cc  >> 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]  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]  >> 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]