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Tree Inventories

Norwalk Tree Inventory Training

Tree inventories are a great starting point for community urban forestry planning. These inventories often show their value most when a community is faced with a challenge, such as dealing with a destructive insect or addressing environmental inequities. Having ready access to information about what trees a community has and where they are located can be invaluable to a manager in making a decision and in implementing that decision once made.

Some Key Terms:

Inventory - the collection, into a database, of information on individual trees within a community.  This information usually includes:

  • species of tree

  • size in diameter

  • condition

  • location 

As most often used in urban forestry, a tree inventory refers to a 100% inventory, in which all trees in the population are included in the database. The area inventoried, however, may be less than a whole town - one could have a 100% inventory of a neighborhood, for instance. This data is usually collected by individuals in the field, visiting each tree to collect the data.

Street Tree Inventory - This is the most common type of inventory in urban forestry. In a 100% street tree inventory, data are collected on all publicly-owned street trees. However, there could be other types of tree inventories, such as those of park trees, high risk trees, inventories of individual species, and so on.

Partial or Sample Inventory - Rather than collecting data on all trees, a municipal can learn about trees through sampling a sub-set of those trees. These partial inventories are very useful for drawing general conclusions about the tree population as a whole but are less useful for providing information on individual trees.

Urban Tree Canopy (UTC) Analysis - A UTC analysis is different from an inventory. UTC studies of tree canopies are based on the computer-aided interpretation of aerial photographs. UTC data tend to be very precise regarding the location of trees and the extent of tree canopy. Most UTC studies of today are not able to provide detailed information on tree species or condition.  Advancing technology, however, may significantly change that.

GIS and Mapping - One great value of both inventories and UTC analysis is the degree to which both lend themselves to being used within geographic information systems (GIS). In turn, this allows the results of inventories and UTC analyses to be presented as maps. 

i-Tree Tools - These tools are a software suite developed by the USDA Forest Service to aid in the detailed quantitative assessment of urban forests. The suite currently consists of 6 applications and 5 utilities. These tools allow the user to assess the benefits, costs, location and management considerations associated with urban trees.

How to and Why Create a Tree Inventory:

The North Carolina Forest Service webpage Urban and Community Tree Inventories discusses the details of developing an inventory, including how to collect the data and what data to collect.

The Vermont Tree Inventory Guide, produced by the Vermont Urban and Community Forestry Program, is an excellent document that outlines the steps in creating an inventory and discusses the reasons for conducting an inventory.

Cornell University provides information on how to conduct a Community Street Tree Inventory.

The Urban Resources Initiative in New Haven has an interactive, on-line inventory of New Haven's street trees. This compilation demonstrates the extent to which technology can be applied to inventories and also how inventories can be used as a communication tool.

Analyses based on UTC studies are available for Hartford, New Haven, Bridgeport and the Greater Bridgeport area. MetroCOG in Bridgeport has produced a storyboard on the Greater Bridgeport UTC.

Additional Points to Consider:

  • Before developing an inventory it is very important that a community consider why it needs an inventory. Otherwise, a community runs the risk of developing an inventory that does not provide information useful to that community.

  • Successful inventories can be conducted by volunteers with notepads as well as by professionals with state-of-the-art tools. It all depends upon what a community is looking for and the options available given budgetary constraints. The State Urban Forestry Coordinator can provide additional guidance regarding how to conduct a street tree inventory and the various tools and approaches that can be used.

  • The Community Resource Inventory tool developed by a partnership between DEEP and UConn can be used by municipalities to develop other types of natural, cultural and economic resource inventories. 

Trees and Urban Forests: Learn More  | Forestry Main Page

Content last updated October 2019