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Compositions. Anyway Just to say, I’ve started recording so everyone knows. I I think the best way to use this document is for you to have a read and start commenting up and, adding references or adding your own opinions. I think that that was the main reason, we compiled it, But I think we can use this call just to go through it. And maybe, I know.
On the now we could maybe focus more on the questions or on the statements. True. Okay. Starting starting with her, I have here, four questions, but the three of them, it is they go into detail. For example, what are the mechanics, hydraulics, or pneumatics of gas exchange of plants?
And this one is is not, let’s say, strictly important for the story. It’s, it’s something that we actually have no information, and, we find ourselves the more we dig, we redefine what the story is because we we start the story with a certain assumptions, and then suddenly, we read something something new in terms of how plans work, and this actually goes back and and redefines the story. So we try to be to to cast a wide net, and if we’re curious about something, we drop it in there. What is, so how is CO2 used by plants? Is it, is it used for, only for photosynthesis and for, for carbon storage and sugars, or is there, or are there more ways that carbon, that c o two is used?
How does c o two, get inhaled? Like, what is the the mechanism of the stomata? And, essentially, the third bullet point sort of an elaboration on the first one. But I think the most important of these four is the last one, because we do we don’t measure these, these pollutants with meter group sensors, but we have a very a very large collection, from the Copernicus, atmospheric data store for every every man made, human made pollutant that is measurable. And through some of our paper some of the papers we read for the silver fur, for example, we we saw that sulfur dioxide reductions in the the area of, Central Europe has led to an increase of their growth rates.
And we we we we know there is a correlation between certain pollutants and, tree growth, pre health, and we would love to be sure about them. So we had a a quick chat with GPT about what are the main pollutant. We actually gave it the list of all the pollutants we we can measure, and we asked, about the the main risks when it comes to when it comes to plants. And we understand that some of them are direct, some of them are indirect through the, the effects on other organisms that plant rely on. But, essentially, we would like to have a very clean, very clean story, very clean narrative that out of all the possible pollutants, maybe these three, are the most critical for each area, and then we would correlate them we would correlate all the data that we can, get our hands on and see what’s the health of a tree.
And in terms of in terms of the narrative, it would be interesting to see, is is there a downward trend? Are things getting better or are things getting worse? Are there spikes? Are there seasonal trends? All these things we can, we can analyze.
So knowing where to focus out of these dozens of, of of emissions, that would make our lives much easier. Because the more we get into it, the more we we realize that maybe everything is important, but we still need to focus on the most important things to have a story. So I think, yeah, can we scroll down? And we had some questions for the meter group. We have a question about the atmospheric pressure, and do these fluctuations that we’re already getting, do they mean something for the trees we are looking at?
Are they are the differences too small? Is it something we we can ignore, or is it can it be part of the story? And we were also looking at the vapor pressure and the vapor pressure deficit. We understand a bit, about the the process well, the the mechanism that of the upward movement of water in plants and that vapor pressure deficit can tell us how much a plant can, exhale water vapor to the atmosphere, how much potential there is for that. Correct me if I’m wrong.
Sure. Do you wanna jump into this right now? Yeah. Let’s do it. Or okay.
So just just a small small thing. I think last week, there was a period where there was very, very, very low vapor pressure deficit, and we were wondering how would the three describe these, like, three days. I think if you yeah. Chris, if you go down Dana has a question. Yeah.
Yeah. So we have this very, very, flat region. So what would the tree say about about this situation, about this experience? I think the position of where you take a VPD measurement is super important. So, we need to because all of all this is based on below the canopy.
Right? We saw where those are are measured. So, the tree is gonna have very different BPDs, and I don’t remember how tall these are. Are they fully up in the canopy? So the the one we are the one we are measuring is, seven about seven meters from, roots to the very tip.
It’s quite small, but the ones next to it are quite tall, 30 meters or so. Okay. The bottom line is they might have really different VPDs where the sensor is than where the top of the canopy or different canopy positions are. So, I think, yes, this is a piece of the of the puzzle. But, you know, it it’s kind of just describing the, the water environment of the atmosphere.
Dana, do you wanna jump in here? Yeah. I thought maybe I’d start big picture a little bit so that you can sort of see how the the the gas flow and the water and the stomata and all of this are connected. I think that’ll be helpful. There’s a reason why we’re called carbon life forms.
Right? All all of life is uses carbon at its core, and carbon just has this unique property. If you think of, the old tinker toys where you have a a block of wood with a certain number of holes in it. Right? And you can only connect based on how many holes.
So carbon can connect four times. Right? It’s got four holes. And so that’s why we have c o two because oxygen has two holes. Right?
And so oxygen two oxygens connect with the two holes, and one oxygen connects with two and the other connects with two. And life uses carbon because it’s pretty stable. Right? It’s it’s both reactive and that it’s got four holes, but it’s also really stable. So all of life is interested in acquiring carbon from various sources and, using that to create what we call long chain hydrocarbons.
Right? And a long chain hydrocarbon is or short chamber would be sugars, and long chain could be thing like cellulose. And, of course, the really, really long high hydrocarbons are the, you know, the oil that we’re getting out of, which, of course, is old, compressed plant matter. So the process in which life does this, it it gets its carbon from the atmosphere. It gets it from c o two.
And it needs a process to unplug those holes to get rid of the oxygen that’s attached to it. And then it also needs the hydrogen. It needs the hydrogen from somewhere to plug in those holes with the hydrogen so that it has a stable form because you don’t wanna have these open holes all the time. Life needs its hold those plugged in. So the water is coming from the soil, and it’s traveling up through the xylem.
And it is traveling through a process of capillary action. So if you remember way back in chemistry class when you saw the water sticking to the side of the the glass, what and when the smaller that glass is, it’s it it’s so small that it uses capillary action, and it it’s pulled up the sides. It’s just that attraction because water has a little bit of a charge, so it’s pulled up the sides. But it can only be pulled if it’s vacating somewhere else. So in the leaves, you have the stomata are windows, essentially.
The window’s either open or the window’s closed. So when the window’s open, the vapor pressure deficit basically says if there’s less water outside than there’s water inside, the water’s gonna keep flowing out. Okay? Yep. And when it’s really low and the windows open, the water will pull.
The capillary action pulls out of the soil. I’ll describe a little bit more, but that’s that’s that principle. So now I’ve got water, which is my source of hydrogen, and I’ve got when the window is open and it’s really passive. It’s a passive process. When the window is open, the c o two comes in the window.
So now I’ve got hydrogen, which is pretty stable. You’ve got carbon dioxide, which is pretty stable. I need some energy to break those bonds. I need some energy to pull the oxygen out of the holes and pull the hydrogen out of the oxygen. Well, that’s what sunlight is.
Sunlight is that source of energy, and I saw somewhere else a reference to electricity. Yeah. It’s essentially some electricity. And what a chlorophyll molecule is is a long, long, long molecule. When sunlight hits that molecule, it excites an electron.
The electron bounces up the length of the molecule. And then when it falls back down, because the electron doesn’t wanna be excited, when it falls back down, life uses that energy as a power source to break some bonds. So when the bonds are broken, now we can have hydrogen plugging in the holes. We can start assembling and creating sugars. Sugars assemble to create cellulose.
And now I happen to have this extra oxygen. Well, when the window is open, that oxygen is just gonna flow out the window. Right? What controls this is the really cool self regulating part of this. What controls whether the window is open or not is is controlled by turgor pressure.
So the stomata essentially have, like, two balloons around the outside. You can think of the balloons used to make toys, the toy balloon and stuff. Long balloon. We have a section about that. It’s quite fascinating.
It’s super cool. And so when there’s enough moisture in the air, then the balloons expand. So So instead of they would be flat and the balloons expand, they open the window. And that’s really important when, and the and the whether there’s enough turdle pressures controlled by the vapor pressure and deficit. Right?
That’s an indicator of the amount of moisture in the air. So when it’s really dry, then the stomata are not gonna be open. So your VPD number but it’s not in the larger forest. It’s really what’s at the surface of that stomata. Right?
And leaves have all sorts of strategies to to actually reduce the vapor pressure deficit, the differential, because they would like their stomata open. That would be the best. You know? Then the water can come, and I can get in my c o two, and I can release my o two. That would be the ideal scenario.
But, yes, when it’s dry or it’s windy or whatever. So leaves use all sorts of strategies. They cluster their needles. They have leaf hairs, to manage when that moisture level drops or the deficit becomes so large that it’s just pumping out water faster than it can replenish from from the soil. So that’s, like, the the high level of how all these pieces fit together, and it has bearing in a a number of questions that, I saw through here.
So I wanted to sort of frame that for us. Thank you. Thank you, Dana. This makes sense, and I think it’s a very good overview. There’s something I didn’t quite, something that confuses me.
I thought that when the air is dry, this means that it has the capacity for more water. That’s when the stomata would open up, but you said the opposite. When the air is dry, then the differential between what’s inside the plant and what’s outside is bigger. Yeah. So the BPD is a bigger number.
That means there’s more demand. There’s more draw. There’s more likelihood that the water will move out, which in a place where you’ve got really moist soils, that’s no problem. Like, if you go to a mangrove forest, the stomata are basically open all the time. Right?
They they actually need that water to move out constantly because they’ve gotta also fight the salt in the water. Mhmm. But if you’re in a desert, like, desert plants have special adaptations. They don’t even open their stomata in the day at all. Right?
To conserve to conserve water. Yeah. To conserve water. So carbon dioxide is not the limiting factor. Water is the limiting factor of how much, a plant can grow.
There’s plenty of c o two. That’s not that’s not the risk factor. But water is the limiting factor. So life has to work on this careful balancing act to make sure that it has enough water to to feed the system. I think this answers lots of stuff from the next section about water.
And if I understood correctly from what you, Dana, said and what Chris said, essentially, measuring VPD in allocation doesn’t tell you that much because, ideally, you would want a full matrix of measurements to understand what’s going on volumetrically. Because, Dana, you you mentioned that what matters is VPD on the surface of the leaf. Right? Or like But the yeah. But the the key the key with the VPD is that the high v b t VPD is when the plant’s at the highest risk, from and that that keyword is risk that Dana used there.
So that is gonna be, you know, when the in you know, if there’s plenty of water in the soil and not too much stress on the water column, then the plant is gonna be fine. But, when the plant is going to be in danger is when it’s at the highest VPD. I see. I see. So it’s not let’s say it’s not very accurate to say that a situation with a low VPD is risky or unpleasant to the tree.
It’s actually when the VPD is high that it’s more risky and stressful in a way. Yeah. Definitely. Because the plan will always find a way to release like like, what I had in in my mind, like, I was trying to visualize it, and I was thinking, what but if the stomata close and then this kind of pump vertical pump action can be very efficient because there’s not enough pool, maybe that’s a problem, for the treatment. It’s it stops.
Right? So when the stomata are closed, that process of moving water up stops. But that’s okay because the stomata are closed, and there’s no c o two to work with, and so I don’t need water. Like, I I really only am photosynthesizing when the stomata are open, which is why I say, again, desert plants, they grab their c o two during the day and, or sorry. They grab their c o two at night.
They open the stomata at night, and then they work on on processing it the next day when the sunlight’s there. Because they can’t afford to but they that’s why desert plants grow so slow. I’m in the desert now. I’m looking outside. They’re, you know, they’re not very, very tall.
So it’s, and and why in the rainforest, you have huge amount of carbon that’s locked up because you’ve got no shortage of water and no shortage of sunlight. And as long as you got plenty of that and temperature, you’re not limited by by temperature, which is another thing we can talk about, especially the fir. And I can also, when we get to that point, talk about the difference between deciduous and evergreen and how that plays role in this. Yeah. I’m itching to jump around because lots of the things you mentioned, we we have them further done, but let’s let’s make it orderly.
I I guess it would be nice to know if, atmospheric pressure is a metric that is significant, is something that we should pay attention to, or if it’s actually not as important as the other things we’re measuring. It’s a strong oop. Go ahead, Dana. I was gonna say probably not for the trees that we’ve got, but yeah. It It’s a strong predictor of weather.
So it’s on almost every weather station. But as far as tree to tree and, Dana, Britney, correct me if I’m wrong. It’s it doesn’t have a strong effect on trees’ day to day life. Okay. Cool.
Unless you’re growing in the top of the Himalayas, then you might have some concerns, but that’s about it. Yeah. We’ve got then we have marginal pressures. Right? So it’s Yes.
Okay. We’re definitely not installing at the top of the Himalayas in the next two weeks. That’s good. Okay. Okay.
One one one tiny little thing, and I don’t want to take us off with the scientific route. But throughout the project, I’ve always been kind of looking for and then checking myself whenever I come up with these sort of slightly overly humanizing ideas about how the tree might feel or speak or behave. When you were talking, Diana, about this this tomato opening and closing in that very sort of passive way, it immediately made me think of whether or not someone is open to or closed off from the world. And I think this is kind of very physical biological process, which the tree is not really consciously controlling. It’s a result of its environment.
It may be a sort of nice idea to hinge something on and say that when when the conditions aren’t such that it can be active and generating those sugars, it is physically closed off from the world. It’s existing in its own little thing. And then when situation changes, it becomes more often. The funny thing is be because tomata means in Greek literally mouths, plural. Every time we talk about it, I keep thinking of a choir with, like, lots of people singing with their mouths open.
Just can’t help it. Yeah. And it’s a little bit more passive. Right? So it’s like it’s just, you know, open all day long and then closed at night.
Right? And it it’s not like there’s I mean, there there there is differentials. So the leaves that are, say, in really, really bright sunlight and at that surface right there, the VPD is too high. And the stomata are not on the top of the leaves. Remember, they’re actually on the bottom of the leaves because there’s too much risk of I mean, because, of course, the sun dries things out.
So stomata are on the bottom of the leaves or often in the case of, like, evergreens needle clusters, where there’s a cluster of needles that all fold together, the stomata aren’t on the inside. So that’s, again, another strategy at the very like, when when back when I was studying, you know, you measured vapor pressure deficit as it mattered to the plant at the at the level of the stomata. Like, you stuck a little probe in there right at the level of the stomata because that’s the the, number that matters to the plant. What’s happening, you know, a meter away is it it gives you a general indication of the overall humidity in the air, but, life has a lot of really cool strategies to ensure what’s happening at the level of the stomata is key. Is this where the leaf wetness measurement that we’re taking could maybe play a factor?
I’m not sure what you’re measuring with leaf wetness. It is the duration that a leaf is wet. So the leaf wetness is a little different. It’s going to it’s going to correlate with VPD a lot. Basically, when you get low, low, low VPDs is when you’re gonna start seeing condensation on your leaves and the leaf wetness sensor mimics that.
So, it’s going to be more of a, you know, when your nighttime when your temperatures are lower, they’ll they’ll track really pretty closely because they have the same drivers, and that’s temperature, and the amount of water in the air. But the main thing that’s changing from day to day is generally the temperature. Mhmm. So those are the two components that we’re getting that are going to that are gonna drive the readings on the BPD and the, leaf wetness sensors. The amount of water in the air and the temperature.
Yeah. And, yes, essentially, the the leaf wetness kind of correlates to this to the metrics. Right? Because it’s how much water actually condenses on the sensor and how fast or slow it it evaporates because of Exactly. Okay.
Cool. And so and and in the chat, Brett was right in saying that I suppose the tree isn’t completely closed off to the world in that scenario because it’s still there’s still all this information feeding in through the networks below it. Mhmm. So it’s not it’s not like it completely cuts itself off. Yeah.
And it has an interest to have its stomata open as much as possible. Yeah. Right? So even if 80% are closed, 20% might still be in the lower branches or, you know, wherever it might. And it’s still in relationship with everything in the soil, so that’s not on either.
It’s not an on or an off. That’s a gradient of Yeah. Openness. So we move to, yeah, to the next section, the water. Yeah.
I mean, this text is essentially information about EPD that, would love I mean, this conversation actually is very fruitful, but if you can also have a look here and confirm or react to it. It’d be great. But let’s move to the water. So the mains the main statements here, it it is the act of drinking. It’s via the roots.
Trees can be said to be biological pumps. Can we say that sap is the tree’s blood maybe? Can we say that xylem is the tree is the water highway? And that we we have three, rows of the water here and transportation medium from roots, sometimes directly from leaves in the foliar uptake, I think, situation. And it’s probably true in any of the species we have that there’s foliar uptake.
You didn’t find any, right, Brett? I don’t think so. Mm-mm. Yeah. Secondly, water is a reactant in photosynthesis, and it can act as a stiffener or, like, I don’t know.
I I don’t have the English word for it. But, essentially, it’s a part of the turgor pressure mechanism that keeps keeps things tight. Anything that needs to be tight stays tight using it. Thank you. Then if we go down to the secondary statements, something I actually didn’t know, or maybe I didn’t know, but that was only taught in Greek.
It is not in English. I I never thought, I never heard the word phloem. So is is it correct to say that xylem is all about going from roots to leaves and phloem is the the other way around, distributing sugars downwards? It is it is bidirectional. So it’s not just, you know so it because you also need the sugars to meet make the leaves.
Right? So you you it it moves in all directions. And I I’d I’d be a little worried about upward and downward, because there’s outward and, and sugar sugar will go down to feed the roots, and it will go up to feed the growing tip. Right? So it it’s going all dry is going out to the edges of the leaves.
But the xylem, I really don’t think of it as up and down. It’s more like it’s a it’s a path from the soil to the air. Yep. So that’s why I put quotes because it’s, in my head, it’s topologically up and down. Not physically, but going from, let’s say, the start nodes to the end nodes or the start nodes being the roots and the end nodes being, being the leaves.
Mhmm. And yeah. And another thing we were really, really excited to learn was the the concept of turgor pressure. Mhmm. And, especially, when when I did the math and realized that, these, two megapascals is actually an incredible an incredible amount of pressure able to break concrete and things like that, which is a pressure.
This is, from Wikipedia. Haven’t I mean, there is a a reference to it. Wikipedia haven’t verified it, but it was like a crazy number to to see. And Dan Richards, I think this is an interesting thing to think about that a a plan that is considered delicate to us, humans, can actually exert so much pressure. Let let’s say we can cut down a tree and we can destroy a tree in a million ways, but we don’t have the physical strength to exert that much pressure onto something as trees can exert internally through their cells.
Yes. I’m Yeah. And it’s important to keep in mind that it’s living cells only. So especially for trees, the trunk is a lot of dead cells. Right?
And and the xylem, the pipes that make up the xylem are surrounded by dead cells. So, or or we think of as dead. Right? Like, I mean, that’s a it’s they’re not actively engaged in the pumping of metabolic processes and growing and and so on. But, they’re still very much a part of the tree.
And that’s why, of course, when you cut down a trunk, you have you still have rigidity and structure because the cellulose has has locked up. But so if but if you’ve got, like, a young palm or you’ve got the leaves on a palm and and those sorts of things. But, again, keep in mind that it’s a mix. Like, even a palm leaf when it come falls off, it still has that cellulose, that’s built up and created structure. So it’s it’s very, very important for stomata.
It’s very, very important for young leads. Right? So buds and buds opening and, you know, that’s part of the turgor pressure. Insects also use it, like, to unfurl their their wings. It’s it’s part of the process of using water as pressure to open, as a system and hold it until the molecules backfill and give it some rigidity.
I see. So at some point, cellulose takes the role of turgor pressure. Yeah. And it depends on how long that those cells need to last. Right?
So in the tulip, you’ve got deciduous leaves, four or five months maybe that they need to be activated. So why waste a lot of energy producing too much cellulose for those leaves because they are only needed for four to five months. But the silver fir and I and I’m not sure exactly how long they live, but it’s probably four, five, or six years maybe. So there you need to invest in something that’s gonna last five, six years. Because if you rely on turgor pressure to hold everything up and then you have a dry day or the soil is dried out, then you’re in trouble.
Because if you’re not spreading out your your leaves to the sun, forget photosynthesis. Right? So it’s it’s not a it’s helpful, but not an exclusive strategy. So you’ve got I think the idea of investment’s really interesting. I think the idea of, yeah, the the actual physical manifestation of a of of a tree’s being being a result of how it’s adapted to.
I need to hang on to my leaves for this amount of time versus I can just grow them quick and delicate and then chuck them. I think that’s maybe quite an interesting contrast in in personality there that we’ve got between the different species. Well and since you oh, you have a question, George, but I can talk more about the deciduous evergreen here since you opened that up. Can we say that cellulose is expensive and water is cheap, but cellulose is more permanent and water is more volatile? Wouldn’t say it’s super expensive in the sense of, you know, of all the molecules to assemble and build in the world.
There’s definitely more expensive. The molecules the molecules Your secondary your secondary metabolites, those are pretty expensive. Cellulose is pretty cheap because cellulose is carbon and hydrogen, and there’s lots of carbon and hydrogen. Right? And and it’s things went like, chlorophyll is more expensive in terms of the sense that it’s it’s got nitrogen at its core, and and therefore, it’s it’s a harder molecule to find and therefore more expensive too.
But, also, I mean, this depends on the supply side. So if you’ve got a high supply of water, carbon gets a lot cheaper. Mhmm. If you’re if water is scarce and and the strategies that all three of these plants have are very different around water, right down to their anatomy. So, it’s yeah, I I I think the supply of water kind of comes into this in a in a huge way.
Mhmm. Yep. And water is a source of hydrogen and water is a is a transport mechanism to getting you the minerals and the other things that you need. Right? So every everything gets more expensive as water supply drops.
It’s Yes. Yeah. Yeah. And I don’t like the word expensive, but gets more challenging. Challenging.
Mhmm. We have some some questions in the similar vein of curiosity as in the first one. What is SAP made of? Why why can’t we call it blood? Like, it inevitably feels like blood feels like one of these simplifications that people make.
You cut you cut a tree and it bleeds sap. Like, I I find that too I find that hard to believe that that is it has any relevance to blood in the way that we think about blood. Well, I mean, it it is it is also a transport mechanism. I mean, right, the phloem. And, it’s primarily sugars, but it also has water.
It also carries other building blocks. So just like our blood does. Our blood the difference is, of course, our blood transports c o two as the metabolic waste of cells, from the system, and there’s not a waste processing in trees. Like, they they it doesn’t have a a filtration mechanism to remove any metabolic waste. It just gets embedded in the cellulose or in the dead cells.
So so that would be a fundamental difference. But in terms of transporting a means to transport nutrients, and, yes, when when you have an insect attack, and it it you there is a I mean, one of the ways that insects can kill trees is they drill so many holes that it’s like, yeah, you’ve been cut in a gazillion places and you just leak out. Right? And you don’t have enough pressure to hold the system together. And phloem, of course, is on the outside of the right.
It’s just under the bark. It’s that that living layer that’s right beneath the bark. It’s not in the inside. So it is the part that is most susceptible. But at the same time, as you noted elsewhere, that, you know, when loam will fill a wound, right, it will backfill.
And it I wouldn’t be surprised if there’s also some antibiotic and antimicrobial properties in sap that, help help heal and protect that wound. Because it crystallizes, the sugar crystallizes, you could think of it also like a blood clot, that, locks up so it doesn’t continue to ooze, out in the system. Yeah. We we have some information that we would like, for you to look at in the chemical warfare section. I think here, the the most important questions, is how exactly do roots take in, h, water?
And the second one is that we’ve read that three zeros extend chemical signals through their roots between it’s between individuals. And this means that they don’t they don’t only uptake chemicals, but they emit. And that’s this sounds fascinating, and we would love to, to hear more about this process. And for for meter group, the the main question is, from a point of view of a tree, a tree’s health, how shall we interpret the metric potential we discussed about last time with the soil moisture and the leaf wetness? And can we can we map, these values into some fuzzy categories of this is a good situation here now because of this.
This is a bad situation. Good or bad. I mean, they might not be the right adjectives, but let’s say, problematic or or ideal or comfortable? Starting from starting with tree hydraulics, let’s go back to the leaf, basically, leaf water potential. Right?
The minus two megapascals you were talking about. Basically, the tree doesn’t do a lot of work when it’s moving water. This continuity between the soil, the plant, and the atmosphere is is the driving force for the water from the trees. And that’s, I I mean, our company is based on biophysics, and that’s exactly how we how we put everything together. And it’s just moving water moves from a high potential to a low, just like everything else.
And even when that potential is negative, it it’s still you’re going from a higher concentration in the soil to the air, which is which is the endpoint for this whole thing. So the air is basically pulling everything from the soil through the tree. And just to use your, just to start with the with the potentials, your leaf potential is anywhere between minus one and a half to minus yeah. I’m gonna get myself in trouble here. Let’s stay at minus two megapascals, and the water or the leaf is minus two.
Let’s say the air is minus a hundred about a minus a hundred megapascals. Let’s just make that assumption. And so that’s why water is going to water vapor is going to move from the leaf into the atmosphere because that minus two mega pascals is a higher potential than the minus 100 mega pascals of the air. And so then when you’re looking at soil potentials, the soil has the highest potential. If it’s totally wet, it’s gonna be near zero if it’s completely saturated.
If it’s if it’s gets drier and these are gonna be some of the things we see with the different species that we have, it can get down to minus, you know, minus two mega pascals is really common in some places. And if you think about that, if your soil is at minus two mega pascals and your leaf is at minus two mega pascals, then the water isn’t going to move up through the tree, especially if your stomata stomata are closed. So that’s the basis of of how water moves through a tree is that is that progressive gradient of potentials from soil to water soil to air. Sorry. And, yeah, this this is, understood.
And, is it right to say that if we combine the metric potential on the soil with the VPD, we can sort of have an image of that of that model of for what’s going to happen, in terms of vertical, movement? In a general sense, you have In the in the limits of of of the sensors, of course. Yeah. Exactly. Yeah.
As Dana mentioned that when she was doing this work, they measured the Yeah. Right at the leaf surface from where they’re measuring the stomatal conductance. So if you think about a tree canopy that has all kinds of different conditions all throughout it, you can use the VPD from the sensor as kind of the a general, a general from day to day plant condition, but not not to the point of, like, calculating your vapor flux or anything like that. Mhmm. Well and one thing that’s, I think, interesting part of the story.
So remember I was saying there’s these adaptive strategies that are around reducing that differential. And it’s, you know, leaf configuration, it’s leaf hairs, and we call that the boundary layer. So the leaf has strategies that control the boundary layer. And it’s a very, very thin layer in which that differential that Chris was just talking about might just be a you know, it’s a buffer between the minus two and the the minus a hundred. And the thicker you can make that buffer, the the less pressure there is to just, you know, pull all of this.
Right? And that’s why you see, like, you see waxy leaves in the desert. You might see a lot of fuzzy leaves, right, where they’re the those long leaf hairs. Those are the boundary layers. But boundary layers also scale.
So a whole forest also has a boundary layer. And so when a tree is not in isolation, but it’s in this community. And so if you were to measure the the vapor levels underneath the canopy versus at the top of the canopy versus five meters above the canopy, you would also see. And when you have a monoculture, you don’t have a boundary layer. You think of it as like a very smooth surface at the top of and then wind blows over and it just shears off that different you know, the boundary layer.
But when you’ve got a polyculture and you’ve got all these different thing, you’ve got all these places. You could think of them as as macro leaf errors. You’ve got all these places where those moisture pockets can get get trapped. And so that’s feel of the leaf also extends to the forest. What about a tree stuck out on its own, like a little chewed up tree who seems to be by themselves.
Is it that drastic in that even just like a small collection of trees would have this effect? Yes. Yeah. Mhmm. Yep.
Yep. And, again, it matters most where water is limited. If water isn’t limited I mean, there’s other advantages and disadvantages to being by yourself. But if when water is limited, having a community around you is a good thing. Yeah.
Interesting. Can I make calls signals? Yeah. So I I think, Britt, maybe if you speak to anything you found around exudates. So a number of plants produce what are called root exudates, and those are like repellents.
They are, compounds that leak out of the roots that are tolerable to the plant producing them, but intolerable to other roots from other species. So it’s a little bit of a, like, don’t grow here. This is kinda my territory. I got something you know, this is I’m I’m stinky. Stay out of here.
Right? Or whatever it might be. So you have some of that. The the other communication channels, there’s very few circumstances that I’m aware of of, like, root to root. It’s root to mycorrhiza to root.
Mhmm. And so it’s through the mycorrhizal connections. Some trees are very specific on which mycorrhiza they’ll connect with, and others are more generalists. Right? And, likewise, for some mycorrhiza, they, might only connect with a few different species, and others are more generalist.
So you can see the the, the negotiations of reciprocity happen at the contact point. Mhmm. So you’ve got some, like, horizonal, network, and it’s bumping up against the roots. And there’s a like, okay. Is this gonna work?
Are we gonna have an exchange here? The mycorrhiza in addition to phosphorus is a really important one. Water is also an important one. It increases the surface area, essentially, right, of the tree when it’s in relationship with these mycorrhiza. So I might be having a little relationship over here with some trees, or some tree roots, but another end of my mycorrhizal network over here might be also negotiating a relationship, and in exchange for carbon because it’s really hard to get carbon when you’re buried underneath the soil.
So share some of that, carbon, those sugars with me, and I’ll give you some phosphorus. I’ll help you with water. I’ll increase your surface area. My suspicions are we don’t know what intent is here in any of this. Right?
But because the network in the middle, my left hand is actually talking to my right hand. And so any conversation my left hand is having with that tree and a, you know, clues, can travel potentially through the roots, through the mycorrhizal network and into the right hand and convey that information to the other adjacent tree. If you remember the other day, I talked about trees are keen to sense and pick up any information they possibly can. It might be volatiles that are in the air. So trees can sense the volatiles that are produced when a neighboring tree is being attacked and being like, oh, I need to bump bump up my defenses, before those attackers show up here.
But there also can be signals that can carry through the the mycorrhizal networks. And, Brett, in your research, you were saying that part of the reason that the Judith Cree has been so successful is because it is very friendly with lots of different mycorrhiza. I mean and that’s also true with what most plants. Right, Dana? Like, it’s it’s not like it’s just that one, but yes.
Yeah. And I think only the the only species that we’ve, like, bred out the relationship with mycorrhizae. But it and and some are more obvious than others, but yeah. But there are I don’t know about the tulip in terms of how what the diversity of mycorrhizae that it connects with might be. Well, I think it’s also kinda worth knowing because Dana was talking about, like, the whole system and the whole network.
A lot of times when we just, like, go plant one tree or we just randomly plant a couple trees or we try to uproot a tree and plant it somewhere else, they don’t have those connections. They’re individuals. And so sometimes if you’re not keeping up on the care of that tree, then it’s gonna be potentially more at risk than something that’s already in its ecosystem and is getting those signals and and materials and water sort of back and forth. So I think the point of, like, it’s the system and sort of toggling back and forth from that to the individual tree is just something to think about. Yeah.
And The tree’s help isn’t just about its own body. Mhmm. Yeah. This is something we’ve been oscillating with the client as well. They they like the the story of a tree as an individual, as a hero.
That’s something that it can cut. As a thing that’s in a position to be able to write to author something. So they like the idea of the tree as a writer or a journalist, which suggests an individual, which isn’t. Yeah. Well, maybe it’s spokesperson.
Mhmm. You know, that it’s that it’s speaking because nobody else is really part or because you didn’t ask anybody else, right, in the opportunity. I’ll be the one to talk on on our behalf, right, our collective behalf. That was nice. Yeah.
Yeah. I mean, we we love the idea of of the hive mind and kind of spark. So this, sci fi, sci fi ideas about species that can do so many things we can’t. So we’re oscillating between the three as an individual with a voice and, also the knowledge that it’s actually speaking on behalf of lots of others. I think the more we can move away from the individual as we were talking in the first session Mhmm.
Around transforming our perceptions. I mean, just the notion that we still think of ourselves as individuals is a little obnoxious. Right? Like, we completely missed that. We are walking ecosystems.
So, you know, the more we can encourage that awareness that every organism is deeply interconnected with everything around it, I think is is a better way to go. Yeah. Yeah. It it could be a core angle, a core characteristic of of that persona. Like, always phrasing or always referring to the fact that it’s not alone.
It’s never alone. It’s channeling the voices of others all the time. Me, not an I. It’s a me? Mhmm.
It’s a we. Yeah. Yeah. Yeah. Yeah.
It could become the the subtext of everything, it’s it says. I I wanna come back to that, actually, so that’s not glossed over. That was great, Britney. Like, you could almost have a simple rule that I is never used. Mhmm.
That it is always we. We spoke we spoke a lot. Speaking of me on that. Yeah. Well and I think the thing to consider too when you’re thinking about those networks, perhaps a certain tree needs water or it, you know, it’s it’s struggling in some way.
That might be the I, but then it’s still connecting to the we for the help. So while you might have a sensor, you know, okay, but, really, it can’t survive very well without everything else. I’m gonna say it can’t survive, period, without every everyone else. Yeah. Neither can we.
We can’t survive without our ecosystems. But we’ll scaling. Like, Dana just mentioned, we’re walking ecosystems. You know, we know that our microbiome is enormous both on the surface of our body and inside. Our elbow’s a different ecosystem than our armpit.
And then the tons I mean, it’s not just mycorrhizal stuff that’s underneath the ground too. There’s all sorts of other organisms and bacteria and different things down there too. So, you know, the scale isn’t just at a forest level and isn’t just mycorrhizal. There’s probably way more going on there that’s smaller and maybe we haven’t even found yet. Well, they just started documenting leaf microbiomes.
Yeah. That doesn’t surprise me at all. Ten, twenty years. Right? Like, that wasn’t even we’re like, really?
They have their whole ecosystem. You know, it was seen as parasites or, you know Right. Biofilms or molds. Yep. But now there’s, like, a whole part of the part of the healthy part of the ecosystem is Yeah.
And that that ties into the palm too and, like, other rainforest plants where you have bromeliads and sort of other things that are on there. We used to think that it was just a problem. And if there’s enough on there, you know, it gets too heavy or whatever. But we know that there’s still, like, nutrient flow. There’s still some things that are happening there.
There’s still some communication. You know, the sort of matted areas underneath some of those, organisms can get into, like, these little, like, sort of traveling roots that a tree can have that aren’t just below the surface. Because if you think about a rainforest, you don’t have very, like, good soil for, like, deep, deep, deep, deep, deep. It’s not how that works compared to, like, probably where the tulip tree is, where you probably have rich oil. So where you think about roots and where you’re getting materials from may be a little bit more dispersed.
So again, sort of checking ourselves to be like, is this bad? It’s always more complicated than that. And again, it’s a system at just a different scale. So like how you might consider the relationships the palm has is probably gonna be a slightly different story than what this deciduous tree has because it probably has really, you know, thick, biodiverse soils that it’s pulling from. The roots are gonna be different things.
They’re gonna go way deeper underground Mhmm. For example. That was really interesting. Yeah. That’s very helpful for me as well coming at from a sort of outside the data, but using the data and the way that you, Britt, have described things.
I was very taken with the idea of the relatively shallow roots of the palm, the fact that it wouldn’t have a tap root. It wouldn’t you know, everything that we would potentially think of the tree, you know, when you’re growing up and you have the idea of a tree as a tree because, you know, at a very childhood level. And then some of us, depending on where we go as people beyond that, don’t necessarily carry this this the complexity. You know? We never get beyond that.
And it’s been a sort of thorough and very interesting education for me. But interestingly, from the very start, we’ve started talking about this idea of, the relationship of trees to time, the relationship of trees to each other, the relationship of, you know, if they have a if they had a consciousness, a shared consciousness, and consciousness is obviously a knotty word, but it would be a hive mind in that way. And the the I would be, you know, perhaps used about the specificity of one tree, but there is a the the actual relevance of that is communal, if that makes sense. You’ve spotted it in one individual, but it’s almost impossible. It’s incredibly unlikely that that is only that only occurs in that one individual tree, you know, and it obviously has a relation to all the other trees around it and then further extrapolating out to, you know, to potentially all the trees in that area, you know, and and tracing it down, which is what we tried to do.
And I think what what I see my job is to kind of try and make this polyphony, but at the same time make it accessible. But, ironically, I think the more interesting and weird and correct that we are, the more accessible it becomes because it awakens this childhood fascination that I think we all have for the multitudes that exist in that way and the fact that it’s not a, sort of monoculture in that way, that nothing is. And when you’re talking about this the walking ecosystem of us and the idea of the microbiome, It’s fascinating to me. So all this is incredibly helpful. So thank you.
Thank you, everyone. Well, and some of our language is is we’re we’re all projecting from how we see ourselves. Right? So we see ourselves as individuals. We look at a tree and we’re like, oh, that’s an individual tree.
But, like, if you look at aspen, you know, and aspen is like, the largest organism on the planet is an aspen stand in Utah. Mhmm. That’s 80 square miles. So that’s, like, what, 40 square kilometers? That’s the organism because it’s genetically all identical.
It’s just all these individual stems, but it is all one organism. So you we just don’t even have the language because we’re limited to the language that we evolved to describe ourselves. Or even how we think about death, for example. Like, if we have a a dead tree in the forest, that’s not a waste. If you have a snag, that becomes a home.
If you have a downed tree somewhere, that might turn into a nurse log. So even just how we perceive things like that are gonna be a really different story again, think about the system. So, like, you know, in the rainforest, you might talk about, like, the strangler fig, which I hate that because it it puts that tree in, like, a negative context. But, you know, even if it does eventually kill the tree that it’s on, first of all, that tree was going downhill anyway. And secondly, now you have some more diversity.
You’ve opened up some space, and you’ve created more of that mosaic in the rainforest. So now that’s more opportunities from different species that they didn’t have it before. So I think Dana has such a strong point there because it’s not just us as an individual. It’s also how we consider intelligence, how we consider the entire life cycle of something. You know, just because you have dead manner in matter in the inside of yourself as a tree, it’s all useful.
It’s all good. All an opportunity. So, like, disruption. You know? We think about a fire or a flood or a big storm.
You know? How that tree might think about it versus the whole system might think about it over time is really different. It’s an opportunity. It’s not, oh my god. This is devastating.
Unless we have, you know, huge fire after huge fire after huge fire, and that thing can’t respond with the time that it needs in between those. Mhmm. Mhmm. It’s it’s also signing value to stuff, isn’t it? It’s also immediate so it’s immediately going, that’s the thing.
That’s bad. And, actually, we need to look at it monolithically. Right? I think I was thinking earlier, rather than necessarily banning the word I, maybe it’s more useful, at least specifically within the context of the thousand words article or story. Maybe it’s more interesting if we’re constantly blurring the boundaries between when it says I, when it says we, when it says them.
And sometimes when we think it should say instinctively, when we think it could say I, it instead says we or them. And, actually, because this this tree that we’re monitoring, the tree that we’ve attached the leaf wetness sensor to, that came into being ten years ago. But in reality, the kind of genetic memory of the we and the they is has always kind of been there a lot longer. Yeah. I do need a spokesperson.
You know? Like Dana said, that feels a lot more accurate. Yeah. Yeah. It it’s the kind of the point at which we’re measuring rather than the Yeah.
The trees are speaking for the trees. You know? Yeah. It’s not just the Lorax doing it. The trees are speaking for the trees.
Yeah. Brit, we we were lucky enough to find some great specimens that we three d scanned. One was a a log. I think it was a beech tree, and there were small, fir trees. It it was horizontal, and there was a crack.
And there were these little firs, coming up from the bark. Uh-huh. And we we actually have a three d model of that that that’s really crazy to have. And Oh, that’s There were there were dead logs everywhere, and they were full of fungi. Mhmm.
And I don’t know. I’ve never been in a in a forest in in this region. So it was fast the colors were fascinating because I could see the the the the firs that were alive and the beaches that were alive. And the ones that were dead, they were so different color, but they were still alive because you you saw all the fungi on them. So it was, there wasn’t a concept of of death.
It was in my eyes, it was just different colors that linked to different things going on. Well, decomposition too. Right? You’re getting those nutrients back into the soil and back into the system. So it’s like feeding what’s right here, but it’s also feeding what’s down.
Yeah. And I have a sentence, I think, at the bottom where I say that evergreen trees feed on the necrotic matter of their deciduous neighbors. Yeah. I won’t come back to that one. We’ll get to that one.
Yeah. Yeah. Well, can I just well, oh, go ahead, Dana? I was gonna say that in this sensitivity around I and we, I would also have a radar out for any references that sound linear that suggest a a an, you know, a one way path. And that’s And and more and more conversation around the flow and the and the circularity.
And even if the scales, you know, you play with them at different scales will be important. Just so it’s a little thing, but I think it’s important is how we’re using the word evergreen versus deciduous. Evergreen doesn’t necessarily mean that it’s a conifer, that it’s a pine. Evergreen, it’s staying green. Right?
When you go to the rainforest, some of those rainforests, trees are dropping their leaves. They’re deciduous that, like, they’re dropping, they’re coming back, whatever. But some of them don’t. And they have an an evergreen tree that’s a broadleaf tree. So there’s some some nuance there about how we use those words.
Dana, go ahead. Yeah. And I maybe I’ll pipe in a little bit because I think it’s important for this larger picture here. Mhmm. So there’s there’s two strategies.
Right? You you shed your leaves every year or you retain them for, I wanna say, as long as possible. No no tree is for forever green, but it it it’s holding its leaves in a way that we are not witnessing that common turnover. So the the oldest conifers that are evergreens are the spruces, and they might go, like, fourteen years, before the needles drop. So but there if you looked under a spruce, you will see some dead needles, and that is for the fourteen year cohort.
Pines tend to be a little shorter. They’re, like, two, three years. But we don’t see it because there’s always green on the tree. A lot of time. And same with the the tropical evergreens, the broad leaves.
They’re still shedding leaves, but they last for many, many years. And the difference between this, so, is water driven. Right? So whether or not, and and there’s two ways to approach that. So if you’re in the in the, near the poles where you have a winter season, effectively, winter to a plant, cold matters, but it’s more about access to water.
Right? So the the ground freezes. When the ground freezes, there is no water move. Yeah. And I wanted to ask you about about this in the heat stress culture section, but yeah.
Yeah. Well, I’ll pipe it in here because it’s all connected. So the ground is frozen. So I need a strategy to deal with the fact that I don’t have access to that water. So I can either do the deciduous strategy when I don’t have access to water.
And let me expand that. In the tropics, there are places where you have a wet and dry season. So same thing. The dry season, no rain for months at a time. The soil completely dries up.
Gotta have a strategy to deal with that. So no water. I can do one of two things. I can eliminate the demand for water by eliminating the photosynthetic machinery. Right?
I just drop my leaves so that’s not there. Or I shut down my photosynthetic machinery, which is what a conifer or evergreens do. Conifer evergreens do. Is I just shut that down and I go into dormancy. Now with the deciduous trees, because I’m reestablishing new photosynthetic machinery every year, I’m growing new leaves.
Those, chlorophyll, the the chlorophyll, it’s like young and and nimble and can grow really fast, and it’s gotta do its whole thing over the season. Right? The spring, summer, fall, and fit it all in there. So they are very, very productive. There’s actually two types of chlorophyll, chlorophyll a, chlorophyll b.
Chlorophyll a is a brighter green. When you think of, like, fresh leaves, they have that bright, bright green. They’re mostly chlorophyll a. Chlorophyll b is the dark green. Right?
The evergreen conifer color green or the evergreen broadleaf in the rainforest, that dark, dark green. So there’s a ratio of a and b. The a is, you know, go fast, live fast, die young. Mhmm. It it it can’t last for very long.
Chlorophyll b is a little bit more slow and steady, because it’s gotta keep producing for the spruce for twelve years. It’s gotta keep delivering on that. So I drop my leaves. It’s fine. Next year, I can grow new ones.
And then what’s super cool, and I think this could be fun for the tulip, is the core the core, element in chlorophyll is nitrogen. Right? Like, that’s why we use nitrogen is for like, everybody needs the the the, nitrogen to build their their chloroplast. In a deciduous tree, it has strategies to extract that nitrogen from the leaves before it drops them because they’re so precious. Nitrogen is really hard to get.
So it pulls back the green. Oh. It actually extracts the green. So that’s when we see the reds, the oranges, the yellows, the browns, in in the fall, those colors have actually been there the whole time, but the green masks them. So when the green pulls back, then you’ve got all you got left in the leaf is carbon, hydrogen.
I can get some of that next year. No problem. I’ll just drop these leaves. Those leaves don’t turn back into like, all of the tulips leaves and the millions of carbon, molecules are not now what makes the same set of leaves the next year. Right?
They’re in the larger ecosystem. So your comment around, yes, the evergreen is taking advantage of some of those nutrients that are dropped, but so is everybody else. Like Yeah. Like, whatever on the forest floor is fair game And, but the carbon is not brought up through the roots. The carbon is broke down by the decomposers, the insects or whatever.
They exhale it. It goes back to the atmosphere, and then it’s available the next year as a building block from the atmosphere. Their their roots their roots never actually get, the carbon from the ground? No. Okay.
Uh-uh. Only from the air. Some of it in to give to the the fungi and things that are underneath. Yeah. They send carbon to the send it down, but they don’t bring it out.
They don’t take it from the soil. Which is crazy to think about. Right? Like, the majority of the tree’s body, people think it all comes from the roots. Like, if you ask an average person, but, no, they’re building their bodies out of the air.
Yeah. And that is funny. That’s a big thing. It’s not it’s not soil being food thing. Right.
Which is why you why you immediately think, oh, the carbon, the food is coming from Like vitamins? Yeah. You know, you can’t survive on that alone? Well and this the way they figured out how trees grow, it was as I can’t remember the scientist, but, you know, centuries ago, planted a tree in a pot, little seedling, and then measured the weight of the pot every day and measured the weight of the soil. And then, of course, the tree grew and the tree got increase in mass, but the soil never lost any mass.
And that’s where they figured out that it was coming from, the air. Didn’t quite know how to explain it at that point, but that was this expression. But nitrogen nitrogen comes from the soil, though? Nitrogen comes from the soil. Yes.
And, some plants have partners. They’ve got, bacterial partners that grow nodules and all the legumes. We don’t have a legume in our group, but the legumes, have nodules where the bacteria fix nitrogen. It actually comes from the air into the soil and then through the soil, right, into the into the plant. But the the evergreen conifers, their strategy is just to shut down while the soil and and it’s largely driven by temperature.
You’ve got this, you know, cold and sunny and stuff up on the screen. But the cool thing is is as soon as that ground defrosts, then they’re ready to go. They’ve got their machinery in place. The you know, everybody’s ready. The the needles are all there, and they can start photosynthesizing right away.
And so they’re whether or not you have deciduous broadleaf in in in the temperate climates or evergreen has to do with a little bit of the predictability of spring. And the more variable it is, the more likely you’re better off being an evergreen. Because, if spring comes early, you’re ready. If spring comes late, you’re ready. And you’ve got that extra advantage even if it comes at the cost that your photosynthetic rate and therefore your growth rate is slower.
So that’s where our our fur is kind of That’s where your fur is. Yeah. And that’s how the fur differs from the tulip. Mhmm. Whereas the tulip and most of those deciduous trees are more like, you know, pretty strong and steady.
Now the other thing in this type because I’m on this this root here, you’ve got the cold stress and and things like that. Sometimes what’s happened and I suspect the silver fir, it has this risk. And this is the big thing with climate change. When the soil is still frozen, but the air starts warming up, then the tree can be tricked into thinking I should open my stomata. Mhmm.
And what happens then is that pull start but the ground’s frozen, so there’s nothing to feed it. So then what you have is called xylem cavitation because the pole is so great that it breaks the water column. And when it breaks the water column, it creates little air bubble. Now what’s really, really cool in these evergreens, because that’s a risk. It’s not like it’s an unknown risk.
It happens. They have some sideway channels. The air will never dissipate. The air is always there. That channel is forever broken.
But each of those pipes has some sideway connections so that there can be another path. Now if it happens too much, there’s too much cavitation, then, then it will kill the trees. And it’s a it’s effectively a winter kill. Sometimes you can see it on the side of the mountain. It’s called a red belt where there’s an inversion, And the inversion created a warm temperature zone that lasted too long, and then the needles die and they all go red and it makes that red belt, when it’s too extreme.
It’s Good. That we’ll see more of that. But then once we get over the threshold where the soil doesn’t freeze anymore, then it’s no big deal. The evergreens are gonna be like, what? We’re just gonna grow year round.
Thanks for the XP temperature. This is great because it connects, like, two, three parts of this entire document. And, I think when we talk up up when we open the sun, I think we should also open the heat stress, cold stress because the questions there are related. So, Dana, you you say that when when there’s a different temperature in the soil and the air, this can lead to xylem cavitation if the air is warmer than the soil? No.
If the soil is frozen. If the soil is frozen. If it’s the soil is below zero, essentially. Yeah. Yeah.
It has to be frozen so that no water can be pulled into the the What we see actually now in in The Czech Republic is that the air is about seven to nine degrees colder than the ground. So when we get minus nine in the air, we get, like, two degrees in the soil at the most extreme. Yeah. It’s up it’s up there. Well, and how and how deep are the soil, probes?
Because you gotta go you have to measure it at the depth of the roots. Right? Yeah. I think I I wasn’t in front of it when they installed it. Chris, do you remember?
I mean, it wasn’t deep. It was thirty, forty centimeters, but that’s where the roots were because it was a young tree, and we had a lot of rocky it was very rocky soil. Yeah. The the roots weren’t able to penetrate that deep. Didn’t think it was deeper than that.
Yeah. 34. 30, 40, 70. And, again, tolerate it for a little bit of time, but it’s it’s over how much time that becomes a problem. Yeah.
And bigger trees, because they have a lot more side channels, are more tolerant than young seedlings are. This was one of the factors in my dissertation that I looked at because what in my case, it was another tree that provided shade. So even though the air temperatures got warm and the ground was frozen Mhmm. Because the seedling was in the shade of the other tree, it wasn’t subject to such a big shift in temperature, and that’s what allowed it to survive. If the c it was also a fir.
If the seedling was out in the open, it would have had that greater temper temp and they died. Like, all the seedlings I planted out in the open died. Yep. I had I had a big question when I was looking at the, climate envelopes and what people tend to measure. I I didn’t see I didn’t see anyone measuring sunlight hours.
They were using temperature as a metric as maybe as an indicator. So I was thinking, what is more important? Is it is it temperature or sunlight? Because we measure both with our sensor with meter sensors. Well, I’d love to hear Chris’s thoughts.
But I will I will say from my perspective, sunlight is almost never limited unless you’re growing in a cave, like a limiting factor, or you’re in the deep, deep understory of a rainforest, and you’re waiting for a light gap. So there’s really not a reason to measure how much sunlight because that’s not a limiting factor, and it’s highly variable with the weather. Mhmm. I I mean, it is quite frequently measured, so I’m not sure where, exactly that, everything from a daily light integral, which is the total amount of solar radiation hitting. And, yeah, I think I’d get a bit more information or some context on that statement.
I was referring to, to a list of 19 biomarkers that, essentially can can give you a good idea about, the health of a forest, and they only deal with temperature and precipitation. And Gotcha. Okay. Yeah. No.
That’s yeah. That’s probably a lot like Dana said because light’s hardly ever the limiting factor, you know, unless you’re looking at the bottom of the canopy. Yeah. Chris, I don’t have the I don’t have the the table there. Alright.
Good. Paper. Sorry, Chris. What you what what are you saying? Yeah.
It’s frequently not the limiting factor unless unless other trees are shading it. It it so your canopy position is huge for light. Beyond that, light measurements are made for other reasons frequently, but you’re usually measuring light so that you can calculate evapotranspiration, in which case the net radiation is super important, or, you’re trying to get a handle on productivity. But most of those the other part of productivity is photosynthetic efficiency, so which is generally limited by water or one of these other variables. So that’s why the health light generally doesn’t come into health because the entire forest is usually getting the same amount of light based on your latitude or altitude or, you know, one of those other factors.
Mhmm. I see. So is it true that measuring radiation is more important for crops or for productive plants and less important for the types of, trees we’re looking at? I I think it’s a % dependent on the questions you’re asking. There’s situations where you’re not going to really Jeff might have a different perspective on this too.
Jeff joined us a bit a bit ago after his, after, you know, he was able to get in. I think it’s if you’re gonna do anything predictive with photosynthesis or productivity, then light’s gonna be hugely important and not just the light that’s striking the plant, but the light that’s being absorbed by the plant. And, again, canopy position is gonna be a really important factor in how much light a a a plant in a forest are getting. Jeff, what are your thoughts here? No.
That that’s that’s about right. I I mean, so light directly influences certain timing events, flowering, those sorts of things. But largely, the developmental stages are driven by, you can think about as heat accumulation. And so that’s why a lot of time we talk about things like growing degree days as far as, you know, how how much a plant can can grow, because everything all all enzymatic activity slows down when when, when it gets cold. So, and and radiation is obviously a part of that.
So I I guess the point is that light is very important in a lot driving a lot of those meteorological parameters, you know, vapor pressure deficit, which which drives ET and all that. It is directly responsible for some some events, but, I think that there’s just a lot that goes into it. They all kind of tied together as far as what the plant is looking at. But but I think you’re right, George, from an agricultural perspective where what we’re trying to do is maximize productivity. Right?
You you want the plants to grow as fast as possible, as much as possible. That’s gonna be far more interesting than over the life of a tree where, you know, some and and just like you see when you look at, say, the growth rings of a temperate tree, you see some years, it grew a lot more than other years. Some rings are super tight because they were, you know, deep in the canopy. They didn’t have much light. Other years, maybe there was a slight gap, and they got a lot more productivity that year.
But but for a tree, it’s like, yeah, whatever. It was a slow year. It was a fast year. There’s no value associated with that. In fact, growing too fast can actually be problematic.
Okay. I I have a question about that in the growth section, actually. But, in in this in this area about heat, essentially, correct me if I’m wrong, whether it’s too hot or too cold has to do with the availability of water in the soil when it comes to plant to tree health plant health. If it’s too hot, you you don’t get enough water because it evaporates. If it’s too cold, it can freeze.
And the is that is that scheme correct? I’m trying to simplify intentionally. Yeah. And I’m I’m I’m being very risky here. I’m just in this vulnerable position Yeah.
Yeah. I know. To rub my head on. I’ll buy the cold, but not so much the heat. I mean, plants love it hot and wet.
Right? Like, that’s their favorite, hot and wet. And that’s where you see the greatest productivity, the greatest growth. So rainforest is like the happy place for plants. But plants that don’t get to live in that sort of optimal place have a lot of adaptive strategies.
If you took a cactus and planted it in the middle of the rainforest, it would not be happy because its strategies are not designed for that particular location. So, yes, when it’s really, really hot, but but generally speaking, for the basic physiology of plants as long as water is available? Climate change is a good thing for plants. Yep. Yep.
Mhmm. So it it could be terrible for humans, like, the combination of really high humidity and heat, but it could be quite good for trees as long as there’s no drought. Right. Mhmm. Exactly.
Fires, etcetera, but the carbon peaks. Mhmm. And I had a question. Can we have a situation where it’s so cold that the sap can become really viscous or even freeze entirely? Yep.
Totally. Mhmm. Okay. And that’s the problem. All the trees in Montana, my home state, are frozen right now.
It’s been it’s been minus probably minus 20 to minus 30 Celsius for the last month. They they are frozen solid. But the damage to the plant, it kind of depends on how ready the plant is for it. Right? If it’s senescent and not actively growing, then it it might not necessarily be that damaged.
But if it has taken off and put out a bunch of new shoots and and then gets a really hard freeze, that’s when it’s gonna be more susceptible to to serious risk or Yeah. Yeah. What would that risk be? I’ll use the plumb in my in my front yard as an example. Last year, we got, like, a minus a minus five degree Fahrenheit breeze right after the early the early trees like the forsythias and the plum.
They’d taken off. They were already growing. They didn’t have concentrated sugars to to to have that viscosity to lower their freezing point in their in their buds. Mhmm. So, basically, it it didn’t flower at all.
There wasn’t a single flower on this thing that is usually just covered in them. And it it put on very little growth because all of the all of the buds really just got got froze and ruptured. And the tree is the tree is mostly fine except for missing a reproductive year. Yeah. Well and and some of the challenge is the decoupling.
Right? So another climate change challenge is the decoupling and the timing of the events to what Chris just said. You know, if they’ve like, oh, this is spring, and now we’ve got all this light because and then we’re seeing this in Montana. You know, it’s it’s late April. It’s May.
We got a ton of light, but then, oh, shit. There’s a big freeze or a big snow. But we’ve had we’ve had trees that have just been dumped on with snow after they have leaves, and they can’t handle the weight of the snow on the leaves and the branches just, you know, break off. The whole tree breaks over. And so when they’re fine, normally, in the winter, in the snow so it’s when the timing of temperature and water availability and leaf production or bud production are off that it can be high highly risky.
But it’s not yeah. It’s not just the conditions themselves. It’s when those conditions are happening. Yeah. Yep.
And and are they aligned with what evolutionarily it’s been adapted to tolerate? Mhmm. Mhmm. And I the last question up above, I just wanna add real quick because you asked about the light. We said light is not limited.
You have tree how can trees thrive in very cloudy environment? There’s so much light that gets through clouds that just because we can’t see the sunlight, it’s plenty. Yep. That being said, the reason why we had the last mass extinction when the meteor hit the planet was because the cloud the the dust cloud was so thick that and it stayed in the atmosphere over the whole planet for about three to four weeks, and that was not enough for sunlight to get through. So the plants all died.
When the plants all died, the dinosaurs all died because they had nothing to eat. And only a few mammals squeaked by that happened to be the ones that fed on the rotting carcasses of the dinosaurs until the cloud dust settled and new plants, you know, grew and and then the explode next, biodiversity explosion, you know, began. So, yeah, there is a limit to, you know, if you if they if, if we had a an eclipse that didn’t end for, you know, forever. Yeah. But on a smaller scale too, Dana was talking about the decoupling.
You know, in nature, the biodiversity we have is also based a lot on timing. So if something blooms and your pollinator, you know, isn’t there at the right time and this you know, the caterpillar’s eating this thing, but now the birds aren’t ready or vice versa. All those things are happening simultaneously too. So if those timepieces get knocked out of balance, then other organisms aren’t ready for the opportunities they might have normally had. So again, it’s not just the trees or the plants.
It’s also insects. It’s also birds. That whole system could be disrupted. Yep. I’ll add one more to the extreme cold because this is also a big thing, which is ice damage.
Right? So not just ice damage of weight, and snow. That’s why evergreens have those long bows that point down. Right? That’s actually to shed the snow.
But ice sheer. Right? So if you’ve got evergreens and you’ve got ice crystals flying through the air, that’s gonna, take away your wax coat. It’s gonna it’s gonna literally scar and and scrape. And oftentimes, you’ve probably heard of Krumholtz, which is a process I love this word.
I don’t know if you can put it in, Dan, but are you ready for it? Ready? Sigmomorphogenesis. I have it there. I think it’s down there.
The in the tremorrows. There. Good. So, yeah, it’s it’s basically in the presence of extreme wind, fig, which is what’s Greek for wind? Must be something related to fig.
Fig, it it has to do with touching, actually. Oh, okay. And, morpho, right, is shape and then growth through shape shaped by wind. So all the trees at the top of high alpine or highly exposed to wind, the ice kills off the growing edges, the buds, and and so then it really only grows on the the backside. So what I love about trees is that their shape tells the story of their history.
And everything from house you know, whether the soils were sloughing or what wind exposure or what light exposure or who their neighbors might have been fifty years ago. That’s all part of the the physical form that we get to see. Had a question I think we we’ve answered answered it. Essentially, it’s important to bet to measure both air and soil temperature, and we get bad news when the soil is frozen and the air temperature is, let’s say, above five degrees? Some No.
The like, the site where I was, we have a process called, they’re called Chinook winds, and it could be like a 60 degree difference. The wind comes down, melts all the snow, doesn’t melt the ground, and then it’s like it feels like early summer to the tree with the upper leaves. So it’s that level of of difference. Like, five degrees, that won’t that won’t be enough. Mhmm.
Trigger the the enzymatic reactions to, you know They’re acting out there. I see. Yeah. Then we have about the the four deaths. It’s, well, about the the tremors.
I think, it’s something we don’t measure, but it’s incredible. And it’s it’s it’s something that’s fascinating because, Chris, I don’t know about you, but I had no idea about this. Mhmm. I mean, only only in the, like, hearsay sense of people saying heavy metal is good for plants. Yeah.
Like, classical like, all of that. I’ve I’ve heard those stories, but I haven’t, yeah, ever. I’ve referenced the paper from 2020 that’s a general review on the relationship of plants and sound. And it all these, in these sections in italics are from it and talk about plants emitting different sounds due to, processes happening internally in the roots and, cells. And the sounds they create, they’re also the sounds they’re able to respond to.
It’s kind of their, their range. And then I found some other research about certain certain species being, sensitive to caterpillar chewing sounds to the point that they were playing it playing back those sounds to it. There was no caterpillar, and the tree was responding to it, but not responding to other insect sounds. Now these things we don’t measure. We don’t have microphones on-site or anything, but it would be they could still be part of the story.
They could still be part of what the tree talks about. We do measure wind. So I wanted to ask, Mitter, can we use wind strength to infer something about the tree to can there be a micro story there, a micro narrative that relates to the wind speed or or direction? And, yeah, I think there there’s not much to discuss about these tremors because we don’t we don’t have any data apart from wind. Yeah.
I’m not sure if the wind is really going to give us much here. It’s it’s super important if we’re gonna if we’re gonna calculate, like, energy transfer or an energy balance of the plants and leaves or evapotranspiration. So it’s used it’s necessary in those kind of equations, in that math. Beyond that Does the Yeah. Sorry.
Does the Copernicus data have long term wind measurements? Yep. Yep. It does. Because it could be interesting I mean, at least what I’ve noticed anecdotally is that wind is just generally picked up in the places that I’ve been.
And if there’s long term increases in wind, that affects the boundary layers. And then that affects the water, which affects, you know, plant growth and how much they can have their stomata open and, you know, all of that. So, if there’s that long term trend, that that could be interesting in one of these sites. I don’t know. What do you think, Chris?
I mean, it Yeah. The long term trend could be really interesting. The difference between what’s happening what’s picked up by the Copernicus and what you’re getting within the canopy are could also be could also be pretty interesting because you can get something howling, up above the canopy, and you’re also gonna pick I don’t know about the resolution. But you also get turbulence and things like that due to the canopy itself. And since these are further in there, it’s gonna be a much more sheltered sheltered environment.
Well and didn’t we find Britt, are all three of the species have potential for well, they’re all wind pollinated and wind seed dispersed? Not the that that has dual. It has both. Yeah. Large birds, like your toucans and things like that are really helpful, for that.
So but, yeah, they’ve got They don’t rely on wind to a degree. Right? To a degree. Yeah. Even the liri That’s hindrance.
I thought that was insect pollinated. But yeah. The tulip the tulips have some insect pollination too. And they’re they’re, the super generalists, so it’s not just, like, one Okay. Beetle or whatever.
So both of them just having multiple systems and not just one that general is but the seeds are wind dispersed. Yep. The seeds are wind dispersed. Yep. Yeah.
Yeah. Yeah. Yeah. So sorry to jump back. But, Chris, did I understand correctly that with the data we we have from, the Atmos, we can, plug them into a evaporation model and actually get some, some numbers out of it about the rate of evaporation.
Yes. It will the way you the way it’s positioned, it will be quite different than any remote sensing ET that you get, because for for that model to work best, it should be positioned above the canopy. So if it’s right down in the canopy, the solar radiation is gonna be different. The wind is gonna be different. The the the assumptions of the model are kind of valid are kind of I mean, they’re not kind of.
They are complete completely broken. But, in where it’s positioned, you can you can use it as kind of a a a microclimate ET estimation. And the main, you know, the main factor in it is probably gonna be the solar radiation that’s incident. So, it’s gonna be it’s gonna be specific to the location it’s in, so you won’t be able to use it on, like, a bigger scale. And it’s gonna be very different from the ET that you remotely sent, but, it it it can it can add to the story.
Mhmm. Can you share a link relevant link to this? Or is this something we can calculate directly from the Yeah. Center cloud. I can send you a link on how to get that set up, so you can actually get the ET, estimation as a reference.
Hang on. There’s a let let me chat about it with Jeff a little bit, because I wasn’t thinking about one variable that we don’t have. But we, it can be kind of a kind of an index variable, let’s say, instead of instead of a quantitative Mhmm. Instead of a quantitative estimate. Okay.
We’re not we’re not publishing any vectors. This is a this is an artistic telling. Sure. And then I can see the disappointment in Dan’s face. Right.
There there’s always that, we we work with so many scientists. We’ve gotta make sure we’ve got, you know, those caveats in there. Okay. Let let’s I just wanna go through everything even if we don’t go in-depth. I’m super aware of time.
I’m through it. Yeah. Yeah. I have I have to jump in seven minutes. I’m not sure if when I leave, it’s gonna kick everyone out of the call.
I hope not. But, yeah, as George said at the top of this meeting, please scribble all over this document, and we will say no. Yeah. We’re we’re pretty close to the bottom, so that’s good. Yeah.
No. No. Yeah. We we had identified this four this comes from a paper. It’s number two in the references.
These four types of, deaths that we can have. It’s xylem, cavitation, carbon starvation, bionic attacks, which, I guess, correlate with some sort of shortage of nutrients, or they’re just coincidental, and fire. And what you see below are, like, four short sentences of the LLM when we instruct it to be really dramatic, really, really poetic. And the question is if we can identify other general ways that the tree can die, and if the sensor set we have can potentially warn us about some risks and which values would would we need to track. I know that the time scales we’re talking about are below timing.
Just wondering if we were to monitor for longer term, what would someone look look at? Or if if it’s sufficient or if if someone would need more sensors. I mean, if in doubt, George, you can just play them some, the recordings of Beatles that they don’t like and induce some sort of PTSD reaction, which you were talking about earlier, which I found just worryingly sort of very, you know, anybody who’s ever had noisy neighbors, and then you play them that. They’re like, oh, my back. You know, we could probably do that in real time.
But, yeah, I mean, yeah, the time scales are so small, and I’ve been so aware of this that this is a very good question that you’re asking. This, yeah, I’m just gonna point out that especially the biotic attack is very much in the tree as an eye and kind of avoids the whole we of the community. I mean, I think death in general suggests that, doesn’t it? Like saying, our tree dies, therefore, the story ends. It’s kind of goes against what we were talking about earlier.
And, also, the tree being a home for a whole ecosystem in and of itself and But it still knows when it’s dead. It still knows when it’s dead. I’m just I don’t know. I hope an I hope an entomologist doesn’t read that. I have a banquet for the damned.
It’s a little sepulchral. I’m not gonna I’m not gonna judge. I’m out of my lane. I’ll make it clear. These are not suggestions for what will be going in the end article.
I’ve just said death is not the end. That’s the the only note I’ve made of the last two minutes. So, I think I think it’s interesting the fact that there are different forms of life, different sorts of energy that obviously, you know, must continue because that’s, you know, new tonic laws and things like that. But it’s very, very interesting, that idea of, it being a host as much as it’s, you know, a life in its own right and, ecosystem that’s stretching, you know, maybe 80 square miles. It’s, extraordinary thought.
So I’ve keen to explore that a bit. And many trees that, that are that that know they’re at risk, and, you know, I use the word no in the context of how we’ve been, like, con having this whole conversation, will have a flush a a massive reproductive event before, you know, in the last couple of years where, you know, they have, like, reproductive timing for trees isn’t it’s a kind of its own special thing where every, like, the speed people synchronize and have massive years called mass years where they just throw out huge amounts of seeds and flowers. And individual trees can can do this near the end of their life cycle as well. So it’s, the the reproductive side adds different a a different, I don’t know, I guess, dimension. Yeah.
Speaking of knowing, I mean, that happens with the chemical signals too. Like, if you’ve got an Acacia tree over here and it’s been nibbled on too much and it’s sending some chemicals through the air, and the other trees get it, they’re like, oh, I’m gonna make myself more disgusting, or the tree itself might increase or decrease what it’s making and sending it to the leaves. So on a scale, how they’re adapting and learning from each other, like, that’s happening too. But it strikes me that we have this the phrases in the language, we have this idea of the final flush. We have this idea of being overshadowed in this whole conversation the last couple of hours.
You can see how, you know, they have the the genesis of these phrases is probably, you know, arboreal agricultural in that way where we you know, but the general populace just take it to mean, obviously, it all refers to people, doesn’t it? Because everything must all the time. And it’s very, very interesting that this is already in the language. And, you know, you just kind of like it’s a it’s a recognition of an echo rather than, you know, we already have it. We’ve just, again, been disconnected from from the root of it.
I’m I’m tempted to end on that statement. I, try and leave silently without, breaking the call for everyone. If you’ve got time, please please continue. I think I I I need to jump on that call with you. If, yeah, if you want to.
Yeah. It’s not gonna be fine. But it’s it’s really beyond amazing having all of you here contributing on this shared project. We already feel wiser. And from the looks of it, we didn’t say strange incorrect things.
No worries. We tried to live we tried to do a lot of stupid things. Okay. I I think we’ll we’ll follow-up. We’ll, we’ll send all of you an email with some summary of of this discussion and what we would like, from you to do.
But in a nutshell, it would be great if you could go through the document and, and just react to it. And