Rydal-Meadowbrook Civic Association

Apart from the people and architecture, the character of historic Abington is defined by magestic trees that have taken many generations to reach maturity. These trees add significant value to properties and the Township by contributing the to health, safety and welfare of residents:

• In 1996, an elderly couple were killed in rising flood water. Abington contains flood plains along the Meadowbrook (and its tributaries) that lead to the Pennypack Creek and the Sandy Run that leads to the Wissahickon. Properties with dense areas of trees can offset that massive deluge that runs-off the slopes, saving property and lives of neighbors.

• One acre inch of water = 226,610.6763 pounds (or 113 tons). Philadelphia has an average annual rainfall of 42.05 inches. That means that one acre without trees is subject to erosion caused by 4,751 tons of water in one year. Most of Rydal-Meadowbrook is zoned as R-1, so each property-owner has a responsibility to maintain and add trees.

 • Trees with mature root systems not only minimize erosion, but also absorb water. According to Steve Nix, a single acre of forest land, during the course of a growing season can add 4 tons of biomass but uses 4,000 tons of water to do so. Trees efficiently dispose of water; this is called "transpiration ratio."

 • In addition to water run-off management, trees also contribute oxygen to the neighborbood. According to the New York Times, "One acre of trees annually consumes the amount of carbon dioxide equivalent to that produced by driving an average car for 26,000 miles. That same acre of trees also produces enough oxygen for 18 people to breathe for a year." Northwest Territories Forest Management studied mature trees and found that a 100-ft tree, 18" diameter at its base, produces 6,000 pounds of oxygen" in one year. According to Science Daily, low levels of oxygen impact human health. Mark Jacobson, a professor of civil and environmental engineering at Stanford found that upward of 20,000 air-pollution-related deaths per year per degree Celsius may be due to this greenhouse gas, on a Worldwide basis. There were two important findings: 1. Higher temperatures due to carbon dioxide increased the chemical rate of ozone production in urban areas; and 2. Increased water vapor due to carbon dioxide-induced higher temperatures boosted chemical ozone production even more in urban areas.

• Trees have a significant impact on the cooling effect of neighborhoods. The U.S. Department of Agriculture (USDA) has found that “he net cooling effect of a young, healthy tree is equivalent to ten room-size air conditioners operating 20 hours a day.” USDA Forest Service also found that "trees properly placed around buildings can reduce air conditioning needs by 30 percent and can save 20–50 percent in energy used for heating.”

• Energy consumption impacts U.S. national security. According the the U.S. Department of Energy, the nation spends over 500 billion dollars annually on energy and energy supply and demand plays an increasingly vital role in our national security and the economic output of our nation. Use of energy that exceeds the domestic capacity requires the importation of energy resources from other countries. Instability in the Middle East is a threat that cannot be overestimated.  

Calculating the Economic Value of Trees
The U.S. Forest Service has a suite of online calculation tools:
i-Tree Benefits Calculator
i-Tree Hydro (model the watershed-scale effects)
i-PED Pest Evaluation and Detection module

Apart from the health, safety and welfare of neighbors, there is economic value that can be calculated in a number of different ways. The Business School at the University of California, Davis has created a sample Excel worksheet that can be downloaded here. Each property-owner can assess the value of the existing treess with this calculation tool. 

Southern Urban Forestry Associates has developed cost-based methods calculate the value of a tree:

Appraised Value = Basic Value x Condition x Location

Basic Value = Replacement Cost + (Basic Price x [TA(A) - TA(R)] x Species)

Condition = A rating of the tree's structure and health and based on 100 percent

Location = the average for the tree's Site, Contribution and Placement and based on 100 percent

Replacement Cost = the cost to purchase and install the largest locally available and transportable tree in the area.

Basic Price = the cost per square inch of trunk area of a replacement tree measured at the height prescribed by the American Nursery Standards.

TA(A) = Trunk Area at 4.5 feet above the ground of the appraised tree.

TA(R) = Trunk Area at 6 inches or 12 inches above the ground of the replacement tree.

Species = the rating for a particular species and based on 100 percent.

The Burnley Method of Tree Valuation (modified) uses the following formula:

VALUE ($) = TREE VOLUME x BASE VALUE x (E) x (FV) x (L).

Golf & Greens Industry Professionals define value as it relates to insurance claims, tax deductions, legal claims and real-estate assessment, among other things. The appraisal process begins by determining the four variables that make up the formulas for each method of assessment.

1. Size. The first step in an appraisal is to measure the tree, usually its height or its trunk diameter. You should measure the trunk diameter at between 1 foot and 4.5 feet from ground level, depending on the overall height of the tree. You might also need to measure branch spread and bark thickness.

Leaning or sloped trees, low branching, excessive trunk flare, trees cut or broken below 4.5 feet and multi-stem specimens may complicate your measuring. Plant-appraisal guides provide more detailed discussions of how to treat such measurements.

2. Species. The species of tree alters appraisals in a variety of ways. Simply put, some species are more desirable than others, and, therefore, more valuable. Some take a long time to reach the desired form or size, so an old specimen may be particularly valuable.

Conversely, some species are known to be prone to certain pests or diseases. These are less likely to achieve their desired mature form or age. For example, a Bradford pear tree might be considered less valuable than other species in storm-prone regions because of its propensity to split.

3. Condition. Evaluate the tree's structural integrity and overall health. Examine all aspects of the tree, including the roots, trunk, scaffold branches, twigs and foliage, and check for general health and vigor as well as specific problems. In estimating damage, it may be necessary to consider the tree's condition prior to a particular injury. Damage from diseases, phytotoxicity and environmental causes are all considered components of the tree's condition.

4. Location. Assess the tree's site, placement and functional and aesthetic contributions to a property. Consider the overall quality of the general area-the buildings, hardscape and plantings. Note how the tree contributes to the site's function and aesthetics. Determine how effectively the placement of the plant provides those benefits.

Methods of assessment After completing these four steps, you can begin the actual assessment. There are various methods to do this. Real-estate and insurance appraisers, accountants and landscapers might use different calculation methods; one is not inherently better. Appraisers sometimes (use) more than one method to ensure accuracy. If you have any uncertainty about which method to use or how to use it, contact a qualified professional.

* The replacement-cost method estimates the cost of replacing a tree at the same location with one of the same species, condition and, if possible, size. Many times, a specimen is too large to be replaced by a single tree and still be of equal value. In this instance, appraisers may allocate several smaller trees deemed collectively to be equivalent to the larger original. This is simply a matter of calculating the cost of the replacement trees and their installation. (You'll notice that this method seems similar to cost of cure and cost of repair; however, the essential difference is that the replacement-cost method is used in situations when the only viable option is to replace the tree.)

* The trunk formula is used to estimate the value of a tree that is too large to replace with nursery or field stock, or when the trunk is the only remaining part of the tree. You determine the appraised value by calculating the tree's basic value and adjusting it for the variables of condition and location.

The basic value of a tree is the sum of two factors: the cost of transplanting the largest normally available tree of the same or comparable species; and the increase in value due to the larger size of the tree being appraised compared to the size of the replacement tree.

* Somewhat similar to the replacement-cost method, the cost of repair and cost of cure methods are used to appraise monetary loss when trees are damaged or destroyed. Cost of repair does just what it indicates: assesses the cost of repairing a damaged tree. Treatments might include wound treatment, cabling, bracing, pruning, or insect and disease management. Cost of cure is used to determine the treatment that will return the property to the closest approximation of its original condition. Both of these method account for the following steps: - Remove debris and clear the site - Replace, repair or restore tree to its pre-casualty condition - Post-restoration maintenance.

Using the appraisal The method you use will affect the final value you attribute to a tree. The appraised value of a tree should be reasonable in relation to the value of the property on which it sits. Identical trees in different neighborhoods could have vastly different dollar values. Studies have estimated that trees may account for up to 15 percent of the value of a residential property. (For example, a $200,000 house on a lot with three mature trees might owe as much as $30,000 of its value to the trees. Assuming that all three trees are of equal value, each tree would be valued at $10,000.)

The Internal Revenue Service (IRS) allows deductions for losses of property sustained during the taxable year that are not compensated for by insurance or other means. Refer to the IRS Code of 1986, section 165 (a) for further information. Otherwise, tree appraisals are used for determining the value of trees in settlement for damage or death of trees through litigation, insurance claims or direct payment.

Additional uses of tree appraisals include real-estate assessments, agency budget justification, condemnation proceedings, sale of nursery property and establishing the value of trees damaged during construction operations.

For a copy of the Guide for Plant Appraisal, contact the International Society of Arboriculture at (217) 355-9411, or visit their website at www.ag.uiuc.edu/~isa/welcome.html. ISA is a non-profit organization supporting tree-care research around the world and dedicated to the care and preservation of shade and ornamental trees. For more information on the society itself, contact: ISA, P.O. Box 3129, Champaign, IL 61826-3129.

The Council of Tree & Landscape Appraisers (CTLA) is composed of the Association of Consulting Foresters ((703) 548-0990), the Associated Landscape Contractors of America ((703) 736-9666), the American Nursery and Landscape Association ((202) 789-2900), the American Society of Consulting Arborists ((301) 947-0483), the National Arborist Association ((603) 673-3311) and the International Society of Arboriculture ((217) 355-9411).

To locate a tree appraiser in your area write the American Society of Consulting Arborists at 15245 Shady Grove Road, Suite 130; Rockville, MD 20850; or call at (301) 947-0483.

Sources and References:
PA Trees: The Tree Resource Guide for Pennsylvania
Golf & Green Industry Professionals 
Business School at the University of California, Davis 
Southern Urban Forestry Associates 
National Tree Benefit Calculator 
Burnley Method of Tree Valuation 
About.com on Forestry 
RSS Weather on Philadelphia Rainfall 
Philadelphia Weather by Idcide 
NDSU: Dickenson Research Extension Center 
About.com on Oxygen Produced by Mature Trees 
Science Daily on CO2 and Human Health 
Arbor Day Foundation on the Benefits of Trees 
U.S. Department of Energy