Inventorying and Assessing the Values of Urban Trees in Kingston, PA using CITYgreen ® 5.0 Brian Keating, Elizabeth Roveda, Megan Smith, Kenneth Klemow, William Toothill and Marlene Troy

Biology Department, Wilkes University, Wilkes-Barre, PA 18766

Background

•Past research (www.americanforests.org) has demonstrated that trees in urban areas have several important functions:

•They intercept rainfall and retain water on their leaves and direct stemflow to the trunk where it flows into the soil. Otherwise precipitation would land on impervious surfaces (streets and sidewalks) and flow directly to the nearest sewer. Therefore, urban trees reduce the chance of downstream flooding.

•They absorb and store carbon. Burning fossil fuels release carbon dioxide, which is a greenhouse gas, into the atmosphere. Trees take in and store carbon as woody tissue, thus offsetting CO2 emissions.

•They purify air by absorbing dissolved pollutants, filtering particulate matter, and releasing oxygen.

•Kingston, PA is a municipality of approximately 13,500 located in the Wyoming Valley of Northeastern Pennsylvania. Kingston has an active shade tree program that requires citizens to secure permits before pruning or removing of their trees. Yet, Kingston does not have an inventory of the trees under its jurisdiction.

•To quantify the benefits of urban forests, the nonprofit “American Forests” developed CITYgreen® 5.0, a software program that uses a Geographic Information System to assess the economic and environmental values of urban trees.

Study Area

The analysis was done in Kingston, PA. We analyzed trees along Butler Street (high density) and Penn Street (low density).

Parameter Butler Street Penn Street P value

D.B.H. 16.6 + 0.7 11.1 + 1.8 0.009

Tree Height 49.3 + 1.9 28.8 + 3.1 1.1 x 10-6

Methods

•Trees located along the tree lawn of Kingston, PA were inventoried during the fall of 2004 and early spring of 2005.

•Two streets were surveyed: Butler Street (3100’ long, high tree density) and Penn Street (1300’ long, low tree density).

•Parameters were measured and recorded into a handheld computer including: latitude, longitude, diameter at breast height, height, and tree health.

•The data were then downloaded into an Excel spreadsheet and ArcView GIS.

•After the data were analyzed, two parameters (DBH and height) were chosen for comparative purposes. Their means were calculated for the trees on each street by using a t-test.

•ArcView was then used to produce a map of the area analyzed. The values of the trees, including amount of storm water runoff absorbed by the trees and air quality with and without trees present were estimated using CITYgreen ® 5.0 software.

Butler Street (High tree density)

Statement of Purpose

•This project was conducted to serve two overriding purposes:

•To establish an inventory of the street trees in Kingston, PA using Arc View GIS as a data storage and mapping program.

•To use the entered data to evaluate the importance of the trees to reduce stormwater runoff, mitigate pollution, save summer energy, store carbon, and model tree growth. The second purpose was aided by use of a CityGreen module which is part of ArcView GIS. Data from a street having many trees will be compared to data from a street having few trees.

Penn Street (Low tree density)

South side North side South side North side

# trees/ 1000’ street 22.6 18.7 9.2 9.2

Butler Street Penn Street

Conclusions

•Recording the data for each tree proved time-consuming (3-5 minutes/tree). Thus, we could not complete a total inventory for all of Kingston’s 12,000 trees. Instead we were able to analyze the trees from the two representative streets. A full inventory would take approximately 3-5 years. The best time for this research to be done is during summer months.

•The density of trees on Butler Street was more than double the tree density on Penn Street. The trees on Butler were significantly larger in diameter and height than those on Penn. Comparative data would be useful in noting similarities and difference in regards to trees in other urban areas.

•Tree cover is shown to improve environmental quality in several ways, including reduced stormwater runoff, more absorption of pollutants, greater carbon sequestration, leading to likely economic benefit in streets with a high density of trees.

Table 3. Trees measured on Butler street were significantly taller and wider than trees measured on Penn street.

Table 1. The density of trees on Butler Street was more than double that measured on Penn street.

Butler Street

Penn Street Trees

Penn Street Butler Street

Site Statistics:

Tree Canopy 8 % 17 %

Air Pollution Removal:

Ozone 25.7 lbs 52.3 lbs

Sulfur Dioxide 12.7 lbs 25.8 lbs

Nitrogen Dioxide 14.1 lbs 28.7 lbs

Particulate Matter 34.7 lbs 70.7 lbs

Carbon Monoxide 2.3 lbs 4.8 lbs

Carbon:

Carbon Storage 24.5 tons 49.9 tons

Carbon Sequestration 0.55 lbs 1.12 tons

Stormwater Control:

Runoff 0.28 in 0.58 in

Time of Concentration 0.44 hrs 0.44 hrs

Peak Flow 1.42 cu ft/s 4.54 Cu ft/s

Economic Benefit:

Annual Savings $ 500.44 $1,046.76Table 4. Valuation of urban tree benefits as calculated by Citygreen.

The trees along Butler St. provided approximately double the capacity of water storage, pollution removal, stormwater control,

carbon storage, and economic benefit compared to those on Penn St.