Episode Introduction

Roger 0:02

Talking Trees with Lily and Jad . Welcome to Talking Trees . Today we're exploring the dynamic stability of trees under wind loads . We'll discuss James' 2010 dissertation comparing freely growing and plantation trees , focusing on the important role of branches in their response to stress . We'll also cover Kane and James' 2011 study on deciduous trees , revealing how leaves impact tree stability more than pruning or frost . Let's dive in .

Jad 0:37

Hey everybody and welcome to our deep dive . You know , as arborists , we work with these amazing living structures every day . These trees , yeah . And today we're going to really get into understanding how trees respond to wind . I mean , that's critical stuff for us right From risk assessment to you know crooning decisions and our overall approach to tree care .

Lilly 1:01

Yeah , and I think what's really interesting

Ken James' Research Team

Lilly 1:03

is that the person that we're going to talk about today , Ken James , he actually challenged a lot of assumptions in our field .

Jad 1:10

Oh , really , yeah , Okay , so who is this Ken James guy and what got him interested in how trees and wind interact ?

Lilly 1:19

Well , so you know how trees aren't just like rigid poles stuck in the ground right . They move , they sway in the wind , but they usually don't fall over right , yeah and that's kind of what got him thinking like how do they actually withstand these huge forces , especially those open grain trees that we see a lot in like urban setting ?

Jad 1:35

yeah , the ones that bear the brunt of the wind . Yeah , okay . So was he like like a lab rat or did he actually get out in the field and like observe real trees ?

Lilly 1:43

Oh , he was definitely out in the field .

Jad 1:45

Okay , good .

Lilly 1:45

Yeah , and he wasn't alone . Actually , he collaborated with people like Dr Nick Caritos who was , like this , dynamics expert . And then Dr Brian Kane , who was more of a tree specialist .

Jad 1:56

Okay , so a real team effort .

Lilly 1:57

Yeah , so they were coming at it from different angles , which is really cool .

Jad 2:01

Yeah .

Lilly 2:05

And it sounds like they like shook things up a bit in the tree world . They did , yeah . So he started out by kind of questioning how trees were traditionally modeled . You know , people used to think of them as just like simple poles .

Jad 2:14

Yeah .

Lilly 2:14

But he was like wait a minute , that's , that's way too simple , especially for these open grown trees with

Mass Damping and Tree Stability

Lilly 2:19

all their branches Right .

Jad 2:20

He was like those branches .

Lilly 2:21

They got to be doing something more , right , yeah , you can't just ignore them . Yeah , and he was really interested in this thing called the slenderness ratio . It's basically the tree's height divided by its diameter , okay , and he said that ratio is like super important for understanding how stable a tree is .

Jad 2:39

Okay .

Lilly 2:40

Especially in those urban environments I was talking about , where the wind patterns are all crazy .

Jad 2:45

Right yeah , you think about like a tall skinny tree .

Lilly 2:47

Yeah .

Jad 2:48

In a wind tunnel .

Lilly 2:49

Yeah .

Jad 2:49

You know , compared to like a stockier tree .

Lilly 2:51

Yeah .

Jad 2:52

It's going to be a different story .

Lilly 2:53

Totally , and that's where this idea of mass damping comes in .

Jad 2:56

Okay , mass damping , though physicists break that down for me a little bit .

Lilly 3:00

Okay , so like imagine each of those branches with all those leaves on them like a little shock absorber ? Okay , like the suspension system in a car .

Jad 3:09

Oh , okay .

Lilly 3:10

So when the wind hits the tree , all those branches , they kind of create friction .

Jad 3:15

Okay .

Lilly 3:15

And they dissipate the energy .

Jad 3:17

Yeah .

Lilly 3:17

They're working together to soften the blow for the whole tree .

Jad 3:20

Ah , I see . So it's not just about , like , the strength of the wood , it's about how it's the whole system . It all works together . Yeah , it's like how we look at root systems too Exact For stability , okay . So how did he figure this out ? Like how

Measuring Tree Movements

Jad 3:35

?

Lilly 3:35

do you even study ?

Jad 3:35

how a tree moves in the wind .

Lilly 3:37

So this is where it gets cool . He designed these really interesting instruments to measure it .

Jad 3:42

Really .

Lilly 3:42

Yeah , like he used strain meters that he attached to the tree trunks kind of near the base , and these meters they measured the bending moments .

Jad 3:51

But not just how much it was swaying , but the force involved .

Lilly 3:55

Yeah , the actual force .

Jad 3:56

That's smart .

Lilly 3:57

Yeah , and to make sure those measurements were actually accurate , he would calibrate the instruments with static pull tests .

Jad 4:03

But that way he could directly relate those readings to what was happening when the wind was hitting the tree .

Lilly 4:08

That's clever .

Jad 4:09

Yeah .

Lilly 4:10

So he was bringing like engineering principles into the study of trees . Totally I like it . So what kind of data did he get from all this ? Was it valuable ?

Jad 4:18

Yeah , it was super valuable .

Lilly 4:20

It . Let him figure out the wind loads for different tree species .

Jad 4:24

Okay .

Lilly 4:24

Which is like really important for understanding how stable they are and what kind of risks they might face .

Jad 4:29

Right .

Lilly 4:29

But the really cool stuff comes from how he used this data to actually figure out how trees move .

Jad 4:36

Okay , I'm intrigued .

Lilly 4:37

Yeah .

Jad 4:38

So it was more than just swaying back and forth .

Lilly 4:40

Oh , way more complex .

Jad 4:42

Okay .

Lilly 4:42

So he was able to map the tree's movements in response to wind .

Jad 4:46

Okay .

Lilly 4:47

And what he found was that they don't just sway like a pendulum . Okay , it's more of like this intricate looping motion .

Jad 4:53

Like a dance .

Lilly 4:54

Yeah , kind of like a dance . Wow , motion

Complex Tree Movements

Lilly 4:59

like a dance .

Jad 4:59

yeah , kind of like a dance , wow , yeah so that that blew the whole symbol pole model out of the water .

Lilly 5:01

Trees are more graceful than yeah , they got their own moves we give them credit for yeah , and so then you start to think , well , okay , if they're moving in these complex ways , how does that affect how much force they're actually feeling from the wind ?

Jad 5:12

right , because I'm guessing it's not a one-to-one relationship between like wind speed . It's not that simple .

Lilly 5:18

No , it's more of like a dynamic interplay between the gusts of wind and how the branches are moving , and then the whole tree's response .

Jad 5:26

So even if you know how fast the wind's blowing , you can't really say for sure how much stress a tree's under . Exactly it's way more complicated than that . So what does all this mean for us as arborists ? Like , how does knowing about these fancy tree dances actually help us ?

Lilly 5:42

Well , it definitely changes how we think about things like pruning . Okay , remember how I said removing leaves had a bigger impact on tree dynamics than even pruning branches .

Jad 5:52

Yeah , those leaves are little powerhouses , they are yeah .

Lilly 5:54

So maybe we need to rethink those drastic crown reductions we sometimes do .

Jad 5:59

Okay .

Lilly 5:59

Maybe a lighter touch , focusing on removing specific branches , would actually be better for the tree in the long run .

Jad 6:05

So it's like we need to shift our thinking from just getting rid of the bad branches to looking at how the whole system works together .

Lilly 6:13

Yeah , and it's not just about pruning either . This research also changes how we think about assessing tree risk .

Jad 6:20

Right , because if you

Implications for Arborist Practices

Jad 6:22

know how branches contribute to stability , Exactly . You can start to identify trees that might be vulnerable .

Lilly 6:28

Yeah .

Jad 6:29

Even if they don't have obvious signs of like decay or whatever .

Lilly 6:32

Totally . We can look at things like the slenderness ratio Right , how the branches are distributed . Ok the overall shape of the crown to get a much better idea of how well a tree can handle the wind .

Jad 6:44

So we're not just doing those basic visual inspections anymore . Right , we're using science , but did James ever actually see these theories play out in the real world ?

Lilly 6:55

Yeah .

Jad 6:55

Like . Did he witness any trees failing ?

Lilly 6:58

He did actually he did . Yeah , he spent years collecting data , even during windstorms . Oh wow , and during one really intense storm he was watching these trees near his research site and some of them actually failed .

Jad 7:11

Oh no .

Lilly 7:11

Yeah , but the trees that he had been studying , the ones with more branches and those complex movements , they were fine . Wow , so it was like his theories coming to life .

Jad 7:21

Proof ? Yeah , in real time .

Lilly 7:23

Yeah , it was pretty amazing .

Jad 7:26

So what does all this mean for the future of tree care ? Like , where do we go from here with this knowledge about tree dynamics ?

Lilly 7:33

I think the biggest thing is we have to change how we think about trees .

Jad 7:37

Okay .

Lilly 7:37

We can't just see them as static objects anymore .

Jad 7:40

We have to see them as dancers .

Lilly 7:41

Yeah .

Jad 7:41

With their own unique moves .

Lilly 7:42

I love that .

Jad 7:43

So we have to be more like dancers too .

Lilly 7:45

Yeah , observing , yeah .

Jad 7:47

Listening to their rhythms , observing listening to their rhythms , adapting our approach to each individual tree .

Lilly 7:51

James gave us this amazing foundation , but there's still so much more to learn .

Jad 7:55

Yeah , that's what's so exciting it is we're not just following a rule book .

Lilly 7:58

No , we're exploring , we're pioneers .

Future of Tree Care

Lilly 8:01

Yeah .

Jad 8:01

I like it . So for everyone out there listening , remember you're not just pruning branches , you're engaging with these incredible , dynamic living beings . Right , take the time to really observe them . Yeah , ask questions .

Lilly 8:14

Yeah .

Jad 8:15

And appreciate their amazing dance with the wind .

Lilly 8:18

Absolutely .

Jad 8:19

And , hey , maybe you'll discover some new steps of your own .

Lilly 8:22

Who knows ?

Jad 8:23

I like that .

Lilly 8:23

Yeah .

Jad 8:24

All right . Well , thanks for joining us on this deep dive into tree dynamics .

Lilly 8:28

This was fun .

Jad 8:29

It really was . I learned so much , you too . Until next time , happy tree whispering everybody .

Lilly 8:33

See you later .

Episode Conclusion

Roger 8:38

Thank you for joining us on this episode of Talking Trees . Today we explored how trees respond to wind loads , from the role of branches in dynamic response to the impact of leaves on tree stability . We hope this episode gave you a deeper understanding of tree structure and resilience . Stay tuned for more insights and discoveries in future episodes . Until next time , keep growing and protecting nature . You .