Tree Inventory at Southwestern College

In January of 2018, Southwestern College, called ArborPro interested in a GPS tree inventory for their campus. After an online demonstration of the ArborPro software and methodology, Southwestern College decided to move forward working with ArborPro to conduct the tree inventory of their campus forest. ArborPro had recently performed a tree inventory for UCSD, and at the time we were conducting an inventory for the City of San Diego. ArborPro presented local references to the Southwestern College convincing the committee that ArborPro would be the best solution for managing the campus forest.

GPS Tree Inventory

On March 26, 2018, ArborPro, Inc. began operations on a comprehensive GPS inventory of campus trees at Southwestern University. ArborPro assigned an ISA Certified Arborist to collect detailed information on the condition, size, species, maintenance recommendations, etc. for all trees on campus. We inventoried a total of 1,327 trees over the course of the survey and found that 90% of the trees were in good condition. We also found the Southwestern College campus forest to be diverse with 151 unique species.

iTree/Eco-benefits

ArborPro used the i-Tree Streets application to quantify the benefits provided by Southwestern College’s trees. This application uses growth and benefit models designed around predominant urban trees to calculate the specific benefits that trees provide in dollar amounts. The benefits calculated by i-Tree Streets include energy conservation, air quality improvements, carbon dioxide (CO2) reduction, stormwater control, and aesthetic/other. It creates annual benefit reports that demonstrate the value urban trees provide to the surrounding community.
The trees on Southwestern College’s campus provide a total of $180,757 in annual benefits.
The total replacement cost for all campus trees is $ 6,968,696.

Energy Conservation

Public trees contribute to energy conservation by providing shade that reduces cooling costs in the summer and diverting wind to reduce heating costs in the winter. The savings in electricity and natural gas are converted into monetary values to illustrate the annual energy savings that trees provide. Southwestern College’s trees account for a savings of $12,093 in energy consumption each year.

Air Quality

Trees improve air quality by removing pollutants from the atmosphere, including ozone, nitrogen dioxide, and particulate matter. The estimated value of pollutants removed by the inventoried tree population each year is $30,100.

Stormwater Control

Trees reduce the costs associated with diverting stormwater by intercepting rainfall before it hits the ground and enters the storm runoff system. Intercepting rainfall greatly reduces the strain placed on public stormwater runoff systems and can represent significant monetary savings by reducing the amount of infrastructure needed to divert stormwater throughout the campus. The estimated savings for the College in the management of stormwater runoff is $1,643 annually.

Aesthetics

Trees provide many social and economic benefits that are classified as aesthetic/other in the i-Tree Streets application. The major economic benefit in this category is increased property values. Trees contribute to higher property values when compared to similar properties that do not have trees. The major social benefits provided by trees are lower crime rates, improved mental health, greater time spent in businesses with tree-lined streets, and higher productivity in the workplace when a view of nature is available. The inventoried trees contribute $134,139 annually in aesthetic/other benefits.

Total Replacement Value

In addition to Environmental Benefits, the college can consider the Total Replacement Value for its urban forest. Total Replacement Value is the amount of money it would take to completely replace the existing urban forest with trees of the same size. While this is a scenario that will likely never happen, it gives the City a specific dollar value of its trees in their current state. Replacement value differs from Environmental Benefits in that it shows how much the trees are worth instead of the dollar values that they provide in benefits. For example, a mature sugar maple could provide $2,100 in environmental benefits by reducing stormwater runoff, improving air quality, etc. but the total cost of replacing an 18” DBH sugar maple would be $24,270. According to i-Tree Streets, the total replacement cost Southwestern College’s trees is $ 6,968,696.

Turf & Asset

After experiencing the benefits and functionality of ArborPro, Southwestern College has decided to purchase ArborPro’s Turf & Asset module. With Turf and Asset, Southwestern College will be able to manage all their assets like signage, fire hydrants, emergency call boxes, picnic tables, water fountains, backflow valves and more. ArborPro will begin Southwestern College’s asset inventory in the following months.