i-Tree Eco is designed to use standardized field data and local hourly air pollution and meteorological data to quantify urban forest structure and its numerous effects ( Nowak and Crane 2000 ), including :
• Urban forest structure ( e . g ., species composition , tree health , leaf area , etc .).
• Amount of pollution removed hourly by the urban forest , and its associated percent air quality improvement throughout a year .
• Total carbon stored and net carbon annually sequestered by the urban forest .
• Effects of trees on building energy use and consequent effects on carbon dioxide emissions from power sources .
• Structural value of the forest , as well as the value for air pollution removal and carbon storage and sequestration .
• Potential impact of infestations by pests , such as Asian longhorned beetle , emerald ash borer , gypsy moth , and Dutch elm disease .
Typically , all field data are collected during the leaf-on season to properly assess tree canopies . Typical data collection ( actual data collection may vary depending upon the user ) includes land use , ground and tree cover , individual tree attributes of species , stem diameter , height , crown width , crown canopy missing and dieback , and distance and direction to residential buildings ( Nowak et al 2005 ; Nowak et al 2008 ).
During data collection , trees are identified to the most specific taxonomic classification possible . Trees that are not classified to the species level may be classified by genus ( e . g ., ash ) or species groups ( e . g ., hardwood ). In this report , tree species , genera , or species groups are collectively referred to as tree species .
Tree Characteristics :
Leaf area of trees was assessed using measurements of crown dimensions and percentage of crown canopy missing . In the event that these data variables were not collected , they are estimated by the model .
An analysis of invasive species is not available for studies outside of the United States . For the U . S ., invasive species are identified using an invasive species list ( Massachusetts Invasive Plant Advisory Group 2005 ) for the state in which the urban forest is located . These lists are not exhaustive and they cover invasive species of varying degrees of invasiveness and distribution . In instances where a state did not have an invasive species list , a list was created based on the lists of the adjacent states . Tree species that are identified as invasive by the state invasive species list are cross-referenced with native range data . This helps eliminate species that are on the state invasive species list , but are native to the study area .
Air Pollution Removal :
Pollution removal is calculated for ozone , sulfur dioxide , nitrogen dioxide , carbon monoxide and particulate matter less than 2.5 microns . Particulate matter less than 10 microns ( PM10 ) is another significant air pollutant . Given that i-Tree Eco analyzes particulate matter less than 2.5 microns ( PM2.5 ) which is a subset of PM10 , PM10 has not been included in this analysis . PM2.5 is generally more relevant in discussions concerning air pollution effects on human health .
Air pollution removal estimates are derived from calculated hourly tree-canopy resistances for ozone , and sulfur and nitrogen dioxides based on a hybrid of big-leaf and multi-layer canopy deposition models ( Baldocchi 1988 ; Baldocchi et al 1987 ). As the removal of carbon monoxide and particulate matter by vegetation is not directly related to transpiration , removal rates ( deposition velocities ) for these pollutants were based on average measured values
I-Tree Report of Ecosystem Analysis at Mount Auburn Cemetery Insert to the Climate Action and Sustainability Plan
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