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Climate Change, Mountain Pine Beetles, and Whitebark Pine

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Climate Change, Mountain Pine Beetles, and Whitebark Pine Forests of the Greater Yellowstone Ecosystem


Ashley Fortune:  Good afternoon from the U.S. Fish and Wildlife Service's National Conservation Training Center in Shepherdstown, West Virginia. My name is Ashley Fortune, and I would like to welcome you to our webinar series that's held in partnership with the U.S. Geological Survey's National Climate Change and Wildlife Science Center.

The NCCWSC Climate Change Science and Management Webinar Series highlights their sponsored science projects related to climate change impacts and adaptation, and aims to increase awareness and inform participants like you about potential and predicted climate change impacts on fish and wildlife.

I would like to welcome Emily Fort, Data and Information Coordinator for the NCCWSC to introduce today's speaker. Emily?

Emily Fort:  Hi, and thanks everyone for joining us. I just want to introduce Polly. She's a research associate in the Department of Geography and a PhD student of Environmental Science at the University of Idaho. She has a master's in Wildlife Biology from the University of Montana and a bachelor's in Wildlife Biology from Colorado State.

Currently, she's working on understanding the influences of climate on mountain pine beetle outbreaks and incorporating outbreak potential into ecosystem process models. She's also working with the Forest Service to develop a framework for downscaling regional vulnerability assessments to local levels. With that, I'll turn it over to Polly. Thanks everybody.

Polly Buotte:  Thank you. Thank you all for tuning in today. I appreciate the opportunity to be able to share this research with you. First, I'd like to acknowledge the coauthors, Jeff Hicke at the University of Idaho, Haiganoush Preisler with the Forest Service, and Ken Raffa at the University of Wisconsin. Today, I'd like to share our research on climate change, mountain pine beetles, and whitebark pine forests of the Greater Yellowstone Area.

For today's webinar, I'll start with an introduction to whitebark pine and mountain pine beetles. After the objectives, we'll have a brief description of our methods, spend some more time on our results and some discussion of those results, the conclusions that we're drawing from this research, and then I'll finish with just a oneslide summary.

Whitebark pine is a keystone species in high elevation forests of western North America. It can survive in very cold and arid conditions, and once it's established it then allows other lesshearty conifers to establish.

It's a very slowgrowing species and it allocates a lot of its resources to producing seeds with a very high energy content. These seeds are an important seasonal food resource for a range of animals, including red squirrels, Clark's nutcrackers, grizzly bears, and, as I've learned recently, alpine fox also eat these pine cones.

Currently, Whitebark pine is declining across much of its range in the western U.S. The Fish and Wildlife Service has Whitebark pine listed as warranted for inclusion under the Endangered Species Act, but currently it's excluded due to funding constraints.

This decline can be attributed to several reasons. One is the occurrence of an introduced pathogen, which is shown in this upperleft photo, white pine blister rust. This infects the tree and, if it gets to the trunk of the tree, can girdle it, interrupting the transport of water and nutrients.

Another reason is encroachment from lowerelevation conifers that are more shadetolerant and faster growing. This is primarily a result of fire exclusion policy.

Most recently, and perhaps most extensively, Whitebark pine is declining due to attack by mountain pine beetles. Mountain pine beetles are a native forest insect. Historically, they've been more common in lowerelevation lodgepole pine forests, but recently, there's been a significant, substantial amount of Whitebark pine mortality from mountain pine beetles.

Ashley:  Polly, sorry to interrupt. Can you get a little bit closer? We have some people who are having some trouble hearing you.

Polly:  OK.

Ashley:  Thank you.

Polly:  This is a map showing forested areas in gray, with areas with Whitebark pine mortality from beetles in red. The time series along the bottom is showing the area with observed mortality in the Greater Yellowstone region, beginning in 1998 through 2009. This recent outbreak has affected about 66 percent of the range of Whitebark pine in the Greater Yellowstone.

The photo on the right, that's what a tree that's been attacked by mountain pine beetles looks like. The needles all turn red, because the tree has died.

I'd like to give you a little bit of background on the life cycle of mountain pine beetles, they start as a native insect that has been most common in the lodgepole pine forests. As adults, these beetles fly into trees where they bore through the bark. They're trying to construct egg galleries, to lay their eggs.

As they bore through the bark and begin constructing their galleries, they emit a pheromone, which is a chemical signal to other beetles that says, "Come attack this tree. Everybody, concentrate on this tree," because then a massive attack of beetles can overcome the defenses that a tree mounts to prevent that attack.

When an attack is successful, the eggs are laid in the galleries. They develop then through the fall into larvae and come winter, development stops. They overwinter in the larval stage.

In the spring, as temperatures warm, development resumes again until the following summer, when new adults emerge and fly to attack new trees, so a tree that is red this summer was actually killed the previous year.

There are a couple of places in this life cycle where climate plays a really important role. First is adaptive seasonality. This is for the beetles to have a one year life cycle and you have a synchronous development such that there's a mass emergence of adults in late summer. This is known as adaptive seasonality.

This depends strictly on temperature. Their development rate, each life stage, has an optimum temperature for development. This life cycle is controlled strictly by temperature.

Another important point in this life cycle is during the winter, so larvae develop cold hardiness and the later larval stage are the most cold tolerant, to temperatures low enough to kill even those coldhardened larvae. So in winter, beetle mortality becomes important, particularly in these higher elevation whitebark pine forests.

Another important place is when the adults are attacking trees. As I said, the trees have some defensive abilities. They try to literally pitch out the beetles, using the pine pitch. This photo is showing a pitch tube on a whitebark pine. The tree is trying to eject the beetle from it before it can get in and lay its egg gallery.

But a tree that is experiencing drought stress then doesn't have as much resources to allocate to defense. It's allocating more of its resources to simply surviving and storing carbohydrates.

A weakened tree can be successfully attacked and killed by fewer beetles than a healthy tree can, but even a healthy tree can be successfully attacked and killed given a large enough beetle population.

This defensive capability has been fairly well studied in lodgepole pine, but it’s thought, and initial research has been showing, that whitebark have a lower defensive capability, although they still obviously do have some ability to defend themselves.

It's thought that they have this lower ability because they've had less interaction with mountain pine beetles through their evolutionary history, because they live in the higher elevation, colder places.

Our research objective, we had three primary objectives. First was to quantify the climate/beetle relationship in Whitebark pine. The second was to understand the causes of the recent outbreak and the third was to estimate the historical and the future weather suitability for beetle attacks in whitebark pine.

We divided the range of Whitebark pine in the western U.S. into three different geographic regions. Today, I'll be focusing just on the results for the greater Yellowstone area.

To get to objective one, to address objective one, we used statistical modeling, or developed a model for the probability of tree mortality, given beetle pressure, stand structure condition, and climate condition. Our response variable is the presence of Whitebark pine mortality from mountain pine beetles.

This comes from Forest Service Aerial Detection Survey data in which observers in aircrafts record the tree species and the mortality agent as they fly regions on the western U.S., and this has been done in Canada as well. This was gridded to a onekilometer spatial resolution by Meddens and others.

For final explanatory variables, with beetle pressure, we had two variables. One was local beetle pressure which was the number of trees killed last year within that onekilometer cell. Second was dispersal beetle pressure, that's the number of trees killed last year in a sixkilometer radius outside of that local cell.

We wanted to seperate the effect of beetles developing locally or those coming in from somewhere else. These, again, come from Aerial Detection Survey data.

For stand structure, we represented that with the remaining Whitebark pine. Because we're working in a onekilometer spatial resolution, that is equal to a hundred hectares. 100 minus the cumulative mortality area since the outbreak began in 1997 gave us an estimate of the potential remaining Whitebark pine.

We also used the percent Whitebark pine in each grid cell, and this comes from a 30meter map of the range of Whitebark pine developed specifically for the Greater Yellowstone Area by Lisa Landenburger and others.

Finally, we evaluated data sets that provide estimates of tree biomass, and tree diameter or tree size, and basal area, but there were too many places where Aerial Detection Survey indicated a very high number of trees killed, and one or all of these databases had no biomass or a diameter of zero indicating it was not forested, or basal area is zero. Therefore, we were unable to include any of these in our analysis unfortunately.

For climate, we represented the process of adaptive seasonality with several variables using average, fall, and spring temperatures. This comes from 800meter PRISM data. We also used the Logan Adaptive Seasonality Probability, which is a process model developed to estimate the probability of a oneyear life cycle of development and mass emergence.

Several daily temperature metrics that describe lengths of temp and beetle development days and growing degree days. Your daily adaptive seasonality probability comes from a BioSIM software along with daily weather station data. For these variables we looked at the current year which would have been the winter before the tree was killed, the fall before the tree was killed. Previous years, we captured the possibility of there being a twoyear life cycle, not just one really.

Beetle winter mortality, we represented with two different variables. The minimum winter temperature, which is the minimum monthly December, January, February temperature. And from PRISM, we can do metered data, and cold tolerance which is another process model that, I guess, the probability of beetle survival over the winter, which again comes from the BioSIM modeling framework.

And these, we also represented which was the current and previous year to capture this possibility of a twoyear life cycle.

Tree drought stress, we used water year precipitation, summer precipitation, climatic water deficit, and vapor pressure deficit. Previous research has indicated that a range of timing of drought can be important, affecting tree defensive capabilities. So we included current to fiveyear lags for each of these variables. This comes from PRISM data.

For our model structure, we used the logistic model as a binary response for presence or absence of tree mortality. We used the generalized additive model which allows for a nonlinear relationship between the explanatory and response variable. We developed a set of candidate models. Each of which had representations of beetle pressure, stand structure, and one variable representing adaptive seasonality, winter mortality, and tree drought stress.

Then, we used an AIC model selection process with this set of candidate models to select the very best model.

Here's objectives two and three which were, what were the causes of the recent outbreak and what did historical and what will future weather suitability look like. We took our best model and applied it to historical weather using monthly PRISM data from 1900 to 2009 and then for future projection.

In here, we wanted to be sure to capture a range of future possibilities, so we used 10 different general circulation models or GCMs under three emission scenarios. These are RCP 2.6, 4.5, and 8.5 which represent low, medium, and high emission scenarios. After applying the model to these data sets, we then calculated the weather suitability index as the sum of the weather terms in the model.

Now, our best model, on to results. Our best model, we retained both the local and dispersal beetle pressure, percent whitebark pine representing stand structure. Adaptive seasonality, that's represented by the combination of fall temperature and spring and summer temperature. Beetle winter mortality was best represented by winter minimum temperature, and tree drought stress by the cumulative twoyear summer precipitation.

We wanted to know, how well did the model do? This shows in black, the observed area with mortality each year. In red, the predicted area with mortality. Those dashed lines, the 95 percent confidence interval. The predictions are very similar to the observations. Spatially as well the predictions are similar to the observations. These maps show the cumulative years with mortality of light blue being no years, and for the bright pink being up to 11 years with mortality.

Again, we felt the model did quite well capturing the temporal and spatial variability. We felt we could move on to address objective one, which is what are the climate beetle relationships in Whitebark pine?

Each of these next slides will have the line graph on the top which describes the relationship between the variables and the probability of tree mortality. The histogram on the bottom showing you the distribution of that variable in the input data.

Here, on the left, is fall temperature. If fall temperature is increasing on the xaxis, from left to right, the probability of tree mortality is increasing very steeply.

Here, this is probably portraying synchrony. That is, allowing the eggs that are developed at different weeks, different days in the summer are all developing until they're reaching that coldhardy larval stage before winter. Their survival is greater. Their synchrony is greater. Therefore the probability of tree mortality, their ability to kill trees, is greater, up until it plateaus. Further increases in temperature really have no effect. They've all reached the ideal development stage.

On the right is the effects of April through August temperature. It's showing a similar response, but see the solid line in the middle is the average response and the dashed lines are the 95 percent confidence interval.

We can see that these confidence intervals are very wide for April through August temperature. They bound zero, across most of the range. Therefore, what that's saying is given the data that we have to work with we really can't see anything conclusive about the effects of temperature in the summer.

Moving next to beetle winter mortality, as winter minimum temperature increases on the xaxis from left to right, beetle survival is increasing from not being killed by the very cold temperatures. Therefore the probability of tree mortality is also increasing. More beetles survive the winter, who then emerge following summer and attack trees, which they then kill.

Again this is showing a plateau effect where enough of the population has survived when you get above approximately 14 or 13 degrees Celsius, but it's not increasing the tree mortality anymore. Enough have survived.

Finally looking at the relationship to drought stress. This one in the axis is precipitation. As precipitation increases from left to right, drought stress is increasing in the opposite direction. A decline in precipitation moving from 800 millimeters back to 300 millimeters is an increase in the tree level of drought stress.

If trees are stressed, the probability of mortality is increasing because they have less resources to defend themselves, to allocate to producing pitch to get rid of the beetles. You notice at the very highest levels of drought stress are the very lowest levels of precipitation. There's an apparent decline in tree mortality.

Again, the confidence intervals were so wide we can't say anything conclusive here, but it can offer a couple of potential explanations. One is that the trees become severely drought stressed and their tissues dry out. They don't provide very good food for beetles. The eggs that are laid simply don't have enough to eat and starve to death. They don't develop into new beetles who hatch and attack the trees.

Another possibility is a geographic explanation. All of the places in this region that have these lowest levels of precipitation are in the southern Wind River Range which is part of the study area that receives the least amount of precipitation. It's also the part of the study area that is quite cold and has seen the least amount of fetal attacks over the recent decade. Again, we can't be conclusive about the very highest levels of drought stress.

Now I want to move to our second and third objective, which were what caused this recent outbreak and what did the past look like and what does the future look like. To do this again, we'll be looking at the weather suitability index that we're calculating after we apply the model to historic and future climate data.

This is a look at weather suitability from 19002009. The light gray line shows the outbreak area so you can get a sense for when this recent outbreak began. Throughout this half century there has been a lot of fluctuation. There's been some years of above zero, which is suitable for attacks, and there's been quite a few years of below zero, which is unsuitable for attack.

This red dashed line here indicates minimum suitability observed during the recent outbreak. What we see is that once the outbreak began the weather was consistently suitable. This is an average of all of those one kilometer pixels within the greater Yellowstone for each year. There was one year where the average dips below zero.

Concurrent also the area with mortality declined in that year, but it wasn't enough to end the outbreak.

If we look more closely at this, the colors now represent each of those three important variables, winter minimum temperature in blue, fall temperature in orange, and summer precipitation in green. What is really noticeable is a lack of cold winters during the recent outbreak.

Throughout the previous century there are periods where you see the blue line dipping very low and indicating here it's cold winter. The temperature was cold enough to kill even the coldhardiest beetles.

That was preventing outbreaks from really getting going, preventing the beetle population from really getting established. But beginning about two years before this outbreak really took off, winter temperatures became suitable and they remained suitable for the duration of the outbreak.

Then in 2000 when the outbreak was really increasing in area, there was concurrence of not only a lack of cold winters, but also a summer drought.

This is looking at the spatial variability and weather suitability across the region and mapping the number of cumulative years with suitable weather conditions for the blue being no years of suitable weather through red being up to 10 years. This is based on PRISM data from 20002009 for the range of Whitebark pines.

For those familiar with this area, you'll notice that this looks like more than the range of Whitebark pines. I just did that so the distinction in the colors would show up better.

What we see is that there are some places, particularly in the upper right, the northeast corner of the study area, that patch of blue...The Beartooth Plateau, which is a high elevation, really cold place. In the lower right, the southeast portion of the study area, those are the Wind River Range jutting out. The unsuitable places are again falling out of mostly the high elevation parts of the study area.

What does the future hold? This I'll take a minute to walk through. The upper panel is future winter minimum temperature projections. The middle is future fall temperature. The bottom is future precipitation projections. The left hand column is RCP 2.6, the low emission scenario. Middle column is RCP 4.5, middle emission scenario. The right hand column is high emission.

The black line is the average over the greater Yellowstone for PRISM historical data. The solid darker gray line is the average of the 10 GCMs that we were using. The lighter gray polygon shading is the range founded by those three GCMs.

What we can see is that future warming is occurring. The models agree on future warming in fall and winter, particularly under the higher emission scenarios, and particularly later into the century.

Future precipitation, however, is less certain. The GCMs don't all agree on what precipitation will look like into the future. Although it does appear to be mostly within the range of historic variability.

We've then applied our model to this data. What will future weather suitability look like? This is top panel, low emissions. Middle panel is medium emissions. Bottom panel is high emission scenarios.

Again with the solid black, the historical PRISM data. The average of the GCM and the shading abounding with the GCM. I've indicated here with the red box the recent outbreak so you have a sense of what the weather suitability looked like through the historical period, the outbreak period, and into the future.

What we're seeing unfortunately is weather suitability through the past is increasing again as under higher emission scenarios and later into the future. We also want to look a little more closely here and now we're looking again. Top panel is winter minimum temperature. Middle panel is fall temperature. Bottom panel is precipitation.

The yaxis is weather suitability for the three emission scenarios. We're seeing that there are still some years with low winter suitability, even under RCP8.5 and later in the century.

Fall temperature is not having any limiting effect into the future. It's all become suitable. Fall temperatures will be allowing for beetles to develop into a synchronous, not to emerge until the following summer. We're seeing a lot of variability in the effect of precipitation.

This, I would add, is also the variable that we're the least certain of its effect. This is the one that I think needs more research done on it. There are a couple of reasons why precipitation could be having an effect on mortality. Not only for tree defenses, but it could be an effect of the pheromone signaling in the trees themselves to emit chemicals when they are drought stressed that are similar to the pheromone signals that the beetles emit.

I would just point out that there is still a lot of uncertainty in the effects of precipitation. But there is less uncertainty in the effects of temperature. We're seeing that if temperature increases that is increasing the suitability for beetles to exist in these forests.

But there still is the chance for unsuitably cold winters. When we were looking at the historic weather suitability, that was the most noticeable change was that lack of cold winters was the big difference between the recent outbreak and the previous century, in which there had been several other, smaller outbreaks in Whitebark pine.

But unfortunately the probability of unsuitably cold winters that kill a large part of the beetle population is really declining under all emissions scenarios in the future.

We looked at the Beartooth Plateau, that was a place that has been very unsuitable for beetle activities in the last decade. But just a few weeks ago we were there and looking around at what was happening. These red trees that you see in the trail have, under their bark, these developing beetles that will emerge later this summer to fly to attack new trees.

I wouldn't classify this as outbreak conditions, but it is persistent, low level beetle activity even in this place that, from the modeling, is the least suitable place for beetles.

A few things. Of course, every bit of research has its caveats and ours does as well. The first is that we're relying on aerial survey data and there is certainly the potential for error when people in airplanes are mapping tree species and mortality agents. There is always potential for visual errors, for misidentifying tree species.

Another missing piece of the puzzle is lack of meaningful stand structure data. The previous work in both lodgepole pine and whitebark pine has shown that beetles prefer and select larger trees. We just didn't have the data available to be able to conclude that.

But I will say that we did include a very finegrained spatial term which was trying to account for variability on the landscape that could be due to the structure. Including that didn't at all influence our interpretation of the climatebeetle relationship that I have just presented. Even if we can include structure and it is important, I don't think it will influence our interpretation of the climatebeetle relationship.

Some conclusions and implications that this has led us to. One is concerning the persistence of Whitebark pine on this landscape. This will largely be determined by this intersection of the time to conebearing age and the time between cold winters. Even in places that have experienced heavy mortality, there are still medium sized and certainly small regenerationsized Whitebark pines.

Persistence, then, becomes this tradeoff between how long does it take the remaining trees to grow to produce cones and how often can we expect there to be a severely cold winter that will knock back the beetle population, as well of course as what is the spread of blister rust and encroachment from other conifers, how are those factors influencing tree survival.

There are some planting efforts currently going on where people are planting out blister rustresistant seedlings in hopes that because some of the trees that there have enough genetic differences that some trees are showing resistance to blister rust, which is a really great thing. We would recommend that these planting efforts focus on high elevation areas, places that experience cold air drainage, wherever the places on the landscape that are the most likely to experience cold winters to give those trees the most time to grow and reach conebearing age before a beetle attack can come and kill most of them.

We, as a global community, we need to work to reduce global carbon emissions. With RCP 2.6, which is a reduction from current emissions, is the best, brightest possible future for the persistence of Whitebark pine on this landscape. I recently heard Cara Pike from Climate Access say that we are not preaching to the choir. We need to make sure the choir is singing.

In summary then, we've seen that whitebark pine tree mortality from beetle attacks increases with both higher fall and winter temperatures and increasing summer drought. The recent outbreak was initiated by the combination of warm winters and summer drought.

The lack of cold winters is the most noticeable change over the last century. Future weather suitability for beetle attacks is unfortunately mostly higher. There are some projections with reduced suitability and those are from GCM and emissions scenarios with greater precipitation.

The trend of fewer cold winters is only increasing into the future. Therefore we really would suggest that restoration and planting efforts focus on those places that have the best chance of experiencing cold winter in the future.

I'd like to thank our funders, particularly the Northwest Climate Science Center. Thanks also to our Scientific Advisory Committee and particularly to Arjan Meddens. Thank you all for your interest and participation today.

Ashley:  We did have a question early on, on I think your first map that was the red and gray. It was, “Why was California left off?”

Polly:  California was left off because the aerial detection survey there is very spotty. They can't fly everywhere every year. California just doesn't have very good coverage. There just isn't enough data to do this across the whole Sierra Nevada. Also I'll say that in our modeling, anywhere that was not flown was excluded from our analysis. We didn't assume no mortality just because there were no flights.

Ashley:  Thank you. We have a question from Darren, and it says he is just making sure that he heard you correctly, that some beetles have a two year life cycle. If that is what you said, what is the difference between the one year and the twoyear life cycle populations?

Polly:  The beetles can have a twoyear life cycle, particularly in colder environments because their development is controlled by temperature and so it may take two years for enough heat to be accumulated for them to develop into adults. When that happens, that just increases the chances that the beetles will die before they reach adulthood. They have to overwinter twice instead of just once. When that happens it leads to, usually, a lower beetle population.

We were including that in the model to see if in this area did it appear that they were functioning on a one-year life cycle or a twoyear life cycle. It was overwhelmingly apparent they were functioning on a one-year life cycle.

Ashley:  Thank you. A question from Dave and it says “could you contrast the MPB outbreak thresholds and behavior in the whitebark pine versus the lodgepole pine?”

Polly:  Yes, that is an interesting distinction. This is the part where the drought stress is so interesting because there has been a lot of work done on mountain pine beetle outbreaks and lodgepole pine. That work has shown that there is this interaction between beetle population and drought stress. When beetle populations are low and trees are stressed, the beetles are able to kill the tree. But then as the beetle population grows, drought stress becomes less important and beetles can kill even healthy trees.

But in the Whitebark pine, we looked at an interaction between beetle pressure, the number of trees killed last year, and drought stress. We didn't see any differences in the effects of drought stress at low populations and at high populations.

That's another indication that we just don't yet understand the role of drought stress in whitebark pine. Is it primarily affecting tree defenses, or is it affecting the chemical production and the trees are producing chemical signals that are similar to the beetle communication signal? We really don't have a clear picture just yet.

Ashley:  Another question from David and it says can these findings be extended to other high altitude pine species in the West?

Polly:  We're trying to extend this to the Northern Rockies and the Cascades. But what we're finding is that, even for the Whitebark pine modeling, the models just aren't performing as well in these other regions. I think that is probably because of the way Whitebark pine grows in other areas. In the greater Yellowstone, there are lots of stands of trees that are mostly Whitebark pine. But in the Cascades and the Northern Rockies, there is more of an intermixing of tree species.

In the Northern Rockies, there has also been a lot of mortality from blister rust. Knowing exactly, even working at a one kilometer spatial resolution, how much of that really is Whitebark pine is really hard to say. Right now it is not clear to me if the relationships are all that different or if the data is just not as robust to be able to identify this relationship.

As of yet, I am sorry I don't have a very clear answer to that. Although it is still winter mortality and drought stress, summer precipitation influence on drought stress that are coming out as the top variables. We are seeing some similarities, but the models aren't as good.

Ashley:  Polly, is it OK if people contact you with any additional questions that they may have?

Polly:  Yes, certainly. My email is at the bottom of the screen, Certainly, feel free.

Ashley:  Thank you very much, Polly.

Polly:  Thank you all.

Ashley:  Thanks everybody, have a great day.

Transcription by CastingWords



Title: Climate Change, Mountain Pine Beetles, and Whitebark Pine


This webinar was conducted as a part of the USGS National Climate Change and Wildlife Science Center's Climate Change Science and Management Webinar Series. Whitebark pine (Pinus albicaulis) is an important, high-elevation tree species that provides critical habitat for wildlife and supplies valued ecosystem services. These trees currently face multiple threats, including attack by mountain pine beetles. The project team, including Polly C. Buotte and Jeffrey A. Hicke (University of Idaho), Haiganoush K. Preisler (US Forest Service), and Kenneth F. Raffa (University of Wisconsin), aimed to increase the understanding of the causes of the recent mountain pine beetle outbreak, and to estimate future outbreak potential given future climate change. As Polly will discuss in this webinar, researchers developed generalized additive models of the probability of tree mortality from mountain pine beetles, and then applied the best model to future climate projections. The team determined the presence of whitebark pine mortality from mountain pine beetles using USDA Forest Service aerial surveys. Researchers found that the probability of tree mortality increased with increasing winter minimum temperature, increasing average fall temperature, and decreasing summer precipitation. Across all climate models, scenarios, and time periods, the average odds of whitebark pine mortality were greater in the future than in 1950-2006, and similar to or greater than the odds of mortality during the recent outbreak. These results suggest the potential for severe future mountain pine beetle outbreaks, given there are suitable whitebark pine trees present. Join the webinar to learn more about the findings from this project!

Location: , Yellowstone, USA

Date Taken: 7/22/2014

Length: 44:03

Video Producer: Holly Padgett , U.S. Geological Survey

Note: This video has been released into the public domain by the U.S. Geological Survey for use in its entirety. Some videos may contain pieces of copyrighted material. If you wish to use a portion of the video for any purpose, other than for resharing/reposting the video in its entirety, please contact the Video Producer/Videographer listed with this video. Please refer to the USGS Copyright section for how to credit this video.

Additional Video Credits:

Polly Buotte, University of Idaho;
Ashely Fortune, FWS National Conservation Training Center;
Holly Padgett, USGS National Climate Change and Wildlife Science Center;
Emily Fort, USGS National Climate Change and Wildlife Science Center;
Northwest Climate Science Center


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