i-Tree Eco Methods, Model Descriptions, & Journal Articles

Methods and Model Descriptions


i-Tree Eco model enhancements for version 6 - A (pdf) document describing enhancements and changes in the i-Tree Eco v6 methods pertaining to air pollution modeling processes and valuations, which may cause pollution removal and monetary estimate differences from Eco v5 outputs. (Updated May 10, 2016)

i-Tree v6 Pollutant Removal, Biogenic Emissions and Hydrologic Processes Descriptions v1.1 - A document (pdf) describing i-Tree Eco v6 ecosystem services methods and processes integrated in i-Tree Landscape, Canopy, Design and Forecast including international adaptations for Australia, Canada and the United Kingdom. (Updated April 14, 2016)

UFORE Methods - This document describes methods and documentation for each model component.

Air Pollution

i-Tree Eco Dry Deposition Model Descriptions - Provides an overview of the i-Tree Eco dry deposition model and descriptions of its calculations, updated Feb 27, 2015.

UFORE-D Model Enhancements - An overview of the UFORE-D model enhancements used for pollution effects in Eco v4.0

UFORE-D Model Descriptions - Provides an overview of the UFORE-D model and descriptions of its calculations updated Feb 27, 2015. Note - the previous UFORE-D v1.3 document was updated and combined with the i-Tree Eco Dry Deposition Model Descriptions v1.1 on Nov 27, 2012.

i-Tree Eco Biogenic Emissions Model Descriptions - A description of the biogenic emission model integrated in the i-Tree Eco version 5 application.

Single imputation method of missing air quality data for i-Tree Eco analyses in the conterminous United States - A description of the methods used to handle gaps in hourly air quality data in i-Tree Eco across the United States.

Weather and Hydrology

Global Precipitation Measurement (GPM) Integration - A white paper (pdf) describing the process of obtaining and validating GPM data for integration into i-Tree Eco. This precipitation data provides a complimentary alternative to NCEI data and may be more complete, especially in locations outside the US. (Updated 5/17/2022)

Surface Weather and Upper Air Pre-processor description (v1.2) - A description (pdf) of methods to process hourly weather parameters which are required in the i-Tree Eco and i-Tree Hydro v5 and v6 applications. (Updated 04/19/16)

i-Tree Eco v6 Pollution and Weather Station Availability - A spreadsheet (xlsx) list showing available weather and pollution data and number of monitors for the years 2005 to 2013 for Australia, Canada, Puerto Rico, the United Kingdom, and the United States.

i-Tree Eco v6 Weather Station Validation Description - A (pdf) document describing the i-Tree Eco v6 methods used to validate weather stations and interpolation process used for missing data gaps.

i-Tree Eco v6 Weather Station Validation Results - A spreadsheet showing weather station validation results for existing weather stations from 2005 to 2015. Validation results include all countries with available weather data.

i-Tree Eco Precipitation Interception Model Descriptions A description of the precipitation interception model integrated in the i-Tree Eco version 5 application. (Updated 01/30/13)

i-Tree Streets/Design/Eco Rainfall Interception Model Comparisons A document discussing the differences in methodologies between the rainfall interception model, used by i-Tree Streets and Design, and the avoided runoff model methodology used in the i-Tree Eco version 5 application.

Carbon Storage and Sequestration

Tropical Carbon Equations

Carbon storage and sequestration by trees in urban and community areas of the United States - A 2013 journal article providing updated national urban tree carbon storage and sequestration estimates based on additional city and state urban field data and newer land area and tree cover estimates.

Social Cost of Carbon for Regulatory Impact Analysis - Under Executive Order 12866 - A technical support document from the Interagency Working Group on Social Cost of Carbon. United States Government. May 2013. A updated 2013 reference document used for i-Tree version 5 & 6 carbon valuation updates.

Other benefits and costs

i-Tree Eco avian modeling methods - A (pdf) research paper published in 2014 which includes the methods used for avian modeling in i-Tree Eco: "Using urban forest assessment tools to model bird habitat potential" by Lerman, S.B., Nislow K.H., Nowak D.J., DeStefano S., King D.I., & Jones-Farrand D.T.

i-Tree Eco leaf nutrients - A brief summary of how the leaf nutrient related results are estimated in i-Tree Eco, with a link to the research paper from which the methods were derived.

i-Tree Eco wood product estimates - A 2019 journal article assessing the potential value lost to urban tree waste in the US. This is the basis of wood product estimates and values included in i-Tree Eco. Nowak, D.J., E.J. Greenfield, R. Ash. 2019. Annual biomass loss and potential value of urban tree waste in the United States. Urban Forestry and Urban Greening. 46: 126469.

i-Tree Eco allergenicity estimates - Published research into the impacts of species composition, land use, and the proximity of vulnerable populations on local allergen conditions. This work is the basis of the allergen related reports in i-Tree Eco. Nowak, D.J., T.L. Ogren. 2021. Variations in Urban Forest Allergy Potential among Cities and Land Uses. Urban Forestry and Urban Greening. 63: 127224.

Stratified Sampling Statistics

Stratified sampling statistics used in i-Tree Eco plot-sample type projects - i-Tree Eco plot-sample type projects use traditional stratified sampling statistics that are summarized in many places on the web and taught in most introductory statistics courses. This document describes how those methods are implemented in i-Tree Eco to expand plot samples into stratum and population level estimates. These estimates include sampling variance and standard error which capture sampling error associated with measuring a portion of the population (i.e the plots) to represent of the whole population.

Journal Articles

Residential building energy conservation and avoided power plant emissions by urban and community trees in the United States - 2016, David J. Nowak, Nathaniel Appleton, Alexis Ellis, and Eric Greenfield.

i-Tree Eco estimates of grass effects on air pollutant removal - A (pdf) research paper published in 2018 which reports on air pollutants removed by grass and associated health benefits in the conterminous U.S: "Air quality and human health impacts of grasslands and shrublands in the United States" by Gopalakrishnan, V., Hirabayashi, S., Ziv, G., & Bakshi, B.R. The methods described in this paper are implemented in i-Tree Eco.

A Ground-Based Method of Assessing Urban Forest Structure and Ecosystem Services - A 2008 journal article describing the Urban Forest Effects Model (UFORE) data collection variables, model methods, advantages and limitations.

Effect of Plot and Sample Size on Timing and Precision of Urban Forest Assessments - A 2008 journal article discussing how plot and sample size can affect data collection time and precision for UFORE (i-Tree Eco) assessments.

Tree and forest effects on air quality and human health in the United States - A 2014 journal article describing the use of the EPA's BenMap public health incidence reduction model related to tree attributed air quality improvement modeling in i-Tree

Air Pollution Removal by Urban Trees and Shrubs in the United States - A 2006 journal article examining management of urban tree canopy effects as a viable strategy to improve air quality.

Modeling of urban trees' effects on reducing human exposure to UV radiation in Seoul, Korea - A 2014 journal article describing the UV model implemented in i-Tree to quantify urban trees' effects on mitigating the intensity of UV radiation on the ground within different land use types across a city.

Compensatory Value of Urban Trees in the United States - A 2002 journal article focusing on the Council of Tree and Landscape Appraisers (CTLA) tree-valuation method used to determine structural values for urban forests across the United States.

Carbon Storage and Sequestration by Urban Trees in the USA - A 2002 journal article discussing carbon storage and carbon sequestration estimates of the urban forest on a national scale.

A community-based urban forest inventory using online mapping services and consumer-grade digital images - A 2010 journal article discussing the feasibility of using aerial imagery for Eco data collection.

Carbon Dioxide Reduction Through Urban Forestry: Guidelines for Professional and Volunteer Tree Planters. PSW -GTR-171. McPherson & Simpson. - A 1999 Forest Service technical guide used for estimating regional tree effects on building heating and cooling energy use.


i-Tree Eco Reference List - updated November 2012 - A bibliography of i-Tree Eco (UFORE) reference articles, reports and other resources.