Overview & Applicability
i-Tree is a suite of several different applications that focus on the benefits of urban trees, however this page will focus on tools that specifically address the carbon and greenhouse gas emissions benefits of urban trees, including i-Tree Eco, i-Tree Streets, i-Tree Vue, i-Tree Canopy and i-Tree Design. In general, each of these applications requires the user to define a study area, whether it be a residential home with a single tree or a larger area, such as a neighborhood, city or county, with a large population of trees. It then uses field inventory or sampling data (Eco, Streets, Design) and/or land cover data (Vue, Canopy) to calculate tree and forest structure and the benefits those trees provide. Communities can use existing tree inventories or can conduct a new project inventory depending on the application.
When an i-Tree project is completed, reports are provided to inform users how neighborhood trees contribute to carbon sequestration, building energy savings (through shading and/or blocking wind), air quality improvements, and storm water interception. Some applications assist users in summarizing and evaluating the structure of their urban tree communities and examine management needs.
More thorough descriptions of each application are available on the i-Tree website: http://www.itreetools.org/applications.php
The original i-Tree suite of tools was launched in 2005 with two urban forest assessment applications. It has since been through many updates and improvements; the 2014 release features six different applications and several management utilities. Several of these applications have additional capabilities and features when compared to previous versions. One application (i-Tree Hydro) is in beta testing. Users who have previously installed versions of i-Tree can use the "Check for Updates" option on their installation to ensure they are using the latest version. More information about progress and updates to i-Tree can be found on the What's new page: http://www.itreetools.org/news/whats_new.php.
Inputs and outputs
Inputs and outputs will vary with individual application, but in general the tools require a user to define a project study area and input data about the general land use and the trees in that area (species, size, health), whether from an existing or new dataset. Understanding the effect of trees on building energy use also requires information about tree locations in relation to adjacent buildings.
Outputs may include:
Urban forest structure analyzed by land-use type, air-quality & pollution control benefits of urban forests, total and annual carbon sequestration and energy savings benefits, total carbon storage, potential impacts of pests on tree populations, impact of tree pollen on allergies, the monetary value of tree populations or individual trees, possible management needs (tree diversity, planting, pruning), overall cost vs. benefit of tree maintenance, tree canopy projections and available space, and storm water interception benefits.
See the i-Tree Applications page to explore more specifics about each application.
Restrictions and limitations
Several applications (i-Tree Eco and i-Tree Streets) require a tree/land-use inventory or sample for the area of interest. A user's manual with inventory protocols are included with each i-Tree application, however the quality of the final outputs from i-Tree will depend heavily on the quality of these user collected data. i-Tree also offers mobile data collection utilities.
Some of the applications allow users to customize information to fit local circumstances, local electricity prices or local air pollution data for example. Other applications are limited in their customizability and rely on regional averages. While this approach can make it easier to use and learn the tool, it also has limitations insofar as it can make the output less specific to local conditions.
Most of the applications were built for use in the United States; international users may still be able to use them, however they may be subject to modeling limitations and may need to supply their own location and geographic data if not included with the tools (e.g. pollution data).
Accessing the tool and additional information
The i-Tree website features clear descriptions of each application, its inputs and reporting features, as well as multiple learning and support resources for users: http://www.itreetools.org/index.php.