate only ash trees and their location, size, condition and hazard potential. This strategy is sufficient for planning and managing for EAB but is limited to that. This type of inventory could be done with trained volunteers if necessary.
Measure and evaluate trees on a sub-sample of streets, and extrapolate to the entire municipality. This method could be helpful for initial budgeting purposes, but is not sufficient for management planning. The Canadian Forest Service has developed an Urban Street Tree Survey protocol, to assist with planning a sub-sample inventory.
Hyperspectral imaging (HSI):
This method is still being developed at present and is expensive, however, in the future may be an effective tool for inventory. In HSI, aerial imagery is processed so that electromagnetic energy reflected from objects on the ground (in this case, trees) is captured. Each tree species has unique spectral properties; with ground-truthing, this allows the identification of tree species from the imagery. With this method an inventory of all trees in the community could be conducted, including trees on private property and in woodlots.