Seminar #74 from Online Seminars for Municipal Arborists – May / June 2017
Sections Go directly to the section by clicking on the title below
Sections Go directly to the section by clicking on the title below
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Creating a Tree Risk Management Plan
By Gordon Mann
Editor's Note: In the last Seminar, Gordon provided a definition of tree risk management. In this article, he goes to the next step and describes the requirements for creating a Tree Risk Management Plan.
Creating a tree risk management plan involves the identification and assessment of the tree population to be considered. The risk assessment consists of identifying and inspecting the subject trees to analyze for risk.
A risk assessment is different from a full inventory. In a full inventory, every tree will be listed and some information collected. In a risk assessment, the list should only include those trees that are found to have a level of extreme, high, or moderate risk. These are the trees that should have mitigation options to reduce risk. Trees with low or limited risk will be inspected and are generally not be considered for active discussion at the time the risk management plan is implemented. Low risk trees generally don’t require any short term mitigation. Along with identifying the risk, the most important element of a risk assessment is the mitigation options which are the steps to reduce or eliminate risk in the trees identified to have extreme, high or moderate risk.
Tree Risk Assessment Rating Systems
The two most common rating systems used for tree risk in the US have been the PNW-ISA TRACE and Matheny and Clark's qualitative numeric 12-point system that considers 3 components, and adding together numbers for:
(1) the size of the tree part,
(2) the likelihood of failure or incident, and
(3) the target being struck.
These assigned numbers are categorizations and not quantifiable to be added together to develop an overall risk rating. Also, the 12 point systems do not include conflicts.
The system of primary consideration in the 2011 ISA Tree Risk Assessment Best Management Practices (BMP) is the Matrix Based Qualitative approach to Tree Risk management. It considers 7 steps in developing a risk rating:
1. Identify possible targets and conflicts.
2. Identify tree parts that could strike the target, or identify the tree part causing the conflict.
3. Evaluate the likelihood for each part to fail, or the likelihood of conflict.
4. Evaluate the likelihood for each part to strike a target.
5. For each failure mode, identify likelihood for tree failure impacting a specified target.
6. For each failure mode, estimate consequences of failure.
7. For each failure mode, designate the risk.
In each step above, conflicts are to be considered along with the failures in the site inspections. Many trees may have one potential conflict and/or failure, or multiple conflicts and/or failures. A tree can contain both very high and low risk with different identified issues, and mitigation. The critical step is not simply rating the tree, but defining the mitigation options and actions to reduce the risk. Just listing trees based on the rating score without understanding what mitigation is available to reduce the risk does not provide the tree manager the tools needed to make sound risk reduction decisions.
Most people focus on the risk of tree part or whole tree failure. In my experience, there are usually more conflicts in a community’s tree population than high risk structural issues. While observing structural issues and their mitigation options is a primary arborist function, conflict mitigation is often simpler and more trees may be retained with lesser residual risk when mitigating conflicts. For example, many small low branches may cause an eye-level poking risk on a school campus, but can be easily mitigated by pruning. There may be options to mitigate sidewalk offset conflicts by grinding or ramping offset sidewalks.
It is important to gain as much site information as possible to assess the risk. For example: a school district tree impacted a water line that cost $38,000 to repair before my risk assessment was scheduled. This tree was still on the manager’s list of concerns while we were looking at all the trees on the property. I would not have known there were any underground pipe issues; the tree looked normal, the water line was repaired, and the site restored, the extent of root removal was not evident, and the tree was not showing signs of decline, even though significant roots were pruned during the pipe repair. The information about the root cutting raised the tree’s risk rating during the assessment.
Tree Risk BMP
Using the ISA’s 2011 Tree Risk BMP, managers base decisions on the identified risk. The risk rating matrices are used to determine the level of risk present. A situation with a low branch over a walkway could be high to extreme risk, and easily mitigated while retaining the tree. If the tree had a high impact clearance issue and a high dead branch over a walk or parking area, the tree would have both high risk and moderate risk. The risk manager may choose to prune the low branch to obtain clearance and mitigate the high risk, and not climb to prune the dead branch, because another tree under their control has a higher risk and priority to expend their limited resources on.
Risk is rated in four terms in the BMP, Extreme, High, Moderate, and Low, which can be used to sort the trees in the order of highest risk. Based on risk and mitigation options, a tree owner or site manager, can view the risk present on their site. I rarely list low risk trees unless it is specifically requested in the assignment because usually mitigation cannot reduce the risk lower than low.
Prioritization of Tree Risk
Most site managers have limited resources, and the risk assessment will generally require some prioritization to assist the site manager to reduce risk. The prioritization is usually based on the consideration of use and targets, and likeliness of incident, and the cost of mitigation. The size of the part, height, and location (both in the tree and over targets) are generally considered in the consequences of failure. The owner may have the resources to mitigate all risk found on a site. In that case, prioritization may only affect the order of how some of the work is scheduled.
When resources are limited, I find most property managers consider mitigating the extreme risk first, then high risk, then maybe moderate. The basis of their decisions is mitigating the highest risk first, then addressing the next highest risk, and so on with the available resources.
Risk Factors
One approach to sort the risk and assist the site manager in making decisions is to create prioritized numerical risk factors, and sort the trees by the risk factor. Some trees will have more than one risk factor, and still should be sorted by the highest risk factor while listing the other lower risk factors. Unless mitigation of the highest risk factor is by tree removal, the higher risk mitigation often can be performed, and the lower risk mitigation may be delayed until resources allow; or maybe the lower risk is acceptable, for now.
Trees may be prioritized by numerical risk factors 1, 2, and 3 based on the targets, use frequency, and situation.
1. Risk factor 1 trees are the very high or extreme risk situations.
2. Risk factor 2 trees are high risk situations.
3. Risk factor 3 trees are moderate risk situations.
Low risk situations are not considered unless the site owner requests an inventory and risk assessment for all trees. If an owner does not want any risk, they may not want any trees.
The risk factors 1-3 are used to sort and prioritize the mitigation work. Risk Factor 1 trees should be considered first for mitigation, then Risk Factor 2 trees, and then Risk Factor 3 trees. If the agency has limited funds, the risk factor 1 trees may be all or partially what they can afford to mitigate. If they cannot perform all the risk factor 1 trees, they may need to prioritize which trees are addressed first. This is a management decision. Since the process is managing risk, the decisions have to consider the site use and risk, the mitigation, and the available resources.
The risk factors may be helpful in future re-assessments, since those trees with previous risk issues can be re-checked to see if the risk has increased as the tree has grown or declined.
Residual Risk
After mitigation is performed, there usually will be some risk remaining in the tree. The risk management approach is to lower the risk to an acceptable level, and the residual risk is tolerable. As long as the residual risk does not exceed the tolerable risk threshold, the risk has been managed.
Dealing with Risk
Once the risk mitigation options are available, the tree owner can put the work out to bid, or schedule the work with available in-house or contract crews. The amount of mitigation that can be accomplished with available resources is known, and risk is being managed.
Some insights to the mitigation and prioritization of the work include figuring out the simplest way to mitigate the risk without removing every tree. Generally pruning can remove weak and dead branches, and clearance conflicts that may pose high risk. Another example of reducing cost in mitigation is to reduce a long large co-dominant stem to an acceptable height, when possible, instead of removing it completely. Reducing height reduces leverage and should cost less than the full stem removal and disposal.
The other advantage of using the Risk Factor system is a tree can have both a risk factor 1 and 3. The 1 may be a large hanging branch over a busy walkway. The branch can be pulled down or pruned off, and the tree now has a lower 3 rating, and the cost of mitigation was simple and low.
Training to Recognize Risk
Training of staff to recognize advanced risk issues requires some experience working in trees, some knowledge of tree species, and an understanding of what is normal, and what is not normal in trees. An observant person can be trained to identify conflicts, obvious risk issues, and which issues require the assistance of a more knowledgeable arborist.
Simple standards such as clearance heights, sight-distance needs, and level walking surfaces will cover most conflicts. Understanding a species propensity for included bark, tight branch attachment angles, long heavy branches, different decay issues and root issues, differences in growth and bark characteristics, how long a dead branch can remain in the species before failing; and targets, use, and conflict issues, will all assist in making sound risk assessments. Much of this comes with experience. Some site inspections require minor excavation to see the flare on a tree, buttressing roots, or check for a lower bole cavity. Other times a cavity may require insertion of a probe to learn how much decayed wood is present. These can be part of a Level 2 Basic visual inspection as listed in ANSI A300 Part 9. The need for full root crown excavations or additional decay detection would be part of a Level 3 Advanced assessment.
Risk managers should establish inspection procedures, time lines, and understand mitigation options. The goal of most risk managers is not to eliminate risk; it is to understand, manage, and mitigate the risk to an acceptable level with the available resources.
On a final note, I recommend that all arborists read the ISA Tree Risk Assessment BMP and the ANSI A300 Part 9 Tree Risk Management standard.
Gordon Mann is an ASCA Registered Consulting Arborist, an ISA Certified Arborist and Municipal Specialist, TRAQ Qualified Tree Risk Assessor, and urban forestry consultant in Auburn, CA. He is the SMA ANSI A300 Committee alternate and a Director on the ISA Board.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Gordon Mann
Editor's Note: In the last Seminar, Gordon provided a definition of tree risk management. In this article, he goes to the next step and describes the requirements for creating a Tree Risk Management Plan.
Creating a tree risk management plan involves the identification and assessment of the tree population to be considered. The risk assessment consists of identifying and inspecting the subject trees to analyze for risk.
A risk assessment is different from a full inventory. In a full inventory, every tree will be listed and some information collected. In a risk assessment, the list should only include those trees that are found to have a level of extreme, high, or moderate risk. These are the trees that should have mitigation options to reduce risk. Trees with low or limited risk will be inspected and are generally not be considered for active discussion at the time the risk management plan is implemented. Low risk trees generally don’t require any short term mitigation. Along with identifying the risk, the most important element of a risk assessment is the mitigation options which are the steps to reduce or eliminate risk in the trees identified to have extreme, high or moderate risk.
Tree Risk Assessment Rating Systems
The two most common rating systems used for tree risk in the US have been the PNW-ISA TRACE and Matheny and Clark's qualitative numeric 12-point system that considers 3 components, and adding together numbers for:
(1) the size of the tree part,
(2) the likelihood of failure or incident, and
(3) the target being struck.
These assigned numbers are categorizations and not quantifiable to be added together to develop an overall risk rating. Also, the 12 point systems do not include conflicts.
The system of primary consideration in the 2011 ISA Tree Risk Assessment Best Management Practices (BMP) is the Matrix Based Qualitative approach to Tree Risk management. It considers 7 steps in developing a risk rating:
1. Identify possible targets and conflicts.
2. Identify tree parts that could strike the target, or identify the tree part causing the conflict.
3. Evaluate the likelihood for each part to fail, or the likelihood of conflict.
4. Evaluate the likelihood for each part to strike a target.
5. For each failure mode, identify likelihood for tree failure impacting a specified target.
6. For each failure mode, estimate consequences of failure.
7. For each failure mode, designate the risk.
In each step above, conflicts are to be considered along with the failures in the site inspections. Many trees may have one potential conflict and/or failure, or multiple conflicts and/or failures. A tree can contain both very high and low risk with different identified issues, and mitigation. The critical step is not simply rating the tree, but defining the mitigation options and actions to reduce the risk. Just listing trees based on the rating score without understanding what mitigation is available to reduce the risk does not provide the tree manager the tools needed to make sound risk reduction decisions.
Most people focus on the risk of tree part or whole tree failure. In my experience, there are usually more conflicts in a community’s tree population than high risk structural issues. While observing structural issues and their mitigation options is a primary arborist function, conflict mitigation is often simpler and more trees may be retained with lesser residual risk when mitigating conflicts. For example, many small low branches may cause an eye-level poking risk on a school campus, but can be easily mitigated by pruning. There may be options to mitigate sidewalk offset conflicts by grinding or ramping offset sidewalks.
It is important to gain as much site information as possible to assess the risk. For example: a school district tree impacted a water line that cost $38,000 to repair before my risk assessment was scheduled. This tree was still on the manager’s list of concerns while we were looking at all the trees on the property. I would not have known there were any underground pipe issues; the tree looked normal, the water line was repaired, and the site restored, the extent of root removal was not evident, and the tree was not showing signs of decline, even though significant roots were pruned during the pipe repair. The information about the root cutting raised the tree’s risk rating during the assessment.
Tree Risk BMP
Using the ISA’s 2011 Tree Risk BMP, managers base decisions on the identified risk. The risk rating matrices are used to determine the level of risk present. A situation with a low branch over a walkway could be high to extreme risk, and easily mitigated while retaining the tree. If the tree had a high impact clearance issue and a high dead branch over a walk or parking area, the tree would have both high risk and moderate risk. The risk manager may choose to prune the low branch to obtain clearance and mitigate the high risk, and not climb to prune the dead branch, because another tree under their control has a higher risk and priority to expend their limited resources on.
Risk is rated in four terms in the BMP, Extreme, High, Moderate, and Low, which can be used to sort the trees in the order of highest risk. Based on risk and mitigation options, a tree owner or site manager, can view the risk present on their site. I rarely list low risk trees unless it is specifically requested in the assignment because usually mitigation cannot reduce the risk lower than low.
Prioritization of Tree Risk
Most site managers have limited resources, and the risk assessment will generally require some prioritization to assist the site manager to reduce risk. The prioritization is usually based on the consideration of use and targets, and likeliness of incident, and the cost of mitigation. The size of the part, height, and location (both in the tree and over targets) are generally considered in the consequences of failure. The owner may have the resources to mitigate all risk found on a site. In that case, prioritization may only affect the order of how some of the work is scheduled.
When resources are limited, I find most property managers consider mitigating the extreme risk first, then high risk, then maybe moderate. The basis of their decisions is mitigating the highest risk first, then addressing the next highest risk, and so on with the available resources.
Risk Factors
One approach to sort the risk and assist the site manager in making decisions is to create prioritized numerical risk factors, and sort the trees by the risk factor. Some trees will have more than one risk factor, and still should be sorted by the highest risk factor while listing the other lower risk factors. Unless mitigation of the highest risk factor is by tree removal, the higher risk mitigation often can be performed, and the lower risk mitigation may be delayed until resources allow; or maybe the lower risk is acceptable, for now.
Trees may be prioritized by numerical risk factors 1, 2, and 3 based on the targets, use frequency, and situation.
1. Risk factor 1 trees are the very high or extreme risk situations.
2. Risk factor 2 trees are high risk situations.
3. Risk factor 3 trees are moderate risk situations.
Low risk situations are not considered unless the site owner requests an inventory and risk assessment for all trees. If an owner does not want any risk, they may not want any trees.
The risk factors 1-3 are used to sort and prioritize the mitigation work. Risk Factor 1 trees should be considered first for mitigation, then Risk Factor 2 trees, and then Risk Factor 3 trees. If the agency has limited funds, the risk factor 1 trees may be all or partially what they can afford to mitigate. If they cannot perform all the risk factor 1 trees, they may need to prioritize which trees are addressed first. This is a management decision. Since the process is managing risk, the decisions have to consider the site use and risk, the mitigation, and the available resources.
The risk factors may be helpful in future re-assessments, since those trees with previous risk issues can be re-checked to see if the risk has increased as the tree has grown or declined.
Residual Risk
After mitigation is performed, there usually will be some risk remaining in the tree. The risk management approach is to lower the risk to an acceptable level, and the residual risk is tolerable. As long as the residual risk does not exceed the tolerable risk threshold, the risk has been managed.
Dealing with Risk
Once the risk mitigation options are available, the tree owner can put the work out to bid, or schedule the work with available in-house or contract crews. The amount of mitigation that can be accomplished with available resources is known, and risk is being managed.
Some insights to the mitigation and prioritization of the work include figuring out the simplest way to mitigate the risk without removing every tree. Generally pruning can remove weak and dead branches, and clearance conflicts that may pose high risk. Another example of reducing cost in mitigation is to reduce a long large co-dominant stem to an acceptable height, when possible, instead of removing it completely. Reducing height reduces leverage and should cost less than the full stem removal and disposal.
The other advantage of using the Risk Factor system is a tree can have both a risk factor 1 and 3. The 1 may be a large hanging branch over a busy walkway. The branch can be pulled down or pruned off, and the tree now has a lower 3 rating, and the cost of mitigation was simple and low.
Training to Recognize Risk
Training of staff to recognize advanced risk issues requires some experience working in trees, some knowledge of tree species, and an understanding of what is normal, and what is not normal in trees. An observant person can be trained to identify conflicts, obvious risk issues, and which issues require the assistance of a more knowledgeable arborist.
Simple standards such as clearance heights, sight-distance needs, and level walking surfaces will cover most conflicts. Understanding a species propensity for included bark, tight branch attachment angles, long heavy branches, different decay issues and root issues, differences in growth and bark characteristics, how long a dead branch can remain in the species before failing; and targets, use, and conflict issues, will all assist in making sound risk assessments. Much of this comes with experience. Some site inspections require minor excavation to see the flare on a tree, buttressing roots, or check for a lower bole cavity. Other times a cavity may require insertion of a probe to learn how much decayed wood is present. These can be part of a Level 2 Basic visual inspection as listed in ANSI A300 Part 9. The need for full root crown excavations or additional decay detection would be part of a Level 3 Advanced assessment.
Risk managers should establish inspection procedures, time lines, and understand mitigation options. The goal of most risk managers is not to eliminate risk; it is to understand, manage, and mitigate the risk to an acceptable level with the available resources.
On a final note, I recommend that all arborists read the ISA Tree Risk Assessment BMP and the ANSI A300 Part 9 Tree Risk Management standard.
Gordon Mann is an ASCA Registered Consulting Arborist, an ISA Certified Arborist and Municipal Specialist, TRAQ Qualified Tree Risk Assessor, and urban forestry consultant in Auburn, CA. He is the SMA ANSI A300 Committee alternate and a Director on the ISA Board.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Seeing the Map for the Trees
By Ian Hanou
I love trees, mapping, and technology. My career has basically involved anything where these three intersect. For almost 20 years I’ve been using Geographic Information Systems (GIS), which is really just computer software for mapping, for forestry, urban forestry, and natural resources planning. I often joke that when I’m at a GIS conference, I can hold my own in terms of knowledge on trees and forestry, and conversely when I’m at a forestry conference, I can look like a real GIS wiz.
Personally, I think every arborist can be a GIS wiz, especially with new mobile mapping applications for smartphones and tablets. It’s never been easier to “do GIS” without even knowing it. But before we can get there, it’s important to go over some GIS fundamentals and then discuss why this matters to arborists and urban foresters now more than ever.
GIS for Dummies: a 101 for Arborists
What really is a GIS? I like to think of it as a spreadsheet that’s linked to a map. Every row of data in your spreadsheet is a record, and with GIS, that record also has a location with coordinates tied to the Earth (e.g. latitude/longitude). These GIS records are often called features. One thing that’s cool is these GIS features can come in the form of points (e.g. a tree), lines (a road or trail), or a polygon (a forest stand, property boundary, etc.). These points, lines, and polygons are a type of GIS format called vector data. They’re usually referred to as a “layer” because you can layer various representations of real world objects on top of one another in a map.
The second type of GIS data is called raster. It’s kind of like cells in the old “dot grid” method used in forestry field measurements. Raster images are similar to the photos we take on our phones or digital cameras because they’re made up of pixels, but the unique thing is each pixel has a location (an x/y coordinate). The most common raster images are aerial or satellite imagery. Land cover maps are often raster layers as well, where a forest area is represented by a group of pixels that all have the same pixel value (i.e. digital number).
Global Positioning Systems (GPS) is a related technology to collect location information. You can then layer those data points into a GIS map. GPS uses a constellation of satellites to triangulate your location on the Earth. The accuracy of that location is dependent on a number of factors, and can get complicated and expensive. Using a GPS to create a “dot in the map” can be accomplished just the same by using a GIS software with an aerial or satellite image. You simply place (“digitize”) a point into the map and the location is joined and stored from the underlying x/y coordinate of the pixel in the imagery. It’s identical to what a GPS receiver locates for you, just a different method. Aerial imagery in urban areas is typically very accurate, within 1-2 feet (horizontal), so mapping the location of a tree as a point using GIS is not only easy and inexpensive, but can be highly accurate and without having to wait sometimes for a strong GPS signal.
To recap this intro to GIS, let’s get back to the spreadsheet concept. When you add a point, line, or polygon to a GIS map, there are a series of associated fields like the column headings in a spreadsheet and attributes such text boxes, dropdown lists or values used to attribute collected data. With GPS, this is commonly referred to as a “data dictionary”. Whether GPS or GIS, it does take some technical knowledge, software, and experience to create these. Now enter the age of online and mobile GIS tree inventory software.
Tree Inventories Just Got Easier
While I’ve always loved GIS and trees, I used to think tree inventory software was boring. Just hearing the words “tree inventory” might conjure up bad memories of expensive GPS units, a steep learning curve involving new hardware and software, and cumbersome processes to process, format, and transfer data. A lot has changed with advancements in web and mobile mapping technology and available “base maps” from Google, Esri, and Bing (Microsoft). Now all you need is a smartphone or tablet.
With an internet connection and a web browser, you can zoom into an aerial base map and inventory tree characteristics such as location, species, DBH, condition, maintenance needs, and defects. With this information, you can determine tree quality, density, diversity, potential planting sites, and monetary ecosystem benefits from i-Tree.
Another benefit is being able to determine which trees require priority attention, maintenance, long-term monitoring or simply no maintenance at all. With a mobile, online inventory system, you have the ability to update from the field in real time and communicate assignments from multiple locations. Some programs also now include fields, dropdown lists, and calculations based on ISA TRAQ (Tree Risk Assessment Qualifications). Once an inventory is completed, data can be saved to a spreadsheet and other reporting formats for easy delivery to a client or manager.
Discussion
Many cities, environmental nonprofits, campuses, and private consultants are on the forefront of web/mobile technologies for urban forest management and will enjoy many benefits. There are also challenges in terms of learning curve, changes in technologies, paying for long-term hosting and maintenance, and adoption by users.
Inventorying trees and using more advanced software features like reports, queries, and work orders has never been so simple. Ideally, the right tool should be like the intern or executive assistant you always wanted … easy to work with, accessible anywhere anytime, speedy, and versatile.
To close, here are a few considerations when venturing into the world of tree inventory software in the “age of apps.”
· Will you have an internet connection in the field?
· Can the data fields be customized?
· What device(s) will you use in the field?
· How should you design data collection for a specific management and maintenance program?
Ian Hanou is the Founder of Plan-It Geo and has been working in GIS, project management, software development, and urban forest management for over 15 years.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Ian Hanou
I love trees, mapping, and technology. My career has basically involved anything where these three intersect. For almost 20 years I’ve been using Geographic Information Systems (GIS), which is really just computer software for mapping, for forestry, urban forestry, and natural resources planning. I often joke that when I’m at a GIS conference, I can hold my own in terms of knowledge on trees and forestry, and conversely when I’m at a forestry conference, I can look like a real GIS wiz.
Personally, I think every arborist can be a GIS wiz, especially with new mobile mapping applications for smartphones and tablets. It’s never been easier to “do GIS” without even knowing it. But before we can get there, it’s important to go over some GIS fundamentals and then discuss why this matters to arborists and urban foresters now more than ever.
GIS for Dummies: a 101 for Arborists
What really is a GIS? I like to think of it as a spreadsheet that’s linked to a map. Every row of data in your spreadsheet is a record, and with GIS, that record also has a location with coordinates tied to the Earth (e.g. latitude/longitude). These GIS records are often called features. One thing that’s cool is these GIS features can come in the form of points (e.g. a tree), lines (a road or trail), or a polygon (a forest stand, property boundary, etc.). These points, lines, and polygons are a type of GIS format called vector data. They’re usually referred to as a “layer” because you can layer various representations of real world objects on top of one another in a map.
The second type of GIS data is called raster. It’s kind of like cells in the old “dot grid” method used in forestry field measurements. Raster images are similar to the photos we take on our phones or digital cameras because they’re made up of pixels, but the unique thing is each pixel has a location (an x/y coordinate). The most common raster images are aerial or satellite imagery. Land cover maps are often raster layers as well, where a forest area is represented by a group of pixels that all have the same pixel value (i.e. digital number).
Global Positioning Systems (GPS) is a related technology to collect location information. You can then layer those data points into a GIS map. GPS uses a constellation of satellites to triangulate your location on the Earth. The accuracy of that location is dependent on a number of factors, and can get complicated and expensive. Using a GPS to create a “dot in the map” can be accomplished just the same by using a GIS software with an aerial or satellite image. You simply place (“digitize”) a point into the map and the location is joined and stored from the underlying x/y coordinate of the pixel in the imagery. It’s identical to what a GPS receiver locates for you, just a different method. Aerial imagery in urban areas is typically very accurate, within 1-2 feet (horizontal), so mapping the location of a tree as a point using GIS is not only easy and inexpensive, but can be highly accurate and without having to wait sometimes for a strong GPS signal.
To recap this intro to GIS, let’s get back to the spreadsheet concept. When you add a point, line, or polygon to a GIS map, there are a series of associated fields like the column headings in a spreadsheet and attributes such text boxes, dropdown lists or values used to attribute collected data. With GPS, this is commonly referred to as a “data dictionary”. Whether GPS or GIS, it does take some technical knowledge, software, and experience to create these. Now enter the age of online and mobile GIS tree inventory software.
Tree Inventories Just Got Easier
While I’ve always loved GIS and trees, I used to think tree inventory software was boring. Just hearing the words “tree inventory” might conjure up bad memories of expensive GPS units, a steep learning curve involving new hardware and software, and cumbersome processes to process, format, and transfer data. A lot has changed with advancements in web and mobile mapping technology and available “base maps” from Google, Esri, and Bing (Microsoft). Now all you need is a smartphone or tablet.
With an internet connection and a web browser, you can zoom into an aerial base map and inventory tree characteristics such as location, species, DBH, condition, maintenance needs, and defects. With this information, you can determine tree quality, density, diversity, potential planting sites, and monetary ecosystem benefits from i-Tree.
Another benefit is being able to determine which trees require priority attention, maintenance, long-term monitoring or simply no maintenance at all. With a mobile, online inventory system, you have the ability to update from the field in real time and communicate assignments from multiple locations. Some programs also now include fields, dropdown lists, and calculations based on ISA TRAQ (Tree Risk Assessment Qualifications). Once an inventory is completed, data can be saved to a spreadsheet and other reporting formats for easy delivery to a client or manager.
Discussion
Many cities, environmental nonprofits, campuses, and private consultants are on the forefront of web/mobile technologies for urban forest management and will enjoy many benefits. There are also challenges in terms of learning curve, changes in technologies, paying for long-term hosting and maintenance, and adoption by users.
Inventorying trees and using more advanced software features like reports, queries, and work orders has never been so simple. Ideally, the right tool should be like the intern or executive assistant you always wanted … easy to work with, accessible anywhere anytime, speedy, and versatile.
To close, here are a few considerations when venturing into the world of tree inventory software in the “age of apps.”
· Will you have an internet connection in the field?
· Can the data fields be customized?
· What device(s) will you use in the field?
· How should you design data collection for a specific management and maintenance program?
Ian Hanou is the Founder of Plan-It Geo and has been working in GIS, project management, software development, and urban forest management for over 15 years.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA management credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
TREE OF THE SEMINAR #74
By Len Phillips
Botanical Name: Nyssa sylvatica
Common Name: Tupelo or Black gum
Family: Nyssaceae
Height: 30' - 50'
Spread: 20' - 30'
Form: Pyramidal shape in youth, horizontal branches with age, highly variable
Bloom Period: Spring, with leaf break
Flower: Small, 2-4 flowers per cluster, not attractive
Fruit: Pendulous, black drupe, ½" long, eaten by birds and mammals in fall
Summer Foliage: Dark green and glossy
Autumn Foliage: Brilliant fall tones, ranging from scarlet to maroon, yellow and orange.
Winter Color: Fruits persist until early winter and become dark scaly bark
Bark: Dark gray to black, thick fissured blocks
Habitat: Northeast US and Canada, south to Florida and Texas
Culture: Moist, well drained, acid soil, will tolerate dry, compacted, shallow, and poorly drained soil
Hardiness Zone: 5 – 9
Heat Zone: 9 – 7
Growth Rate: Slow to medium, 12' after 15 years
Pest Problems: Nothing serious
Storm Resistance: Good
Salt Resistance: Fair
Planting: Difficult to transplant, best as B&B in early spring or in containers if small
Pruning: Prune only in fall
Propagating: Tissue culture and seeds are best
Design Uses: Excellent specimen for homes, streets only if pollution is limited, good in naturalized setting
Companions: Use with ferns
Other Comments: Adaptable to urban conditions, and one of the most beautiful trees in the fall
Available From: Many nurseries in eastern US and Canada
Photo
For information about the USDA Hardiness Zone Map
For information about the AHS Plant Heat-Zone Map
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
By Len Phillips
Botanical Name: Nyssa sylvatica
Common Name: Tupelo or Black gum
Family: Nyssaceae
Height: 30' - 50'
Spread: 20' - 30'
Form: Pyramidal shape in youth, horizontal branches with age, highly variable
Bloom Period: Spring, with leaf break
Flower: Small, 2-4 flowers per cluster, not attractive
Fruit: Pendulous, black drupe, ½" long, eaten by birds and mammals in fall
Summer Foliage: Dark green and glossy
Autumn Foliage: Brilliant fall tones, ranging from scarlet to maroon, yellow and orange.
Winter Color: Fruits persist until early winter and become dark scaly bark
Bark: Dark gray to black, thick fissured blocks
Habitat: Northeast US and Canada, south to Florida and Texas
Culture: Moist, well drained, acid soil, will tolerate dry, compacted, shallow, and poorly drained soil
Hardiness Zone: 5 – 9
Heat Zone: 9 – 7
Growth Rate: Slow to medium, 12' after 15 years
Pest Problems: Nothing serious
Storm Resistance: Good
Salt Resistance: Fair
Planting: Difficult to transplant, best as B&B in early spring or in containers if small
Pruning: Prune only in fall
Propagating: Tissue culture and seeds are best
Design Uses: Excellent specimen for homes, streets only if pollution is limited, good in naturalized setting
Companions: Use with ferns
Other Comments: Adaptable to urban conditions, and one of the most beautiful trees in the fall
Available From: Many nurseries in eastern US and Canada
Photo
For information about the USDA Hardiness Zone Map
For information about the AHS Plant Heat-Zone Map
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Fixing Compact Soils
Edited by Len Phillips
Compacted soils occur when developers come in with heavy equipment to build structures, install utilities, and layout streets and sidewalks. They need to have compacted soil so foundations do not settle and sidewalks and streets would not crack. While this process may be good for development, it is not good for growing trees and other plants. Their roots cannot penetrate the compact soil in sufficient quantity to support tree growth.
Prevention of Soil Compaction
There are several steps an arborist can take to prevent damage to soils from compaction during the construction process.
· Prior to the start of construction, the soil where trees exist or are to be planted should be protected from compaction. This is most easily done by installing fencing around the tree's drip line and other areas where roots are expected to be growing. The intent of the fencing is to keep construction equipment away from the root zone of the existing and proposed trees, but this step must be monitored throughout the project. At the same time a deep layer of wood chips or other mulch should be spread over the root zone of all the existing and future trees to absorb the compression of heavy machinery on surrounding soils.
· All equipment must be kept off of wet soil. Compaction of wet soil will result in irreversibly damaged soil. Wet soil has water in the pore spaces making the soil elastic and easily crushed. The crushed soil then no longer has the pore space that is essential for containing oxygen and water molecules that are needed by the tree roots for survival.
Treatment of Compacted Soils
If the prevention efforts were not applied to the site and the soil is severely compacted, there are several steps an arborist can take to encourage root growth in compact soils. Some of these efforts were developed for agricultural fields, but they apply to large areas where tree roots are expected to be growing years after construction is complete. They include the following:
· Replace the compacted soil with suspended pavements, structural soils, or soil cells prior to installing surface pavements, curbs, etc.
· Soils only marginally compacted can be improved with the addition of:
◦ biosolids which have a high nutrient content and are products of sewage treatment facilities.
◦ biochar which is not a fertilizer but has large pores and are composed of pure carbon, that will improve soil quality.
◦ biosolids and biochar together provide an effective treatment for many marginally compacted soils.
◦ compost which contains a wide variety of micro-organisms and nutrients makes a good soil amendment.
◦ composted woodchips that are often used in conjunction with compost or after a compost treatment will provide a long period for compaction treatment.
◦ mulch on the surface provides long-term nutrient replacements.
· Consider manipulation of heavily compacted soil with:
◦ backhoes that can dig holes and trenches to loosen the soil as it is being replaced by dropping the soil from 6 ft. above the surface. Compost should be added in the same manner.
◦ trenching equipment can loosen the soil to provide a channel that directs root growth to non-compact soils beyond the construction limits.
◦ vertical boring of 2 inch diameter holes 18 in. apart within the root zone of existing and proposed trees should be at least 18 in. deep. The holes may receive fertilizer and other amendments prior to the soil being replaced in the holes.
◦ air tillage (Air Spade™) may be used to blow the compact soil off of all the roots so it can be pulled back over the roots in a non-compacting manner.
◦ an aerator attachment to a small, light weight tractor with balloon tires will loosen the top 6 to 8 inches of soil by punching holes in the soil. This equipment may require several repeated treatments to relieve severe compaction and the tines may occasionally damage existing unseen roots.
◦ a subsoiler is a large probe in the shape of a fish hook, that is lowered into the soil and pulled through the compact soil to the depth and area necessary. This process needs a powerful light weight tractor with balloon tires to pull the hook in heavily compacted soil.
◦ plows on the back of a tractor will loosen the soil in the same manner as the subsoiler, but only 8 to 10 inches deep. If the soil is wet when the plow is used, the bottom of the plow will sometimes seal the bottom of the trench and prevent water penetration below the plow depth.
◦ rotary tillers are very effective at loosening the soil but they are limited in the depth to which they can work by their design and the engine power. Very large tillers that attach to tractors can go as deep as 18 inches.
◦ add soil amendments such as mulches, compost, and fertilizers on the surface prior to the start of a manipulation so the amendment is worked into the improved, non-compacted soil.
Follow-up after Treatment
The arborist should access the extent and quality of the compacted soil prior to planting any trees. Monitor the treatments to be sure they were effective and covered the area sufficiently. Most of the products mentioned above should be applied by air tillage or cores, followed by mulch and/or compost surface treatments as necessary for nutrient replacement.
Often several years are required to determine the effectiveness of the treatments. In locations where treatments were not applied, as evidence by historic dirt roads, the compacted wheel ruts are still visible 100 years after the use of the road ceased.
Source:
Scharenbroch, Dr. Bryant, “Fix Compact Soils”, lecture, November 2016.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Edited by Len Phillips
Compacted soils occur when developers come in with heavy equipment to build structures, install utilities, and layout streets and sidewalks. They need to have compacted soil so foundations do not settle and sidewalks and streets would not crack. While this process may be good for development, it is not good for growing trees and other plants. Their roots cannot penetrate the compact soil in sufficient quantity to support tree growth.
Prevention of Soil Compaction
There are several steps an arborist can take to prevent damage to soils from compaction during the construction process.
· Prior to the start of construction, the soil where trees exist or are to be planted should be protected from compaction. This is most easily done by installing fencing around the tree's drip line and other areas where roots are expected to be growing. The intent of the fencing is to keep construction equipment away from the root zone of the existing and proposed trees, but this step must be monitored throughout the project. At the same time a deep layer of wood chips or other mulch should be spread over the root zone of all the existing and future trees to absorb the compression of heavy machinery on surrounding soils.
· All equipment must be kept off of wet soil. Compaction of wet soil will result in irreversibly damaged soil. Wet soil has water in the pore spaces making the soil elastic and easily crushed. The crushed soil then no longer has the pore space that is essential for containing oxygen and water molecules that are needed by the tree roots for survival.
Treatment of Compacted Soils
If the prevention efforts were not applied to the site and the soil is severely compacted, there are several steps an arborist can take to encourage root growth in compact soils. Some of these efforts were developed for agricultural fields, but they apply to large areas where tree roots are expected to be growing years after construction is complete. They include the following:
· Replace the compacted soil with suspended pavements, structural soils, or soil cells prior to installing surface pavements, curbs, etc.
· Soils only marginally compacted can be improved with the addition of:
◦ biosolids which have a high nutrient content and are products of sewage treatment facilities.
◦ biochar which is not a fertilizer but has large pores and are composed of pure carbon, that will improve soil quality.
◦ biosolids and biochar together provide an effective treatment for many marginally compacted soils.
◦ compost which contains a wide variety of micro-organisms and nutrients makes a good soil amendment.
◦ composted woodchips that are often used in conjunction with compost or after a compost treatment will provide a long period for compaction treatment.
◦ mulch on the surface provides long-term nutrient replacements.
· Consider manipulation of heavily compacted soil with:
◦ backhoes that can dig holes and trenches to loosen the soil as it is being replaced by dropping the soil from 6 ft. above the surface. Compost should be added in the same manner.
◦ trenching equipment can loosen the soil to provide a channel that directs root growth to non-compact soils beyond the construction limits.
◦ vertical boring of 2 inch diameter holes 18 in. apart within the root zone of existing and proposed trees should be at least 18 in. deep. The holes may receive fertilizer and other amendments prior to the soil being replaced in the holes.
◦ air tillage (Air Spade™) may be used to blow the compact soil off of all the roots so it can be pulled back over the roots in a non-compacting manner.
◦ an aerator attachment to a small, light weight tractor with balloon tires will loosen the top 6 to 8 inches of soil by punching holes in the soil. This equipment may require several repeated treatments to relieve severe compaction and the tines may occasionally damage existing unseen roots.
◦ a subsoiler is a large probe in the shape of a fish hook, that is lowered into the soil and pulled through the compact soil to the depth and area necessary. This process needs a powerful light weight tractor with balloon tires to pull the hook in heavily compacted soil.
◦ plows on the back of a tractor will loosen the soil in the same manner as the subsoiler, but only 8 to 10 inches deep. If the soil is wet when the plow is used, the bottom of the plow will sometimes seal the bottom of the trench and prevent water penetration below the plow depth.
◦ rotary tillers are very effective at loosening the soil but they are limited in the depth to which they can work by their design and the engine power. Very large tillers that attach to tractors can go as deep as 18 inches.
◦ add soil amendments such as mulches, compost, and fertilizers on the surface prior to the start of a manipulation so the amendment is worked into the improved, non-compacted soil.
Follow-up after Treatment
The arborist should access the extent and quality of the compacted soil prior to planting any trees. Monitor the treatments to be sure they were effective and covered the area sufficiently. Most of the products mentioned above should be applied by air tillage or cores, followed by mulch and/or compost surface treatments as necessary for nutrient replacement.
Often several years are required to determine the effectiveness of the treatments. In locations where treatments were not applied, as evidence by historic dirt roads, the compacted wheel ruts are still visible 100 years after the use of the road ceased.
Source:
Scharenbroch, Dr. Bryant, “Fix Compact Soils”, lecture, November 2016.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
UtiliTrees™ - Three
Edited by Len Phillips
Several Seminars ago, Nancy Buley wrote an article describing nine trees that are suitable for growing under a city’s utility lines. Frequent requests for advice on the best trees to plant in this challenging zone led J. Frank Schmidt & Son Co. to develop a list of preferred trees branded as UtiliTrees™. Launched more than 20 years ago, the list has been expanded over the years to include nearly 50 time-tested trees that perform well in many growing regions of the US, Canada, and beyond. Urban foresters, utility arborists, landscape architects, and other specifiers have embraced the list and have customized it to suit their own unique local growing conditions.
This list of trees is well suited for planting in the restricted zone between the street and sidewalk and beneath the utility lines. All these trees mature at heights that are unlikely to tangle with overhead lines. These trees are also considered pedestrian friendly because their branching is compact or vase-shaped which allows for pruning without destroying the shape of the trees. Disease and pest resistant, these cultivars are also tolerant of varied soils, climates, and urban growing conditions and require minimal maintenance.
Here is a list of the nine UtiliTrees™–One, that were discussed in Seminar #51. Paperbark Maple, Rugged Charm® Maple, Spring Flurry® Serviceberry, Crushed Velvet™ Silverbell, Pink Flair® Cherry, Jack® Pear, Ivory Silk Japanese Tree Lilac, City Sprite® Zelkova, and Wireless® Zelkova.
The ten UtiliTrees™–Two, discussed in Seminar #67 included: Hedge Maple, Flame Maple, Autumn Brilliance Serviceberry, Cole’s Select Serviceberry, Crimson Cloud Hawthorn, Washington Hawthorn, Adirondack Crabapple, Golden Raindrops Crabapple, Big Cis® Plum, and Crimson Pointe Plum.
UtiliTrees™ List – Three
This list and the trees that follow continue with recommendations for cities seeking to develop their own list of trees to grow under the wires. Several favorites, plus some newer additions are described. This link goes to the entire UtiliTree list and it shows height, spread, and form at a glance. The ten trees that follow are on this UtiliTree list and are described here for those who are interested in making their own list of UtiliTrees. The photos for each may be downloaded by clicking on the word 'Photo'.
Trident Maple Acer buergerianum – Zone: 6; Height: 20’; Spread: 20’; Shape: low, spreading and round; Foliage: glossy and pale green underneath; Fall Color: red and orange. Adaptability to urban environments make Trident Maple a good choice for confined sites and tough growing conditions including drought and air pollution. Photo
Princes Diana Serviceberry Amelanchier grandiflora ‘Princess Diana’ – Zone: 3; Height: 20’; Spread: 15’; Shape: gracefully spreading; Foliage: small green leaves; Fall Color: brilliant red; Flowers: white clusters; Fruits: edible, similar to a blueberry. Princess Diana is a gracefully spreading small tree with excellent fall color early that lasts late into the season. Photo
Paul Scarlet Hawthorn Crataegus laevigata ‘Paul’s Scarlet’ -- Zone: 4; Height: 22'; Spread: 20'; Shape: dense, upright spreading oval; Foliage: green with deep lobes and small; Flower: double, clusters of rose to scarlet; Fruit: sparse and deep red. The brilliant colored flowers make Paul’s Scarlet the showiest of all the Hawthorns in the spring. Unfortunately, this selection is susceptible to leaf spot, but it is not always a problem. Photo
Columnar Goldenchain Laburnum anagyroides ‘Columnaris’ – Zone: 5; Height: 20’; Spread: 10’; Shape: upright and narrow vase; Foliage: dark green; Fall Color: yellow; Flower: bright hanging clusters; Fruit: dried capsule.
Densely packed clusters of bright yellow flowers are borne on stiffly upright branches of this compact, narrow goldenchain tree. The heavy bloom creates an outstanding display late in every spring to early summer season. Photo
Red Barron Crabapple Malus 'Red Barron' – Zone: 4; Height: 18'; Spread: 8'; Shape: narrow columnar form; Foliage: purple to bronze-green; Flower: dark red; Fruit: dark red; Disease Resistance: Scab: fair, Fireblight: good, Cedar-Apple Rust: excellent, and Mildew: excellent. Ascending branch structure, narrow form, and adaptability to urban conditions should earn Red Barron a place in many city landscapes. Photo
Red Jewel™ Crabapple Malus 'Jewelcole' – Zone: 4; Height: 15’; Spread: 11'; Shape: upright and rounded; Foliage: green; Flower: white; Fruit: very persistent, red, 1⁄2” in diameter. Disease Resistance: Scab: good, Fireblight: fair, Cedar-Apple Rust: excellent, and Mildew resistance: good. Bright red fruits of Red Jewel are among the most profuse and persistent of any crabapple. The apples hold fast until spring in mild winter areas, when they are replaced by an abundance of white blooms. Photo
Snow Goose Cherry Prunus ‘Snow Goose’ – Zone: 5; Height: 20’; Spread: 20’; Shape: upright when young, becomes wider with age; Foliage: bright green; Fall color: orange; Flower: single, pure white. Pure white flowers bloom before clean, bright green leaves unfold. Apparently resistant to common cherry foliage diseases, Snow Goose is a strong upright tree that widens considerably with age. Photo
Newport Plum Prunus ‘Newport’ – Zone: 3; Height: 20'; Spread: 20'; Shape: upright spreading to broad oval; Foliage: purple to red; Flower: light pink; Fruit: small, dark. Newport plum is hardy and widely used because it is quite adaptable and performs well in tough climates. Photo
China Snow Tree Lilac Syringa pekinensis ‘Morton’ – Zone: 5 Height: 20'; Spread: 20'; Shape: upright and spreading; Foliage: dark green; Fall Color: yellow; Flower: creamy white clusters. Large sprays of cream-white flowers are borne in June by this small ornamental tree. Amber to orange-brown exfoliating bark extends seasonal interest through the winter months. Photo
Summer Sprite® Linden Tilia cordata ‘Halka’ PP 10589 – Zone: 4; Height: 20’; Spread: 15’; Shape: dwarf, dense narrow pyramid; Foliage: green; Fall Color: yellow. Summer Sprite is perfect for confined city spaces. This natural semi-dwarf develops a dense and compact form with a rounded to upright oval shape and it provides a sheared appearance without the labor of actually shearing the tree. Photo
Source
J. Frank Schmidt & Son Co.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Edited by Len Phillips
Several Seminars ago, Nancy Buley wrote an article describing nine trees that are suitable for growing under a city’s utility lines. Frequent requests for advice on the best trees to plant in this challenging zone led J. Frank Schmidt & Son Co. to develop a list of preferred trees branded as UtiliTrees™. Launched more than 20 years ago, the list has been expanded over the years to include nearly 50 time-tested trees that perform well in many growing regions of the US, Canada, and beyond. Urban foresters, utility arborists, landscape architects, and other specifiers have embraced the list and have customized it to suit their own unique local growing conditions.
This list of trees is well suited for planting in the restricted zone between the street and sidewalk and beneath the utility lines. All these trees mature at heights that are unlikely to tangle with overhead lines. These trees are also considered pedestrian friendly because their branching is compact or vase-shaped which allows for pruning without destroying the shape of the trees. Disease and pest resistant, these cultivars are also tolerant of varied soils, climates, and urban growing conditions and require minimal maintenance.
Here is a list of the nine UtiliTrees™–One, that were discussed in Seminar #51. Paperbark Maple, Rugged Charm® Maple, Spring Flurry® Serviceberry, Crushed Velvet™ Silverbell, Pink Flair® Cherry, Jack® Pear, Ivory Silk Japanese Tree Lilac, City Sprite® Zelkova, and Wireless® Zelkova.
The ten UtiliTrees™–Two, discussed in Seminar #67 included: Hedge Maple, Flame Maple, Autumn Brilliance Serviceberry, Cole’s Select Serviceberry, Crimson Cloud Hawthorn, Washington Hawthorn, Adirondack Crabapple, Golden Raindrops Crabapple, Big Cis® Plum, and Crimson Pointe Plum.
UtiliTrees™ List – Three
This list and the trees that follow continue with recommendations for cities seeking to develop their own list of trees to grow under the wires. Several favorites, plus some newer additions are described. This link goes to the entire UtiliTree list and it shows height, spread, and form at a glance. The ten trees that follow are on this UtiliTree list and are described here for those who are interested in making their own list of UtiliTrees. The photos for each may be downloaded by clicking on the word 'Photo'.
Trident Maple Acer buergerianum – Zone: 6; Height: 20’; Spread: 20’; Shape: low, spreading and round; Foliage: glossy and pale green underneath; Fall Color: red and orange. Adaptability to urban environments make Trident Maple a good choice for confined sites and tough growing conditions including drought and air pollution. Photo
Princes Diana Serviceberry Amelanchier grandiflora ‘Princess Diana’ – Zone: 3; Height: 20’; Spread: 15’; Shape: gracefully spreading; Foliage: small green leaves; Fall Color: brilliant red; Flowers: white clusters; Fruits: edible, similar to a blueberry. Princess Diana is a gracefully spreading small tree with excellent fall color early that lasts late into the season. Photo
Paul Scarlet Hawthorn Crataegus laevigata ‘Paul’s Scarlet’ -- Zone: 4; Height: 22'; Spread: 20'; Shape: dense, upright spreading oval; Foliage: green with deep lobes and small; Flower: double, clusters of rose to scarlet; Fruit: sparse and deep red. The brilliant colored flowers make Paul’s Scarlet the showiest of all the Hawthorns in the spring. Unfortunately, this selection is susceptible to leaf spot, but it is not always a problem. Photo
Columnar Goldenchain Laburnum anagyroides ‘Columnaris’ – Zone: 5; Height: 20’; Spread: 10’; Shape: upright and narrow vase; Foliage: dark green; Fall Color: yellow; Flower: bright hanging clusters; Fruit: dried capsule.
Densely packed clusters of bright yellow flowers are borne on stiffly upright branches of this compact, narrow goldenchain tree. The heavy bloom creates an outstanding display late in every spring to early summer season. Photo
Red Barron Crabapple Malus 'Red Barron' – Zone: 4; Height: 18'; Spread: 8'; Shape: narrow columnar form; Foliage: purple to bronze-green; Flower: dark red; Fruit: dark red; Disease Resistance: Scab: fair, Fireblight: good, Cedar-Apple Rust: excellent, and Mildew: excellent. Ascending branch structure, narrow form, and adaptability to urban conditions should earn Red Barron a place in many city landscapes. Photo
Red Jewel™ Crabapple Malus 'Jewelcole' – Zone: 4; Height: 15’; Spread: 11'; Shape: upright and rounded; Foliage: green; Flower: white; Fruit: very persistent, red, 1⁄2” in diameter. Disease Resistance: Scab: good, Fireblight: fair, Cedar-Apple Rust: excellent, and Mildew resistance: good. Bright red fruits of Red Jewel are among the most profuse and persistent of any crabapple. The apples hold fast until spring in mild winter areas, when they are replaced by an abundance of white blooms. Photo
Snow Goose Cherry Prunus ‘Snow Goose’ – Zone: 5; Height: 20’; Spread: 20’; Shape: upright when young, becomes wider with age; Foliage: bright green; Fall color: orange; Flower: single, pure white. Pure white flowers bloom before clean, bright green leaves unfold. Apparently resistant to common cherry foliage diseases, Snow Goose is a strong upright tree that widens considerably with age. Photo
Newport Plum Prunus ‘Newport’ – Zone: 3; Height: 20'; Spread: 20'; Shape: upright spreading to broad oval; Foliage: purple to red; Flower: light pink; Fruit: small, dark. Newport plum is hardy and widely used because it is quite adaptable and performs well in tough climates. Photo
China Snow Tree Lilac Syringa pekinensis ‘Morton’ – Zone: 5 Height: 20'; Spread: 20'; Shape: upright and spreading; Foliage: dark green; Fall Color: yellow; Flower: creamy white clusters. Large sprays of cream-white flowers are borne in June by this small ornamental tree. Amber to orange-brown exfoliating bark extends seasonal interest through the winter months. Photo
Summer Sprite® Linden Tilia cordata ‘Halka’ PP 10589 – Zone: 4; Height: 20’; Spread: 15’; Shape: dwarf, dense narrow pyramid; Foliage: green; Fall Color: yellow. Summer Sprite is perfect for confined city spaces. This natural semi-dwarf develops a dense and compact form with a rounded to upright oval shape and it provides a sheared appearance without the labor of actually shearing the tree. Photo
Source
J. Frank Schmidt & Son Co.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA practice credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Tree Communication
Edited by Len Phillips
A forest is composed of many individual trees and together, all the individual trees can moderate the weather. They can create an ecosystem that changes temperatures and humidity as well as stores a great deal of water. All the trees in the forest form a unit and as such they protect all the trees from damaging windstorms. As a result of this unity, protection, and climate modification in the forest, the individual tree can grow much older than the same tree growing in a city or by itself.
Every individual tree is a very important part of the whole forest. Each tree is very aware of its surroundings and is very compatible with its neighboring trees. For example, branches grow toward other trees, but they stop growing when they get too close to another tree's branches. They give each other space to grow and do not block the sunlight from the neighboring trees.
Communication
It has been well documented by scientists that in the forest there is a form of communication going on among trees. For example, when an animal or a pest takes a bite out of a leaf, the tree responds by pumping toxic substances into their leaves. A short time later, the same toxic substance appears in nearby trees as if the first tree warned the others of the attack. Scientists assumed the first tree gave off a warning sound or an odor or gas warning to the other trees. However, the odors and gas would disperse very quickly in the wind and would only be detected within a few hundred feet and some neighboring upwind trees might not get the message.
The reality, discovered by recent research indicates that the tree actually sends out an electrical signal, in the same way that humans feel pain where they have been injured. Instead of the pain going from the injury to the brain, the tree sends an electrical signal from the wound to all parts of the tree, including the roots. Underground, the roots of trees in the forest, in combination with mycorrhizal fungi, often intertwine and link up with roots of other trees. This means that the electrical signal is passed from one tree to the next, so they received the signal sent by the first tree.
Another example of linkage occurs when one tree has been struck by lightning and it dies. Soon after, it has been observed, that all the nearby trees also begin to die because the electrical impulse from the lightning spread to all the trees with root connections to the original tree.
Trees also have the ability to produce different compounds that might be used to repulse a pest. Other times, the tree under attack can produce a pheromone that attracts other insects that might feed on the pest. For example, if a caterpillar is eating leaves on a tree, the tree might produce a pheromone that attracts a wasp that will lay its eggs in the caterpillar. The eggs soon hatch and the larvae eat the pest from the inside out. The pheromone compounds can also act as warnings to other trees through their root system communication networks.
Trees that have this ability to repulse a pest, do so because they can also identify the pest by its saliva as it is eating the leaves. Their genetics identify the pest and which internal action or predator contact is most effective at attacking the pest. The fact that trees can recognize the saliva, indicates that trees seem to have a sense of taste.
Other trees have their own defense mechanisms. As mentioned previously trees carry toxic chemicals that will kill a pest that is eating its leaves or at least produce a bad taste so the pest will go somewhere else. However, other times, if a pest arrives that the tree is not familiar with, the pest may win the battle. The Emerald Ash Borer is a prime example. Only the Manchurian Ash which co-exists with the EAB in its native land, can survive the borer's attack.
The Fungal Network
Fungi generate extensive networks in the soil. A single teaspoon of soil can contain miles of fungal hyphae. The fungal connections in a forest can, over time, transmit messages for many square miles. It is these fungal networks that transmit signals from one tree to another, root to root.
If a tree has become very old or for some other reason has broken its linkage to the fungal network, signals become lost and the tree can not adequately establish a defense against a pest before the pest arrives. Soon after the tree will die or become very weak and defenseless against other diseases or pests.
Urban trees, on the other hand, are usually isolated from each other, especially street trees. So there is very little, if any communication among them. This is why pests such as the Asian long horned beetle and elm bark beetle have progressed so rapidly in our city trees.
Positive Communication
Not all communication among trees is for defensive purposes. Trees have developed perfumes in their flowers that attract beneficial insects. The insects will collect pollen off the anthers of one flower and deposit the pollen on the stigma of another flower, resulting in a seed which propagates the tree species.
Another clue about positive communication lies with cooperation among all the trees. Scientists realized that in a forest of the same species, the trees are all functioning at the same rate of photosynthesis. This is despite the fact that the trees may be growing in different soils, they may have different access to ground water levels, and sunlight may be different. The reason for this photosynthetic equalization is because the trees are all sharing the water and nutrients through their root systems.
All of this information sharing by the trees is still being researched but the findings so far, give trees a lot more credit than humans would like to believe.
Source:
Wohlleben, Peter, “The Hidden Life of Trees”, Greystone Books, 2015.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.
Edited by Len Phillips
A forest is composed of many individual trees and together, all the individual trees can moderate the weather. They can create an ecosystem that changes temperatures and humidity as well as stores a great deal of water. All the trees in the forest form a unit and as such they protect all the trees from damaging windstorms. As a result of this unity, protection, and climate modification in the forest, the individual tree can grow much older than the same tree growing in a city or by itself.
Every individual tree is a very important part of the whole forest. Each tree is very aware of its surroundings and is very compatible with its neighboring trees. For example, branches grow toward other trees, but they stop growing when they get too close to another tree's branches. They give each other space to grow and do not block the sunlight from the neighboring trees.
Communication
It has been well documented by scientists that in the forest there is a form of communication going on among trees. For example, when an animal or a pest takes a bite out of a leaf, the tree responds by pumping toxic substances into their leaves. A short time later, the same toxic substance appears in nearby trees as if the first tree warned the others of the attack. Scientists assumed the first tree gave off a warning sound or an odor or gas warning to the other trees. However, the odors and gas would disperse very quickly in the wind and would only be detected within a few hundred feet and some neighboring upwind trees might not get the message.
The reality, discovered by recent research indicates that the tree actually sends out an electrical signal, in the same way that humans feel pain where they have been injured. Instead of the pain going from the injury to the brain, the tree sends an electrical signal from the wound to all parts of the tree, including the roots. Underground, the roots of trees in the forest, in combination with mycorrhizal fungi, often intertwine and link up with roots of other trees. This means that the electrical signal is passed from one tree to the next, so they received the signal sent by the first tree.
Another example of linkage occurs when one tree has been struck by lightning and it dies. Soon after, it has been observed, that all the nearby trees also begin to die because the electrical impulse from the lightning spread to all the trees with root connections to the original tree.
Trees also have the ability to produce different compounds that might be used to repulse a pest. Other times, the tree under attack can produce a pheromone that attracts other insects that might feed on the pest. For example, if a caterpillar is eating leaves on a tree, the tree might produce a pheromone that attracts a wasp that will lay its eggs in the caterpillar. The eggs soon hatch and the larvae eat the pest from the inside out. The pheromone compounds can also act as warnings to other trees through their root system communication networks.
Trees that have this ability to repulse a pest, do so because they can also identify the pest by its saliva as it is eating the leaves. Their genetics identify the pest and which internal action or predator contact is most effective at attacking the pest. The fact that trees can recognize the saliva, indicates that trees seem to have a sense of taste.
Other trees have their own defense mechanisms. As mentioned previously trees carry toxic chemicals that will kill a pest that is eating its leaves or at least produce a bad taste so the pest will go somewhere else. However, other times, if a pest arrives that the tree is not familiar with, the pest may win the battle. The Emerald Ash Borer is a prime example. Only the Manchurian Ash which co-exists with the EAB in its native land, can survive the borer's attack.
The Fungal Network
Fungi generate extensive networks in the soil. A single teaspoon of soil can contain miles of fungal hyphae. The fungal connections in a forest can, over time, transmit messages for many square miles. It is these fungal networks that transmit signals from one tree to another, root to root.
If a tree has become very old or for some other reason has broken its linkage to the fungal network, signals become lost and the tree can not adequately establish a defense against a pest before the pest arrives. Soon after the tree will die or become very weak and defenseless against other diseases or pests.
Urban trees, on the other hand, are usually isolated from each other, especially street trees. So there is very little, if any communication among them. This is why pests such as the Asian long horned beetle and elm bark beetle have progressed so rapidly in our city trees.
Positive Communication
Not all communication among trees is for defensive purposes. Trees have developed perfumes in their flowers that attract beneficial insects. The insects will collect pollen off the anthers of one flower and deposit the pollen on the stigma of another flower, resulting in a seed which propagates the tree species.
Another clue about positive communication lies with cooperation among all the trees. Scientists realized that in a forest of the same species, the trees are all functioning at the same rate of photosynthesis. This is despite the fact that the trees may be growing in different soils, they may have different access to ground water levels, and sunlight may be different. The reason for this photosynthetic equalization is because the trees are all sharing the water and nutrients through their root systems.
All of this information sharing by the trees is still being researched but the findings so far, give trees a lot more credit than humans would like to believe.
Source:
Wohlleben, Peter, “The Hidden Life of Trees”, Greystone Books, 2015.
The test that follows contains 10 questions. Before taking the test be sure you have read the article carefully. The passing grade is 80% on the entire test.
ISA will award .5 CEUs* for a passing grade. SAF members will earn 0.5 Cat. 1-CF for every five passing test scores. The cost for taking this test is $10. If you purchase an annual subscription for 15 credits, the cost per credit is reduced by 50% (see Annual Subscription link below). We will report all passing test scores to ISA and/or SAF. If you are a member of ISA and SAF we will report your passing test scores to both for no additional cost. Please be sure to add both of your certification numbers when you sign in. Tests with passing scores may be submitted only once to each organization.
*Members of ISA may apply the 0.5 CEUs toward Certified Arborist, Municipal Specialist, or BCMA science credits.
California UFC members will receive credit for passing the test. Please add your CaUFC number after your ISA and/or SAF certification number.
ASCA members may submit your ISA certification record to the ASCA and receive credits one for one.
MTOA members must follow the ISA instructions indicated above.
To take the test by the pay per test option, click on the 'Pay Now' button below where you can send payment online securely with your credit card or Pay Pal account. After your payment is submitted, click on ‘Return to Merchant' / gibneyCE.com. That will take you to the test sign in page followed by the test. Members with certifications from both ISA and SAF, please be sure to add both of your certification numbers. These numbers are important for reporting purposes.
To take the test as an annual subscriber with reduced rates, click on Password and enter your test password which will take you to the test sign in page. If you would like to become a subscriber see our Annual Subscription page for details.
When you have finished answering all questions you will be prompted to click ‘next’ to send your answers to gibneyCE.com. You can then click ‘next’ to view your test summary. A test review of your answers is available upon request.
All passing test scores are sent from gibneyCE.com to your organization(s) at the end of every month and they will appear on your certification record 4 to 6 weeks* after that. ISA maintains a record of CEU credits on their website.
*SAF requires 5 passing test scores before reporting.
Test re-takes are allowed, however you will have to pay for the retake if you are using the pay per test option. You can spend as much time as you would like to take the test but it is important not to leave the test site until you have answered all the questions and see the 'sending your answers' response.