Acustic Tomography

Talking Trees with Lily and Jad . Welcome to today's episode . We're diving into the world of tree stability assessment , with a focus on methods for detecting internal decay in trees . We'll dive into sonic tomography and the PICUS Treetronic device , an advanced tool for measuring wood resistance .

Welcome back everyone Ready for another deep dive . This time we're focusing on sonic tomography , especially for all you professionals out there . Sounds good . We're going to figure out how it's used , what its advantages are , what are the limitations , and we've got some interesting cases to look at too .

Yeah , definitely .

And we've got a mix of sources this time , which is always fun . We've got a software manual , We've got some of those really in-depth scientific papers and even some visuals you sent over which are pretty cool .

Yeah .

So first things first . What exactly is sonic tomography ? I mean , I think a lot of our listeners have probably heard the term , but maybe not everyone knows exactly how it works .

Well , think of it this way it basically lets us see inside a tree without having to , you know , chop it down or anything .

Whoa hold on . That's like x-ray vision for trees .

Exactly . It uses sound waves , so you measure how those waves travel through the wood and that reveals the internal structure , like you know , is there decay hidden in there ? Are there cavities , things like that .

That's got to be so useful for like assessing the health of a tree right Absolutely .

You can detect problems really early , even before you see any signs on the outside .

Wow , that's incredible . So what would you say are the biggest advantages of sonic tomography ? And we've touched on a couple already , but for the professionals listening , what really makes this stand out ?

Well , like I said , it's non-invasive right . You're not harming the tree at all .

True , true .

Which is huge , especially when you're dealing with , you know , maybe a really old tree or one that's important for historical reasons . You don't want to be drilling into that just to see what's going on inside , Right ?

right .

And then those tomograms , those visual representations you get , those are really easy to understand , even if you're not , you know , a tree expert .

Oh , so you can actually show those to clients and they can kind of get a sense of OK , this is what's happening inside my tree .

Exactly . It makes it much easier to explain things . And then , of course , the early detection part is huge . Catching decay early can make a big difference in how you manage the tree , maybe even save it .

Okay . So it's non-invasive , it gives you these easy to understand visuals and it helps with early detection , but every tool has its limits , right .

Of course .

What are some of the limitations of sonic tomography that we should be aware of ?

Well , one of the biggest things is that the accuracy depends a lot of how you set things up , like where you place those sensors , how accurate your measurements are . That all plays a role .

So it's not just point and shoot . There's definitely some skill involved .

Exactly , and then even once you have those tomograms , interpreting them correctly . That takes some expertise too . You got to be able to distinguish between different types of decay , or maybe something that looks like decay but isn't . It's not always straightforward .

So training is important .

Oh yeah , definitely , and it's important to remember that tomography shows you what's going on , but it doesn't necessarily tell you why it's happening .

That's a good point .

Like , you might see decay , but you don't know what kind of fungus is causing it , right ? So you might need to do some more investigating to figure out the best way to treat it .

That makes sense . So it's a really valuable tool , but it's not a standalone solution . It's part of a bigger approach .

Exactly , exactly .

Okay , so we've talked about the basics , the advantages , the limitations . I think it would be really helpful to see this in action .

Well , sonic tomography relies on the principle that sound travels at different speeds through different materials .

So if the wood is solid and healthy , the sound waves will zip right through . But if there's decay or a crack , those sound waves will slow down . It's like the difference between running on a smooth track versus slogging through mud .

And the tomograph measures those subtle differences in sound velocity .

And translates them into a visual map . Now , this isn't a photograph of the inside of the tree .

It's a representation of how well the wood transmits sound waves .

And that transmission ability is directly related to the wood's density .

And its ability to bear weight .

Which is why sonic tomography is so valuable for assessing tree health and risk .

Absolutely so . Let's break down the process of creating a sonic tomogram step by step .

The first step is visual inspection .

Before we even think about placing sensors , we need to carefully examine the tree .

We're looking for cracks , damaged bark , fungal growth cavities .

Anything that might indicate underlying structural issues .

So this initial assessment helps us figure out where to place the sensors .

Exactly and we can focus on the areas of greatest concern .

For example , if we see Crutchmeria diosta fungus .

Which often grows upwards from the roots .

We know , to focus on the root system and choose a lower measuring level .

Makes sense right .

It does so after playing detective .

We move on to installing the nails that will hold the sensors .

These nails are our measuring points .

And placement is crucial .

First things first .

Make sure those nails are clean and free of rust .

Why is that ?

Because rusty nails can interfere with the electrical conductivity and mess up our measurements .

And , speaking of accuracy ,

Not too close , not too far . Goldilocks Exactly . A minimum spacing of 12 to 15 centimeters ensures we capture enough data .

But we don't want them too far apart either .

Right . A maximum spacing of 45 centimeters prevents us from missing important details .

But those are just guidelines .

We can adjust them based on our visual inspection . So if we see a large crack , we might cluster nails more closely around that area to get a better picture of the damage .

But be careful not to place nails directly into heavily damaged areas .

Right , because that can distort the color scale of the tomogram . Finding the sweet spot between capturing detailed information and maintaining the integrity of our data .

Got it . So once the nails are in place , what's next ?

Geometry measurement .

Time to channel our inner mathematicians .

That's right , because precision is absolutely key here .

Even small errors in these measurements can significantly impact the accuracy of the final tomogram .

Imagine a builder using inaccurate measurements for the foundation of a house . Oh , the whole structure could be compromised .

So no pressure right .

Not to worry , there are tools and techniques to help us get it right .

Like what .

Well , the simpler method assumes the tree trunk is a perfect circle .

We measure the circumference and the distances between each nail along that circumference . Easy peasy . But trees are rarely perfect circles , are they ?

You're absolutely right so what then ? That's where the elliptical method comes in .

Tell me more .

This method involves measuring the circumference plus the longest and shortest diameters of the tree trunk .

Recognizing that most trees have a slightly oval shape .

Exactly , and for those really irregularly shaped trees .

What do we do then ?

We have more advanced options like triangulation methods .

How do those work ?

They use a series of baselines to pinpoint the exact location of each sensor .

Sounds complicated .

It can be , but the key is to be meticulous in our measurements and use the correct units .

Which are Millimeters , millimeters , got it .

And thankfully we have software tools like the Pi CUS program .

That helps us calculate those theoretical distances based on our measurements .

So we don't have to rely on mental math alone . So , with our nails in place and our geometry measured , it's time to install the sensors and begin the sonic measurement .

This is where the magic happens .

We carefully attach each sensor to its corresponding nail , making sure they're secure and won't get damaged during the measurement process . It's like equipping our tree with a network of listening devices .

Very cool .

And just like with any wiring job , organization is key .

We don't want a tangled mess of cables .

That's right . So we'll use clips to keep those sensor cables organized . So with everything set up , we're ready for the sonic scan itself .

This is where we tap each nail with a specialized hammer .

Sending sound waves through the wood and collecting data from all the measuring points .

But wait a minute , I thought we only attached sensors to some of the nails .

Yes .

Do we need to collect data from all of them , even the ones without sensors ?

Yes , absolutely .

Why is that ?

Because the software analyzes how long it takes for those sound waves to travel between each and every measuring point .

Even those without a sensor directly attached . Exactly so if we have more measuring points than sensors .

We'll need to do a sensor changeover during the scan .

Moving the sensors around to collect data from all the nails .

You got it .

This all sounds pretty intricate .

It is , but the software guides us through the process .

So how does all of this sonic data get transformed into that visual tomogram ?

It is pretty amazing the tomograph software downloads all the data .

And then what ?

It starts crunching the numbers . It analyzes the velocity differences between all those measuring points .

Looking for patterns .

Exactly Patterns that indicate potential defects .

So it's not just about individual sound speeds .

No , it's about the relationships between them .

The software is looking for anomalies .

Right Areas , where the sound waves slowed down significantly .

Which often means .

Decay cavities , cracks or other structural weaknesses .

And then all of that gets translated into the tomogram .

That colorful visual representation .

Okay , so let's talk about those colors . Sure , we mentioned earlier that black and brown are generally good signs .

Those dark colors represent high sonic velocities .

Meaning .

The sound waves are traveling through the wood quickly .

So that indicates D dense healthy wood . It's like a strong bone in the tree .

That's a great analogy , but remember the tomogram doesn't show us wood density directly .

Right .

The wood's ability to transmit sound waves .

Which tells us about the density and strength .

Exactly .

So what about when we start seeing green on the tomogram ?

Green is a bit of a caution flag . What would it mean ? It could mean a few things Minor variations in wood density . Early stages of decay .

So it's not necessarily a huge problem .

Not always , but it's a signal to pay closer attention .

And investigate further .

Right . We need to consider the tomogram , our visual assessment and the specific tree species .

So a green area in a young tree might be normal .

But in an older tree , especially with visible signs of decay , it could be a bigger issue .

Makes sense . What about those blues and whites ?

Those are the ones to be more cautious about .

What do they represent ?

They represent low sonic velocities .

Meaning .

Significant disruptions in the wood structure .

Like fractures in the tree's skeleton .

That's a good way to visualize it .

So these low velocity zones often indicate .

Advanced decay cavities or other major defects .

That weaken the tree .

Exactly so . If we see a large area of blue in the center , what could that mean ? It could indicate a cavity that's been present for a while .

And the tree has compartmentalized it .

Right , it's formed a strong boundary around the decay .

Like a wall to contain the damage .

Exactly , but if we see a smaller area of bright white

So the size , shape and location of those blue and white areas , combined with our other observations , Give us a clearer picture of the problem . It sounds like there's a real art to reading these tomograms .

There is . It's like learning a new language .

Understanding the nuances of those color patterns Exactly . Speaking of patterns , are there any specific ones we should look for ?

Absolutely . There are a few classic patterns that often show up .

Like what .

One is the bullseye .

What does that look like ?

A circular area of low sonic velocity in the center , surrounded by rings of higher velocity .

So the center is the most affected area .

Right . It often suggests decay spreading outwards from the center .

Like ripples in a pond .

Exactly . What about the pie slice pattern ?

I've heard of that one . What is it ?

It appears as a triangular or wedge-shaped area of low velocity .

Usually extending from the edge towards the center .

Right , often indicating decay that's entered through a wound .

Or a branch attachment point .

Makes sense . Right the decay follows the path of least resistance . Interesting , and then there's a linear pattern that one appears as a straight or slightly curved line of low velocity .

Running vertically .

Often yes .

So what does that usually mean ?

It could indicate a crack , a split or decay following the grain of the wood .

Wow , these visual patterns provide so many clues .

They do , but remember . These are just a few examples .

Right and interpretation can vary .

Depending on the tree species , its age , location and other factors .

So we still need to use our professional judgment .

Absolutely so . Let's shift gears for a moment and talk about sonic velocity and wood strength .

Okay , this is where things get a bit more technical .

It is , but it's important . As we mentioned earlier , sonic velocity is a good indicator of wood density .

And density is a key factor in wood strength .

Exactly so generally those dark colors on the tomogram .

The areas of high sonic velocity .

Tend to be stronger than the blues and whites .

The areas of low sonic velocity .

Right , but it's not a perfect relationship . Other factors can affect wood strength too , Like the type of wood , moisture content and the presence of knots or other defects .

So we can't just look at a tomogram and know for sure .

No , we need to consider all the available information .

But the sonic velocity data can still give us valuable insight .

Absolutely . For example , a large area of blue .

Probably means that area is weaker .

Than an adjacent area of brown .

Even if we can't pinpoint the exact strength .

Exactly Now . Let's talk about the limitations of sonic tomography .

Okay , no , technology is perfect .

That's right . So what are some of the limitations ?

I'm all ears .

One limitation is that sonic tomography only gives us information about a single cross-section of the tree .

At the height where we place the sensors .

Exactly so . It's a snapshot , a slice of the tree's internal structure .

But the tree structure can vary above and below that level .

Absolutely .

So we can't assume that a defect extends throughout the entire trunk .

Right , it might just be a localized issue .

And another limitation .

Sonic tomography is most sensitive to defects located directly between the measuring points .

The nails .

Exactly so if a defect is hidden behind a nail .

We might miss it .

That's possible , which is why careful sensor placement is so important .

Based on our visual inspection .

Right , we need to think strategically about nail placement .

Trying to find those hidden defects Exactly .

And another thing to keep in mind .

What's that ?

Moisture content can affect sonic velocity readings .

How so .

If the wood is very wet , the sound waves will travel more slowly .

So it might look like there's decay , even if the wood is sound .

That's right . So it's best to take measurements when the wood is relatively dry .

Or use other tools to confirm our findings .

Right , we can't rely solely on the tomogram .

It's just one piece of the puzzle .

Exactly so . Let's talk about the companies offering sonic tomography systems .

Who are the main players ?

Well , there are three main companies right now .

Tell me about them .

The first is FUKOP from Hungary .

What are they known for ?

They offer the most affordable systems .

So they make the technology more accessible .

Absolutely . The second company is Picus , where are they from ? Germany .

And what about them ?

They're known for their advanced technology and user-friendly software . So if you want the latest features , Picus might be a good option , but regardless of which company you choose , the principles of sonic tomography are the same .

That's right . We're still using sound waves to map the tree and learn about its health .

It's amazing how this technology allows us to see inside the tree without harming it , it is . But remember what's that ? Sonic tomography is just one tool .

We need to combine it with our experience and knowledge Absolutely To make the best decisions for the trees .

Exactly , and that's what makes this field so fascinating we're always learning and finding new ways to understand trees .

You mentioned some case studies earlier .

Yeah , I've got a couple of examples from the research that I think really highlight how useful sonic tomography can be . One study looked at a Norway spruce that was suspected of having some internal decay , but there were no outward signs .

Oh , wow , so you couldn't tell just by looking at it .

Right . But when they did the sonic tomography it showed the decay pretty clearly

Oh , so this one was visible .

Yeah , but the sonic tomography didn't just show the cavity , it also showed the area around it where the decay was still active .

So it showed how far the problem actually extended .

Exactly , and that information was really important for figuring out how to manage the tree , like should they try to support it or was it too far gone and needed to be removed .

Okay , so in both of those cases the sonic tomography really helped to make a more informed decision about how to manage the tree . Do you have any other ?

examples trees that were infected with this really aggressive fungus called Crechmeria deusta , and in those trees the tomogram showed this really distinct pattern , what they called a conductive center , which is typical of that particular fungus .

So by seeing that pattern they could be pretty sure what was causing the problem .

Exactly , and that can be really helpful for figuring out the best course of treatment .

These cases are really interesting . I mean they really show how a sonic tomography can be really helpful for figuring out the best course of treatment . These cases are really interesting . I mean they really show how a sonic tomography can be used in a practical way to help manage trees .

Well , it really complements the other methods out there . Like you should still be doing visual inspections , you know , looking for those external signs of problems . And there are other tools like the resistograph that measure drilling resistance .

Right right .

And even sometimes you do a tree-pulling test to assess stability . But sonic tomography gives you this extra layer of information , that internal view that you wouldn't get otherwise .

So it's like putting all the pieces of the puzzle together to get a more complete picture of what's going on .

Exactly .

Okay , so we've talked about what sonic tomography is , the advantages , the limitations , some case studies . I think it'd be really fascinating to dive a little deeper into the science of wood decay itself . Sure , yeah , what can you tell us about that ?

So wood decay is a really complex process . Actually , there are different

Fungi huh .

Yeah , these fungi . They release enzymes that break down the wood , basically eating it , and the way they break down the wood that's what determines the type of rot . Like brown rot fungi , they mainly go after the cellulose in the wood , so what's left behind is this crumbly brown stuff .

Wow , so it's like they have different tastes in wood .

Yeah , you could say that . And then soft rot . That's usually caused by fungi that thrive in really wet conditions and it can make the wood soft and spongy .

So depending on the type of rot , it can have a really different impact on the strength and stability of the tree .

Right oh absolutely , and that's why it's so important to be able to identify the type of decay , so you know how to manage it .

Okay , so the type of fungus determines the type of rot , but what are some of the other factors that influence how decay develops in a tree ?

Well , the species of tree definitely plays a role . Some species are more resistant to decay than others .

Oh , that makes sense .

And then how aggressive the fungus is . That matters too . Some fungi are real powerhouses . They can spread really quickly . And then the environment plays a big role . Moisture is key . Most wood decay fungi need a certain amount of moisture to thrive . So if a tree is in a really dry environment , it's less likely to have decay problems .

So , like a tree growing in a swamp versus a tree growing in the desert , they're going to have really different decay risks .

Exactly , and then the tree itself can fight back to some extent . Some trees have really strong defense mechanisms , like they can form these reaction zones around the decayed area , trying to wall it off and prevent it from spreading . But other trees have weaker defenses .

So it's like a constant battle between the tree and the fungi .

Yeah , kind of , and the outcome of that battle depends on a lot of different factors .

This is all really fascinating stuff but you know , I keep thinking about all the professionals listening who might be using sonic tomography . It seems like you really need a good understanding of all of this the different types of decay , the factors that influence it to really interpret those tomograms correctly .

Oh , absolutely . You can't just look at the pretty colors on the tomogram . You've got to understand what those colors mean . You can't just look at the pretty colors on the tomogram

So , basically , learning never stops for a tree professional .

Definitely not .

You've always got to be up to date on the latest research and techniques . Well , I think this has been a really great overview of the science behind sonic tomography and wood decay .

Yeah , definitely .

I'm sure our listeners are eager to learn more about the practical applications of this technology .

For sure . But before we move on to those practical applications , I think we should touch on something else that's really important the ethical side of things .

Oh yeah , that's a good point . We've been talking about all the cool stuff sonic tomography can do , but like any tool , it's got to be used responsibly .

Exactly . I mean , we've talked about how it's non-invasive , but even driving those nails into the tree that still creates a wound .

Right .

Right . So you have to be really careful about , you know , sterilizing everything , using the right size nail for the tree , placing the sensors in spots where you're not going to cause extra damage .

So it's not completely without risk , even though it's less invasive than some other methods .

Yeah , and then there's also the risk of misinterpreting the results , right ?

Oh yeah , we talked about how that takes some expertise .

Exactly so . If someone doesn't have the right training , they might misinterpret the tomogram and make a wrong decision about the tree .

Like maybe they remove a tree that was actually healthy , or they think a tree is safe when it's not .

Right , exactly . That's why it's so important to have qualified people doing these assessments .

And on that note , I guess there's also the risk of bias , right , Like if someone already thinks a tree is dangerous they might see what they want to see in the tomogram , even if it's not really there .

That's a good point . Yeah , it's important to be aware of that potential for bias and to try to be as objective as possible when interpreting the results .

So maybe having multiple people look at the tomogram or using some kind of standardized guidelines for interpretation ?

Yeah , definitely Anything that can help reduce that bias and make sure the assessment is as accurate as possible .

Okay , so ethical considerations definitely important to keep in mind , but I'm also thinking about , you know , the practical side for professionals . What about the cost of all this ? Sonic tomography ? It sounds pretty high tech , so I'm guessing it's not exactly cheap .

Yeah , you're right , it can be a significant investment . The cost of the equipment itself can vary a lot depending on the features and capabilities , and then there's the cost of training and software and maintenance .

So it's something professionals need to factor into their budget definitely .

Right , but on the flip side you have to think about the value of the information you're getting .

Like , if you can identify a hazardous tree before it falls and causes damage . That could save a lot of money in the long run , true , true , so it's an investment , but it's an investment that could potentially save you money and headaches down the road .

Exactly , and there are ways to make it more affordable . Headaches down the road Exactly , and there are ways to make it more affordable . Like some , companies offer sonic tomography services on a contract basis , so you don't have to buy the equipment outright .

Okay . So there are options out there , but even if the cost is manageable , you still got to make sure it's worth it . Right Like , is there enough demand for this kind of service ?

Yeah , that's a good point , but I think the demand is growing . Actually , as people become more aware of the benefits of sonic tomography , they're starting to ask for it specifically .

So it could actually give you a competitive edge if you offer it .

Definitely .

Okay , so we've talked about the cost , the demand , but what about the future ? Where do you see sonic tomography going in the next few years ?

Oh , there are some really exciting developments happening , like one of the big things is artificial intelligence or AI . They're starting to use AI to analyze sonic tomography data , which could make the interpretation process much faster and more accurate .

Wow , ai for trees .

Yeah , and then there's also this idea of using machine learning to create predictive models , so they could use data from past sonic tomography scans along with other information about the tree to predict whether it's likely to develop problems in the future .

Oh wow , that would be amazing , like preventative tree care .

Exactly . And then there's also work being done on integrating sonic tomography with other technologies , like ground penetrating radar , which could give you an even more complete picture of the tree's health .

That sounds really cool . So it seems like there's a lot of potential for sonic tomography to become even more powerful and useful in the future .

Definitely . I think we're just scratching the surface of what this technology can do .

Well , I'm definitely excited to see what the future holds for sonic tomography , but for all the professionals listening who might be thinking about getting into this field , I guess the big question is where do you start ?

Yeah , that's a good question . Well , first and foremost , education is key . You need to understand the science behind sonic tomography , how to operate the equipment and how to interpret the results .

So finding a good training program is crucial .

Absolutely . There are some great programs out there offered by organizations like the ISA , asca and TCIA .

Okay , so you get the training , you understand the science . What's next ?

Well then , it's about choosing the right equipment for your needs and your budget . There are a lot of different devices out there , so it's important to do your research and figure out which one is best for you .

And once you have the equipment and the training , then it's just a matter of practice right Exactly .

The more you use it , the more comfortable and confident you'll become . Start with simple assessments

So don't be afraid to start small and build your skills over time .

I think that sums it up perfectly .

This has been a really fascinating discussion about how professionals can incorporate sonic tomography into their work . But you know we've been focusing a lot on the technical and practical side of things . I think it would be really valuable to step back for a moment and think about the bigger picture , sure .

Yeah .

How does sonic tomography fit into the broader context of tree conservation and sustainability ?

That's a great point . I think sonic tomography has a really important role to play in those efforts , like it can help us to identify and preserve veteran trees , those really old and valuable trees that are part of our natural heritage .

Right , those trees are irreplaceable .

Exactly , and it can also help us to manage urban forests more sustainably , like if you can accurately assess the health of trees in a city , you can avoid unnecessary removals and make sure those trees are around for as long as possible .

So it's about using technology to make sure we're making the best decisions for the trees and for the environment .

Exactly , and all of that information can help us to develop strategies to protect trees and make sure they're around for future generations .

That's really inspiring . Actually , it seems like sonic tomography is more than just a tool . It's like a way of connecting with trees on a deeper level .

I think that's a beautiful way to put it . It's about seeing beyond the bark and understanding the life that's going on inside those trees , and I think that understanding can lead to a greater appreciation for trees and a stronger commitment to protecting them .

It's been amazing exploring the world of sonic tomography with you . We've really gone deep , from the science behind it to the ethics , the costs , what's coming next and how it all ties into taking care of trees in the best way possible .

Absolutely . It's a really fascinating field and I think we've just scratched the surface .

For sure .

Thank you for joining us for this exploration of tree health assessment techniques . Today we covered the essential tools and methods arborists use to detect hidden decay and structural weaknesses . We're grateful for your support on heroheroco slash talkingtrees , which enables us to continue bringing you valuable insights from the world of arboriculture .