by Jeff Stehm
We are often caught up in the here and now, or at best, think only in human time scales. But have you ever wondered about what Shenandoah National Park looked like millennia ago or might look like a millennium in the future?
Shenandoah National Park today hosts a rich Appalachian Oak forest consisting of hickory, maple, and tulip poplar, with oak as the dominant tree species. Pine predominates on warmer southwestern faces of the southernmost hillsides. In cooler areas with northeastern aspects, small, dense stands of moisture loving hemlocks exist.
The average annual temperature in the Park is about 46.5°F at Big Meadows (located in the north central area of the Park), and ranged from about 44°F to a little over 50°F over the last 75 years.
Forty-five thousand years ago it was a very different place. North America was in the midst of the last throws of the ice age. Temperatures fluctuated (over centuries) from cold to warm and back again. Litwin et al. (2004) estimated that the mean annual temperatures around Big Meadows varied about 20°F over the 45,000 year period, ranging from about 35°F to 55°F. In today’s climatic terms, these variances in temperature was equivalent to those existing today from latitude 55°N (Northern Newfoundland) to 32°N (Georgia).
Such temperature swings profoundly affected the forests of Shenandoah National Park. The Park experienced temperatures almost 10°F colder to 5°F warmer – enough to shift forest biomes drastically back and forth between cold artic boreal forests and warm Oak-Hickory-Pine and Southern Mixed forests.
Forest biomes shifted back and forth a minimum of 37 times during the last 45,000 years as shown below.
Forest Type Years Ago Climate
Boreal 45,000-37 000 Cold
Northern Hardwoods 36,000-35,000 Warming
Northern Harwood-Spruce 32,000 Cooling
Boreal 28,000 Cold
27,000 Last Glacial Maximum
Northern Hardwoods 26,000 Warming
Boreal 25,000 Cold - Northern Hemisphere Insolation Minimum
Northern Hardwood-Spruce 24,000 Warming
Boreal 22,000 Cold
NE Spruce-Fir 17,000 Cool
15,000-13,000 Warming - Bolling-Allerod Interstadial Warming
Northern Hardwood-Spruce 13,000-12,000 Cooling - Younger Dryas Cold Pulse
Appalachian Oak 10,000-6,000 Warming
Southern Mixed 6,000-4,000 Warming
Appalachian Oak 4,000-present Cooling
Source: Adapted from Litwin et al., 2004.
Climate is continuing to change in Shenandoah National Park. Average temperatures in the SNP are expected to shift upwards any where from 1.7°F to 12.7°F depending on the climate model, assumptions, and baseline years. By the end of the century, temperatures are likely to exceed the upper end of the historical range of the last 45,000 years.
In addition to temperature changes, annual precipitation is expected to increase from 1.5 to 8.5 inches by the end of the century. The future climate at the Park, therefore, is likely to include on average milder winters with fewer frost days, hotter summers, and wetter and cloudier conditions.
As a result of these climate changes, Shenandoah National Park is likely to evolve from an Appalachian Oak biome to a Southern Mixed Pine biome.
This may mean a loss of species such as maple, eastern hemlock, northern red oaks, yellow poplar, beech, and other northern hardwoods, and an increase in hickory, sweet gum, shortleaf and longleaf pine, loblolly pine, various elms, and southern oaks (National Park Service, 2015b).
Appalachian Oak Forests Southeastern Mixed Pine Forests
Source: Wikipedia Source: Wikipedia
But climate changes are occurring faster today than they did 45,000 years ago. Temperature and precipitation changes that occurred in the past over thousands of years are occurring today in less than 100 years. In the short term this is likely to:
For example, native brook trout are a cold-water fish. Park officials have measured warmer stream temperatures in recent years, which could put the brook trout under stress and may ultimately eliminate or greatly reduce their numbers in the Park (Saunders, et al., 2010; Flebbe, et al., 2006; National Park Service, 2017a). Another animal that may become a climate change casualty is the Shenandoah salamander, an endangered species that is found nowhere else on the planet.
About a quarter of bird species and 10 percent of the mammals in the Park will likely shift their ranges into and out of the park as the result of either direct or indirect climate effects (National Park Service, 2019d; Wu, et al., 2018; Burns, et al., 2003). Some mammal species, such as the red squirrel and the southern red-back vole, are particularly sensitive to climatic conditions and may be lost to the Park (Burns, et al., 2003). Species reshuffling, however, may result in a net gain to the Park, as more species move into and colonize the Park than move out.
So when you next consider the Good Ole Days, think longer term, both in terms of the past and the future.
Burns, C. E., Johnston, K. M., & Schmitz, O. J. (2003). Global climate change and mammalian species diversity in U.S. national parks. Proceedings of the National Academy of Sciences, 100(20), 11474–11477. DOI: 10.1073/pnas.1635115100
Flebbe, P. A., Roghair, L. D., & Bruggink, J. L. (2006). Spatial Modeling to Project Southern Appalachian Trout Distribution in a Warmer Climate. Transactions of the American Fisheries Society, 135(5), 1371–1382. DOI:10.1577/T05-217.1
Litwin, R. J., Morgan, B., Eaton, L. S., & Wieczorek, G. (2004). Assessment of Late Pleistocene to recent climate-induced vegetation changes in and near Shenandoah National Park. USGS OFR 2004-1351. DOI: 10.3133/ofr20041351
National Park Service (2019d). Projected Effects of Climate Change on Birds in U.S. National Parks, Briefing Note. Retrieved from https://www.nps.gov/subjects/climatechange/upload/01-NPS_Overall_Project_Brief_508Compliant.pdf
National Park Service. (2017a). Climate Change Impacts at Shenandoah National Park. Retrieved from https://www.nps.gov/shen/learn/nature/climatechange.htm
National Park Service. (2015b). Climate, Trees, Pests, and Weeds: Change, Uncertainty, and Biotic Stressors at Shenandoah National Park. Project Brief.
Saunders, S., Easley, T., & Spencer, T. (2010). Virginia Special Places in Peril: Jamestown, Chincoteague, and Shenandoah Threatened by Climate Disruption. The Rocky Mountain Climate Organization and NRDC. Retrieved from http://www.rockymountainclimate.org/images/VA_SpecialPlaces.pdf
Wu, J.X., et al. (2018). Projected avifaunal response to climate change across the US National Park System. Plos One, 13(3): e0190557. DOI: 10.1371/journal.pone.0190557.
By Diana Madson on Jan 8, 2020
Yale Climate Connections
You may enjoy gazing out the window and seeing familiar birds like goldfinches, robins, or warblers flitting between tree branches. But as the climate warms, many bird species will need to leave some of the places they’ve long considered home.
“These areas just become no longer suitable, and they’ll have to move to new areas,” says Brooke Bateman, a senior scientist at the National Audubon Society. She says for bird lovers who want to visualize what this means in their own yards, Audubon created an online tool. Users can enter a ZIP code and learn more about local climate threats and the risks they pose to birds.
“It really gives you a local snapshot of what’s happening with climate change,” she says. The tool highlights which species will no longer find suitable local habitat by the end of the century. Users can toggle between different levels of future warming. Bateman says this lets people see that without climate action, “Oh, these birds that come to my feeder, or these birds I see in my backyard … they’re not going to be there anymore.”
But if carbon pollution is sharply reduced, the risks to many species are, too. The tool shows how climate action can help your favorite birds return to your feeder year after year.
Reporting credit: Sarah Kennedy/ChavoBart Digital Media.
By Bonnie Beers
Two studies published in October 2019 document changes and potential challenges facing North American bird populations:
Cornell’s study describes actual changes over the past 50 years. The Audubon study predicts population declines based on 140 million observations from 40 different data sets interfaced with habitat preferences and needs of each species and on climate change projections. The web-link above describes details of the study and allows viewing of predictions that illustrate vulnerabilities of specific species typical of a given zipcode at projected temperature rises of 1.5, 2.0, and 3.0-degree Celsius.
Both studies present some grim realities, but also provide pathways for hope, at both individual and policy levels. Make a New Year’s Resolution to do something for birds!
Submitted by Charlene Uhl
Article appearing in the Washington Post, Dec. 18 2019
By Adrian Higgins Columnist
It is hard to overstate the value and cultural importance of the American chestnut tree for those who came before us.
The native hardwood was once so ubiquitous, it has been said, that a squirrel could travel from Maine to Georgia in the chestnut canopy. The largest trees, spreading 100 feet or more, dropped 10 bushels of nuts, and in the fall the ground was covered with a nut blanket four inches deep, writes sociologist Donald E. Davis in a 2005 paper.
The bears and turkeys feasted, the farmer’s hogs feasted, and the people who lived in chestnut territory feasted — on that sweetened Appalachian ham but also on the economic value of the trees and their nuts. The chestnut’s arrow-straight timber was valued for its size and rot resistance and today endures in the posts and beams of old farmhouses and barns.
For us city folk, the chestnut evokes everything that is nostalgic about yuletide season, the notion of a vendor plying hot roasted chestnuts on a street corner. The aroma, the warmth in the hand, the nutty flavor all conjure one of the more cuddly images of a Dickensian world.
, this diminished holiday custom is carried on with nuts from Asia and Europe, which are bigger but less sweet.
The American chestnut was killed off by the arrival of a blight in 1904 that within a few decades had virtually wiped out an entire, dominant species. In modern parlance the fungus, Cryphonectria parasitica, went viral.
This environmental catastrophe is widely known. Not so broadly understood is that we are closer than ever to returning the American chestnut to its old haunts — or something akin to it. This resurrection has been several decades in the making and has taken two parallel tracks. The first is in the slow, methodical work of traditional hybridization, attempting with each successive generation a tree that will be naturally resistant to the fungus. This has been led by the American Chestnut Foundation, based in Asheville, N.C. The second is by way of genetic modification, undertaken by scientists at the State University of New York in partnership with the foundation. In a world wary of organism-mixing in the lab, this has proved more controversial.
Naturally resistant trees can reach nut-bearing age before the blight knocks them back. This tree is in western North Carolina. (American Chestnut Foundation) The winter garden is full of promise and productivity.
The conventional breeding began by crossing the blight-tolerant Chinese chestnut with some surviving American chestnut individuals that had proved resistant to the fungus, if only to die back to the roots after reaching nut-bearing age.
The foundation was created in 1983 by plant scientists and others who saw the potential of systematic development of a blight-resistant tree through a series of “backcrosses” in which successive generations of American-Chinese hybrids could be bred with resistant American chestnuts. Once these crosses produced trees that were carrying chiefly the American chestnut genome — as much as 90 percent — they were crossed with each other. The challenge has been to select seedlings with enough Chinese blood in them to ward off the disease and yet still look like the American chestnut. At maturity, the American tree is tall and spreading with a thick, straight trunk. The Chinese species is shorter and more branching.
Most of this work goes on at a research station in southwest Virginia named Meadowview Research Farms. The foundation is supported by 5,000 members and chapters in 16 states.
Jared Westbrook, the foundation’s science director, said that of 60,000 seedlings planted and evaluated, 4,000 have made the cut so far. That number will be reduced to 2,000 in the coming months, and a final cut will leave 600 trees by 2021 as the culmination of the breeding program. These will be used to re-populate the Appalachian forest — though earlier-generation trees produced at Meadowview have already been planted on 40 private, state and national sites in the chestnut’s historical range. Westbrook is using a technique called genomic selection to pick the finalists — by analyzing their DNA he can identify individuals with the desired traits.
This is not to be confused with genetic modification, which is the tack employed by William Powell and his colleagues at SUNY’s College of Environmental Science and Forestry. They have used a wheat gene to counter the effects of the disease and have asked the Agriculture Department to sign off on its release. Also, Powell said, the Environmental Protection Agency will decide whether the antifungal properties constitute a fungicide, which would require pesticide registration. In addition, the Food and Drug Administration will determine whether the nuts are safe to eat.
The foundation is working with the researchers. “If it gets through the review process, the American Chestnut Foundation would breed that gene into a diverse population,” Westbrook said. “We are using all the tools available to us.”
The genetically engineered or transgenic chestnut is facing opposition from an alliance of environmental groups named StopGEtrees, which claims its release into the wild would be “a massive and irreversible experiment” and pave the way for other forest tree species to be genetically engineered and released.
“This would be the first one to be released into nature,” said Rachel Smolker, co-author of a report critical of the plan. The restoration of the American chestnut is such an appealing idea that the proponents of genetic engineering are using it to win acceptance of the broader biotechnology, she says. “It’s about winning public support for genetically engineered trees, which has met with tremendous public resistance,” she said. “It’s a very deliberate strategy. A tree engineered for biofuels doesn’t win over the public in the same way.”
Powell says the bacterium he used to carry the wheat gene into the chestnut chromosome is already found, naturally, in the DNA of some tree species, including the walnut. “Walnut is a natural GMO,” he said. The biotechnology “can be applied to other trees,” he says. “But it’s a good thing, it can save more trees.”
This fall, residents of the Lyon Park neighborhood of Arlington County gathered in their community park to plant two non-transgenic saplings from the chestnut foundation to mark Lyon Park’s centennial. They are just a few inches tall, but they are latent giants. “We are protecting them and doing the best we can,” said resident Gray Handley. A hundred years after the demise of the American chestnut, there is hope that future generations will witness something denied ours, the return of the big old American chestnut.
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