 Hi, I would like to begin today's event with a land acknowledgement. The Archeological Research Facility is located in Huchin, the ancestral and unceded territory of the Chuchenyo-speaking Aloni peoples. Accessors of the historic and sovereign Verona Band of Alameda County acknowledge that this land remains of great importance to the Aloni people and that the art community inherits a history of archaeological scholarship that has disturbed Aloni ancestors and erased living Aloni people from the present and future of this land and is therefore our collective responsibility to critically transform our archaeological inheritance in support of Aloni sovereignty and to hold the University of California accountable to the needs of all American Indian and indigenous peoples. With that, we'll begin our event today. Welcome everyone. We have a special guest today, Clark Knight. It's going to be speaking and Dave Wall from Geography will be introducing her. Take it away, Dave. Alright, thanks, Nico. Yeah, it's my pleasure to introduce today's speaker, Clark Knight. Clark is a postdoc researcher at USGS in Menlo Park and she's interested in forest responses to climate change, both past and present. She's primarily worked in California's mixed conifer forests where disturbance regimes and particularly wildfire are driving community composition and ecosystem system function. She's a recent graduate from UC Berkeley's PhD program in environmental science where she leveraged reconstruction techniques from paleoecology to compare modern forests to those from the late Holocene and Euro-American settlement and an important aspect of this work is as we'll hear about today was considering and integrating traditional ecological knowledge with paleoproxy data to really enhance our interpretive capabilities. And as I said, she's currently a postdoc at USGS. She's focused on producing well-dated high resolution reconstructions of past climate to understand climate variability and its impacts on local ecosystems in Western North America, with a particular focus on extreme hydrological events like atmospheric rivers. And so with that, I will turn it over to Clark. Great, thank you so much for that really lovely introduction, Dave. I'm excited to be here with you all and to talk about some of the research that I did while a Berkeley student. Hopefully you can see this when we play from start. Looks good. OK, thank you. Great. So as Dave mentioned, I am a postdoc at USGS. Dave is my advisor and I'm going to be presenting some work that I did as a PhD student at Berkeley, specifically looking at the historical role of fire in the Klamath Mountains, California. We're going to be going through the history of this area as well as the land use history and trying to take a holistic look at what has been happening in this area. I consider myself a paleo ecosystem scientist. So I am really interested in all aspects of the environment and how they change through time. And so this is a picture actually of the Trinity Alps up in this area. But it has a really beautiful lake highlighted in this photo, which I'm going to be talking a lot about lakes and the paleo ecological information that can be harnessed from them. So I just want to plant that seed now. So in this area, if you're not familiar, it's in the Northwestern part of California and it's called the Klamath-Siskew Bioregion. It also intersects with Six Rivers National Forest. This is a really gorgeous area up in Northern California. It has a lot of mountainous topography. As you can see from the photo on the right has a lot of water, hence Six Rivers in the name. And really importantly from a paleo ecological standpoint is it has a lot of small lakes and these are lakes that have been formed from glacier retreat as well as landslides. And there's almost 100 of these small lakes up in this area. So it's a very great area to do this kind of work. And from a floristic standpoint, this bioregion is really, really cool. It has the most endemic conifer species outside of the tropics. So that's a really interesting feature of this landscape. There's actually a place called Miracle Mile that has 18 endemic conifers. If you have a chance to go up and see them and if you're interested in trees, it's a great place to go look at them. And the geology of the area is also really interesting. There are serpentine rocks. This is an example from when I was doing field work up there. And this area is historically speaking has had a pretty different fire regime from what we think about in terms of Southern California. So this might be some review, but I think it's really important to highlight this dichotomy in California with the different fire regimes because that's played such a huge role in constructing the conditions of these forests. So in Northern California and in the Sierra Nevada, by and large, traditionally, there would be fire regimes of high frequency and low severity. So there would be fires pretty frequently in the area, but they wouldn't kill that many trees and the trees are involved to cope with this recurrent fire on the landscape. And in general, in the South, we have a different fire regime where we have more time between fires or lower frequency, but they're usually much higher severity. So for example, we have a vast Chaparral landscape in California. It's particularly in the South that has crown fire and is burned completely high mortality. It's a high mortality event when that occurs. So just to kind of get that into your mind, because we're going to see a big deviation in the fire regime, particularly where I worked and the impact that that has had on the landscape. I'm actually able to quantify some of that impact of changes in the fire regime. And so before I get too far deep into my research, I think it's really important to ground this research in an understanding of some of the traditional ecological knowledge and publications that have come out of this area. And we know from the oral histories published by many people in this area that there has been a history of forest stewardship. And that has included things like cultural burning for ceremonial purposes or for clearing trails for crop cultivation. A lot of different reasons why fire has been put on this landscape. In particular, where I worked this map from the native land project has a really nice representation of some of these boundaries of the traditional territory of some of these tribes. So up in this area where I worked, I was really at the boundary between the Uroch tribe and the Karuk. And in fact, some of my lakesites were a joint use between the two of them. And some of them were purely in Karuk traditional territory. So there's actually a lot of tribes in this area, as you can see from this map, but where my sites were located was really at this intersection of the Uroch and the Karuk. And I think it's important to make note that a lot of these practices are ongoing to this day. This is not something that's just relegated to the past. And this is a really nice example from one of my collaborators, Dr. Frank Blake, from one of his recent publications. This shows a nice picture of a prescribed cultural burn of bear grass going on in this landscape. OK. So. OK, so with California Forest, one of the reasons I was really attracted to working in a landscape like this is that these forests are vast. They take up something like thirty three million acres of California's landscape. And they're really valuable. We like to recreate in them. And they also perform a lot of ecosystem services for us. You know, they store carbon, which is a huge part of California's climate mitigation goals is to keep California Forest as carbon sinks rather than carbon sources. And so they have a lot of dimensions to how we interact and use these forests. But I think a lot of what my work is showing is that the forest looked a lot different in the past than they do today. And in fact, our forests are very threatened. So the integrity of our forest is being threatened by a couple of main drivers, the biggest of which is mega wildfire, as we're probably all familiar with, as well as hot drought. And this is just an image of what was happening in September of last year. And I'm sure that this will continue this year as well. So these mega fires are basically taking out huge areas of forest, causing really high mortality and, in fact, probably leading to type conversion in a lot of these previously forested areas. And so why did this occur? Well, a lot of it has to do with fire suppression, which was a mandated federal and state policy used to prevent fires or quickly extinguish them once they started. And when people think of fire suppression actually began around 1905, when the forest reserve system was created. But it's a lot more than just putting out fire. It was actually the creation of infrastructure. So the roads to get to remote places in California, the setup of ranger stations, personnel, equipment, all of these things really coal lasting California to be very, very active and effective at suppressing fire for nearly an entire century. And this also led to public communication campaigns. As you're probably aware, Smokey the Bear, which did a lot to get in the minds of the public about fire being a negative force on the landscape. And so just to give a kind of review of some of the conditions that I am thinking about when I when I talk about these historical landscapes. I'm sorry, I hope you can't see this like other beeping thing that's happening on my computer. But with pre suppression forests, the Nature Conservancy has put out a lot of really nice graphics about this. And I want you to think of the forest before suppression as much more open than they are today, much more park like. So if you were to stand in a forest in the 1800s, you would probably have high visibility around you could see 300 meters away. And these conditions really were evolved to handle the fire that was coming out to this landscape in a very frequent recurrent way. And so these low severity fires would would definitely burn and kill some trees. But they wouldn't kill everything. You would still have many healthy many trees survive and it would produce this healthier forest forested landscape. But when you have fire suppression for at least 100 years, as you get really dense overstocked forest like this, which allows any fire that then comes through to climb up through the trees, burn everything pretty much and you get this moonscape of a high mortality environment where there is no more forest anymore. And this is creating a really big problem for California because the state is using carbon in the forest as part of their climate mitigation strategy. And we can't combat climate change of all that carbon in the forest is just rereleased to the atmosphere. So these are some images I took near my field sites. You can see just how dense this landscape is. And actually, a fire had gone through relatively recently when I was doing field work and you can see, you know, just everything was killed. And these really high mortality post fire events are just undoing a lot of the good that has been done with carbon storage in our forests. So this really gave me the motivation for my PhD research, which I'm going to now get into, which is I wanted to understand are there any long term data sets? Can I even create a data set that's long term about forest biomass and fire to help us get an evidence base for the management decisions that we need to be making in California? Because a big part of California is restoration. But restoration to what? What can we quantify anything we want to get back to in terms of historic forest conditions, which are thought to be these more stable and healthy and resilient forested systems? So that's what motivated me to work on this. And it led me to this really fabulous field called paleo ecology, which I'm now obsessed with. And paleo ecology does exactly that. It allows you to study past ecosystem processes and in particular, I've been interested in the last 3,000 years or so of California forest in this area. And, you know, I use a lot of different methods to reconstruct what this area might have looked like. I'm going to go through the main ones. You know, the biggest one probably being pollen. If there's anyone in here that's familiar with that, it's a really powerful technique to reconstruct vegetation, particularly around lakesites, which is where we got our pollen from as well as charcoal from those lake sediments, fire scars from tree stump tree stumps and then taking that kind of empirical foundation and combining it with, you know, the really vast and deep and helpful ecological traditional ecological knowledge from our partners at the Karuk and Yurok tribes was became this really powerful narrative for what was happening on this landscape. And I also am going to talk a little bit about the historical inventories and management data sets that are available for this landscape that, again, really informed our understanding in a quantitative way what was happening. So I'm going to actually talk a little bit about the paleo and the pollen side because I think it's, you know, really interesting and also allow you to understand what I did a bit better. So pollen is a really powerful tool, like I mentioned, because it acts basically as a time machine. It helps you understand what was happening in the past. And the way it does that is that pollen grains, individual pollen grains are unique, typically for a genera of taxa, sometimes down to the species level. But it allows you to look under a microscope at a pollen grain and determine what taxa it came from. And so you can start classifying those pollen grains. As you can see, they come in different shapes and sizes. And it allows you to build up this assemblage of taxa on a landscape. And hopefully this video will play. But we are in the spring season, which is big time allergy season. And you can see just how much pollen comes off of one conifer tree, one conifer species here. It's, you know, trillions and trillions of grains of pollen. And if you now imagine an entire landscape that has trees on it, is just the sheer abundance of pollen on a landscape is vast. Most of our atmosphere has pollen in it. And what typically happens is that the pollen's purpose is to, of course, pollinate another tree. But what happens is it usually fails. It usually does not pollinate anything at all. And in fact, it ends up in other places like the gutter or the top of your car or in many cases on the surface of a lake, which is really valuable for us paleoacologists. This is where we want it to go. So this is a nice example here from Crater Lake up in Oregon. And you can see the green pollen swirling on the surface of this lake. I really like this photo because it shows the dynamics of the currents and it also kind of suggests the fact that the pollen will be mixed a lot in this lake and then will slowly actually percolate down through the water and become incorporated into the sediments of those lakes, which can then be cored by scientists. So that's the process basically of how pollen gets into lakes and why it's valuable. So for my own research, we went and got lake cores from seven different lakes up in this area. This is a nice example of one of our lake sites. You can see here mud and then this blue clay layer transitioning into other mud. And this was exactly what we were hoping to get. We got all these lake sediment cores. It was a really fun experience as well. And I looked at the pollen in these lake cores and that helped reconstruct the vegetation. So again, the lake sites that I worked in are these blue squares here and there's been some other work as I mentioned because there's so many lakes up in this area from existing paper. So I kind of knew growing in a little bit about the paleoepological history and that really helped when I was doing my work. So from the pollen record, basically what I learned from this was that the vast majority of the pollen from these lake cores came from only a couple of different taxa and specifically pine pollen. So this looks like this Mickey Mouse shape here on the right as well as Douglas fir, which looks like this broken Pac-Man and then this tan oak pollen. These are as well as other kinds of oaks but these were some of the dominant taxa on the landscape. And what I wanted to do was reconstruct this pollen history from these taken together with some work from done by Jeff Crawford. Some of his data is look at how this changed in the last 3000 years. So this is one example at our lake, a lake called Lake Agurantok. And we found that there was a 3000 year peak or high in shade tolerant taxa, likely due to fire suppression based on what we counted from the pollen. So we can see here the 20th century in this little red bracket and we have 3000 years of data shown here on the y-axis. And then we have our different taxa ranked by how intolerant or tolerant they are to shade which is a proxy for how fire repellent they are. So for example, Quirkus is very shade intolerant. So it's not gonna grow in shady environments. It needs fire usually to keep that shade down to keep other competition down. And what we found is this really big spike in things like Pseudosugos or Doug fir which is a more shade tolerant species and Nothylithocarpus as well, TCT and even an AB so fir. And that was true on the landscape for most of these species. So there's a signal of increased amount of vegetation on this landscape which I'm going to get to as well as in the pollen signal giving us this longer term view of what's been happening that there's been this spike here in shade tolerant species. Okay, so I'm gonna quickly talk about charcoal. I think it's just an interesting way of looking at past fire events. What charcoal is is it's incompletely combusted organic matter. It's also found in these lake sediment cores. The difference between macroscopic and microscopic isn't super important, but there is data about the macroscopic charcoal from this area. And charcoal gets into a lake in a somewhat similar way as pollen does. There's a fire event, it creates charcoal and it's either lofted into the air and it's deposited into a lake or over time there's surface runoff. So if you get a lake core and sample it you're gonna charcoal in this area because there has been a lot of fire. It's a high-frequent fire system. So when we look at another one of our lake sites, so this is Fish Lake up in this area is we can get kind of a qualitative interpretation of what's going on using charcoal accumulation rates which is the amount of particles per centimeter square per year. And I have plotted here our Z scores of charcoal so it's standardized and we have increasing amounts of charcoal going up decreasing amounts of charcoal going down on our Y axis and it's plotted over 3000 years. And what I think is interesting just purely from a qualitative standpoint is we actually have a peak we have increasing charcoal through the little ice age and the little ice age is a period where we have cooler and water climate not a time period that you would necessarily assume with increased fire. So that was pretty intriguing. And we looked at one of our other lake sites as well like Agarom talk with this kind of data. And again, a similar story where we have increasing and even actually a peak at this lake of charcoal through the little ice age. So it's been increasing through time and it peaks in the little ice age and then it drops off drastically in the 21st century which would be on the very right hand side of this graph near minus a hundred. So in calibrated years BP. So again, you see potentially the influence of fire suppression as a reason for this big drop but this has been really intriguing to us why there was so much accumulation during the little ice age. And we tried to look at this quantitatively and what we did is we thought about what our expectations would be if climate alone was what was driving fire on this landscape. So for example, if you have only climatically driven vegetation change if you had a hotter and drier climate like for example what we have today you probably see more fire on the landscape because fuels are dried out and if there's therefore a fire it's more likely to burn and that would lead to forest opening and the promotion of shade intolerant taxes such as oak. And if you contrast that with a correspondingly cooler and wetter climate you might expect less fire in the landscape because those fuels don't have as much time to dry out and perhaps forest closure and the increase in the amount of shade tolerant taxa. But what if you wanted to try to detect an anthropogenic impact? So if you have human cause vegetation change it's not just climate alone. In a cooler and wetter climate you might actually expect to see more fire on the landscape that promotes more forest opening and more shade intolerant taxa. And this is actually what we see in our data set. So in the little ice age which is really the period for which we can test this the best which lasted through the middle ages 1300 through about 18 or excuse me after the middle ages 1300 through 1850 AD we see this exact trend. So we looked at it quantitatively we did correlations between charcoal, the PDSI which is a polymer drought severity index it's a measure of how dry the landscape was as well as vegetation openness or closeness. And what we found was significant and positive correlations between the amount of charcoal in the landscape so more fire and how open that vegetation was it would became more open. And this was happening during this period in the little ice age right around this period of about 500 to 100 calibrated years BP. This goes against a pure climatic alone expectation of this landscape. So we thought that this was a really nice finding for our data set. It also occurred at Lake Agarom talk I'm just not going to show that graph but we found the same significant and positive correlations. So we wanted to understand a little bit more detail about this fire on the landscape. And so we turned to fire scars which if you're not familiar they are caused by fires that burned at low intensity that injured the bark cells of a tree but to not actually kill that tree. And so much like tree rings can be dated and cross dated with other trees in an area fire scars can also be dated and cross dated. So you can actually determine past fire events based on fire scars. It's actually a very conservative measure of fire in a landscape. So whenever you look at a fire scar record I like to think that there's probably more fire happening but it's just not been detected for various reasons which I'd be happy to talk about. You know, it's interested in the methodology. So again at our two lake sites Fish Lake and Lake Agarom talk is we had these various fire scar sites shown here in red. And they were kind of opportunistically taken where there were stumps of trees but allowed us to build up this nice data set right around these two lake sites. And we focused on these two lake sites because they were in areas of cultural importance to both the Yurok and the Karuk. So Fish Lake is in an area of joint use between the Karuk and the Yurok whereas Lake Agarom talk is a sacred lake site for the Karuk. So we're really interested in trying to reconstruct the fire around these two specific lakes. And what we found is that there was really frequent fire. So this is what the graphic looks like when you count the fire scars. There's a lot of different tree species that we looked at but what I really want you to focus on here is the composite here at the bottom which shows with each of these lines a fire event. And so you can see there was a lot of really frequent fire between the 1700s and the 1900s and then it completely drops off after 1900 when we know fire suppression was happening. And this was true for both of our lake sites. And in fact, when you calculate the median fire return intervals as you see really frequent fires about every seven years at Fish Lake and about every 12 years at Lake Agarom talk. And this work was really led by Dr. Eric Knaps I want to give him full credit for this. We also found interestingly that most of the fire scars were present in the latewood or the dormant wood of the tree ring. We think that this is potentially really interesting although we need to do more research about the fire scar ecology in this specific region of California. But it's kind of tantalizing because a lot of the cultural fire that was being put on the landscape, the indigenous ignitions were occurring in the late fall and early spring according to oral histories and current practitioners in this area from the tribes whereas lightning fire was typically occurring earlier in June and July. So the fact that those scars are kind of aligning with when we might expect indigenous ignitions is just a really tantalizing though inconclusive point from this fire scar study. And so, this came up a lot in my work and I started to form some views about this about the paleocology side and the native stewardship. And I really settled on this idea and view that I know is echoed in many other papers that have some nice reading material and examples at the bottom here about, it's really important to talk to, listen and learn from the people who have lived in the area since time immemorial and particularly in paleoecological research because they are implicated in your findings. And so for our sake, we were really curious about the role that they had in influencing the past ecosystem. And we talked to members of the crew in the Iraq and included them on our publications to understand what the forest stewardship was like. And in particular, we ask questions like, what is the relationship between human ignitions and natural processes, natural or lightning ignitions? And how can we best detect these native actions in the paleo record? Again, coming back to this idea of we wanna choose lakes that are culturally significant and we know that they were around and using so that we have the best possible chance of detecting those actions. And it also is important for the interpretation of the data sets. So in terms of getting really scientifically sound, robust findings, you gotta talk to people who know the area, especially when there's implications for today's management actions. And so as part of this process, we did what's called a practicing pick yaw, which in the Karuk language, that means to fix or to repair. And what was really lucky for me is that being a Berkeley grad student is I had access to the Karuk UC Berkeley Collaborative. And as part of this collaborative, they have set up tribal policy to do a practicing pick yaw before any kind of research collaboration begins. And so through this practicing pick yaw, I was able to develop a project with mentors who had worked with the Karuk before members of the Karuk Triber on my research committee. And I presented my proposal to the council and they decided to approve my research and I went forward. But what's really powerful about this policy is that it gives you mutually agreed upon expectations for the collaboration, as well as protects traditional intellectual property. It's really helpful during the review process because we went through tribal review. So everyone who wanted to be a part of the project was able to give feedback. It informed our research design. It informed the presentation of our results. So it was really a powerful process for producing a scientific product. So I'm really proud and happy about our collaboration there. And I want to contrast this with some other work that's come out in a paleo environment because it's been contentious in the field, actually this role of indigenous fire in the landscape. You may be familiar with this paper last year from Nature that says emphatically in their paper that the charcoal and pollen data and archeological record do not support the interpretation of significant indigenous impact. And they actually make some conservation recommendations based on this finding that there should not be fire in the landscape today. They should instead do chainsaws, cattle and sheep grazing and hay production. So this is exactly what I'm talking about, the significance of indigenous fire may or may not be on the landscape has real conservation impacts. And so what was interesting about this work is that they did not consult or talk to any of the tribes in this area, actually in the area in New England where they worked there was something like 21 different tribes. And so this really raised a flag to me and this is a controversial area but I really think talking to people and bringing them on board would potentially give you a different result. But this has been controversial in California as well, not just New England. So for example, a couple of different papers have published on this and said that burning activities, for example, in Whitlock at all, burning activities from native people are unknown and probably limited. I'm not sure how you get from unknown to probably limited. I don't think you can draw that connection necessarily. And then there was a whole book about it published by Vale in 2002 that basically says there's no, not been significant change on the landscape and not been significant landscape modification with fire before colonization. So my findings are in stark contrast to this but I wanted you to put out there that there has been other findings or in other publications about this controversial topic. And there's been pushback as well. So more recently in the literature, Leonard at all, Armstrong at all have raised questions and I think I've been asking as well of, how do you, why weren't indigenous scholars included or consulted, what relevant or historical history was or was not included? And then also this point about the spatial scale of what was reconstructed. That's a really important point when you talk about what can be done from the paleo ecological side is a lot of what you're doing is really constrained to a certain lake or a group of lakes. And so how much can that be interpolated to a landscape is another really important question to consider. So lastly, I'm gonna talk about some of the findings from the traditional ecological knowledge as well. If I have time, some of the historical inventories if not I'll leave that part off. But we had a lot of information from scholars in this area about the kinds of indigenous stewardship that was going on in the Klamath. So we know, for example, that people have been there since at least the terminal place to seen. And we know that there was really sophisticated application of fire technology by the tribes in this area, which are ongoing to this day. And specifically, the native history suggests the substantial contribution to the fire regime. And at our lake sites, aground talk and Fish Lake, we know from members of this tribe that both sites were gathering places for acorns and mushrooms and that they needed these low level, low fuel levels, low biomass, these open forest conditions to actually cultivate the kind of crops that they were interested in. And some work from the 1970s speculates that there are about 2,000 to 3,000 people before colonization. So that just gives an idea of how many people you would be needing to feed from these crops. It's quite a few people. In the contemporary, Dr. Frank Lake has done an oral history from members of the Karuk and Yurok tribe and his dissertation work that we were able to draw on. And what he found is that from tribal members, they already know that their traditional lands are really over enriched in biomass. They know that the forest is super dense. And in fact, they compare it to, quote, an ecological and cultural desert. This came out of some work from Berkeley professor Sauerwein a couple of years ago. And in fact, one of the Krug elders that Dr. Frank Lake interviewed said that, quote, we've never had this much fuel on the ground. So there's already this convergence between the empirical side about the ahistorical peaks and biomass on this landscape with what the traditional ecological knowledge and oral history is saying. So it's a really nice consistency. And I just wanna make mention here that indigenous burning also isn't a monolith. And in the Klamath there's something like 70 uses of fire that have been on the landscape. And that kind of pyro diversity really supported a mosaic of vegetation types. So this really homogenous dense forest is again, super ahistorical in this context. So those kinds of different fire were developing and evolving over time. And one example of this is the Tula Watt pattern which occurred about 1500 BP. Onwards was this time period of more migration into the Klamath area from the north and more intensive land usage and very likely more burning. So this is a really fascinating area and there's a lot of history just in what happened with the burning trends. I think I'm getting close on time but I will just quickly talk about some of my findings from the colonial era because it's this transition point between the late Holocene and indigenous lead management to Euro-American management that it continued through the modern period. What's really interesting is that there's ecological data from this period from the public land survey data. I'm not sure if you're familiar with that but I'm gonna talk about it. It's really nice written record of what the forest and the kinds of trees that were on the landscape but this is a really important period, the colonial era because it does mark, as I said, this transition but particularly the before period before fire suppression. So it gives you this glimpse into what the forest might have looked like more of a snapshot really than anything from these 20th century changes that were coming. And so I like to use this image of what the forest potentially looked like because this is a real picture from up in the area that I worked from 1910. And back a hundred years later it's the same lake and you can see just how much more dense it is around this lake. So that was the main question I came into this work with was what did this forest look like in the 1880s which is when the public land survey was completed. And in case you're not familiar this actually occurred over much of the US everywhere where you see these colors is where the public land survey took place. And so it had this regional coverage in California which is really nice and what happened is that you'd have people going out who would take field notes and they would document in a really specific way the kinds of trees and their size and their location on the landscape. And so what I was able to do as I calculated I think it was about 21,000 trees were in my data set by the time I got through extracting the tree records. And I was able to find this really big structural change on the landscape. So if you look at what was collected in this historic data set shown in black versus the contemporary as you can see that on our Y axis with density is that it really, really increased in this area is about three times more dense than it was in historic period. And the same goes for the basal area of this landscape. So that again, really just consistent with what we would expect based on the oral history and the ecology of this area after fire suppression. And there was also a lot of compositional change based on this data set. So again, the historic in black and the contemporary in gray, the relative dominance of different taxa by basal area changed a lot. So we have this increase in basal area and Douglas fir from about 34% of the landscape and the historic period to almost 45%. Pines were actually about the same but really dramatic change in the oak taxa where you had a lot more oaks on landscape something like 21% of landscape was oaks in this area in the 1880s. But unfortunately that's dropped to about 9% in the contemporary period. So this huge oak loss which has been documented around California as well. So that gives us a really nice quantitative view as well of this landscape. And when you look at the fire records from Cal Fire you can see the really effective fire suppression in this area. So this is all the wildfires that occurred in Six Rivers since 1908. And you can see that in terms of area burned in hectares is there was almost no fire in the 20th century. And then of course that's changed a lot in the last 20 years but that really aligns with the policies that we knew were occurring. So just to sum up here these results there's about three times more trees on landscape today than there was in 1880. And these modern forests contain a lot more dug for and less oak but about the same amount of pine and that this fire suppression is probably driving the densification in this area. So I think I'm probably not gonna have time to go through this unfortunately. So we can get some questions. But what we recently did in an article was combine all of the different methods that I just talked to you through. And we were able to synthesize and produce this biomass record for the area over 3,000 years and really show the strong impact an indigenous influence of keeping the biomass levels really low in this area. Again, this is what a low biomass forest look like versus a high biomass one and that there was a really long pattern of this at least 1,000 years of low biomass before the modern period here on the right. And in fact, it's about half of what it was today. So the median tree biomass until colonization was about 100 megagrams per hectare then in colonization we see the skyrocketing of biomass and it's about doubled out on the landscape today. I'm just gonna skip this slide and just present our main findings with all of this work. We went through it all these different methods and the Karukin ethnographic data is super vital about these watersheds and that coupled with the fire scar and charcoal history suggests that indigenous stewardship really strongly contributed to the fire regime on this landscape. Our biomass records and the records from the 1880 public land survey also suggests that frequent fire limited the biomass on this landscape relative to how productive these sites can be that we see today really high levels of biomass and that the consistency between our biomass record and these other independent lines of evidence is strong and it gives us more confidence in these results. And so I think going forward if we can integrate paleo and ethnographic records that can be a really powerful way of understanding the ecology of the past and particularly in California when so much of our contemporary forest is unprecedented in at least 3000 years that's becomes really important for restoration ecologists and going forward I think indigenous forest and fire management will be critical to maintaining forest conditions not only those conditions before colonization but helping to restore and have any kind of historical fidelity with the landscape of the past. And so this is basically saying the same thing but just increasing engagement with tribes and the fact that we will probably need a very large scale intervention if we want to achieve historical fidelity and also to temper our expectations about how much carbon we can realistically store in the landscape for a long period of time. So I wanna say thank you to my collaborators and co-authors, my funding sources and to you for listening and I hope I have time to take some questions. Thank you. All right, thank you Clark. I guess before we move on to questions I'll point out for those of you who are interested in this and want to find out more we just had a paper come out two weeks ago I should say Clark had a paper come out in PNAS that covers all of this. And so if you wanna do a deeper dive and look into some of the data, it's all there. Do we have any questions? Dave, hey, great to see you. This is Kent Lightfoot. Can I have actually two quick questions? Sure. Clark that was a really fabulous talk. Great, great presentation. So my question is you got very good evidence that we've got a little ice age there's definitely a successful cultural burning going on and continuing when do you think it actually starts? That is you obviously, you've got a 3000 year window. Is it, it's obviously looks like it's late Holocene but is there, do you see like a when you really begin to see the cultural burning taking place? Oh, can you hear me? Yeah, it cut out. Oh, sorry, it cut out for me. Yeah, that's a great question. I think actually if I go back maybe to this figure, I think unfortunately it's a bit inconclusive but and that's again, I think a bit muddled because of medieval climate warming we would expect more fire in the landscape just from how hot and dry it is. But you do see it pick up in the little ice age. I wish we could conclusively say it's been going on for several thousands of years according to our record but where it really stands out was a little ice age from the oral history as far as my understanding is those, you know, they're not geologically dated. So unfortunately, there's not that kind of specificity from that kind of record. So I think unfortunately it really is just inconclusive but my guess is that if it was happening in the little ice ages that it probably had to be developed by those people before then as well. So it is a tantalizing kind of like it it was probably happening much further beyond that as well. Yeah, well that's good. Hey, my second question is Joe so what are you doing with the USGS right now? You know, what's your current research? Are you still doing this kind of research? I am still doing this kind of research and I'm also broadening a bit. So as you can see this talk focused a ton on carbon which I love thinking about carbon in California. I'm also bringing in water now as another main piece of my work. So with Dave and others in his lab we're looking at atmospheric rivers and how they might be present in the geologic record again using lake sediments as one of our ways of detecting this. So atmospheric rivers, carbon and as well as continuing to work with and build bridges with tribal communities is definitely part of my portfolio right now. Excellent. Hey, well anyway, great job. Great. Thank you so much. Thank you very much. Okay, it sounds like Junco has a question about Oaks. Oh, yes. Thank you very much for a really interesting presentation. I work on prehistoric archeology in Japan where the issue of the use of acorns is a major topic. And one of the things that I'm very curious about is the characters being shade in torrent plans because Japanese archeologists used to think that well, acorn processing, wild food, no need for management. But I think the more we learn about ecology and also many people started to work on slash and burn agriculture and burning the field. We realized that, okay, in no way we realized that, okay, in order to maintain the harvest of acorns to what extent people needed to do environmental management. So my question is to what extent burning and I think it's kind of tied to Ken's question how far the evidence of burning goes back and does that correspond and increase use of acorns as a staple food in your research area? Yeah, that's a great question. Thank you so much for asking it. I think it probably must be tied to it because we know that, you know, tan oak was used for acorns. There's actually several other species of oak in this area that were important for food stuffs. So, you know, talking to some crook members today is that they did try to cultivate these acorns right around the lakes. And, you know, we did find evidence of very frequent burning from our fire scar record taken from tree stumps right around these lakes as well. So I imagine so and, you know, given that we think there are several thousand people at least as part of these communities with villages probably scattered and many of these prime locations with water access points is that there probably is a huge tie there with fire and acorns. One of the downsides of this work, although we had a lot of resolution from using these two culturally significant lakes is that it's unclear exactly how far out to extrapolate this information. We think there's reason to believe that this would be happening in similar places throughout this area, but just in terms of like the spread of how far it would be, it's a bit unclear. We think at least a kilometer, this work would be true for at least a kilometer around each of our lake sites based on some other modeling work that we've done. So it's not a very satisfying answer to your question, but I do agree that if there was a lot of people and they were putting fire in landscape and they did use these acorns, that they're gonna be cultivating cork us using fire, but just how far back that goes, it's pretty inconclusive from the evidence we have right now in terms of the time. Yeah. Thank you. All right. Any more questions here? All right, well, thank you. Once again, Clark, that was a really interesting talk. Thank you so much for having me. And thank you, Arff, for hosting. Sure, thank you. I wanted to quickly mention that today at 2 p.m., one of our grad students, A.J. White, is offering a workshop on perlioclimate databases. Those databases are the one hosted by NOAA. And I'll go ahead and paste the link to the Zoom in the chat here. So if anybody's interested in joining us in one hour, this is the A.J.'s workshop. Hey, Nick goes, someone's asking if a video of the talk will be available. Yeah, I'll post this on our YouTube channel within a week or so. Great. All right, fantastic. Thank you, everybody. Thank you. Thanks for a great talk. Yeah. Thank you.