Tree Risk Assessment: Standards, Best Practices, and Advanced Techniques

Hello everybody. Welcome to another installment of the Tennessee Urban Forestry webinar series. Happy spring, or if you're in Tennessee, false spring, as it's about to be 27 degrees tonight. Um, for those of you that don't know me, hello, I am your host for the TUFC webinars. My name is Hannah Imagine Shaw. Everybody calls me Imagine. Um, I'm a BCMA and a TRAC certified arborist, but really, um, I work on the TUFC board and with the ISA Southern Chapter for, uh, the South part of America. Um, but enough about me. Today we're going to talk about tree risk assessment with JP McDonnell. JP, thank you so much for being here today. We are really excited to be sitting with you. Um, just a quick background on JP before we get into our talk today. JP McDonnell is the assistant manager of Savitree Consulting Group. JP has over a decade of experience in urban forestry and arboriculture and is an ASCA registered consulting arborist. ISA Board Certified Master Arborist, and is a Tree Risk Assessment Qualified and Tree and Plant Appraisal Qualified Arborist as well. Um, on top of that, he serves as Save a Tree's voting representative on the ANSI A300 Tree Care Institute's committee, where he is the chair of Tree Risk Assessment and Managing Trees During Construction Clauses. JP also serves on the ISA Certification Test Committee, ASCA's Membership Committee, and the UCFS's Industry Trends Committee. Prior to Savitree, JP was an urban forester at New York City Parks. JP earned a Bachelor of Science in Forestry from Suwannee University of the South. And he also earned a Master of Natural Resources from Virginia Tech. JP is now based out of Nashville, Tennessee, which is where we are at, at TUFC. So hello, welcome to town. We're very happy to have you. And with that, I'll transition back over to Katie for some quick housekeeping, and then we'll get the presentation started today.

Thank you, Imagine. Hi everyone, let me share my screen. Okay, if you are on here today and you're here to receive ISACUs or SAF CFEs, please make sure that you are registered and that you've paid the $10 fee. Um, also take a moment to have your full name showing at the bottom, and I have instructions here where you go to the partic— Participants tab, you find your name, you click rename, and you rename yourself to what name you used when you registered. If you are a member of TUFC or just a general attendee, you don't have to worry about paying the $10 fee. But again, if you are seeking those CEUs or CFEs, please make sure that your name matches up with the name you used when you registered because that just makes it easier for us. At the end of the, uh, webinar to ensure that we send the correct list to ISA or SAF. Um, at the end, I will also put up a QR code that you can scan, and that's just another way that we can validate who is on this webinar to receive those CEUs and CFEs. Um, also, if you have any questions during the webinar, please put those in the chat, and we will answer as many as we can during our Q&A session at the end of the webinar. And I believe that's all the information. I'll send it back to you, Imagine.

Awesome. Well, I will not keep JP from starting because I heard from a little birdie that if we finish in a timely fashion, he's got some really cool bonus photos for us. So, JP, take it away. Let's get started.

Thank you both, Katie and Imagine, for that warm welcome. Imagine, it was a little hard to hear you. At the end there, but I think she was sharing that we might have a bonus section if we, if we run short at the end here. Can you guys confirm that you can see my presentation?

Yep.

You're good to go.

Sweet. So today we'll be talking about one of my favorite urban forestry topics, tree risk assessment. On the agenda, the agenda for today. We'll go through some tree risk assessment basics. We'll talk about the ANSI A300 tree risk assessment standard, ISA's newly released Tree Risk Assessment Best Management Practice, 3rd edition. We'll discuss the 3 levels of tree risk assessment and some advanced technique examples. So tree risk assessment basics. To understand tree risk assessment, I think you first need to understand the broader process of tree risk management. And as you can see in this flowchart, tree risk assessment is just one piece of tree risk management. So moving through this flowchart, the tree risk manager first establishes the context, um, via a tree risk policy, procedures, and practices. Then the tree risk assessor performs the tree risk assessment or multiple tree risk assessments by identifying, analyzing, and communicating tree risk. Then the tree risk manager evaluates the tree risk and compares that to their risk threshold. After that, risk may be— risk mitigation may be implemented by the tree risk manager. And after that, the trees are typically reassessed for risk. And there is currently no industry standard for tree risk management. On the bottom right, there is a flowchart from the International Organization for Standardization, and, And that is kind of the basis of where true risk assessment comes from. So now, what is true risk assessment? In general, risk is the probability of an event occurring times the severity of the consequences if that event were to occur. And true risk assessment is a systemic— systematic process to identify, analyze, and communicate tree risk, as I mentioned previously. There are qualitative and quantitative approaches to tree risk assessment, and we're going to be focusing on the International Society of Arboriculture's Best Management Practice assessment approach, which is a matrix-based qualitative approach. And so the difference between the two qualitative approaches typically use mathematical formulas and results in a quant— a quantitative risk rating, whereas the ISA-BMP approach uses observations to result in a qualitative risk rating. And so on the bottom of the screen are the two risk rating matrices that risk assessors use to categorize risk, ultimately ending up in a risk rating. So the matrix on the left is the likelihood matrix, which combines the likelihood of tree or tree part failure with the likelihood of impacting a specified target. And once you use that matrix, you move on to the next matrix,, which combines the likelihood of failure and impact with the consequences of failure and impact. So why do we assess tree risk? I think most of us on this call know that trees provide many benefits to society in the form of economic, social, and environmental benefits that increase with tree size and tree age. But also, conditions that may predispose trees to failure also increase with tree age and size. Additionally, the consequences of tree or tree part failure often increase with tree or tree part size and height. Tree owners generally have a legal duty of care to reasonably inspect trees on their property for obvious, uh, conditions of concern. And ultimately, tree risk assessments can help tree managers balance the many benefits that trees provide with the potential risks that mature trees may pose. And on the bottom, I've got a plug for, uh, Tennessee's Champion Tree Program, which catalogs Tennessee's largest trees and a couple diagrams just showing how much more benefits large trees provide, which is on the right largely due to leaf area in the form of shading, transpiration, cooling benefits, and all the other benefits that we know mature trees provide. In general, there are two types of risk associated with trees. You can have conflicts and you can have structural failures. The ANSI A300 and ISA BMP tree risk assessments focus on the structural failures of trees growing near, growing near targets. However, risk can still arise when there are conflicts between trees and societal functions. Example conflicts include allergies, root damage to infrastructure or underground utilities, as you can see on the right, potential fire, flowers, fruit, and debris, insects and animals. Obstructions are a very common one. Trip hazards are also a very common one, and thorns. And I think obstructions and trip hazards can lead to, uh, potential increased liability. But as I mentioned, during an ISA BMP tree risk assessment, those conflicts are not considered. And here's another conflict I ran into in Florida where, uh, instead of removing this tree, they warned the pedestrian that this tree is blocking their, their right-of-way. So apparently they are okay with accepting the risk of this conflict at this time. Here's another conflict. See, see this a lot in urban areas where trees are not in the right place, but somehow they still exist, and there might be some some conflict with foundation there or other infrastructure. So I wanted to talk about ISA's Tree Risk Assessment qualification briefly for those who aren't familiar. This is a program that educates arborists on a standardized systematic process for assessing tree risk, and it requires currently renewal every 5 years to keep arborists up to date on new research, latest standards, and best practices. By the end of the year, a new TRAC curriculum is going to be released, and I think the, the renewals is extending to every 7 years, but you have to retake the 2.5-day class rather than an abbreviated renewal class. And course content includes tree biology and mechanics, tree assessment, data analysis and risk categorization, and risk reporting. And I did want to note that just because one obtains the Tree Risk Assessment qualification does not necessarily mean that one is competent in tree risk assessment. Competence and expertise comes with experience and training in tree risk assessment. Over time. And so I wanted to, for those who don't know, describe the difference between the American National Standards Institute A300 tree care standards and the ISA's BMPs. These are two related but separate and distinct publications. So the Tree Care Standards are an industry consensus document developed by a number of organizations that is predominantly for writing specifications for the, the management of trees, shrubs, and other woody plants. And the Best Management Practices are companion publications to the standards that expand upon and clarify what's in the, the standards. And the BMPs are typically a little bit more approachable and provide a lot more guidance to those who think the standard might be a little dry, although both are, are important. So now we'll get, get into the standard a little bit more. Recently, as of the end of 2023, previously we had 10 standards. Those were consolidated into one document. So now all standards are a part of, uh, the tree care standard, which you can see on the right. And this is the flowchart of Clause 13, tree risk assessment. And most of the flowcharts look very similar where The arborist first starts with the objective. What, why are you doing what you're doing? So the objective of tree risk assessment is typically to assess the likelihood of failure, impact, and consequences of potential tree or tree parts. Next, you develop your specifications. So this is the scope of work that you're presenting to the client, and you'll provide the level of, of assessment, the timeframe, and potentially the targets that you'll consider. Then you'd conduct the assessment, and then you'd analyze the risk, classify risk, develop your mitigation options or recommendations, and present the residual risk for each risk mitigation option. And an advanced assessment is a potential recommended outcome of a basic Level 2 risk assessment. And we'll get into this more in depth for those who aren't familiar with the levels of assessment. After you, you conduct the assessment and analyze the risk, then you prepare and submit a report, ideally, that is ANSI A300 compliant. And note the mitigation box at the bottom is not a part of risk assessment itself, but it is related because typically risk mitigation is recommended during a tree risk assessment. And then recommend monitoring is typically when you recommend a reassessment interval because trees, trees grow, change over time, and weather can affect trees. So typically you'd want to reassess the risk And a note on should versus shall in the ANSI standards. These are very important words. To, to be in compliance with the standard, any shall statement is a requirement. So if a statement says that you shall do something, that means that you must do it in order to be in compliance with the standard. Any statements with should are a recommendation, and typically that means you should have a reason for not complying with that statement. And on the right, I've highlighted all of the shall statements— not all of them, but on two pages of the, uh, risk assessment standard. And the should statements are in yellow, and we'll go over a few of these more in depth here in a minute. So this is taken from the standard. Like I said before, any tree care operation, you should have an objective. And I wanted to highlight this statement: Tree risk assessors shall have sufficient training and experience to perform the specified level of assessment. So just because you have a TRAC qualification does not necessarily mean that you have sufficient training and experience to perform an advanced Level 3 tree risk assessment. For example, risk assessment specifications shall include— so this is your scope of work that you might be presenting to a client, or a client may be looking at. So, um, whether you're an arborist presenting the scope of work or a tree risk manager looking at a scope of work, these are things that must be included for, for the risk assessment specifications to be compliant with the standard. And so risk assessment methodology must be stated, whether you're doing an ISA/BMP risk assessment or a quantitative tree risk assessment, timeframe, location and/or selection criteria, and the level of risk assessment. So those are musts for your scope of work to be compliant with the standard. And now specifications should include— these are recommendations— the objective of the risk assessment, details of the risk assessment, including simple tools or advanced tools and techniques that you might be using, when the assessment will be conducted, the type of report to be developed, written or verbal, to whom the report should be presented, and the due date of the report. Those are recommended to be in your specifications. And at the bottom, these are two important statements in the standard that helps protect tree risk assessors from, um, potential claims for things that were outside the scope of their work. So tree risk assessors shall not be required to assess trees other than those specified in the scope of work. So that's why it's important to specify what trees you're going to be assessing in the scope of work, because if you don't specify that, then you may be held liable for any tree on the property. For example, tree risk assessors shall not be required to perform a higher level of assessment than specified in the scope of work. So That's why it's important to specify what level of assessment you'll be doing, because if you don't specify that, then, uh, some— if something happens, somebody might question you as to why you didn't perform a Level 2 when you only said you were going to do a Level 1, or why did you not do a Level 3 when maybe you verbally said you were going to do a Level 2, but it wasn't specified in your scope of work. So important, important stuff there. Onto risk analysis and reporting. We're still on the A300 standards. Type of report should be specified. The assessor shall analyze the data collected from the tree site and target assessment. So that's telling you that you must analyze your data, your likelihood of impact, Likelihood of failure, consequences, site information, and, and your targets. Reports shall include— these are things that must be in your report to comply with the A300 standards— your objective, tree location, the targets you considered, the date, the time frame, whether it's 1 year, 2 years, 3 years, the risk rating. And your risk mitigation options and/or recommendations. The standard recommends that you include this information below: identification of the assessor and qualifications, species, parts of the tree assessed, methodology used, risk assessment data— that's your likelihood of failure, impact, and consequences— recommendation for additional assessment where appropriate, residual risk rating for any recommended mitigation, recommendations for monitoring and follow-up, and a statement of limitations. So if you don't include that stuff in your report, you should have a reason for doing so. Onto the, some new information included in the 3rd edition of the Tree Risk Assessment BMP. So the BMP clarifies what was introduced in the new risk assessment standard, the difference between a tree inspection, a tree risk assessment, and a worksite inspection, which is very important. So a tree worker isn't held liable because they didn't assess the risk of the tree. So in the BMP, they specify that a tree inspection— there's no industry standard method for inspecting trees. A tree inspection is commonly done by a sales arborist or an arborist rep visiting a property to propose, um, tree care or plant health care.. But just because they're on the property doesn't mean that they should be assessing the risk of every tree, even though they didn't— they weren't contracted to do so. So this is important information. And then tree risk assessment, that's what we're talking about today. Worksite inspection, this is for tree care workers inspecting the site and the tree, essentially as a job hazard analysis before they perform work. So these are three separate and distinct things that you should know what the difference is if you are performing true risk assessments. There's more discussion on the variability of assessors' ratings and examples to help reduce that variability within, um, likelihood of failure, likelihood of impact, and the consequence categories. To ultimately try to get arborists closer on their risk ratings. Some interesting wind and weather guidance changes. Previously in the second edition, the weather was classified as normal, extreme, and abnormally extreme. Third edition, now it's normal, severe, and extreme. This is important because tree risk assessments only consider normal weather. Which is typically an average over the past 30 years of the location of the tree. Um, safety factor is a term broadly used in Europe that is, uh, introduced in the BMP, and that comes from engineering. Uh, target aggregation is somewhat of a new term. I think a lot of risk assessors were doing this previously, but Essentially, that means you can consider if there's multiple structures or houses around the tree rather than performing a risk assessment for each individual target. You can aggregate all the structures and specify that you're performing a risk assessment for all of the structures. New colored figures. Previously it was black and white. Fun, fun to look at. Good stuff. And, and more. So check it out if you want to, if you want to learn more. Limitations of tree risk assessment. This is very important because there are uncertainties in risk assessments, and we don't want to, um, over-exaggerate how precise risk assessments are to tree risk managers. Information is limited on structural conditions of trees, often when we can't see inside trees. Weather and loading of trees is unpredictable, and direction of fall or target occupancy or consequences can all be uncertain. So these are uncertainties in tree risk assessments. Additionally, the study of tree failure is relatively young, so New research and studies are coming out periodically, but more research needs to be done. And then at the bottom, I included limitations that are often included in risk assessment reports. I think this was a question asked in advance of the presentation, and there's, there's a few more included in the BMP. Some of these are from the standard directly, but not all defects or conditions that predispose a tree or tree part failure— tree or tree part to failure are detectable, and not all failures are predictable. And these are important limitations. Only the trees specified in the scope of work were assessed. The time frame is not a guarantee period for the risk assessment. The tree risk assessment considers only specified or known targets. And visible or reasonably detectable tree conditions. A little note about risk mitigation. So I mentioned this is that the action of risk mitigation is not a part of tree risk assessment, but the recommendations or options typically are. And so there's two types of tree risk mitigation: target-based and tree-based. Target-based you want to look to first, where you restrict access to the target zone or remove targets in the target zone if you can. This is often difficult to do when trees are in urban or high occupancy areas, but that's something that you want to look to first before, um, treating the tree. And so tree-based risk mitigation includes Pruning, removing the tree, installing structural support systems, potentially installing lightning protection systems for specific trees. Um, and then for larger populations of trees, you can prioritize risk mitigation based on risk ratings. But you also have to consider budget, number of trees, sizes of trees, locations, targets, logistics, etc. In addition to risk mitigation, you'll typically have a residual risk rating. So this means if you recommend a mitigation action, what will the residual risk be after that action is taken? So this is something the, the tree risk manager needs to know, because if you recommend pruning a high-risk tree but it only reduces the risk rating to moderate, Moderate might be above their risk threshold. And then reassessment. You always want to, or typically want to assess, reassess, or recommend reassessing a tree that you assess. That's a lot of assessing there. And here's an example of prioritizing about a dozen trees that I looked at years ago. So it includes the tree number to identify the specific tree, the species, the specific risk mitigation recommended, the priority that is based on the risk rating, and then post-mitigation risk, same thing as residual risk. So if you remove a tree, there's no more risk. Some would say the stump presents potential trip hazard, but that's not a structural failure risk. These are some of the common errors or omissions I see when people are assessing risk or, um, submitting risk assessment reports. So health and risk are related but separate concepts. So a healthy tree Good condition can still be a risky tree. So you— we typically use good, fair, poor, very poor, or dead to assess health or condition. And that commonly includes structure, health, and form. And for risk ratings, we use low, moderate, high, or extreme risk. And so it is very important to understand the differences between the two. Sometimes I'll see that no time frame was included in a report. And so all trees fail eventually. So if you say the likelihood of failure is, is possible, probable, um, within what time frame? We need a timeframe to, to understand the likelihood of failure. Not rating each factor independently. So when we look at likelihood of failure, impact, and consequences, just because a tree is large doesn't mean it's likely to fail. They're all 3 different factors that you need to look at independently. Targets considered were not specified. You need to know what targets you're looking at to know the consequences. Methodology not described. Did you sound the tree with a mount? Did you just look at the tree? Did you probe the tree? These are, these are things that if something happened to the, to the tree, you'd be asked. Occupancy rate or likelihood of impact sometimes exaggerated, resulting in higher risk ratings. Assumptions and limitations not disclosed. For example, were there vines obscuring your view of, of the trunk flare? Was there poison ivy that prevented you from sounding the trunk or measuring the tree? These are things that you would want to include in your report. And of course, declaring a tree as safe is not recommended and can open you up to potential liability if something happens with that tree. Onto the levels of risk assessment. So there's 3 levels of assessment. We've got the limited visual from a specified perspective on the top left there. And this is a really advanced drawing here. Basic assessment in the middle, 360-degree ground-based visual. Level 3, advanced, using some sort of advanced tool or technique, and we'll talk about these more in depth. So Level 1, limited visual assessment, is from a specified perspective. That could be from one side of the tree, could be remotely, um, and this is the fastest and least thorough assessment intended primarily for quick assessment of Many trees, typically when there are budgetary constraints, and this is often done on natural areas or remotely. And the perspective may be a walk-by, a drive-by windshield survey, an aerial patrol commonly done by utility vegetation management companies, or remote sensing. So, LiDAR, aerial imagery. Google Street View inspection. Those are considered limited visuals. And here's an example, another complicated diagram I created. Imagine if I were walking along this path and looking for open and obvious defects of— on specific trees in the natural area. This would be considered a limited visual assessment. Another example of a limited visual would be looking at this tree from Google Street View. Not personally, I don't know if I would do that because you may miss defects, but some people may want that. Onto Level 2 basic assessments. As mentioned earlier, this is a ground-based 360-degree visual assessment of the tree and surrounding site. Often includes tools such as a mallet, probe, camera, diameter tape, binoculars, etc. And this is the most commonly performed risk assessment in response to a tree owner or tree manager's request for a risk assessment. This includes a risk rating, mitigation recommendations or options, and residual risk rating, as mentioned previously. And another limitation, some internal below-ground or upper-ground conditions may be impossible to see or detect. So this is a flowchart, uh, simplified and adapted from the new BMP. Just going through the basic assessment process, and the second half of the flowchart is going to pop up on the right. But first, you review available information on the tree and site. So any information you can gather on whether there may have been changes to the site previously or why, uh, the tree manager is asking for a risk assessment. Then you define the objectives and scope of work. Are you going to be performing a Level 1 or Level 2 or Level 3? Why, why are we doing the risk assessment? What does the tree manager want to get out of it? Then you visit the site, locate and identify the trees to be assessed, assess targets, determine the location of the targets, estimate occupancy rates. Then you start inspecting the tree. I typically go from bottom up, look at visible roots, trunk flare, trunk, large scaffold branches out to the smaller branches. And so now you're looking for defects or conditions of concern, response growth. You're assessing the tree's health. You're assessing whether there might be a change in loads from either trees being removed nearby or structures being built near the tree. And you're assessing the targets. Then you start recording your observations. Then you'll analyze the data that, that you collect to categorize likelihood of failure, impact, and consequences, determine your risk rating, develop your mitigation options, recommendations and the residual risk ratings for each one. Recommend reassessment or advanced assessment, and then prepare and submit your report according to the agreed-upon scope of work. And quick note on the basic TRAC form that a lot of people use, highlighted here. So that that form is intended for collecting and recording tree risk assessment information. You may adapt that form or use your own method of collecting and analyzing field data. That form in itself may not be considered a tree risk assessment report by some people. So just be aware of that. So here's a little case study of a tree that I assessed a few months ago. Um, one of my colleagues called me up, said, uh, this tree got struck by lightning. So there's a little site history. It's by an entryway to this business, and the tree manager wants to retain the tree if they can. So I proposed a Level 2 basic tree risk assessment to, um, assess what impacts the lightning may have had on the structural integrity of the tree. I visited the site, located it, identified it as a pin oak, I believe. I identified targets which included pedestrians walking on the sidewalk going to work, people sitting on that picnic table potentially, and there's a bench behind this. And you could also consider that picnic table a target and Some of the cars may have been within the target zone of this tree as well. And there's that bench that I was talking about under a branch. So potential targets there. Then you inspect the tree, taking a closer look. Obviously struck by lightning here. As I mentioned, I like to go from bottom up, so I sounded the trunk of the tree, didn't hear any significant decay. And then it went up and inspected branch unions, upper, upper crown, etc. I collect this data on my tablet and categorize likelihood of failure of specific tree parts. In this instance, I think the overextended branches and potential dead butcher's root were the defects. Likelihood of impact, I mentioned the pedestrians, and then the consequences could be severe if somebody got struck by a large scaffold branch. Risk rating was determined to be low. Mitigation options presented included monitoring the tree. A lot of plant healthcare treatments were recommended including watering to try to increase the health of this tree after the stressful event. I also provided an option to lightly reduce some of the overextended limbs if they were worried about potential failure and impact of those pedestrians. And this arrow points to a couple areas for light reduction over that sidewalk. As I mentioned, this is an entryway to a business, so you might have more frequent occupancy than if it were just another old sidewalk. Recommended monitoring this tree. Don't remember exactly how often, but, um, condition in this instance, condition and health were more of a concern than risk, in my opinion. Prepared the report according to, uh, A300 standards and submitted it to the client. Onto advanced assessments. These are performed after or in combination with a basic Level 2 to provide additional information about specific tree parts, defects, targets, or site conditions. Specialized equipment, data collection, or expertise are required for this. Generally take longer and are more expensive. And advanced assessments can provide information that may influence mitigation options. For example, a risk assessment— a risk assessor might think that there's significant or severe decay within a trunk. They recommend a Level 3. There's a decay test performed, and it's actually found that there's adequate sound wood, and the risk rating might be adjusted lower or higher depending upon what you find. And there are many types of advanced assessments. And a note that all technologies have limitations and involve uncertainty, um, as trees are living beings. So here's an example. I don't see this commonly performed, but included it., as an FYI, detailed target analysis. This is the same tree we just looked at. So, uh, you may quantify how long targets are in the target zone to, um, provide a more detailed likelihood of impact factor and categorize that. So you'd essentially quantify where and how often people are in the target zone. Aerial assessment. This is a common form of advanced assessment. On the left, we have a climber, uh, using a resistance drill to, um, inspect the soundness of wood in the upper trunk. In the middle, we have somebody probing a cavity and taking a picture. On the right, another resistance drill at a crotch and an aerial assessment. Can just include a climber taking photos. It may include a climber probing and measuring depths of cavities. It may include a climber using a resistance drill. So the advanced assessments can be used in combination with each other. Decay testing. There's me on the left drilling a tree. Resistance drill essentially quantifies the resistance of the wood in the trunk, which can be used as a proxy for soundness or how much decay, or measuring how much decay is in the trunk. On the right are a number of drills. You read them from right to left. The top 3, you see they quickly go up and then quickly go down. That means there's very little sound wood at those drill locations. Fourth drill down, That one has the most sound wood as you see the reading gradually going up and to the left, and then eventually there's a pretty steep drop. Then right there, you know, there's a cavity or compromised wood. Same thing on the bottom reading. So if I saw these readings, I would think that the— it's not looking good. Another decay testing Advanced assessment. This is sonic tomography on the left. That's the setup with the nails equally spread out throughout the trunk, and this results in a cross-sectional area. And the tomography uses the speed of sound waves moving through the tree to essentially give you a pictorial representation, representation of what the decay or soundwood looks like at that specific cross-section. And you can use multiple, multiple cross-sections to create a 3D image. And this is an example of the output where the blue is likely hollow, pink is probably decayed wood, green might be early decay, and then your light brown and dark brown are sound wood. And your dark brown might be potential response growth that is stronger than your typical wood. Root assessments, root collar excavation to inspect integrity of roots. This one is a smaller tree. I just provided it as an example, but there's some girdling roots there. Typically, you would, you would do this to inspect for potential Decay in the roots might be used in combination with a resistance drill. Ground penetrating radar is another root assessment technique, and that can tell you location and depth of roots, potentially size. On the right, we have a morphology map. Biomechanical stability analysis— these are somewhat new in the industry. And, um, somewhat more common in Europe, but it includes species wood properties, uh, a crown wind load analysis based on photos. And this specific one includes a 3D LiDAR scan of the trunk that you can see on the left, and it essentially determines the weakest cross-section of the trunk. It can be used in combination with resistance drills or tomography to provide a more detailed example and data on the stability of the tree. Here is an example of the 3D LiDAR scan. If you have an iPhone 13 Plus or up, you can, you can do a LiDAR scan on your, on your iPhone. Load tests or pull tests are somewhat infrequent in, in the United States, more common in Europe and potentially Canada. But this essentially simulates wind loading on a tree by attaching hardware and pulling it and quantifying that data. And in a sense, it assesses the strength of the tree and load-bearing capacity of the roots and trunk. And as any good arborist, any good consulting arborist knows, you should include limitations. So it's not my intention to provide tree risk assessment training with this presentation, direction for developing risk management policy, or legal guidance. Concepts— the concepts shared here are based on industry standards and BMPs. But they may not be applicable to every tree or situation. Nothing presented here should be used in place of an on-site inspection by a qualified arborist trained in tree risk assessment. And a final note: big trees and people can coexist. I inspected this tree on the left in 2018, 75-inch tree with many targets, services, things below. And on the right, that's that tree in 2024. If you care for and manage your trees properly, we can have more mature trees in urban environments. And I'll get off my pedestal and end there.

Well, thank you so much, JP. That was great. Thank you for the very nice overview and the clarity on all the components that involve tree assessments and how those are separate from the ISA to the ANSI standards And I know that technically we have 11 minutes left in the webinar. So would you like to share some extra information or do you want to just hop into questions?

I think we can hop into questions if there's enough. I'm actually not looking at the chat.

Um, there's a few questions there. I think I just had one, um, to broadly ask you, um, which is if there are some, if there are individuals in this course that are not tree risk assessment qualified or have experience in tree risk assessment in general,, and they want to start gaining infield experience and becoming a competent arborist in this skill set, uh, what would you recommend that they look into for experience opportunities?

I would recommend trying to find a mentor or somebody who is trained in tree risk assessment because that's how I was trained and you learn a lot more through field experience and training than you do, uh, through a textbook., and you build a lot of confidence by looking at and assessing more trees. And so the more trees you can get under your belt, I think the more confidence, experience, and competence you'd have.

That's a great answer. Thank you. And then I did have one more. So let's say you are, you know, one of those competent arborists on this webinar, and maybe you are looking at expanding your understanding of Tree Biomechanics. Do you have any personal, like, uh, professors or researchers or papers that you've really enjoyed reading on as you guys move into rolling out this 3rd edition?

Um, I, I actually was not involved in the 3rd edition. I was just kind of presenting my opinions on— not even opinions, just the new information. Um, I would just recommend attending ISA events, any local events. I know ASCA puts on a lot of good tree risk assessment related training, obviously attending any TRAC courses. But a lot of that is, I think, is really beneficial. And off the top of my head, I don't have any specific research. I know Ryan Klein out of Florida does a lot of tree risk assessment work. Andrew Kozer, also out of Florida, does a lot of tree risk assessment research. So those two are kind of leading the charge. And if I forgot anybody, I don't want—

like, don't come after me. Yeah, yeah, totally understandable. No, well, thank you. Thanks for giving us some options to look into. And I guess with that, I'll pass it over to Katie, and she can start filtering in some questions for you to answer as well.

Sweet.

Okay, so one question we got in the chat: can a tree risk assessment quality report be done by seeing only photos?

Well, it's not— so not a Level 2 tree risk assessment because you need to see the, the tree in person. But a Level 1, if you're writing a limited visual report, then you could view that tree remotely via pictures.

Okay. And we just got this one. Do you have any problems selling the advanced assessment to your clients? Do they appreciate the benefit versus the cost?

Uh, I think it depends on the region of the country and how much the tree means to that person.

And then I also have some questions that we received before the webinar. Um, this is a long one, so bear with me. Um, This person, Jim, from Franklin, Tennessee, he says, our neighborhood has well over 600 trees that were neglected for 30 years. The plantings include a large number of short-lived invasive species that are at the end of their lives. We've spent several hundred thousand dollars addressing neglect and have several hundred thousand dollars to go. For example, there are over 100 remaining Bradford pears at the end of their lives. We can't afford to remove and replace all of them at one time. Plus we need to maintain a canopy as the replacements grow. What procedures should we follow to identify falling trees as a safety measure? How frequently should they be inspected? And what are indicators of failure among different species? That's a lot.

That's a very broad question, but I would just say consult with a certified arborist or ask a consulting arborist and they'll kind of put you in the right direction.

The next question: Are there best practice tree planting care maintenance classes or workshops or onsite trainings available for frontline workers? The ground staff who are shoveling, driving, who are shoveling, driving equipment, chopping, and mowing need to learn more tree-friendly skills. What do you suggest?

Yeah, I think ISA, depending upon your regional location, puts on those sorts of classes. And you can also look into the ANSI standards, which have tree planting standards, plant healthcare, soil management, all that good stuff, in addition to ISA's BMPs, which might be a little more approachable for people who aren't certified arborists.

The next question, they asked if you could provide details on how to revive trees losing bark and branches, such as a tulip poplar.

That one I would reach out to a certified arborist or consulting arborist because that sounds like it's not doing well. So you probably need an in-person inspection.

This is another— well, this person asked several questions. Um, one, how important is it to know fungal types by heart? Is it enough to send photos to a lab, or do you need to send samples of fungi? Are there any mature fungal fruiting bodies that, if present, are major red flags? And if so, what are some of them?

I would recommend learning some of the more common and prominent ones in your location because that can vary significantly depending upon where you are. Uh, Dr. Chris Luley has a really great fungal ID book that he recently expanded, and I would highly recommend looking into that book and You could also reach out to your local Extension agent with pictures, I'm sure, or send lab samples to confirm identification.

Okay, and I have a couple more, but I'm gonna, I am actually going to share my screen with the CE, or with the QR code for CE's real quick.

I just stopped sharing.

Thank you. That way if anyone needs to log off, they can look at this real quick. Um, well, and— oh no, sorry, I'm trying to get back to where I have all the questions. Just bear with me a second. Well, technology is great when it works. Okay. Do you consider other trees that are close to the target tree? A huge walnut tree was cut out of a common area and now trees are falling from the roots due to lack of support from the lost walnut tree.

Yeah, that's part of your, when you're on site, you're not just assessing the tree, you're assessing the surrounding site and any potential changes that might affect the loading on that tree. So if you remove a tree near another one, then the retained tree might be— there might be new loads acting upon that tree that that tree didn't have before. So It doesn't have that response growth that trees put on over time in response to loads such as wind.

Can you share the author of the fungal ID book that you just mentioned?

Yeah, Dr. Chris Luley, L-U-L-E-Y. This is the old version. Of course it's blurred out.

And— oh, I'm sorry if I interrupted you.

No, I was just gonna say I could show some defect pictures, but we've only got 1 minute left. We're if there's any other questions.

Here's one more. Is there a suggested blanket statement of language that one can place on the tree risk assessment qualification form that would help limit any necessary, any unnecessary liability?

Yeah, I went through several of those limitation statements that are included in the the BMP that I would recommend reviewing and including where relevant and necessary. And you can also look to the ANSI A300 standard for that because there's similar language that can help protect arborists from things outside the scope of their agreed-upon work.

All right. Well, it is 1 o'clock, and those are, I believe, all the questions that I have.

So.

JP, you mentioned, um, a bunch of, quite a few times you mentioned like if you're looking for somebody for these specific questions, maybe look for a competent certified arborist. I just plugged the treesaregood.org website. It's where you can find certified arborists across, I think, not just the United States, um, but at least the United States.

Great. Yeah, that's exactly what I was talking about.

And thank you so much. This was great. This has been— this is really great attendance, and the subject matter was awesome. So we appreciate having you.

Yeah, no, I was happy, happy to be here, and thanks everybody for, for joining today.

Thanks everybody.