 Good afternoon, everybody. Welcome to another talk on the homecoming weekend here. I welcome you all. Thanks for showing up. And we really appreciate your attendance joining us here on campus and for all the different kinds of events. So I'll welcome you again. Before we get going, I'd like to move to the second slide here and acknowledge that the campus, Cal Campus, and all of us are sitting on the Eloni lands. And we want to acknowledge that those lands are very important to us, very important to the Eloni people. And so let's take a moment. There's some text here if you'd like to read it, just to acknowledge the importance of the lands that we're on and the importance of the lands to the indigenous people who were here well before us. So I'll give you a moment if you'd like to read that before I move on to talk about Redwoods. Please feel free to come forward, although it may be better to see the slides if you're further back. So speaking of the Eloni people, they were also very, very fascinated by Redwoods. And they managed Redwood lands long ago. I won't talk about that today, but I want to acknowledge that they also are a big part of the Redwood ecology, the history of the Redwood forests. But today what I'm going to do is I'm going to fast forward and talk about Redwoods in the modern day. And it's fitting that we talk about Redwoods here at Cal. It's our state tree. So it goes along with many things that are all California. And I've been working on Redwoods for nearly 35 years as a biological scientist. I'm a plant scientist. I'm also an ecologist. And it's been a fascinating journey for me to begin working and trying to understand Redwoods where they occur in California, what are the unique features that they possess, and what really makes them special both as a tree but also a piece of us here in California as our state tree. So I'm going to walk you through what we've been learning. I can't tell you everything that we've been learning, but I'm going to try to give you some highlights about Redwoods here in California and some of the neat things that we've learned about them. Some of you may know this, but I'll point it out that today there's three Redwoods in the world. Two here in California, the coast Redwood and the giant sequoia. But also there is the Don Redwoods. Some of you will know this, a species that we thought were extinct until it was rediscovered in Western China in the 1940s. And so today we have these three different Redwoods, two in California, one in China. And the R2 here in California, if you look at this tree here, it's a tree of relatedness. And the closer these names are together, the more closely related those plants are to each other. And one of the things to notice, of course, are California Redwoods are very closely related. But the other thing to notice is the timeline here of how long Redwoods have been around on our planet. They are a very ancient group of conifers. They've been inexistent on planet Earth for more than 130 or maybe 140 million years. And that's one of the things that makes them unique. They've been around for a very long time. And because of that, they've been exposed to lots of different environmental changes, climatic changes, continental movements, which I'll share with you. And those things have really, I think, been a factor in influencing the kinds of features that we actually see in the modern Redwoods today. Their long history and that long exposure to many, many different kinds of environmental changes. If we look at California itself, we have two Redwoods, as I've already mentioned here, our course, our coast Redwood that goes all the way from just over the California-Oregon border, all the way down to sort of the southern tip of the Big Sur area. So it covers a vast range, but as you can see, it's restricted right to that coastal belt, right along the western edge of California in that cool coastal climate. And of course, many of you will know this tree. Some of you may have it growing in your yards. So it's a very special tree for those of us who live in coastal California. We contrast that one to the giant sequoia, which lives up in the Sierra Nevada mountains. And as you can see from these little red dots here, it has a very different kind of distribution. It's a bunch of different separate groves. It's mostly restricted to the southern part of the Sierra Nevada. So down in Sequoia King's National Park, I'm sure some of you have seen that park and visited those trees. And then there's a few trees that make their way up in the mountains in the Sierra Nevada all the way up into the Calaveras and grow a little bit north just south of Tahoe. But you can see it has a very different distribution, a montane distribution, and small groves, not a big continuous distribution, like we see in the coast redwoods. If we look at the environments where giant sequoia lives, they're beautiful montane environments. Some of these forests are probably some of the most magical forests that I've spent my time walking through and working in here in California. If you've gone up into the mountains, they're a beautiful refuge in the summertime. When it gets hot, you run up into those forests and they're a beautiful place to spend time. They're in the Sierra Nevada, so you have granites all around you. And of course in the wintertime, and this is one of the key features of the giant sequoia, is they're exposed to very snowy winters. And in fact, this belt where the giant sequoia trees live is the snowiest belt in the Sierra Nevada mountains. It receives the highest amount of snowfall, and that's also another secret to why it is we find these enormous trees growing there. Without this snowpack, we wouldn't refill the groundwater every year, and these trees couldn't survive. So they have very deep roots, and they really live off the recharge from the snowpack that happens every single winter here in California. So they're restricted to these areas for a very, very important hydrologic reason, and they have some pretty cool physiology that I'll show you in a few minutes that goes along with that. But in addition to snow, of course, in the summertime, these areas are sometimes quite warm, even hot, as we've experienced in recent years, and susceptible to fires. And some of you know that recently we've had some pretty severe fires that have killed a lot of the very oldest giant sequoia trees around the Redwood Mountain Grove and near the Sequoia Kings National Park. So fire is a real threat. They've got some pretty neat adaptations that protect them, make them resilient to fire. But when these fires get very severe, like the ones we've been experiencing lately, not even these trees can make it through some of those very severe fires. And I'll return to that point as we go through and we start looking at some of their unique features. We contrast the coast redwood to the giant sequoia, and of course we find it here at the Land Sea Interface right along the coast of California, which I've already mentioned and showed you in that map. And of course that's a very special climate zone. It's a very cool, very ameliorated climate zone. That's where San Francisco and Berkeley and Oakland are. They're right in this coastal climate zone where it's a very desirable place to live. And not, doesn't get very extreme swings and temperature over the course of the year. And one of the features, of course, it keeps that climate ameliorated, especially here in the summertime, is the coastal fog. The fog season, of course, many of you know it. You probably live in it. And it occurs every May to about October. I wish we had some today, but today's not a foggy day. And one of the really key features about that is that along the coast here of California, where we find the redwood trees, you can see it's much cooler right along that western edge than it is when you go inland into the Central Valley where it can get really hot, of course, temperatures. Daily can exceed 100 degrees Fahrenheit. And of course, that is actually the thing that helps us with our fog, that temperature gradient between the cool coast and the hot inland. When hot air rises, well, something's gotta replace it, right? And it's usually that cool, moist air along the coast that gets pulled in over the hills, the famous pictures of the Golden Gate, where every evening that coastal fog comes in, it's forming out here on the ocean. And it makes its way actually quite a ways inland, up to about 50 miles this fog will come in almost every single day. And of course, that coastal fog occurs all the way from about San Diego, it's patchier in San Diego, but it still occurs there. The Channel Islands also experience fog. But of course, it's very prominent here from about the Big Sur Coast all the way into Oregon, which is where we find our coast redwood trees. And we'll talk a little bit more about why that's important in a few minutes. Now, one of the striking features of both our redwoods, our coast redwood in the Giant Sequoia, is just how bloody big they get, all right? Anybody who's walked around in these forests, you're just stunned by the massive size of these trees here. These are drawings that are taken from photographs by Bob Van Pelt, and these are people, these little specks you see at the bottom to scale. And so if you haven't gone into the redwood forest and measured yourself against a tree, you should do it. Because you'll be blown away at how much larger this organism is and how much longer they actually live. So they get big and they get old. In addition to that, if we go into the environments where they live, they have very different features in the forest itself that are part of what influence the way the forest and the trees actually behave. So if we look at the Giant Sequoia forest, one of the things you notice again from this drawing by Bob Van Pelt is that the stand structure is really different. It's a much more open forest. You can see through it for very long distances. There's not a very diverse understory, but the understory has also got other conifers going in it. Things like white fur and sugar pine and some of our oaks actually grow in the understory of these Giant Sequoia forests in that mid elevation montane belt. So a much more open forest, drier and warmer in the summertime. Then of course, the coast redwood forest where this picture was drawn from, the Prairie Creek Redwood State Park. And you can see here, things are growing a lot closer together. The stands are much more dense. The trees themselves are a lot taller. They actually influence the microclimate in a very, very significant way. If we remove the trees, the climate changes completely. And so the trees themselves are actually creating the ecosystem that they actually live in. And that's one of the keys to understanding the importance of the environment tree interactions when we go into both the Giant Sequoia, but particularly into the coast redwood forest in California. Now I mentioned to you that this was a very ancient group of plants, or redwoods, and they're very well characterized from the fossil record. Here in the Museum of Paleontology in the botanical collections, the fossil plant collections, we have a lot of redwood fossils. Those fossils have been collected globally a lot of different places. Even though we only find redwoods today in California, the fossils are found in Asia, in Europe, all the way up in the Canadian Arctic, and of course in here in North America. We have very nice fossil deposits in Utah, Colorado, they make it into Wyoming. So they show you from the fossil record that these trees used to be very widespread, much more widespread than they actually are today. So the fossil record is a really important record for us to turn to, because it really teaches us that these trees have been not only around for a long time, but they've had really different distributions that have swelled and shrunk over time, and I'll talk a little bit more about that. So here's some really cool fossils. If you haven't gone to the Museum of Paleontology, it's open today, it's homecoming, and you can go and you can take a look at some of the fossils, not only of these plants, but you can also go look at some dinosaurs and stuff like that, you know, all those big things, scary things. Part of that fossil record is to look back at Earth and ask the question, well, wait a minute, we have to acknowledge the fact that as we've gone through time, our continents have not been in the same place that they are today. We all know about polyctonics and continental drift, partly discovered here at UC Berkeley, and if we go back in time many millions of years ago, almost 200 million years ago, the configurations of the continents were really different. The climate was really different. There was places where plants and animals could migrate because there was log corridors. They could move from the Southern Hemisphere to the Northern Hemisphere. They could move across vast areas, east and west. So there was connectivity along in the continents that doesn't exist today. And that's a really important part of the Redwood history because they could move around, right? And that was 200 million years ago, 150 million years ago. We come forward in time to the time of the dinosaurs here in the Jurassic and about 65 million years ago and you can see now our continents have drifted apart. What was once connected is no longer connected. We're drifting into the northern areas so we start to see parts of our continents moving into the poles into very different kind of climatic zones and of course any plants that are on those continents, they're there for a ride, right? They're being taken to a new climatic zone and barriers are being created where migration once existed no longer exists. And so this led to the isolation of many of the Redwoods and led to what we see today in smaller areas than they've experienced in the past. In fact, if we look at a map here of the Earth today and we look at the symbols here, there's our coast redwood, there's our giant sequoia, and there's our dawn redwood and look at the little colored symbols where they existed at one time, all right? They were everywhere, especially in the northern hemisphere. One funny site down here in southern Chile where there's a beautiful fossil site is an extinct species of Redwood. It was a different species. No longer exists there. There's a different tree there now called the alersei. It's very closely related, but that's one fossil site there. But if you look here and look at all these colors, there was Redwoods were very widespread. So they were experiencing really different sort of climatic and hydrologic conditions in the past compared to where they are today. And so this is an important part of their story because that means that they experienced really different sorts of ecological conditions through time, up to the point where they live today. And in fact, if we go back to fossils, we see some really interesting things in some of the fossil wood samples that have been collected. There's a really cool site from the Arctic where there are mummified trees, not fossils, right? They haven't turned to stone. They're still wood, but they're 50 million years old. There were trees that fell over. They got buried in the sediment in some of the Arctic islands. And when we pull the wood out and we actually look at its anatomy, we look across the wood itself. There's no ring boundaries. That means that the trees are just growing. They just kept on growing and growing and growing. And that tells you that the growing conditions, obviously, were very different than the seasonal environments that we actually experience here today in California. So based on some of this fossil wood, some other botanical features that we can pull out of the fossil record, we can say that in the past, redwoods were actually living in sort of a tropical environment. In fact, that tropical environment is now conjectured from other kinds of evidence to be have been much warmer, much warmer than it is in this room today, all right? Much wetter, so tropical. We're getting meters of rain, right? And it was a seasonal. We didn't have a dry summer and a wet winter. It was wet all year long. And so that leads to very different conditions and very different adaptations that the plants possess. They're much more like a tropical tree than they are a temperate conifer, which we see today. And it's really remarkable because if we go into today, we look. And of course, we all know we're sitting in this room today, we know that we now live in a Mediterranean climate, all right? That Mediterranean climate is actually not very old. We've only had Mediterranean climate here in California for about five million years, all right? Well, we have wet winters and dry summers, all right? And that is a radical change for all the organisms that were living here and living in a tropical climate seven, eight million, 10 million years ago. Now they are exposed to new challenges. And one of those big challenges is water. Getting enough water resources to fuel a tree that is much bigger than this room is pretty tough stuff. And it means now that how do these plants are gonna deal with going from a very wet condition, very cool condition to something that's much drier. And so that really leads us to think a little bit about the unique and special features that these trees have. So let me just kind of list some of those characteristics. We've already kind of touched on a little bit. Redwoods are the tallest trees on the planet, all right? 382 feet tall as the coast redwood, all right? Unbelievable how much taller that tree is than anything else that we see on the planet today. Eucalyptus get close down in the southern parts of, southwestern part of Australia. We get one of the eucalyptus trees in Tasmania. We get another eucalyptus tree that gets to be about 350 feet tall. But redwoods still really outstrip them by more than the height of this room, all right? They also are the most massive tree on the planet. Our giant sequoia is the largest tree by volume of any organism that's ever lived on Earth, all right? And lives here today, all right? So really impressive statistics in terms of height and size. They live very long, as I've already said. They have literally billions of leaves. You saw those drawings. The crowns sometime can be 250 feet deep. And there's leaves all the way down, all right? And when we do some of the sub-sampling of the canopies and we calculate how many leaves there are, it's in the billions, in a single tree, all right? There's more leaf area in a single redwood tree than there is on the UC Berkeley campus, all right? In terms of area. Just think about that for a second. One tree, it's crazy. And those trees are functioning. They're losing water. They're fixing carbon. So they're having a big impact because of their massive size. As we say, they're old. They sequester an amazing amount of carbon. Even though they only live in a very narrow location, each tree can really fix a lot of carbon. And because of that, foresters are getting interested, and again, particularly in the coast rivet, about whether this is a species we should be planting more widely for battling the carbon problem on our planet. And maybe growing those trees also for wood in other places other than California. And there's some efforts underway in Chile and in New Zealand where they're trying to grow redwood trees now to, as again, as a carbon sequestration source, all right? So how do they get so big, all right? How do they grow so large? And this is where I came in as a biologist. This is the kind of question that we wanna ask. We wanna say, how do you get an organism so big? What are the characteristics of these organisms that allow them to get so big, live so long, and yet they're still thriving today, even though they're in a narrower range. So what are the traits and what are the adaptations that we can understand that make them so special and so unique? And in studying them here for about the last 30 years or so, we've come to realize that many of the things that you learned about and was written into your introductory biology textbook are not true for redwoods. They are breaking rules, right and left. They don't conform to a lot of the botanical dogma that you read in your textbook. And now it's really fun for us to say, wow, we learned this in our textbook and now these guys don't conform to that. And I'm gonna show you what some of those things are where they've actually broken some of those botanical rules. Okay, so, big challenge. How does someone my size, 70,000 times smaller than a redwood tree, right? How do I study something so big, right? And this is where some of the real challenges came in. And we've really had to innovate in some really important ways, design new ways of doing research because you have to climb. So you can be afraid of heights if you work in my lab and you gotta be fit, you gotta be able to get on a rope and climb into a tree and take some pretty skilled teams. It takes some really new kinds of tools. Things that we could do while we're standing on our feet very different when you're hanging on a rope. So you have to develop new methods and new ways of sensing what the organisms are doing for quantifying things. And then you gotta look at it at all scales. You gotta go look at individual leaves to see what one tree is doing. But then you wanna understand how does that tree behave in the context of the landscape, the forest, the bigger picture of where those trees are actually embedded. So it's taken some really innovative groups of people. I've been fortunate to have great graduate students and postdocs come and join my team and really bring in some new ideas about how it is that we go and study something so big and yet really gain some important understanding. I share a few pictures with you is once we get into the crowns of these trees, it blows your mind because there's whole ecosystems in the tree, all right? You can see in this picture here, there's a big giant branch coming out of the main stem or the main trunk of this close dreadwood. And up in here, there's a soil pocket that's seven feet deep, all right? And there's ferns growing out of it. And in fact, there's other plants that root in it. And of course, because these trees live there so long and there's all this litter that falls in and it accumulates over time, it's just like the soil outside here, we get canopy soils that develop over hundreds of years. And there's lots of things that live in those canopy soils, not just plants, but lots of animals. There's a little newt that lives up here in the tops of these redwood trees. It never comes to the ground, never. It lives in the ecosystem at the top of the tree. So it does all of its whole reproductive cycle, its whole life cycle is in this canopy. And if you didn't climb into the tree, you'd never know that, you'd never see it. So this is also an ecosystem in the sky. It's something that's really, really different and you don't appreciate it until you climb into the trees. You also don't appreciate how bloody hard it is to get metrics on these trees until you start working on them. Here's a couple of people on my past team, one of my former graduate students, Cameron Williams, Rike Norsbar, and this is how we do it. This is how you get all of the metrics. You have to climb the trees, you have to put tapes around them. We're measuring every branch, the taper of those branch, the distances of the branch. We're sub-sampling to get the, this is how we get the calculation for the numbers of leaves. So it's a big effort. We have to do this all the way from the bottom of the tree, all the way up. Here's Wendy looking up going, oh my God, there's so much more work to do as I look up. And so it takes big teams of people, long periods of time to get the data, to be able to quantify just what's there. And then we start installing instrumentation to measure a bunch of physiology. We even get all the way up to the very top of the tree because we want to understand how the carbon balance of the tree is influencing things like cone production. Here's Anthony sampling some cones at the very top of a giant sequoia tree, 300 feet tall. And so this is how we get the reproductive structures and determine what the reproductive investment is. And also what the investment is in the leaf area. And you can see there's a lot of beautiful forest that's right behind him. So let's look at a couple aspects of what we've been learning in these two different redwoods. Here's some statistics about the coast redwood itself, as I've already mentioned, tallest tree in the world. Very large tree as well, got an amazing diameter, 29 foot diameters for some of the biggest ones. They live quite a long time. Coast redwood can be as much as 2,500 years old. If you have had the opportunity to go to Jedidiah Smith State Park, how many have done that? Good on you. Jedidiah Smith State Park. It's the last state park before you cross into Oregon. It's one of the most special places to go on earth. The trees there in one of those groves that called the Boy Scout Grove, the average age of the trees, average age is 1,700 years old. And you walk in there, the ferns are twice as tall as you. It's one of the most magical places in California to go. And so many people don't know that, but this is where some of our big trees are. So if you have an opportunity to go appreciate that park and those trees, go do it. It's just an absolutely magical place. Redwoods though, here in California, the coast redwood, as you can see from the stats there, there's only about 4% of mature groves left. And of course, that's because they're a favored timber tree. We built San Francisco twice from Redwoods, right? Once before the earthquake and the fire, and once afterwards. And so these trees have been favored for building for a long time. Now most of the groves that have mature trees in them are protected. They're either in conservation easements, state parks, national parks, that's good news. We're not losing any more land. And due to some of the conservation organizations, like to say the Redwood League, we're protecting more lands all the time. We're trying to buy them, protect them, set them into conservation easements. But there's also a lot of timber harvesting that's still going on. And if it's done well, of course, we need timber. We need timber products. So we can't just stop, but we need to do it more sensibly. One of the cool features that we spent a lot of time studying here in the coast redwood, is this right here, fog. I already mentioned this. This is a feature that's a really important part of our understanding of the ecology and the physiology of coast redwood trees. And when that coastal fog comes in during the summertime, a lot of it drips off the trees when it's intercepted. Goes into the understory plants as well. But a lot of it is retained up in the canopy on the leaves themselves. You'd never know that unless you climb the tree and actually look at it. And so we've been asking the question when that fog comes in and those leaves get wet, and I'll remember there's a billion leaves up there. So a lot of wet leaves, a lot of water in that canopy. And we wanted to ask the question, what's happening? And remember that here in our Mediterranean climate that that fog comes in in a really important time. When we have rainfall, the dry months of rainfall, this is rainfall at the bottom, this is fog at the top, very little rainfall, but that's our foggy months there. So they're mirror images of each other. So when rain stops, the fog machine gets turned on. And we wanted to say, okay, is that fog machine important in terms of water and what it does to the ecology and physiology of a coast redwood tree? So we started quantifying that. Surprise, surprise to me, no one had ever done it. And of course, think about it a second. Where does precipitation come from? Where does fog come from? Our precipitation collectors don't collect fog because it comes horizontally off the ocean. You have to set up a special collector to determine how much water is coming in and fog. It's not gonna be measured by your standard precipitation gauge. And when we started working on this, we realized how the weather stations were missing one third of the water that comes in to the redwood forest every single year is from fog water. Coming in this way, off the ocean. So we'd be missing 1,000 millimeters of precipitation if we had not put our fog collectors up and realized that was an important subsidy of water. Oh, and guess what? Comes in during the summertime when we don't have any rainfall. The days are long, the days are warm. The trees need a lot of water. They like water, you know? So it's really coming in at a very, very important time. And I won't talk a lot about this over here, but if you remove some of the forest, which is what these bars are over here, particularly for the fog, you can see the fog declines tremendously. And that's pretty simple. You remove the trees, you remove the collectors, all right? The trees are the collectors. And so that's the stature of redwood trees and the interception of that fog moisture really, it fuels the water balance of the forest. So you take the trees away, you take the water away, because it can intercept the trees. Now, one of the coolest things that we discovered when we started working on this at the leaf level is that when fog accumulates on leaves, it goes right into the leaf, all right? Okay, what's your textbook tell you that you took in general biology? Plants take water up with their roots. That's what we learned. That's what's still written there, all right? We start working on these leaves, here's some leaves, this is redwood leaf here. If you can quite see this, but there's little white dots here, each one of those little white dots are what we call the plant stomata. They open and close, they let water out and CO2 in. And really cool is that on the surface of the leaf, there's fungi that grow. And they form these little threads called hyphae and those hyphae dive through the stomata and go into the leaf itself. They create a bridge basically from the outside of the leaf to the inside of the leaf. So if the leaf gets wet here, we started going, oh, hang on, could the water get into the leaf by just following those hyphae and going into the internal part? And so we've been starting to look and looking at this for quite a long time. We've been asking a bunch of questions, okay, we got water entering the leaf and not just the roots. What do the fungi do to that water? Well, we all know that water balls up, like we're used to seeing, you see it on your countertops, right? Well, you add those fungi to the leaf surface, they change the contact angles. They make it look like that. It makes now all of a sudden the surface tension of the water changes and it now starts to change not only the way the surface tension is, but now it'll start to flow down those threads of hyphae that go out from the outside of the leaf to the inside of the leaf. So we've seen that the fungi are also helping these trees break the rules, right? Instead of water behaving the way it normally would, you have fungi in the picture, all of a sudden the rules are now changed because of this unique relationship between the fungi on the leaf and the leaf itself. I am working with a graduate student now, Emily, she's trying to identify who the fungi are, hard thing to do, and then started asking the question, what rules do those fungi have? This is a hypothesis. We need to do a lot more work here. We think they play a role in the water and maybe the nutrient balance, but there's a lot more work to do. That's what we're chasing after, Emily's trying to identify that, and then eventually we're gonna see further impacts on the trees themselves. They not only grow inside the leaf, but they grow inside the entire plumbing system of the redwood tree itself. These are cross sections at 110 meters off the ground and 48 meters off the ground. Just think of it this way. Here's your leaf, the fungi are here, they not only go into your little veins on your fingers, they're going all the way back into the veins in your arm and then back into your main trunk, right? Those are called transfusion tracheids or plumbing, so they're colonizing the plumbing system, and they're not killing anything, they're not killing the tree, they're not changing anything, but they're growing back into the plumbing system of the plant, and so now we're really fascinated what role they're playing, because they're clearly not killing the trees. It looks like there could be a very important symbiotic relationship. It changes the whole water relations of the tree itself. Let me walk you through what this slide is showing you. On this axis here, just think of water flowing, all right? And normally in the daytime, like in these traces here, all the water forces coming in through the roots mostly, going up the tree, out of the leaves into the atmosphere, like all plants do, right? So these traces here are showing you when transpiration is occurring, when the water is being lost from the tree going into the atmosphere, all right? If we look at these, and we measure then at different heights of the tree, that's what the different colored lines are. We measure the water flow at the very top of the tree, the bottom of the live crown here, and then at the very base of the tree, the blue line, and we do that continuously day and night. Look what happens at night. When the lights go off and the sun goes down, here's zero. Now all of a sudden we're not flowing in to the atmosphere, watch the animation. The red line show you that when the fog comes in, we get a reverse flow at the top of the tree, some hours later, these reverse flow, and eventually by early morning, those reverse. So we have two root systems, one in the soil, one in the sky. And this is what we think is part of the reason why these trees can get so big, all right? They have broken the rule. They said, I'm gonna get water right out of the atmosphere. It takes too much energy to get it up 400 feet. Let's just pull it out of the atmosphere. And so they've gotten these remarkable adaptations to be able to absorb water directly out of the atmosphere in this foggy system. Well, there's some really cool things going on below ground too. And one of the students who just finished in my lab, she's now a professor at University of Washington, Claire Willing, started looking at redwood roots. Soon as she, and remarkably no one had really done it. And soon as she started surveying the roots and looking at details of the roots, she made an amazing number of discoveries. And one of the things that she made is she discovered on the roots of redwood trees, there's these little nodes that she calls rhizo nodes. Rhizo means root, node of course. And there's these little things that you find all over close redwood roots. And if you look inside of them, they're inside the rhizo node compared to inside the root versus the soil, they're colonized just like the leaves with fungi. And not only fungi, but bacteria live inside this little node here. And we know from studies of other plants, not redwoods, but what we call nitrogen fixing plants, many plants in the pea family are nitrogen fixers. They form a symbiotic relationship with bacteria and the plant. The bacteria fix atmospheric nitrogen, they hand that nitrogen off to the plant, the plant gives them carbon back. It's a symbiotic relationship. Redwoods are doing the same thing. Who knew, right? Another rule broken. We just went, what is that? So Claire now is gonna be following up on this, trying to do a lot more of the microbiology to determine who these are. How does the system get established? What happens when you disturb it? Like, if you get drought or you get fire, do these relationships change? So there's a whole wealth of research that Claire's gonna be able to follow up on now that she's made some of these early discoveries to really understand more about what's going on beneath our feet that we normally don't study very easily. And Claire's just taking that on. Let's contrast then that what I just told you about with coast redwood to giant sequoia. And as I mentioned, these live in small grows here in montane environments, largest tree by volume on the planet, right? Really massive, stores a lot of carbon. As you can see, it lives for very long time. The oldest tree that has been cored and determined is more than 3,000 years old. And there's lots of 3,000 year old trees still living in this year in Nevada today. Especially in Sequoia Kings area, that's where some of the nicest grows are. Amazing tree. We started trying to figure out how much carbon is in these trees. So we went in, as I showed you in those previous slide, we climb into the trees, we make all these measurements, we use architectural software to basically create a model of what the organism looks like. And you can see these are all the branches that we measured, they match the tree here. And once we know the diameters and the lengths and everything, we can calculate volumes. And from those volumes, we can actually start to get some pretty impressive statistics, all right? We already know the age, over 3,000 years old. The biomass. This may not be a unit that you know. Megagrams of carbon. Or what I've done for you is translated. That's 606 tons of carbon or 1.2 million pounds in one tree. All right, this tree here, all right? And there's a lot of trees in the forest. There's a lot of carbon in the forest standing in these trees here, all right? And that's one thing that makes it special but it also is able to stay that large and grow that well in a really pretty challenging environment. It gets cold in the winter, gets very dry in the summer. And recently, it's being challenged by wildfires. It's another part of its ecology. I'll get to that in a moment but I wanna share one really cool thing that we found in this tree. Again, here's a bunch of graphs I'm gonna walk you through. Here's sun over here, solar radiation. Imagine sun coming up in the east. Goes across the sky, sets in the west. We all know that, happens every day. What we did is we measured the radiation at the top of the tree, at the middle of the tree and the bottom of the tree. Of course, these are massive trees. So there's gonna be a change in the amount of solar radiation the top and the bottom receive. So we had to quantify that. And then what we did is we measured transpiration in the trees. So how much water's leaving the tree? Again, at the top, in the middle, in the bottom. And as you might expect, sun comes up in the east. All the eastern leaves are getting illuminated. And they start transpiring. That's the red line and the green line. Sun passes through the day. The eastern side begins to close down but the western side begins to ramp up. So it's almost like two halves of the tree are doing different things. And the morning the side starts, it closes down and the afternoon this one goes. So because you're such a large organism, it's almost like you're looking at a forest in a single tree itself, all right? So we're looking at these transpiration rates. At the same time, we measure the amount of water stress the tree is experiencing early in the day as it goes through the day. And you can see there's the most stress at the top of the tree, which you can imagine. You have to get all that water up there. And it's pulling against gravity. So there's more stress experienced by the tree at the top than there is at the bottom. And what I wanna eventually share with you is that all of this information, then what we can do is we can calculate liters per hour or even liters per day. And look at those numbers that you see up there in terms of how much water these trees are using. Between 2,800 and about 1,700 liters of water a day. That's a single tree in a single day. If we take that and we scale it up to the entire forest, or hectares of forest or acres of forest, oops, I went right past it. I'll get to that in a second. We can calculate exactly how much water on a land area basis. What we have to do to do that is we get, we calculate, we know what water transport is. We have to know how much area that is transporting water actually in the tree. This is called the sapwood. It's on the outside of the tree. It's the plumbing that's moving things to the leaves itself. So we have to determine how much sapwood area there is. And if you look at Giant Sequoia compared to other plants on the planet, whoa, it's got a lot of plumbing, all right? That means it can move a lot of water. And how much water is that? Well, on a land basis, and this is on per day, per hectare, or you can think of it roughly as acreage, they're moving around 1,400 gallons per acre, or per area per day, all right? You can't do that unless you have lots of water to transpire. And that's why we have these plants growing in the snow belt, where most of the snowfall is, it melts every year, it recharges the groundwater. These Giant Sequoia trees use that groundwater. You can imagine if you don't refill the groundwater, these guys are in big trouble if they're using this much water. And that is, of course, what happened in California in 2012 to 2016, we experienced a massive drought. Probably everybody in this room lived through that. We had two years where we had no snowfall in this era. No water got recharged for these Giant Sequoia trees. So we started seeing the trees throwing leaves away. They didn't have the water they required, so they got rid of a lot of their leaf area and it resulted in massive dieback. Not of Giant Sequoia right away, mostly pictured here are white fir and sugar pine, but we lost 130 million trees in the Southern Sierra Nevada all right, because of this massive drought. That's a game changer. One of the things we wanted to know then is what does that mean that led to that change in the tree mortality? And one of the things we were able to get with remote sensing, we flew over the forest, we use what we call a hyperspectral sensor, you use the wavelengths of that sensor to calculate the water content of the forest, all right? These blue images are high, these are medium and these are low water content, over massive areas of land. And we said with water content goes down, what happens to the trees physiology? This is a really cool composite movie of what this shows you in one of our four series and you can see here's some nice yellow and blue trees, those are looking pretty happy, those are not looking happy, these are not looking very happy. So now from the remote sensing images, we can go to the landscape and we can tell you where we think the trees are gonna be stressed, more in danger of mortality and probably more susceptible to more water losses, due to fire. We made a bunch of other measurements, I'm gonna run out of time here so I'm not gonna be able to walk you through all of these. One of the things that happened though is there was a relationship between the water content that we got from remote sensing, which you saw in the last images and the amount of water stress the trees experienced. So lower water content, more stress and of course lower water content means lower fuel moisture in plants that might be susceptible to fire. So we go past this and we come to today and there's been a lot more fire now in the Giant Sequoia Belt. As you saw last summer, we lost a lot of plants and part of it is related to this, what I'm telling you, water content went down, fuel moisture went down, susceptibility to fire went way up and all of a sudden fires that we would only see small fires before are raging fires and those raging fires lead to full loss of crowns. These trees get gutted and despite the fact that they have bark about this thick that doesn't burn, when the fire gets this hot and the trees are that stressed, they go, they burn up. You can't take it too far. And in fact, some of the data that was really surprising that was collected for three different fires here is that fire, it hit all sides classes. That was really a surprise test. We thought we would lose mostly just the small trees but we were losing big trees too and it was mostly because the water content of everything went down, right? When the groundwater falls away, it falls away for everybody. Doesn't matter how big you are. And so we lost big trees and small trees. That's what's shown in these black bars versus the gray bars. And in fact, when you get damaged to a certain extent and you lose too much leaf area, tree mortality goes through the roof. That's what these graphs are showing you. They're pretty good. They can take a lot of crown damage, right? Until you get to a certain point here and then if you hit that tipping point, the trees die, no matter how big you are. You just can't, you've lost too much of your leaf area. We've pushed you beyond the point where you can live any longer. Okay, I'm gonna close here quickly. Coast Redwood, what are we learning? Well, I've already kind of talked about a bunch of these things. We've seen that they're breaking rules in some ways. Water's coming into their roots but it's also coming into the leaves. This is something that nobody ever expected to see. They use a lot of water per day. I haven't shown you any of the tree ring stuff but of course we can get tree cores through these trees and we can reconstruct climate from them. And in fact, that's one of the longest climate records in California, 2,000 years. 3,000 up in this year. So we're learning some things about how climate has changed in California. And as I pointed out already, we've discovered some really neat things both in the roots and on the leaves for Coast Redwood. Giant sequoias are also breaking some of these rules. They're, we're discovering that they store and use an amazing amount of water and that's despite all their great size. You think when many plants get larger, they're gonna become more conservative because they can't get all the resources they need. These guys just keep going. As long as you give them the right amount of water, they'll keep growing, they'll keep, that's why they get so old and probably so large. They have incredibly deep roots and so of course if we don't recharge the groundwater system, puts them in danger. And that leads to, even though they have thick bark, it really puts them at greater fire risk as I pointed out to you. So it's, we're pushing them of course now into a new area and they're really in some respects, they're becoming at higher risk than they've ever been in recent times because of all the environmental changes that are taking place. Not just climate change, but we're part of the picture. We're encroaching on the groves, cities are coming up, et cetera. So it's pushing both Coast Redwood and Giant Sequoia into a new area. So why are they so unique and special? I pointed out already their longevity, their great size and many of these really cool adaptations. I've been able to share at least a little bit with you today, but the threats that they see today are really different than they've ever experienced in the past, even though they've been around on this earth for 120 million years, things that are coming at them today are novel and rapid and those are not the kinds of climate changes they've experienced in the past. It's outside of their experience. And so because of that, we're not sure what the fate is. Things are happening in ways that they've never seen before. And so the future of the Redwoods kind of sits firmly in our hands, right? We're the solution. We're the problem, but we're also the solution. And so I hope that you look to Redwood Forest, you look to Redwood Ecology, you look to the conservation organizations and think a little bit about, be really sad if we lost our California Redwoods. This work wouldn't be possible without a giant team of people. These are just some names, I can't name them all. These are people that have been in my research group for years, many, many Cal undergraduates, the best undergrads I can imagine ever working with. Lots of really great funding agencies that have stepped up and supported us in the work that we've done, both with Coast Redwood and Giant Sequoia. And so I'll leave it there. Thank you, go Bears, go Redwoods. I'm happy to take questions and there's a couple of people with microphones, but you're also, if you can enunciate, just yell it out. Okay, so for those of you that didn't hear the questions about fog and those of you that read The New York Times, a week ago Thursday, you saw that there was an article about the declining fog around the world. I happened to be in that article. They quoted some of our work here in California. We've been measuring fog in California for more than, while we went back to the fog records that go back 70 years and it's been on the decline, fog has gone down for about 30% in the Bay Area in the last 70 years. And of course that's due to the fact that we're warming the planet. You warm the ocean, you warm the land, you change the conditions that's favorable for fog formation. You need a cold ocean and warm moisture over the top of it. You warm up that ocean, starts to go away, all right? So fog is on the decline. It's been much more variable than about the last decade because we've had other climate events come in. We had El Nino in 18 and 19. We've had the drought that hit 2012 to 2016. Those kind of derail the long-term trends because there are other climate factors that come in there. Second part of the question was, what happens to redwoods when they don't live in the fog zone? What do we do about that? And as you've probably seen, they have much thinner crowns. They don't have as much leaf area. You see that along freeways. If you drive up to Santa Rosa, you see all these redwoods that were planted by Caltrans years ago. I remember seeing those trees 30 years ago. They had a lot more leaf area than they do today. And I'm not sure what you can do about that. They require water. And unless you're gonna water them, they're gonna experience a water stress. And one of their responses to water stress is to throw leaves away, all right? So they don't use so much water. So it's a, yeah, it's one of those tough situations. You're not the first person that has said that to me. You mentioned experiments going on in the Southern Hemisphere to plant coast redwoods for carbon sequestration. Do you envision a role for assisted migration to get trees moving northward in the face of climate change? It's an excellent question. So I'm sure everybody heard that. Assisted migration is one of the ideas that has been out there, especially in conservation science. In the last maybe 15, 20 years of us playing active roles in moving species that have had their habitats endangered or lost, we actively move them to a new zone that's maybe favorable for their existence, their reproduction, their longer term stability. Redwoods, tough thing to move. And you gotta move them into Oregon. And if you move them into Oregon where that climate is gonna be more favorable to them, now all of a sudden something happens. You gain a whole new set of conifers in Oregon and Washington that live in exactly the same habitat. So what are we gonna do? We're gonna have some new competing relationships with redwoods and the Pacific Northwest conifers. They don't exist in California, but they definitely exist in Oregon and Washington. So assisted migration is a dodgy endeavor, right? I imagine you could do it on private lands and there are some people in Oregon that are already considering where they've removed, for example, all the Douglas fir because of timber harvesting. And instead of planting Douglas fir back, they're thinking about planting redwoods. So maybe on private lands or timber lands, there sits a solution, but it's a tough, a really tough problem. It's a great question, yeah. Go enjoy the afternoon. Thanks for coming.