How Trees Survive Winter

Talking Trees with Lily and Jad . Welcome to today's episode of Talking Trees . In this episode , we'll dive into the mechanisms that trees use to survive winter . We'll explore how trees protect their cells from freezing through changes in cell membranes , production of natural antifreeze and a transition into a glassy state .

Let's dive in All right , so let's dive into something pretty cool today . I mean something that you guys deal with every day as arborists . Yeah , and that's how trees especially in the Acadian Forest region , you know survive those tough winters . And we're going beyond the basics digs into some of the surprising ways trees avoid freezing damage .

It is . Yeah , it's really easy to think that you know winter's just downtime for trees , but that couldn't be further from the truth . What we see as stillness is really a super sophisticated survival strategy and it's all happening , you know , on a microscopic level .

Yeah . So let's unpack that strategy a little bit . You know , we know , dormancy is a key part of that , and it's not just cold temperatures , right , it's triggered by those shorter days in late summer , prompting trees to prep for winter well before the first frost even hits .

Right .

And I mean , you guys know this better than anyone but those amazing fall colors , that's a big sign that pre-dormancy is starting .

Well , it is Exactly . And that transition , that transition into dormancy , it isn't just on or off , right ? It's fascinating because it actually involves three phases early rest , winter rest and then after rest . Each phase has its own , you know , its own set of changes happening physiologically . It's also almost like a choreographed sequence , you know , like a manual .

Yeah .

Or you know other practices . Without messing with the tree's natural rhythm Makes total sense , okay , well , or you know other practices , without messing with the tree's natural rhythm , makes total sense .

Okay , well , let's talk about one of the most obvious changes you know , as we see trees entering dormancy , and that is leaf loss .

Right .

The article talks about how important that is , you know , for deciduous trees .

Yeah .

But I'd love to hear you sort of expand on that a little .

Sure yeah , Deciduous trees . They shed their leaves , you know , mainly to conserve water during the winter .

Okay .

If they kept them , you know they'd risk losing too much moisture through transpiration . Yeah , you know the process where water evaporates from the leaves .

Right .

And you know , when water freezes , ice crystals can cause a lot of damage to those delicate cell structures . It's almost like leaving a hose full of water outside when it freezes . You know , not a good outcome .

Yeah , not at all . No . So deciduous trees are like minimizing that potential damage just by getting rid of those leaves .

Yeah , exactly .

But what about ? What about conifers ? They seem to hold onto their needles , you know , pretty much all year round , with a few exceptions , of course .

You're right . You're right , most conifers , they've evolved needles instead of those broad leaves and the needles they're packed with stuff that helps them , you know , conserve water , smaller surface area , waxy coating , so they can reduce that water loss and keep those needles for much longer .

Yeah , it's amazing how different trees , kind of you know , develop different strategies to deal with the same problem .

It is , it is .

Now , even with those strategies , freezing temps are still a threat right .

They are .

The article mentions these kind of mind-blowing ways that trees protect their cells from that freezing damage . It mentions three main ways and and honestly they sound like something out of a sci-fi movie they do .

They're pretty remarkable , you know adaptations they've they've developed over over thousands of years right so the first one involves increasing the flexibility of their cell membranes oh yeah so during cold acclimation those membranes become more pliable . It allows water to actually move from inside the cells to the spaces between them .

Oh , wow .

So it reduces the chance of , you know , ice forming and damaging those cells .

So almost like giving those cells a little breathing room .

Exactly , exactly .

Yeah , okay . Well , what about that second method then ?

So think of it , as you know , like giving the trees their own antifreeze . Okay , as the days get shorter , they start converting starch into sugars , and these sugars they act like you know a natural antifreeze , lowering the freezing point inside the cells .

So the cells actually have like their own built-in defense ?

Yeah , they do .

That's incredible . But that third method , the glass phase that you mentioned , that one really caught my attention . What is that ?

That one's really fascinating so through those first two methods . You know , the stuff inside the cell gets more and more concentrated and then at a certain point it changes into this glass phase . It gets so viscous that it's almost solid .

Oh , wow .

Like imagine the stuff inside turning into , you know , kind of a cellular slushy , yeah . I like that it's this state of suspended animation .

It's amazing . So these processes are happening inside every tree we see during the winter .

Right .

And the article pointed out something . I thought this was really interesting . You know , a tree trunk can have unfrozen living cells right next to frozen dead cells , all at the same temperature .

That's right . That's right and that's what I mean . It's so . It's such a complex , dynamic process how trees experience winter . It's not uniform . Different parts of the tree are changing at the same time . It's really amazing .

That is pretty amazing . This brings up something I was thinking about . You know we've been talking a lot about deciduous trees , but the article also mentions you know the risk of damage to newly planted evergreens , even though they keep their needles right . So what's going on there ?

Well , that's a really good point to bring up , especially for you guys , as arborists See evergreens . They look green and healthy , but they can still lose water through their needles , even in the winter . It's called transpiration and the thing is , those newly planted evergreens they haven't had the chance to , you know really develop those big root systems .

Right .

So when the ground freezes , they might not be able to soak up enough water to make up for what they're losing Right , and this can lead to well desiccation drying out .

Right , okay .

Which it , can you know , damage ?

the tree , even kill it . So even though they're green , it doesn't necessarily mean that they're thriving .

Yeah , exactly their metabolism . It's much slower .

Okay .

And you know their main focus is just staying alive . That's why you know good care , making sure they have enough water in the fall . That's so important .

Right .

Especially for those newly planted evergreens .

Yeah , that makes perfect sense . Now , this is all fascinating , but before we move on , I want to talk about something that really controls these changes within the tree , and that's hormones , specifically abscisic acid , aba .

Yeah , yeah , you could say that as the days get shorter , those ABA levels in the leaves they increase and that signals the tree to you know , start getting ready for winter , and that signals the tree to you know , start getting ready for winter , and that includes , you know , leaf shedding in deciduous trees .

Okay .

Increasing that membrane flexibility that we talked about . Yeah , converting starch to sugars and getting the cells ready for that glass phase we talked about .

Right , so it's like ABA is the conductor of the orchestra , exactly .

Yeah , and it even helps regulate water transport within the tree . It does that by controlling the opening and closing of the stomata , those tiny pores on the leaves . They regulate gas exchange and water loss Right , but as ABA levels rise it makes the stomata close , reducing water loss from transpiration .

It's incredible how everything's connected and ABA is right there in the

Yeah , so this study ? It focused on Sinus , main tree species in the Acadian forest region .

Okay .

And it looked at how simulated winter warming affected their germination rates . Interesting , they simulated a pretty big temperature increase , actually six degrees Celsius .

That's significant .

It is yeah .

Yeah . So what did they find ? Did this warming negatively impact germination ?

Well , this is where it gets really interesting . They found that even with that big temperature increase , there was no big negative effect on germination for most of the species .

Really that is surprising . It is yeah . Why would that be ? I mean the warmer temps . They didn't affect that chilling requirement that many trees need to break dormancy .

Well , the conditions they simulated , even with the warming , they still had enough chilling days for most species to successfully break dormancy . So those crucial chilling hours , they weren't completely gone .

So they still got enough winter , even though it was warmer . Exactly yeah , that's good news , I guess , for those species , at least as far as germination goes .

It is . Yeah , but there's a really important caveat here . Okay , while most species , you know , seemed fine some balsam fir seedlots they showed some sensitivity to the warming .

Ah , so there's some variability .

Yeah , exactly .

So what does that mean , you know , for arborists who are trying to manage these forests ?

you know , as the climate changes , Well , it suggests that some trees are just you know , genetically better at handling warmer winters than others , and as those temperatures rise we might see some shifts in you know what kinds of trees make up the forest .

Right .

You know , those that are more adaptable to those warmer conditions might start to kind of out-compete the ones that are more sensitive .

It's like a slow motion ecological race . It is , it is .

And that could . That could cause a whole domino effect throughout the ecosystem . It could change , you know , the types of wildlife that the forest can support , change the rate of decomposition , even how well the soil can store carbon . This really highlights the importance of having a lot of genetic diversity in these forests . Right , it really does .

It's a lot of responsibility , but it's also a pretty amazing opportunity to be able to , you know , to help shape the future of these forests .

It really is .

Well , this has been . I'm already looking at trees a little differently now .

It's good , that's what we want this has been really eye-opening so far . Yeah .

I'm kind of blown away by all this good good , and we're just getting started .

There's so much more to explore . I'm excited to dig deeper I am too .

I am too it's .

You know it's easy to to get focused on on the tiny details . You know how those individual cells survive freezing , but . But we need to zoom out a little right you know , look at the bigger picture too , like think about the structure of a tree .

Okay , especially the bark , yeah , the bark , that's the tree . But we need to zoom out a little , right , you know ? Look at the bigger picture too , like , think about the structure of a tree , okay , especially the bark . Yeah , the bark , that's the tree's first line of defense .

Right it is , it is . It's like a super efficient insulator protecting those living cells underneath . Even the texture , you know , the thickness , the color , right that can all affect a tree's cold tolerance .

So if I picture like a tree with really thick bark , yeah . You know deep furrows . Would that give it an advantage in a colder climate ?

It very well could those deep furrows . They trap air , creating another layer of insulation , kind of like a natural down jacket .

I like that .

For the tree . And then you know darker bark colors . They can actually absorb more heat from the sun .

Oh , okay .

Which can help in those really cold areas .

It's amazing how all these little details you know work together to help the tree survive the winter .

It is . It's a whole system and it's not just the individual tree either . I'm going to think about the whole forest ecosystem .

Right , the bigger picture again .

Exactly , exactly . The spacing between trees , you know the mix of species , even the stuff growing underneath that understory vegetation , all that can affect how those trees experience the winter .

So a dense forest canopy ? Would that act kind of like a shared blanket ?

It could yeah .

You know , offering some protection yeah yeah , for sure .

Protection from wind .

Okay .

And those extreme temperatures , and a forest that has , you know , a good mix of deciduous and coniferous trees that creates a more resilient ecosystem . You know one that can handle all those different winter conditions ecosystem . You know one that can handle all those different winter conditions .

Well , this deep dive has been pretty insightful so far . We've , you know , we've gone from the microscopic world of those cells to the big picture of forests and climate change .

We have , we've covered a lot .

And we even talked about , you know , those potential ripple effects of climate change .

We've talked a lot about how trees , you know , adapt to the cold and conserve water .

Right right .

But there's another part of surviving winter we haven't really touched on .

Oh , okay , what's that ?

Weathering those winter storms .

Oh yeah , Good point . I mean , as arborists , you guys are often the first ones on the scene , right ?

We are , yeah , after a big storm , yeah .

Dealing with the aftermath of all that ice and snow and wind .

Exactly and understanding how you know each tree species handles those stresses .

That's key for making those decisions about prevention and care . So let's start with ice storms . I mean , I've seen how much damage they can do , especially to deciduous trees . You know , those heavy ice coatings could just snap branches like they're nothing .

It's really simple physics . You know that ice . It adds so much weight , right , and when that weight is more than the branch can handle , it breaks . Yeah , and and the shape of the tree's crown matters too oh , you know those trees . With with those wider spreading crowns , they tend to be more vulnerable why is that ? Well their branches .

So so the way you prune a tree could actually affect how vulnerable it is to ice damage .

It really . Can , you know , doing things like , uh , removing weak branches or branches that are crossing , that can really reduce the risk and and for some species you know . Like willows or birches , they're more susceptible to ice damage , so you might need to , you know , cable them or brace them .

Interesting , so it's really about thinking ahead .

It's about proactive management . Yeah , you know , anticipating those problems and taking steps to prevent them .

It's not just about preventing damage either , right ? I mean after a really bad ice storm . Sometimes you have to make those tough calls you do Whether a tree can be saved or if it needs to be removed .

Yeah , and that's where your experience as arborists that's so crucial , you know you guys have to make those judgments .

Yeah , okay . Well , let's shift gears a little bit , move from ice to snow .

Okay .

I would imagine that heavy snow that's going to be tough , especially for conifers .

Yeah .

You know , with all those needles .

It is . It is Conifers tend to hold on to more snow than deciduous trees do , and that can lead to , you know , branches breaking , especially if that snow is wet and heavy .

Yeah , for sure .

But it's interesting , some species like white pine . They've evolved to have more flexible branches . So they can shed that snow easier .

So being bendy is actually an advantage in a snowy climate .

It is . It's like nature's built-in snow removal .

I like that , and I guess sometimes a little manual help can't hurt either , right , right ?

Carefully brushing that snow off can prevent breakage . But of course safety always comes first .

Absolutely yeah . No tree is worth getting hurt over .

Exactly , exactly . And then , of course , we can't forget about the wind .

Oh , right yeah .

Those strong winds they can uproot trees , especially trees that are already rink , you know , maybe from disease or root damage .

And I imagine trees in exposed areas , you know , like along the coast or in open fields , they must be especially vulnerable .

They are , they are and in those situations you know windbreaks or shelterbelts , those can really help produce those wind speeds , protect those trees and again , good pruning practices can make a big difference .

Yeah , that seems to be a theme . It always comes back to you know , understanding how those trees interact with their environment and then using that knowledge to guide us .

It does , it does . And as we see more of these extreme weather events you know , stronger winds , heavier rain and snow those skills , those are going to be even more important . Yeah , you're right , For you guys .

Well , this has been quite a journey it has . Well , this has been quite a journey it has . We've covered so much , from the microscopic world of cells all the way to , you know , forests and climate change .

Yeah , we've gone from the tiny to the huge .

Exactly To all you arborists out there keep up the amazing work . You guys are the guardians of our forests , protecting these incredible ecosystems that we all depend on . So until next time , happy treeing everybody .

Thank you for tuning in to today's episode of Talking Trees . If you enjoyed this deep dive into how trees survive the winter and want to support our work , check out our exclusive content on heroheroco slash talking trees . Your support helps us bring more insightful episodes to you . See you next time .