University Place

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Michael Notaro

Thank you for joining us this evening. This is the final seminar set of the WICCI seminar series Bracing

for Impact

Climate Change Adaptation in Wisconsin. And for those who probably haven't already heard it, WICCI is the Wisconsin Initiative on Climate Change Impacts, a collaboration between UW system and the Wisconsin DNR. Today we have two speakers and I'm going to introduce both of them right now. The first speaker is Dr. David Mladenoff. A native of the Wisconsin north wood, Dr. David Mladenoff is the Beers-Bascom Professor of Conservation in the Department of Forest and Wildlife Ecology at the University of Wisconsin-Madison. David earned his PhD from the University of Wisconsin-Madison in 1985. He held positions in the Nature Conservancy as western region science and stewardship director and the University of Minnesota Natural Resources Research Institute in Duluth. Now David manages the Forest Landscape Ecology Lab at the University of Wisconsin-Madison and teaches a graduate course in landscape ecology. Work within his lab has been directed at sustainable forest issues in Wisconsin such as old growth forest characteristics, carbon dynamics, developing and testing methods for reconstructing past forest and changes, ecological change in management and modeling a future forest under climate change. David also was editor-in-chief of the Journal of Landscape Ecology from 1995 to 2005. And our second speaker is Dr. Sara Hotchkiss. Sara is an Assistant Professor of Botany and Faculty Affiliate of the Nelson Institute for Environmental Studies and Limnology and Marine Sciences program at the University of Wisconsin-Madison. Sara runs the Quaternary Paleoecology Laboratory at the university, directing projects on Hawaiian and northern Wisconsin ecosystems. She was the former Bryson Professor of the Climate, People and Environment Program or CPEP. Sara received her PhD in 1998 from the University of Minnesota. Her expertise include the study of vegetation history, climate history, ecosystem response to climate change, disturbance and landscape dynamics along with paleoecology. So now our first speaker David Mladenoff. >>

David Mladenoff

Thank you very much, Mike. Can you people hear me? Is my mic up enough? Well, thanks everyone for coming out this evening. Not only is it a beautiful evening outside but I know you had to go through construction and traffic and things like that. Also, I need to mention that for all these many years my mother has wondered what it is that I do and so she's actually here tonight so she'll get to see it.

LAUGHTER

David Mladenoff

Okay, we're going to talk about forests and climate change tonight. And for those of you who have attended this series for a while you've heard a lot about climate change. I know in particular in the beginning and in a lot of other aspects of climate changes effects. This is an image taken from space, it's a satellite image of northern Wisconsin in the fall. And it's kind of nice I think to have this sort of broad-scale view of the subject matter that we're going to talk about. You can see, I hope, different shades of orange, for example, deciduous trees in color in the fall. And we're really going to focus on this part of Wisconsin for the most part. We're going to talk about mostly northern Wisconsin. Along with the details you've already heard about climate change, I just want to show this one image because I think it kind of encapsulates visually and it often helps us a little bit to think about what might climate change might be like. And actually this is just a visual of one scenario. It isn't to suggest that this is exactly what it will be like in 100 years. But it's a way of thinking about it; it's one plausible scenario. You can see here what this actually is suggesting that in a hundred years Wisconsin's climate might be like, in the winter, what Iowa is like now. So maybe not terribly different for those of us in Madison. Somewhat different, certainly, for people in northern Wisconsin. And then in the summer this scenario also suggests it might be like Arkansas. And that's a little more startling maybe. And there are some scenarios actually that suggest well the winter warming might in fact be more extreme than the summer warming. But nevertheless this gives us an idea of how to think about basically how the state might move. And that's an interesting way I think to think about climate change. So we're going to talk about the northern forests and you know these are a couple of the real icons of the northern forests for many of us, paper birch on the left and a large white pine on the right. These kind of images evoke a lot of feelings in us whether we live in the north or not. Some of us associate the north woods with things besides tree species. For example, game animals perhaps. Non-game wildlife. Non-vertebrates. Plants and other things that appear on the forest floor and are enjoyable to watch or photograph. And a lot of us have connections with the north woods maybe through a cabin on a northern lake, for example. This is ours actually, a small lake. And so what does it mean then to start thinking about how might all this change? We saw tree species. Might those change? We saw some various kinds of wildlife species. Does that mean that habitat and some of those species that we're used to will change? And the context of that is again here area a range of projections for continuing climate change in this state over the next hundred years. And those projections range from anywhere from 3 to 4 or more degrees Celsius, that's about 5- to 7-degrees Fahrenheit. And I purposely say continuing climate change because climate has already been changing and warming. And some of us certainly have perceptions of where we think we can notice the springs are coming earlier, that the ice on the lake doesn't last as long, maybe the winters aren't as cold as they used to be. And in fact the climate has been changing already and you can see what the numbers are globally, about a degree and a half so far. So we're going to talk about what effect climate change might have on Wisconsin's future forests. And the way we do that in my lab is by computer modeling. And there are a number of different kinds of data or information that have to be fed into this computer model. And you can see these first two disks up on the left, those are examples of a couple of the different kinds of climate models that are used to actually predict what might climate changes actually be like in the future in terms of temperature and precipitation. And there's a whole suite of these models that vary somewhat. And this is two scenarios that we've used in some modeling that we've done. Other information we have to have is how is the forest managed today, how frequently does wind damage occur to the forest, what are the tree species that are out there now. It's really quite a lot of detail. And then the forest change model actually simulates these things on the landscape. The effects of wind, the effects of insects it may have on tree growth or mortality, fire, logging, things like that. And then this generates, when we're using changing climate in the model, some projections. And the end result is, well, it kind of suggests how tree species might possibly move or decline. Now the general, I'm not going to show you a lot of data, no graphs, no tables. I just want to talk about the general principles because that's about as specific as we can be, actually. But the general idea is this. What our modeling suggests that with the range of warming that has been projected, the numbers that I showed you before, these are the kinds of things that might happen in a hundred to two hundred years. And that is the tree species that we think of as sort of the northern tree species, for example, red pine, jack pine, white spruce, balsam fir, possibly paper birch, the model suggests that these species are likely to decline. And in fact some of them may be lost or just become very, very minor on the landscape. The other possibility, which we thought about in the beginning, was that well that would be sad and it would have all kinds of ecological and economic repercussions if we really lost those species or if they became much less important, but at the same time we expect what we call southern oaks and hickories, that is the tree species more characteristic of southern Wisconsin, they should be able to move up there. And in effect the conditions in southern Wisconsin, that favor oaks and hickories now should be present in the north. So we think maybe they'll just move up there. Well it didn't turn out to be that simple. And I'll tell you a little bit about that. Now here are some other maps related to the same point. These are produced by the US Forest Service. And what you see here on the left is a very general map about what type of forest types are present in the region now. And I guess the big thing that I want you to notice is the kind of a pinkish color in Minnesota and Wisconsin is aspen, birch, and the reddish color in northern Wisconsin and upper Michigan is sugar maple, yellow birch, those kind of species. And then you see down in the lower part of the map the green is oak and hickory, more characteristic of southwestern Wisconsin and also states further south. So the projection, and these were done in another study and I'm guess I'm going to suggest later that this is not what's going to happen, is that well, those pink areas and those red areas, the birch and the aspen and associated boreal or northern conifers are going to move up into Canada or at least they aren't going to move up there because they're already up there, but they're going to retract from northern Wisconsin. And then they suggest that well, then those oaks and hickories, that's what the lake states will be. But it's more complicated than that. Because it takes a long time for tree species to move. So here you see a range map of red pine. And that heavy red line, the more southern line, that's the approximate southern boundary of the natural occurring range of red pine. That's where it occurred naturally historically and north Nevada is where it does best, it reproduces naturally and it always has. So the modeling that we did suggest that the red pine might retract up north, so the southern range limit is now that dotted red line that you see. And so this kind of dynamic is a little more straightforward because it doesn't really involve species moving at all, it just means that they will slowly decline and reproduce less well at the southern margin and so gradually other things become more important. But when we get back to this scenario then, over a hundred or so years, that's a very short period of time for oaks and hickories to move north. Why is that? Well, a couple of reasons. One is that the landscape today, thinking of, for example, southern and central Wisconsin, it's much more fragmented. It's broken up by farms, roads, towns and cities. But there's lots of forest wood lots as well. So if you think of versions of today's landscape, those two blocks over there on the right, a relatively unfragmented landscape would be the first block where the light blue squares are forest, the white squares are non-forest. So if we have tree species with their seeds dispersing out so that they can migrate into a new location portrayed by those red lines, it's relatively easy for trees to move across that landscape. But as the landscape becomes more like the block on the right, that is more open areas, more farms, less forest land, then you can see the representation in the yellow is that tree seeds have fewer places to go. So it's going to take them longer to move across the landscape if you think in the sense of moving all the way across the state. And if we, again a satellite view of the state which we can see here. The dark green is predominately forested areas and then the lighter green in the southeast and the south and through the central part of the state is predominately agriculture. So if we want all the oaks and hickory species that are in the southwest in that southern forest block to move to the north up near Lake Superior, you can see there's literally a barrier of a more fragmented landscape across the central part of the state. And if things really heat up and further into the future maybe and then we start thinking, like well how long is it going to take for Trempealeau to get up to northern Wisconsin. Well the same thing applies at the continental scale. Now if you look at this map of eastern North American, another satellite composite, the forests again are dark green. The light green colors are agriculture. And you can see that that peninsula swoops in into Illinois from Minnesota and Iowa and to Indiana, that's the corn belt. So we have the same thing kind of operating at two scales. So if you think about it, depending upon how much time into the future we're talking about, and how much the climate actually warms, the dynamics might be important at both of these scales. At first we're interested in well can species in southern Wisconsin move to northern Wisconsin. But if things warm up even more maybe we'll become interested, somebody may become interested in, how do species that occur even further south than the state, how are they going to migrate continentally? This happened certainly after the ice age but the plants had a lot more time in which to do it. And the climate typically didn't warm as quickly either. So we had this interaction then between the warming climate, how fast a species can migrate and the fragmentation of the landscape. And the fact that the climate is projected to warm relatively fast, that is in terms of the life cycle of tree species and the landscape we know is fragmented. So the limitations are seed dispersal, that is how fast and how far tree seeds can be dispersed to new sites. And the fact that if a site is already occupied by some forest trees, well then new species, new seeds have a pretty tough time getting in there. So it's another complication sort of at the ecological level on the dynamics of how forests work on a particular site. What we call ambiguous disturbance effects relates to this. So for example, if there's a forest site and it's already occupied, well if it blows down then new seeds will be able to get in there and perhaps become established and so that might, in effect help tree migration north. Then think again 40 years go by and this new, more southern tree species grow up and are almost old enough to disperse seeds and to sort of make the next move and then that stand gets blown down by wind or logging or fire, for example. So then maybe it's retarding the colonization of the landscape by the southern species that we think we will need to move. So that's what we mean by ambiguous disturbance effect, disturbances, things like logging, or fire, or wind. And you can see how it would be complicated because it's hard to predict are they going to be helping colonization and species to move or are they going to be hindering it. The other thing is it generational lags. Trees take a very long time to grow. And if you ever planted an acorn you have to wait for a really long time for a tree that you can put a table and a chair under. And it takes a really long time for a tree species to become true enough to actually have seeds to disperse. So that's the generational lag. And of course the landscape fragmentation. So thinking about these things altogether it makes it very difficult to project exactly how fast these changes are going to happen. But we think that we can say the southern species are going to be a little too slow going north given the rate of warming and the rate at which the northern species may decline. Now some tree species may do what we call escape on the landscape. And these are trees where the modeling suggests that they would tolerate the temperatures okay, even if it warms up. Things like white pine, sugar maple and southern Wisconsin oak trees. But let's focus on the north. We think they'll do fine with the temperature warming, but something else is going to happen and that is this balance of temperature limitation or moisture stress is going to become now very complicated. Because when things warm up they often tend to dry out more. So it just depends are we going to get more precipitation with global change or are we going to get less. Again, that's a thing we're not exactly sure of. The thing is, what will happen is what we call a resorting of the physical environment. We tend to think now of the landscape as pretty static. We know where there are dry ridges, we know where there are lakes, we know where there are wetlands. But if you think about it that's something that may change very radically. Areas that maybe quite wet soils now that are swamps, for example, may dry out and may become what we call mesic. That is sort of Goldilocks, just about right. Areas that are mesic now that support a broad range of tree species may become too dry for most tree species. So this is what we call a resorting of the physical environment. But it means that trees then that can hang around with the temperature okay like white pine and sugar maple are nevertheless are still going to have to move to different locations on the landscape because the conditions of the particular sites where they're growing, where sugar maple is very happy now, it has plenty of moisture, it may become too dry. So it's going to have to move maybe to a place that's maybe a wetland today but a hundred years from now is going to be just right for sugar maple. So complicated dynamics going on whether we're talking very local scales on the landscape or continental. Well, let's think some more about what kind of changes that we might actually see. And there's not a high degree of certainty about this but we have some idea of what the possibilities are. And some might be very rapid, some might be very gradual, some might be kind of erratic and difficult to predict. We think that gradual climate change may mean gradual forest change. That is something that maybe just, it takes decades before it's really observable. Decades at least. And it might mean things like a gradual decline in the growth rate of trees, maybe due to moisture and stress increasing and in turn that may cause susceptibility to different kinds of pests and diseases, they just become more easily stressed. Or there maybe a gradual decline in reproduction. That is, those really good years when a lot of trees, a lot of seeds are produced and a lot of seedlings are established. It just may occur less frequently, but this is still a relatively gradual phenomenon when you think about how long trees live. But there could be extreme events that could also prompt abrupt changes. Things that are observable in just a few years. For example, droughts of a couple of years in northern Wisconsin in the past have resulted in very high mortality of trees like black ash, for example, or paper birch, that generally require pretty moist conditions and can't tolerate drying out for very long. So there could be then relatively abrupt mortality, even, of certain tree species. Or some species might have crop failure, or conditions in the spring might be too dry and the seedlings or the seed germinate but the seedlings just don't ever really get well established. And the most extreme would be rapid decline of mature trees. So two kinds of change that we could observe. Whether we think of gradual climate change or if the gradual climate change is punctuated by more extreme events like droughts. So I've already said that we think from our modeling that there are about five tree species that I've already mentioned that are most vulnerable to decline with warming. Some species will persist maybe with lower productivity and vigor. For example, those really large vigorous aspens that we see in northern Wisconsin might start to look more like they do in southern Wisconsin where they just don't really quite seem too happy. I've also said that some species may escape on the landscape, that is they will be able to tolerate projected temperature changes but they're going to have to find a new place on the landscape for other reasons. So what this suggests, northern species declining but a delay with new southern species arriving is a declining tree species diversity. That is the number of tree species that are present on the landscape. And this has some implications for stability and economic viability and things like that. So we often think that-- or I focus on the fragmentation effect and the slowing the migration of southern species, but there's also this other aspect of even within a species there may be southern genes that will also be inhibited from moving in the same way. In other words, sugar maple occurs in northern Wisconsin and upper Michigan and it occurs all the way down to Arkansas, we call that sugar maple. But we also know there are differences across that gradient in terms of temperature tolerance and when they mature seeds, things like that. So we think about new species moving, but in fact something that's going to be less obvious is the fact that we can also move genes in the same species but that impart more tolerance of warmer climate. So that's a possibility even in terms of management. There are a lot of uncertainties, as I mentioned, in terms of the species responses to these new stresses. Temperature or moisture stress is obvious. Things like growing season length and how long it takes seeds to mature. Growing season total heat units. How hot a growing season is even besides its length. Variability in seasonal changes. It can actually have an affect on trees. How winter cold affects them, as well as summer heat. And also inherent genetic variability. And also the stage of vulnerability of a tree species. Whether it's at the stage of new seedlings that germinate in the spring and really require moist conditions to survive or whether it's mature trees that, because of their root system or because of the way they respire or something like that, are particularly vulnerable to moisture stress or heat. So consequences of change, obviously there's a whole suite. Economic and market changes, and this is very difficult to predict. But if we change the productivity of the forest, if we change the kind of tree species that are most abundant, obviously that will have economic consequences for how people use the forest. Wildlife habitat is another one, particularly in the north. Conifer species are often particularly important for habitat for a lot of tree species and really they've just been really coming back in the last half-century. And yet those are the more boreal northern species that are at greatest risk of declining. So there may be significant consequences for that. A lower carbon sequestration, this is the carbon that trees pull out of the atmosphere and tie up in their woody material, both above ground and below ground. And that's a break that serves in part on global warming. So there's this feedback if our forests become more vulnerable, if they start to decline more, there may be less carbon sequestration that occurs, and it may help to contribute, in fact, to this feedback system that actually causes more global warming. And then the whole issue of sustainability in terms of how we use resources in all these categories becomes very questionable. Well, there are other changes or challenges that I alluded to because they're going to be interacting with climate. Some of you are pretty aware that this picture here is emerald ash borer and it's an Asian pest on our ash trees, for example, and it's now becoming well-established in the Midwest. In fact, there are whole host of new pest species and diseases that are coming into North America. Partly this is a consequence of global trade. But with climate warming and becoming more hospitable for a range of organisms, then there's obviously an interaction going on where it just becomes easier for these new pests to become established and that can be a problem. At a time when forests are under a lot of stress for the climate and pest reasons, the prospect of possibly more intense harvesting, that is if human use and population continues to rise or other intensive harvesting, perhaps biomass, for example, burning or use in bioenergy fuels. All of that may pose a threat and a risk to forest health, as well. And deer browsing is sort of a continuing problem we have. They're just so abundant. And if they're also going to be stressing the forest it isn't really going to help. So what to do? Well, we have to try to reduce some of those stressors. Those are fairly difficult things. The other thing is adaptation. And there's a number of things we can do there. Because there are going to be some changes that we can't stop necessarily, but at the same time they are not all going to be catastrophic at all and in fact some of them may not actually occur. So the idea is I think in terms of forest management to be conservative. Don't do anything rash but take opportunities. Remember there's going to be a fairly high uncertainty of outcomes long term. People often ask that are managing their own forest land, and I think the big thing is don't be rushed into harvesting your forests. Unfortunately there's a little unethical behavior going on already. Not a whole lot but it's happening where people are being told that your trees are dying and it's because of climate change so we better cut them down. Anticipate site changes. That is, the most likely thing is probably going to be that any kind of given site conditions in terms of how moist the soil is in a location and what trees it supports, it's very possible to become drier either because of less precipitation per se or because precipitation doesn't change but it gets a lot warmer. So we might favor southern species and by that I mean species just say from southern Wisconsin. Especially on drier sites. So those oaks and hickories for example that do well on drier sites might be a good bet to plant on sites further north that now maybe are already becoming kind of marginal for species like sugar maple that like a moister site. So experiment with planting southern stock, and again this could mean both species and also in genetic material. In other words, the same kind of species but maybe from a little further south in its natural range. So I've been talking about the future and that's pretty much what we think about when we think about climate change. But now Dr. Sara Hotchkiss is going to take over on her part. She's the paleoecologist and she's really going to give us a case study and an example of what can we learn from changes that have happened with changing climate in the past with our forest and what that might help us to interpret changes in the future. Sara.

APPLAUSE

David Mladenoff

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Sara Hotchkiss

Well, I'm going to try to scale down now to a landscape. If all these projections of the future are often very difficult to relate to the place you care about, the place you manage, the place where you live, how do you think about that place and its context in this changing climate? Well, one way to get some perspective on that is to look into the history of the ecosystems in that place and to see how they have responded to climate changes in the past. We're going to look at some climate changes that are relatively mild compared with what we're looking at in the next even 50 to 100 years. But climate changes of the past few hundred years, and choose a particular landscape in northern Wisconsin to look at the responses of the forest to those past climate changes. And then think a little bit about what we can learn from the past behavior of those places to help us think and strategize about managing those places in the future. Here's the climate history that we're going to be thinking about. If you look on across the bottom of this graph, you're going from 2,000 years ago, the year zero, to the present, roughly. And on the Y axis you see temperature. And this is the difference between current average temperature and the temperature at a particular time in the past. And you're seeing 11 of the very best reconstructions of the temperatures in the northern hemisphere over this 2,000-year period. And there are a couple of events there that have boxes and the first one, the red box, is the medieval warm period. And this was a time when northern hemisphere temperatures were a bit warmer. There were, it was probably in a lot of places, drier. Certainly in the upper Midwest there were at least three or four major drought episodes during this time. This is the time when wine was being grown in Britain. This is the time when in Iceland and Greenland people were farming. It doesn't look like a very big temperature change, but it was big enough to really change a lot of culture issues in Europe. The next period in the blue box is the little ice age when things were a little bit cooler. And probably in the upper Midwest a little bit more moist, as well. And this is the time when farming had to be abandoned in Greenland and Iceland, and when people stopped growing grapes in Great Britain. So it's again just a little temperature shift, not even one full degree. And we're talking about considerably more than that in the next hundred years. So let's use these two periods and watch how the forests in a particular place changed during those two periods and use that to think forward. The particular landscape I want to talk about is in northwestern Wisconsin. It's that yellow sandy soil from the Bayfield Peninsula southwest to Grantsburg and the Minnesota border there. It's a big sandy outwash plain. And the vegetation on that sand plain at the time of European American settlement was mostly jack pines and oaks and red pines. And now on that landscape there's a lot of jack pine and oak, as well. There's much more oak than there was at the time of European settlement, after the trees were cut a lot of oak came back. But there are areas in the landscape that are managed for jack pine barrens and habitat for open barren species like sharp tailed grouse and karner blue butterfly. So it's an area of concern for management and it's an area with some interesting vegetation. And it's an area where you might think that the vegetation will be particularly sensitive to climate change because it's dry. So if it gets a little warmer and a little drier things might really change on this landscape. So what I'm going to do is use the sediments of lakes to reconstruct the history of the forest and the history of fire. And we're going to, I'm showing you a map of that sandy landscape. And the colors relate to the depth of the water table and the coarseness of the sand. And we'll come back to that a little bit. We're going to begin by looking at Lily Lake in the southern part of the sand plain there. And then we're going to look at Fairy Lake, kind of on the border of the darker colors there, and Metzger Lake out in the bright yellow where the open jack pine barrens are. This is a scale of landscape that people can relate to. Here's the open jack pines barren vegetation. And our goal is to think about how the history of different parts of this landscape might teach us something about what we need to see on a landscape to help predict how sensitive the vegetation is likely to be to future climate change. So let's ask how much did vegetation change in these two climate periods. What kinds of changes in vegetation occurred, and then how did the fire regimes change as well. We collected these histories in the wintertime because if you drop your tools while working on a lake in the winter they stay there. You can pick them up and continue working. I'm a terrible tool dropper. And we collected sediment cores from the bottoms of the lakes and analyzed the things that had been accumulating in the lake over time. So the deeper in the core, the older the materials, and we can use radiocarbon dating to put together a history. We count the pollen, the seeds, the charcoal, all of the things that accumulate in the bottom of a lake over time. And use that to reconstruct the history of the ecosystem. So as you can see, the soils in this very sandy landscape, if you look at the scale of the state it just looks very sandy, it's very different from the other soils nearby which are heavier and can maintain moisture better. But there is some variation across the landscape. In this southern part there are more swamps and more lakes and the water table is closer to the surface. And out in the central area the landscape is flatter, more open and there are fewer lakes, so fewer fire breaks and coarser sandy soils. So we'll begin by looking at Lily Lake in the south there. And the first question we're going to ask is how much change was there? How much did the vegetation change? So we use pollen. There can be 600,000 pollen grains in a tiny piece of mud, about a centimeter cube of mud in a bottom of the lake. So you can get a very good sampling of vegetation. It's not a perfect representation of which trees were there because different trees make different amounts of pollen that fly different distances so you see more of the pines than you do of the maples, for example, in a pollen assemblage. But we can use a metric that just compares, that calculates a mathematical distance between two samples of pollen assemblages. And what we're graphing here, on the bottom axis you see time from 4,000 years ago to the present. And the Y axis is that distance, that difference between pollen assemblages. And what we're measuring the distance to is the sample at the time of European American settlement. When the public land survey was done, mapping all of the trees before they were cut. So the little red arrow on the right marks that sample and the line tells you how different each sample is from that sample over time. So now look at the blue box, during the little ice age the vegetation was pretty similar to the vegetation that was seen by those European American surveyors. Before that in the medieval warm period the vegetation was really quite different from the vegetation during the little ice age. So there was a big change even with that fairly small temperature change there was a big change in vegetation. So let's look a little bit more into what kind of change that was. Here on the bottom you see that graph of the amount of change again. So it's less change during the little ice age and more difference during the medieval warm period. And if we look at the pollen assemblages which we have lost-- We'll look at pollen in one of our later sites I guess, but what happens during the little ice age is a little bit more white pine pollen accumulates. So there was more white pine at this site during the little ice age than before, and in fact than during thousands of years before then. And this few hundred years of the little ice age had more white pine growing on this sand than afterwards. We can summarize that history in these colors. And you can see during the medieval warm period there was oak vegetation and then during the little ice age it shifted more to white pine oak or pine oak mixed vegetation. So there's a real change in the stand type. The same time, the number of fires on the landscape really dropped. We've lost that graph too. But we have during the medieval warm period, four or five fires per 300 years and then during the little ice age almost no fires occurred on the landscape. So there was a big drop in fire occurrence on the landscape during the little ice age. So that's a history of a place. More white pine, less fire, with this small climate change. So there was a clear change in vegetation at this site. How representative is that of the rest of the sand plain? Let's look at one on the border there. Fairy Lake, that's just north of Lily and it's kind of on the edge of those coarser sands. Here again we have very low rate of change through that whole period actually. There's an increase in the rate of change at the time of the climate transition. A little after the transition into the little ice age, the rate of change of vegetation increased. Again we don't see our pollen types but what happened is white pine increased during the little ice age. And you can see that history in the vegetation interpretation. It's jack pine/red pine forest during the medieval warm period and then it becomes more pine/oak forest with a little more white pine in it during the little ice age. And once again the number of fires dropped during the little ice age. So that is generally true across the landscape of the dozen or so places we've studied on this landscape ten of them have a drop in fire during the little ice age which makes sense, it's cooler, it's little moister, fewer fires on the landscape. So you can take that generality if you saw this kind of climate change coming and guess that there would be less disturbance by fire or if you were using fire as a management tool you might want to use less fire in order to encourage the kind of vegetation that tolerates this type of climate a little bit better. As we look forward into the future we may want to look backward in time into the forests during the medieval warm period when there were strong droughts and even before that when there was much more oak on this forest, on this landscape. And when you begin to look farther back in this landscape you see very sudden changes in vegetation. At this site, for example, there's a little bit more oak during the medieval warm period but it's still really a pine forest. 4,000 years ago it was really an oak forest. And that transition from oak to pine happened very suddenly, in about a 50-year period. Suddenly it shifted from being an oak forest to a pine forest and there's no obvious fire or any local cause of that sudden shift. It was probably a threshold that was crossed in the midst of a fairly gradual climate change. So we can look to the past to find evidence of that kind of sudden surprise and evidence of the context around when that kind of thing can happen. So the last place that we like to look at is Metzger Lake. It's out in the middle of that open sandy jack pine barrens area. And it has a rather different history than these other two sites that we've been talking about. The vegetation did not change a lot during that trend, this small climate change. It changed a little bit. There's a little bit less red pine, there's a little bit more jack pine. During the little ice age, there's a bit more white pine, but it's really pretty consistently jack pine vegetation through this whole period. And the rate of change of vegetation stays high but fairly consistent through the whole period. The number of fires actually increases through the little ice age, stays fairly high through the whole period but into the middle of the little ice age the amount of fire is actually increasing at a time when it's cooler and moister. So that leads to some of the things that you were thinking about earlier in the first half of the talk. That vegetation responds to changes in climate with increases in growth rates, increases in moisture. Perhaps in this very open, dry environment with a little bit more moisture there was more production of vegetation and therefore more fuel, more available to burn in this fairly dry place where it might still burn, just that there might be more there to burn so you would see more charcoal and more local fire events. So what are the things that one could look at on a landscape to think about whether this particular place might be more or less sensitive to climate change? We saw that soil texture might have something to do with which direction a difference in moisture pushes the vegetation. Which kinds of tree species might escape on the landscape into a particular local area depends partly on the texture of the soil. Also the context in the landscape. Is it surrounded by lakes and wetlands? Is it very unlikely to burn? Are we unlikely to use fire as a management tool, or logging? Those make a big difference in the susceptibility of the vegetation to change in species composition. And we can see in the past that those have made a big difference but kind of in a counterintuitive sense on the this sandy landscape. In the southern area where it's wetter, there are more wetlands and lakes and hills, and fire doesn't travel as well, the vegetation actually changed more with these little climate changes of the fairly recent past. We may expect that vegetation to be more sensitive to future climate changes than the vegetation out in the central barrens area where it's fire adapted and we do a lot of logging and jack pine is pretty much the only thing that can handle it out there. So that's a little counterintuitive. You might think of the most extreme environment as most sensitive to climate change but actually the history of these places suggests that the more moister part of this sand plain where there are more species in the area might be more likely to change vegetation in a particular local place that you might care about. So how do we use that to think about the future? We can draw from this history that places that have responded differently in the past to similar climate changes may also do so in the future. I've been telling you a story about a landscape that's very sandy. The landscape next door that's has more clay in the soil and better moisture holding capacity may have a very different or even opposite story with respect to how the local landscape influences sensitivity of vegetation to climate change. If we focus our thoughts for the future on places that we know have been most sensitive to past climate changes we may see more easily the keys to our best strategies for managing those places in the future. The climate changes we've been looking at were considerably milder than the climate change that's presently under way. And each of those is a few hundred-year period. We're talking about changes in the next 50 to 100 years that are much bigger than the changes that happened between those two periods that each lasted a few hundred years. In addition, the histories that we've been looking at occurred in a landscape that was much less fragmented than the modern landscape. So we can draw lessons from the behavior of species in a landscape in which there was access to migration. Plant species were able to get places more easily than they do now. So if we can look into the past, especially perhaps into the past time on this landscape where there was much more oak, much more of the species we think of as a southern Wisconsin species. We can study those ecosystem's behavior in a more oak dominated forest. We can be able to use those histories to suggest management strategies for the taxa that may have difficulty migrating across either the fragmented belt in central Wisconsin or in the corn belt coming from farther south. So adaptation is the key and flexibility is the key. The thing that we learn from the past, especially the deeper we look into the past, is that surprises happen, surprises can be fairly dramatic, vegetation type can change very quickly. And if we can learn something about where to expect those surprises more often than other places, if we can learn from the behavior of ecosystems when one of those surprises occurs, we can build strategies into our modern thinking about forests in this time in which we know that variability of climate is increasing and we know that the rate of climate change is faster than anything that has been seen in the recent past. So we need those lessons to contribute to the work that you heard about in the first part of this talk from Dr. Mladenoff where we can think about the landscape and the climate and the qualities of the species in the context of our landscape we have available right now and the set of management strategies we have to use. So thank you for your attention.

APPLAUSE