Tree Appraisals & Hazard Risk Assesment
Money doesn’t really grow on trees, yet…TREES HAVE VALUE!
Tree appraisals and tree inventories can provide useful information for numerous situations in several ways:
- Homeowners who need to file an insurance claim for trees that have been damaged or destroyed by the actions of other people or businesses
- Realtors®, and real estate professionals who want to quantify the contributory value of trees and plants of a property to help inform prospective clients who are looking to buy or sell a home or land
- Landscape architects and designers, and construction contractors who need to know monetary values of trees and plants before groundbreaking work begins on residential or commercial projects
- Municipalities and communities who need information to more efficiently manage the quantity and quality of trees located on public grounds such as parks, street boulevards, and cemeteries
- Insurance companies who need to conduct or verify a tree or plant damage casualty claim
The process of tree and plant appraisal can involve multiple factors to attain the appropriate type of value that can be assigned or calculated. The process is dependent on the specific purpose and situation that gives cause for an appraisal assignment. Keep in mind that a tree or plant appraisal is an unbiased, yet qualified, opinion of value. And, it is important to know that four key elements, Species, Condition, Size, and Location, aid in the value determination of trees and plants:
1. SPECIES RATING:
Tree appraisal value is directly related to the type or kind of tree – its species. A native tree that is tolerant of its site environment could be assigned a 100% rating. Tree species that feature reliable cold hardiness, drought tolerance, and an ability to thrive in acidic or alkaline soils also can be assigned high rating. Species that display reliable vitality and vigor, are resistant to serious insect and disease issues, and have long life expectancy, also can attain high species ratings.
2. CONDITION RATING:
The condition of a tree takes into account factors of structural soundness, and biological health. A tree appraiser should examine the integrity of the whole tree system, which includes the roots, main stem or trunk, large scaffold limbs, smaller branches and twigs, the leaf or needle foliage, and the buds of the tree.
3. SIZE RATING:
The tree appraisal method takes into account the cross-sectional area of the main tree stem for assigning Size rating. Although cone-bearing evergreen trees such as pine and spruce are commonly sold by height, trees being rated for appraisal size factors are generally measured at the main stem at 4.5 feet in vertical distance from the soil line or ground level. The American Standard for Nursery Stock, ANSI Z60.1, is an accredited source for measuring tree heights of various stem diameters.
The measured width, or diameter, of the main stem is then converted into total square inches of area, and the measured area of wood is then used to determine a tree’s Size rating.
4. LOCATION RATING:
The appraisal of trees includes Location components of:
Site assessment is linked to the respective market value of a given locality where the tree is placed. And, the collective image of the Site where an appraised tree stands holds notable importance. The Council of Tree & Landscape Appraisers 9th edition of the “Guide for Plant Appraisal” states that:
“A Site is rated in relation to the value of other areas in the same city, county, or region, including the area’s economic, functional, and aesthetic aspects.”
Tree value tends to rate higher marks when located on properties that are well-maintained and visually appealing. Unlike an expensive and popular car whose value remains constant wherever it is located, the value of any particular tree depends in part of where it is located.
Trees and plants can affect the overall property value by offering benefits of function and aesthetics (beauty). These benefits are numerous:
- Screening of unattractive views
- Noise reduction
- Flower color and aroma
- Filtering of dust in the air
- Protection from the sun
- Wind buffering
- Defining, accenting, and protecting private spaces
- Erosion control
Tree Placement rating is a directly related to Contribution rating in terms of how the tree or plant is effectively providing a full-spectrum of its potential functional and aesthetic features. For example, a row of crabapple trees planted along sidewalks in front of several commercial shops may add color and shade and soften the harsh look of concrete and pavement. Yet, the fruit produced by the crabapples may increase risks due to people slipping on fallen fruit, or being stung by hornets that are attracted to the fruit. The added maintenance cost due to removing the fruit is another factor that could affect Placement ratings.
TREE INVENTORY FAQ’s
How is a tree inventory conducted?
I inventory trees by using a state of the art, scientifically designed and reviewed software program developed by the USDA Forest service. This public domain program suite is known as i-Tree. Field data is collected on a hand held mobile device and then downloaded onto a desktop where tree benefit-cost analysis reports are calculated are configured. These reports can be exported in various formats: pdf/word doc/rtf. Reports can also be exported in Excel (.xis) format. For more information go to: www.itreetools.org.
Who can benefit from conducting a tree inventory?
- Insurance companies
- Land owners
- Landscape architects & designers
- Golf course Superintendents
- Construction contractors and builders
What are the benefits of conducting a tree inventory?
Whether you have only 1 tree or 10,000 trees, an inventory can provide beneficial and useful baseline data that makes tree management priority decisions both cost efficient, and sustainably functional.
An i-Tree inventory collects valuable, benefit-cost analysis report data which includes:
- Replacement values: An i-Tree inventory generates tree replacement value estimates of the full cost of replacing trees in their existing condition. Having a credible estimate for the monetary value of your tree can be extremely handy if and when your favorite tree is damaged or destroyed by the negligent actions of other people.
- Energy: This data shows a tree’s contribution in terms of energy conservation from reduced natural gas consumption needed to warm your home or business in winter, and reduced electricity used to air condition your home or business in summer.
- Stormwater: This data calculates the reductions in annual stormwater runoff attributed to a tree’s ability to intercept, slow, and capture rainfall.
- Air Quality: Did you know that trees trap numerous air pollutants and irritants such as sulpher dioxide (SO2)? Did you also know that some trees have the potential to produce pollens that can actually have a negative effect on air quality and cause problems associated with breathing disorders such as asthma?
- This tree data quantifies both positive & negative effects of trees on overall air quality where you live.
- Carbon dioxide: The data gathered in this report shows reductions in atmospheric carbon dioxide (CO2) attributed to tree’s ability to sequester pollutant emissions from industrial power plants. The data also includes the amount of CO2 that is released when trees die and decompose.
- Aesthetics: Most people think trees are beautiful: the sight of apple blossoms in spring, the wonderful scent of Linden tree flowers, the vivid crimson and orange colors of leaves in the autumn, the evergreen foliage of blue and green needles on spruce and pine trees, all contribute to the value of a home, land, business, or municipality. Healthy trees can add considerable value to the overall price of your home! These and numerous other intangible tree benefits are produced by the data in this report.
- Maintenance Recommendation: A summary of recommendations aides tree owners by means of linking maintenance needs such as pruning, insect and disease control, or removal, to associated levels of hazard and risk considerations of safety and liability concerns.
- Priority Tasks: Data gathered in this report emphasizes by order the most important maintenance tasks required to keep your trees healthy and to reduce risks associated with various tree hazards. Priority task rating recommendations is a wonderful way to calculate and plan for the costs of maintaining trees.
The following photographs illustrate some i-Tree inventory information that can easily help you decide on why, how, and when, you need to manage your trees in an economically efficient and environmentally smart manner.
Conducting a tree inventory generates valuable information that most homeowners and tree managers can utilize to make smart decisions that will save money, boost resale value, and enhance the appearance and safety of your property.For more information or to set up an on-site appointment, please go to the “contact Mike” tab.
RISK AND HAZARD TREE ASSESSMENTS
Understanding “dangerous” trees
- Do you think this is a dangerous tree?
- Would you pitch a tent or place a picnic table under this tree?
- Would you let your children play hide-and-seek in the large hole of this tree?
- Would you keep or remove this tree if it was on your property?
As a Registered Consulting Arborist®, I’m often times asked these types of questions regarding the structural soundness of trees. All tree owners perceive risks from living around and under trees differently: some have no idea or can believe that a tree would fail and cause injury to themselves or damage to their property-some tree owners are extremely fearful of trees (especially tall trees) and often times decide to cut them down to remove any chance of failure.
The assessment and evaluation of the so-called “dangerous” tree has been an evolving art and science of arboriculture. In the first place, the term “dangerous” has rightfully been replaced with improved terms that are more descriptively appropriate.
Understanding the updated terminology is an important first step in helping tree owners make better-informed decisions about management options.
*The following information is based on the content found in “Best Management Practices: Tree Risk Assessment” published in 2011 by the International Society of Arboriculture.
Risk: “risk is the combination of the likelihood of an event and severity of the potential consequences”.
Hazard: “a hazard is a likely source of harm. In relation to trees, a hazard is the tree part(s) identified as a likely source of harm”.
Tree risk assessment: “is the systematic process to identify, analyze, and evaluate tree risk”.
Tree risk evaluation: “is the process of comparing the assessed risk against given risk criteria to determine the significance of the risk. Risk is evaluated by categorizing or quantifying both the likelihood (probability) of occurrence and the severity of consequences.”
Targets: “(risk targets) are people, property, or activities that could be injured, damaged, or disrupted by a tree”.
Occupancy rates: “occupancy rates can be classified as constant, frequent, occasional, or rare. Static targets are constant. Movable and mobile targets can be in any of the four classifications. Occupancy rate is a primary component in an assessment of the likelihood of impacting a target”.
Site factors: “Site factors have significant influence on both the likelihood and consequences of tree failure. When performing a tree risk assessment, the site is often first evaluated for targets and consequences of failure”.
Please consider and keep in mind these useful definitions as you view my selection of photographs that illustrate the concept of tree risk
My main point in showing these photographs is to demonstrate that identifying and assessing risk ratings is a complex assignment that should be left to arborists who have the experience, education, knowledge, and training in tree risk management. This also includes predicting tree failure.
Please review my contact page to schedule an on-site appointment for any trees that concern you in terms of hazards and risks.
I will be updating and adding content to this page in the coming weeks, but until then I will conclude with some general “starter” information for all you tree owners out there that are concerned and afraid of tall trees.