Molly Samuel

Trees, grasses and freshwater aquatic systems all play a part in the carbon cycle.

The U.S. Geological Survey is developing a series of reports on how much carbon and other greenhouse gases the nation’s ecosystems hold. Trees and plants, soils and rivers, farms and wetlands all sequester carbon to greater or lesser extents. But how much? And how might that number change in the future? That’s the crux of the USGS study, which was initiated by the Energy Independence and Security Act of 2007 [page 223 of the PDF]. (There’s a simultaneous study, also by the USGS, to assess geologic carbon sequestration).

The national assessment will include details on greenhouse gas sequestration nationwide: how much carbon is stored now, how that carbon sink might be altered by different land use scenarios in the future (for example, increased or decreased logging, urbanization, wetland restoration efforts or agriculture), plus impacts from other sources, such as wildfire and climate change.

To tackle this immense project, the agency divided the country into regions. The assessment on the Great Plains came out late last year. Next up is the West, including California, due out this summer.

“The diversity of California is a story in and of itself,” Ben Sleeter, a USGS research geographer who’s working on the assessment told me. The Coast Range, the Klamath Mountains, the Sierra Nevada, the Central Valley and California’s deserts all store different amounts of carbon. There are diverse land management approaches in each area. And future land use options are varied, too. “It’s enormously complex,” he said.

The USGS study won’t gloss over the details. I asked Sleeter if I’d be able to learn the amount of carbon sequestered in the Sierra Nevada, and he said I could get much more specific than that. “If you were curious about an area near (Calaveras) Big Tree State Park, we will be able to summarize the land use changes and carbon sequestration changes for that area.”

To help present the data, the USGS is collaborating with UC Berkeley’s Geospatial Innovation Facility, the group that developed Cal-Adapt, to create a similar tool, which will make the information in the assessment more accessible.

Lauren Sommer

Climate change and invasive species threaten Lake Tahoe just as restoration funding dwindles.

Over the last 15 years, more than a billion dollars has been spent to protect Lake Tahoe’s clear waters from runoff and erosion. Now, new threats to lake’s clarity are emerging, just as restoration funding is drying up.

Researchers from UC Davis are hot on the trail of one of those threats. On a recent late summer morning, Katie Webb and a team from UC Davis’s Tahoe Environmental Research Center went looking for it on a boat near South Lake Tahoe.

Hear the radio version of this story Wednesday on The California Report.

“So what we’re looking for is a metal clam corral,” Webb says, pulling on her scuba gear. The “clam corral” is a wire basket that holds clams living on the lake bottom. Webb swims down to it and attaches a rope, so the team can pull it on board.

The clams inside are Asian clams, an invasive species. They were not a welcome visitor when they were discovered in Lake Tahoe in 2002. Webb and her team are monitoring these corralled clams to see how fast the population is growing.

“So you can see this individual is number 11,” she says, pointing to a tiny number super-glued on its shell. They use the numbers to track individuals over time. “We can see how much they’ve grown since we checked them in February and it should be a lot. They grow a lot in the summertime,” Webb says.

“What they do is somewhat disturbing,” says Geoff Schladow, director of the Tahoe Environmental Research Center. Asian clams filter massive amounts of lake water and that’s where the problem starts.

“Of everything they filter, they consume about 10 percent of it and 90 percent they excrete. So their excretions are like these huge nutrient bombs,” Schladow says.

Lauren Sommer

UC Davis researcher Katie Webb holds an Asian clam from their population study.

With thousands of clams per square meter in some parts of the lake, their “nutrient bombs” help create algae blooms.

“So you have this bright green, stringy algae, sort of clinging to the bottom, a few tens of yards from the beach. People would be astounded to see this cause it looks like any place but Tahoe,” he says.

In the face of this invasion, a team from UC Davis has been experimenting with rubber mats that suffocate Asian clams on the lake bottom. So far, the treatment looks promising.

Tahoe Basin Building Boom

Keeping the lake blue – and not green – has been a rallying cry for both environmental groups and Tahoe’s tourism industry. Forty years ago, scientists could see 100 feet into the lake. Today, the clarity has decreased significantly to 64 feet.

“We’re essentially like a bowl and what happens on the land affects the water,” says Julie Regan of the Tahoe Regional Planning Agency. The agency oversees development on both the California and Nevada sides.

“What happened on the land in the 50s, 60s and 70s is that we had a lot of development – rampant overdevelopment,” she says. Tahoe hosted 1960 Winter Olympics at Squaw Valley. Casinos went up. Building was booming. And soon, the region had a runoff problem.

“It’s driveways. It’s houses. What you cover on the land then interferes with the soils ability to filter runoff. That’s what’s causing clarity loss,” says Regan.

Over the past 15 years, local agencies have tried to stop this decline with $1.5 billion of federal, state and local money. They’ve preserved open space and built projects to control erosion and filter runoff.

“In 2008 we got the news from the scientific community that we had stopped the slide and decline of lake clarity. That was great news,” says Regan.

Scientists See Climate Change Impacts

In 2010, however, researchers at UC Davis found the second worst clarity level ever recorded. Geoff Schladow says runoff isn’t the only culprit.

“What we’ve had just in the last few years is this explosion, this large increase in algae and they seem to be concentrated right near the surface,” says Schladow.

These algae are invisible to the eye, but they’re the right size to make the water look cloudier. Normally, they’re competing with large algae near the surface. But Schladow says that’s changing. Algae are heavier than water, so they gradually sink.

“The algae in the past tended to be mixed by the wind every few days. So if you’re a large algae and you sank down 50 or 100 feet, you could be brought up again into the light by mixing.”

Recently, the lake hasn’t been mixing as much. The reason, Schladow thinks, is that the surface waters of the lake have gotten warmer with climate change. Warmer water is lighter than the cold, dense water at the bottom of the lake. So it’s little bit like oil and water. The layers of the lake are more resistant to mixing.

“Now when we have less mixing, the large algae sink out. All we’re left with are the small ones. And so their numbers are going up,” says Schladow.

After decades of conservation work to reduce runoff, a lot of people are disappointed to see climate change posing a new threat to Lake Tahoe’s clarity.

Schladow thinks it’s not hopeless. “It’s a call to redouble what we’re doing, not to give up and walk away. It’s now needed not just to restore clarity but to ward off what may be some pretty uncomfortable and disturbing features of climate change.”

Restoration Funds Running Out

After an unprecedented influx of restoration funding, resources are now running low. Senator Dianne Feinstein introduced the Lake Tahoe Restoration Act of 2011 in Congress to authorize more, but has said she’s not optimistic about getting it passed.

“We know the funding picture could potentially be bleak, so we’re looking to any strategy that we can to keep this momentum going in terms of restoration,” says Julie Regan of TRPA.

On top of that, Nevada is threatening to end its forty-year partnership with California by pulling out of the Tahoe Regional Planning Agency, unless concessions are made about its voting power on new development. Regan says it’s just one more challenge that will make the next few years a critical time for Lake Tahoe’s future.

Climate change is threatening the Joshua trees in Joshua Tree National Park all right, according to a new report. But unlike the findings of recently-published study,  this report finds the park’s iconic, spiky namesake is unlikely to completely vacate the premises over the next century.

The new report was funded in part by Joshua Tree National Park, and its author Cameron Barrows, a researcher at UC Riverside’s Center for Conservation Biology, says that he conducted it partly in response to the recent study by Ken Cole of the USGS, which found that the trees would likely be gone from the park within the next 90 years.

“I facetiously say if that was to happen, we’d have to rename the park ‘Creosote Bush National Park’ or something like that,” said Barrows.  “It would be really sad if that’s the case.”

Barrows’s study looked up-close at the park itself, rather than the entire Joshua tree range, using both computer models and on-the-ground fieldwork.  He says that there are pockets of the park, at high elevations and in shaded canyons, where the trees could persist even in the face of significant environmental changes.

“If you look at it from the satellite view, you’re going to lose them,” he said. “But if you’re standing on the ground and looking at these canyons and the very diverse topography of the park, there are places where it looks like the trees will be able to maintain themselves.”

Barrows projects that a 3-4 degree F rise in temperature would shrink the range of Joshua trees in park substantially at lower elevations, but that they’d continue to thrive in higher elevation areas of the park. With a increase of more than 5 degrees, however, he said, the area where the trees could persist shrinks to the size of “about a couple of football fields.”

In the last decade, he said, temperatures in the park have increased close to 2 degrees F.  To test the effects of this warming, Barrows said he sent out teams of citizen scientists with the mission to find the smallest (and therefore youngest) Joshua trees they could.  This way, he could analyze where the trees have been reproducing over the last decade

“We found, in fact, that we’re already seeing the signature of climate change,” he said. “The distribution of the young trees is much smaller than that of the adult trees.  There’s no Joshua tree reproduction occurring right along the southern edge of its current distribution.”

The story is not just one of temperature. According to Barrows, precipitation plays an even more important role in the survival of Joshua trees. And precipitation is one of climate change’s great wild cards.

“The climate models are really pretty robust when it comes to temperature, but they are really not robust at all – the opposite of robust, really – when it comes to precipitation,” said Barrows.  “The only thing they agree on is its going to get more variable.”

He said the last decade has seen four of the park’s six wettest years and two of the park’s driest.  He takes that high variability as an indication that the park is likely already seeing the effects of climate change.

“What is going to kill the baby Joshua trees are these pulses of droughts,” he said.

But with increasing variability, those dry years could likely be followed by some wet ones, when reproduction could occur again, he said.

Even so, it seems that increased variability could make adolescence harder on Joshua trees than it was for their ancestors: Barrows says it takes between 50 and 100 years for a Joshua tree to reach reproductive age.

Joshua trees in Eureka Valley, CA (Photo: Ken Cole, USGS)

Joshua trees, the spiky desert-dwellers that are so iconic to Southern California’s dry country that they got a national park named after them, will likely disappear from 90% of their current range by the end of the century, according to a new study by scientists at the US Geological Survey.

Ecologist Ken Cole, the study’s lead author, said that means no more Joshua Trees in Joshua Tree National Park, which is currently in the southernmost part of the species’ range. It also means elimination of the trees across wide swathes of other parts of Southern California as well as Nevada and Arizona.

Cole and his team used climate models, field work, and the fossil record to project the future distribution of Joshua trees. They compared the projected increase in temperatures for the Southwest (four degrees Celsius, according to a “middle of the road” IPCC scenario) to a similar rapid increase in temperatures nearly 12,000 years ago, at the end of the ice age.

Using fossil sloth dung and packrat midden, the scientists reconstructed how Joshua trees responded to that warming. (Sloths, which are now extinct in the region, and packrats, ate the Joshua tree fruit, spreading the seeds and leaving them behind for the scientists to track.)

“Sometimes the climate changes rapidly, like it did 11,700 years ago,” said Cole. “At that time the Joshua trees squashed into a narrow band at the northern edge of their range. That’ll happen again. The southerly ones will not be able to persist.”

This loss of southern territory is particularly significant for a species like the Joshua Tree, which has a “pretty pitiful” expansion rate, according to Cole. That’s because, unlike the Ponderosa pine, which can expand its range 500 meters a year thanks to birds and other factors, the range of Joshua trees can stretch just about six feet per year.

“They don’t release their seeds until some animal chomps on them,” said Cole, referring to the fruit of the Joshua tree. “They’re spread by squirrels and pack rats that might run 100 feet and stash some seeds in the ground. Some of them might grow, but it could take 20, 30, or 40 years. Going 100 feet every 20 years is not moving as quickly as it needs to to keep up with climate change.”

Researchers mapped where in the Southwest Joshua trees are currently located, where they are likely to disappear, and where they will likely persist (small pockets in Nevada and in southeastern California).  They also mapped where future climate will likely be suitable for the trees, should anyone want to undertake a program of managed relocation.  But even that, said Cole, has its risks.

“We don’t know how well they would grow then,” he said. “Joshua trees are very picky.”

Not only that, but relocating the trees would be expensive, and he said, “You’d have to assume that the climate wouldn’t change again. That’s a really bad assumption.”

Cole says his field observations support the study’s projections.  Temperatures in the region have been warming since 1975, he said, and there’s no record of Joshua trees reproducing in the southern stands in the last 30 years.

“You don’t see any seedlings or saplings in the southern stands,” said Cole.

That’s a big contrast to the northerly stands in the Inyo Mountains above Eureka Valley, where, he said, Joshua trees are thriving.

“The ones in the north are really vigorous,” he said. “They’re going like mad.”

The full study is located on the Ecology Society of America’s website, but a subscription is required to access it.

Read more on climate change impacts facing the national parks.

California's forests provide water, habitat for animals, lumber and tourism dollars, and they sequester carbon. (Photo: Molly Samuel)

For decades the federal government has touted the nearly 200 million acres of national forests and grasslands under its control as a “land of many uses.” But one “use” that’s seldom discussed is as a huge repository for carbon.

But clearly it’s on the minds of officials and scientists as the Forest Service seeks comments on its proposed new planning rule. National Forests and Grasslands are managed individually, but the planning rule guides how those management plans are developed. This new one is replacing a Planning Rule from 1982.

According to the Forest Service press release, some of the highlights in this new Planning Rule include

• Improved ability to respond to climate change and other stressors through provisions to restore and maintain healthy and resilient ecosystems
• Increased protections for water resources and watersheds
• More effective and proactive requirements to provide for diverse native plant and animal species

The Forest Service manages just under half of the forest land in California. Below is a handy map from their website (If you want to see all the federal land in California — not just National Forest — nationalatlas.gov offers this PDF map).

In celebration of the UN’s “International Year of Forests,” I recently went down the rabbit hole of trying to understand how much carbon California’s forests hold. Figuring that out is, according to Forest Service research forester Jeremy Fried, “An accounting problem. And like any accounting problem, you need to have accurate data.”

That’s been a challenge. Fried works on the Forest Inventory and Analysis Program (FIA), which is the Forest Service’s annual census of the nation’s trees. Unlike the census of the nation’s people, the goal isn’t to count every individual, but to count and measure plots of trees all over the country. But the sizes and locations of those plots have changed over the years, and that makes for unreliable data.

In fact, last year was the first time that Fried and other researchers were able to go back and re-measure the same plots. What he found was that on the 15 million acres of forested lands that the Forest Service manage in California, trees sequester somewhere on the order of 1.8 teragrams of carbon a year (almost two million metric tons).

Going forward, Fried says, as long as the funding holds up, the FIA will continue measuring the same plots, and not just in National Forests, but plots in all kinds of public and private forests.

One last note. Fried explained that carbon generally makes up half of the biomass of a tree. To calculate the biomass of a tree, researchers measure its width and height. But a tree isn’t a box, so you have to add in the branches, maybe you measure the stump separately, and what about the bark versus the stem? The list goes on. Just to give me a sense of how complicated this is, he gave me this number: 102,905. That’s how many ways there are of calculating the carbon content of a Douglas Fir. 102,905.

Grand illusion? Water rushes over the spillway at Nicasio Reservoir in Marin County. (Photo: Craig Miller)

A high-profile team of experts is calling for a major overhaul of the way California manages its water. In a 500-page report from the non-partisan Public Policy Institute of California, the authors say decades of well-intended water policies simply haven’t worked, leaving the state vulnerable to major crises, including water shortages, catastrophic floods, decline & extinction of native species, deteriorating water quality, and further decline of the Sacramento-San Joaquin Delta.

“Our system has been dying a death by a thousand cuts,” says co-author Ellen Hanak, an economist and policy analyst at the PPIC. Hanak says that the state’s water management efforts have been “incremental” and “piecemeal,” with little success to show for it.

Among many other conclusions, the report says water management in the state is too fragmented among hundreds of local agencies and the funding for future improvements should shift from bond issues to a system of fees paid by water users.

“It’s not gonna be easy. It’s not gonna be popular. It’s probably cheaper than the alternatives,” said Jay Lund of UC Davis, one of the co-authors. “There’s not much state money and there’s not much federal money, so if you want to accomplish things for the environment and for water supply and flood control, it’s gonna have to be financed largely locally,” Lund told reporters during a Wednesday conference call.

The report also echoes other recent warnings that Californians are dangerously overdrawn on the state’s underground aquifers.

But there were some notes of optimism. The team of authors, drawn from the PPIC, U-C system and Stanford, say that if cities can cut back water use by 30% from 2000 levels, it would remove a huge strain on the crippled Sacramento-San Joaquin Delta.

The map below, featured in the report, shows areas where Californians are “overdrawn” in their water use.

(Photo: Richard Morgenstein)

Last month I went out to Jasper Ridge Biological Preserve near Stanford, where Scott Loarie and Ken-ichi Ueda showed me and about a dozen docents how to use the new iNaturalist iPhone app, which Ueda created. The aim of the app is to make recording and sharing of accurate field observations incredibly simple. It’s still in testing mode and not yet available to the public. “Citizen scientists” can already upload their digital photos and share them with an online community of naturalists around the world, at the iNaturalist website.

This week I spoke with Healy Hamilton, who directs the Center for Applied Biodiversity Informatics at the California Academy of Sciences. Below are some excerpts from our interview about climate change, citizen science, and iNaturalist:

Q: What’s the potential of citizen science?
A: The world is changing faster than ever before in the history of all human  civilization. There’s no way that scientists can monitor those changes. It’s critical for us to understand the pace of change, and where change is taking place the most.

With global change, there’s a fundamental rearrangement of where species live.  We already know almost everywhere we look that species are on the move trying to track their preferred climate envelopes. To understand the implications of this kind of shifting, we need to have people help us monitor these changes, both the rate of the change and the locations of the changes. This is where there’s a profound role for citizen science.

Q: How can a tool like iNaturalist help scientists study climate change?
A:…Citizen science can help us understand how climate change is unfolding in situ. Every species has edges to their range, so there’s sort of a central range, a northern leading edge, a southern edge, eastern and western edges.  Citizens can help us monitor how climate change is impacting the edges of those ranges, which is where climate impacts are most likely to occur.

For example, some of the easternmost redwood forests are likely to experience the highest summer temperatures [in the redwoods' range], and summer temps seem to be changing quite rapidly, maybe more than temps at other times of the year.  So if citizens can help us say, ‘Look, I just saw a grove of redwood trees and the leaves are brown and this is where it’s located,’ we can actually map climate in that area and see how climate change is unfolding on the landscape.  There’s no way scientists can be everywhere at once to understand how these changes are unfolding, but citizens are hiking through redwood forests all the time.

…So applications such as iNaturalist are going to increase the biodiversity data that scientists have to work with. Not all observations are going to be useful, but many of them will be useful to us. Because of our need for verified observations about what occurs where and when on the planet, as scientists, we think citizen science has a huge role to play in improving our models about forecasting future climate change impacts to species and ecosystems.

Q: Why do we need to study these changes?  What’s the big picture?
A: Climate change is the single most important threat that’s facing all of human society.  If we continue to emit the current rates of greenhouse gases into the future, and if we do end up with 900 or 1,000 parts per million of CO2 in the atmosphere at the end of the century, we will be living on a fundamentally different planet, and that transition is not going to be comfortable for us.  All of our society, all of our infrastructure, all of our food resources, our forest resources, the things that we need, the things we’ve evolved our society around consuming, they like the climate the way it was, [at] about 150-300 parts per million of CO2.  So it’s important to understand how climate change is going to influence biodiversity, the biodiversity we depend on, every bite of food we eat, the clothes on our back, all of our paper and forest products. It influences how diseases are transmitted and all kinds of public health, food security, and national security issues.

In this short video, Scott Loarie and Ken-ichi Ueda explain how the iNaturalist iPhone app works.

Ken-ichi Ueda and Scott Loarie demonstrated the new iNaturalist iPhone app at Stanford's Jasper Ridge Biological Preserve (Photo: Richard Morgenstein)

At Jasper Ridge, a biological preserve and study area on the Stanford campus, a dozen of the preserve’s docents gathered this week to learn about a new iPhone application that could ultimately help scientists study how ecosystems are adapting to climate change.

The new app, called iNaturalist, is the mobile version of a citizen-science website by the same name.  The iPhone app is still in testing and not yet available, but the website, iNaturalist.org, is already an active online community of citizen-scientists around the world who use the site to record and share their sightings.

One of the original iNaturalist creators, Ken-ichi Ueda, has teamed up with Scott Loarie, a post-doctoral fellow at the Carnegie Institute at Stanford. The two are hoping to leverage the site and the mobile application to engage more citizens to contribute to a growing database of field observations that could help scientists track biodiversity.

“One of things that’s most pressing in conservation is that species are going extinct about a thousand times faster than they ever have before,” said Loarie.  “So the scale of this problem is just incredible. It’s way too difficult for a handful of museums and graduate students to stay on top of.”

With the iNaturalist site, and especially with the new iPhone app, which streamlines the uploading process, Loarie hopes to get as many “eyes on the ground” as possible, documenting where species are, and where they aren’t.

“You can think about species around the world like little lights blinking on and off,” Loarie explained. “Whats happening with climate change and land use change is that those lights are blinking off faster than they are blinking on, and a lot of them are happening totally under the radar screen.”

Ueda originally co-developed the iNaturalist site as a project during his Masters studies at UC Berkeley’s School of Information.

“My initial goal with the site was to get people engaged with nature, not necessarily to do the science,” said Ueda. “The scientific data is a really valuable and useful by-product, but my primary motivation is to get people outside and thinking about the plants and animals that they’re seeing.”

But now Ueda and Loarie are trying to take iNaturalist to the next level by finding ways this crowd-sourced data can be useful to scientists.

“It’s really cool if I’m walking around and I see a horned lizard because they are really cool animals,” said Ueda. “But it’s even cooler if I see one here at Jasper Ridge, because no one has seen one here for a long time, and it could be locally extinct.”

An observation like that, he said, could be valuable to scientists. One of the tasks now, he said, is to find ways to connect that data with the scientists who care about it and to establish standards of data quality so that scientists can trust it.

Ueda said the iPhone app may not be ready for the public for another month, but in the meantime, users can easily upload their digital photos from the field to the site, once they get home.   The site is connected with Google Maps, and Wikipedia and the photo-sharing site Flickr, so adding comments, information, and geographical information is easy.  The app, when it’s ready, should make logging observations even easier.

In the field on Friday, Loarie and Ueda were showing off a testing version of the app.

“I think the idea has a a lot of merit,” said Ross Bright, a docent at Jasper Ridge who was at the presentation. “Whether its workable and doable is the problem.  My own personal perspective is that most docents are not necessarily literate in the high-tech gadgetry that’s involved in the this.  There will be a learning curve.”

Ueda and Loarie hope that not only will the docents at Jasper Ridge start cataloging their observations with the new app, but also that the public at large will catch on and record their observations wherever they are.

“There are no geographic or taxonomic restrictions on the site,” said Ueda. “You don’t even really have to know what you’re looking at. You can be like, “Oh, sweet, a tree. There are trees in my yard,”  That’s good to think about.  Anyone can do it.”

Near Tioga Pass, Yosemite (Photo: Gretchen Weber)

As the climate warms, plants and animals will need to move uphill to more hospitable climes, right?  Some are — but it turns out that in other cases, the process seems to have shifted into reverse.

According to a new study published in the journal Science, some plants in Northern California are actually moving downhill in response to climate change.   Aided by historical data, researchers from UC Davis and the University of Montana determined that between 1930 and 2000, many California species shifted downward an average of 260 feet.

The reason, according to UC Remote Sensing scientist Jonathan Greenberg, is increased precipitation, which, in some cases is overriding temperature as the main driver for species distribution.

“These wetter conditions are allowing plants to exist in warmer locations than they were previously capable of,” said Greenberg in a press release about the study.

NPR’s Richard Harris has more on the study and on what it could signal for California’s changing ecosystems.

Buds on a Douglas fir. The buds become either new needles or cones. Photo: R.A. Howard from the USDA-NRCS PLANTS Database

Bud burst, when the buds on a tree begin to open up, marks the end of winter dormancy and the beginning of a tree’s growing season. Timing’s important: If a tree buds too early, it may be susceptible to a late frost. Too late, and it misses out on some or all of its growing season. As the climate warms, this delicate timing can go awry.

Scientists at the US Forest Service’s Pacific Northwest Research Station in Portland, Oregon, have developed a model to predict bud burst. They used Douglas firs in their experiments but also surveyed research on about 100 other species, so they expect to be able to adjust the model for other plants and trees.

Both cold and warm temperatures affect the timing, and different combinations yield different outcomes — not always intuitive. With plenty of hours of cold temperatures, trees need fewer warm hours to burst. So earlier spring warmth will drive bud burst earlier. If a tree isn’t exposed to enough cold, though, it needs more warmth to burst. So under the most dramatic climate change scenarios, warmer winters could actually mean a later bud burst.

Genes play a roll, too. The researchers experimented with Douglas firs from across Oregon, Washington, and California. Trees from colder or drier environments showed earlier burst. Trees descended from those lines could fare better in places where their warmer-and-wetter-adapted cousins live now.

The team, led by research forester Connie Harrington, hopes to use the model to predict how trees will respond under various climate projections. With that information, land managers can decide where and what to plant, and, if necessary, plan assisted migration strategies.