By Margaret Nagle
Land managers in New England and eastern New York state have a new tool to help identify eastern hemlock stands at greatest risk for rapid growth decline by evaluating stresses on the trees, including response to the hemlock woolly adelgid and changes resulting from a warming climate.
Today, an estimated 26 percent of the region’s hemlock stands are at high risk. As winters get warmer, the decline will increase, with 43 percent of stands expected to be at high risk, according to a research team led by University of Maine Associate Professor of Forest Resources William Livingston.
The researchers’ comprehensive landscape model maps the varied response to the invasive Asian insect across the Northeast, and identified the site characteristics of stands with the highest potential for tolerance and recovery in order to prioritize management efforts.
Eastern hemlock is a towering foundational species in eastern North American forests valued from southern Canada to Alabama and as far west as Minnesota. But since the mid-20th century, eastern hemlock that can live more than 500 years have been increasingly threatened by the hemlock woolly adelgid that can kill a tree within four years by feeding on its needles and branches, preventing new growth.
Using changes in tree rings — basal area increment (BAI) measurement — in mature hemlock, the researchers quantified annual growth decline in 41 hemlock stands across New England representing a range of infestation density and duration, and species vigor. The model also was applied to 15 hemlock sites in Massachusetts.
Among the findings of the research team using the growth decline metric: Eastern hemlock sited on steeper slopes with increased exposure to solar radiation and warmer January minimum temperatures have a greater probability of experiencing rapid decline.
The results of the study, which involved researchers from UMaine, the University of Vermont and LandVest Inc., in Portland, Maine, were published in the journal Biological Invasions.
By Rachel Sargent
For many of us, winter in the Northeast means cold temperatures and piles of snow, drifting through forests and across fields. It’s hard to imagine that winter here could be different, but the prospect of climate change has scientists asking just what our winters might look like in the future – and how those changes might influence forest ecology.
At the U.S. Forest Service’s Hubbard Brook Experimental Forest, scientists are thinking about the year 2100. How much warming will occur isn’t certain, but some projections suggest that average air temperatures in our region may increase 5.5 to 9 degrees over the course of this century. The effects are likely to be complex and are difficult to predict, with benefits and costs for different organisms. Some tree species, for example, may benefit from longer and warmer growing seasons, but they may also sustain root damage from more frequent soil freezing.
It may seem counterintuitive that soils would freeze more often during warm winters. The reason is a projected lack of snow. The blanket of snow that usually accumulates during winter insulates the soil below, preventing it from experiencing the full, sub-freezing temperatures of the air. When warmer temperatures leave a thinner blanket of snow, or none at all, the soil is more likely to freeze when cold snaps strike.
A study of Front Range forests burned by wildfires between 1996 and 2003 shows they are not regenerating as well as expected and large portions may become grasslands or shrub lands in coming years.
The paper, published in the journal Ecosphere by former doctoral student Monica Rother and geography professor Thomas Veblen, examined the sites of six low-elevation ponderosa pine forest fires which collectively burned 162,000 acres along the Colorado Front Range between 1996 and 2003. Eight to 15 years after the fires, the researchers expected – based on historical patterns – to see young trees cropping up across the landscape. Instead, 59 percent of plots surveyed showed no conifer seedlings at all and 83 percent showed a very low density of seedlings. Although it is possible that more seedlings will appear in upcoming years, future warming and associated drought may hinder significant further recovery.
“It is alarming, but we were not surprised by the results given what you see when you hike through these areas,” said Rother, who earned her doctorate from CU Boulder in 2015 and works as a fire ecologist at Tall Timbers Research Station in Tallahassee, Florida.
by Dan Joling, Associated Press
A type of tree that thrives in soggy soil from Alaska to Northern California and is valued for its commercial and cultural uses could become a noticeable casualty of climate warming over the next 50 years, an independent study has concluded.
Yellow cedar, named for its distinctive yellow wood, already is under consideration for federal listing as a threatened or endangered species.
The study published in the journal Global Change Biology found death due to root freeze on 7 percent of the tree’s range, including areas where it’s most prolific. It cited snow-cover loss that led to colder soil.
Additional mortality is likely as the climate warms, researchers said.
Rudy Boonstra has been doing field research in Canada’s north for more than 40 years.
Working mostly out of the Arctic Institute’s Kluane Lake Research Station in Yukon, the U of T Scarborough Biology Professor has become intimately familiar with Canada’s vast and unique boreal forest ecosystem.But it was during a trip to Finland in the mid-1990s to help a colleague with field research that he began to think long and hard about why the boreal forest there differed so dramatically from its Canadian cousin. This difference was crystallized by follow-up trips to Norway.”Superficially they look the same. Both are dominated by coniferous trees with similar low density deciduous trees like aspen. But that’s where the similarities end,” he says.The real differences are most obvious on the ground, notes Boonstra. In Canada, the ground is dominated by tall shrubs like willow and birch but in the Northwestern European forests found in Norway, Finland and Sweden the ground is dominated by dwarf shrubs like bilberry.
A steady increase in sea levels is pushing saltwater into U.S. wetlands, killing trees from Florida as far north as New Jersey. But with sea level projected to rise by as much as six feet this century, the destruction of coastal forests is expected to become a worsening problem worldwide.
Forests in Switzerland can adapt to a certain extent to climate change but will need forward-thinking management to remain productive and provide ecological services, say experts.
The Swiss environment ministry and the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) have presented key recommendations based on a seven-year research programme dedicated to understanding how best to help Swiss forests weather climate change.
At a press conference in Birmensdorf, Zurich on Monday, the study leaders said that the results provide a first comprehensive view for central Europe of the impacts of climate change on forest species, and the multiple services that forests provide.
They said that climate change will have a profound impact on Swiss forests, resulting notably in the shifting of vegetation zones some 500-700 metres (1,640-2,297 feet) higher in altitude, as well as more frequent periods of drought, forest fires and pest infestations.
Trees that germinate and begin growing in Switzerland today will already experience a marked change in climate during their lifetime, the researchers said. They emphasised that adapting our forest management practices will be essential to helping Swiss forests survive climate change, and continue to provide the key services humans rely on, such as wood production and shelter from natural hazards.
Changes in climate and extreme weather are already increasing challenges for forest ecosystems across the world. Many impacts are expected to remain into the future. This means forest managers, conservationists and woodland owners continually need to address climate change to ensure forests can provide a broad array of benefits and services. The USDA Northern Forests Climate Hub and the U.S. Forest Service provide tools to help address this need.
Collaboration between scientists and managers resulted in the publication Forest Adaptation Resources: Climate Change Tools and Approaches for Land Managers. This publication provides a suite of materials enabling land managers to consider the likely effects of climate change and increase the ability of forests to cope with climate change impacts.
Invasive insects cause at least $77 billion in damage every year, according to a study released Tuesday that says this figure is “grossly underestimated” because it covers only a fraction of the globe.
Climate change is on track to boost the area affected by nearly 20 percent before mid-century, the authors reported in the journal Nature Communications.
Canvassing more than 700 recent scientific studies, researchers looked at the impact of non-native species on goods and services, healthcare and agricultural output.
Most of these studies applied to North America and Europe, which means the devastation wrought by crop-chomping and disease-carrying bugs from afar has not been adequately measured, the authors said.
The most destructive of the insects canvassed was the Formosan subterranean termite, which lives in huge colonies and feasts on wooden structures and living trees.
Forest fires are burning longer and stronger across the western United States, lighting up the landscape with alarming frequency. Residents are forced to flee, homes are incinerated, wildlife habitats are destroyed, lives are lost. Last year, the Forest Service spent more than half its annual budget fighting fires.
Scientists have long theorized that climate change has contributed to the longer fire seasons, the growing number and destructiveness of fires and the increasing area of land consumed, though some experts suggest that the current fire phenomenon is not just a result of a changing climate, but also fire-suppressing policies practiced by the government for the last century or more.
In a new study published Monday in Proceedings of the National Academy of Sciences, scientists from the University of Idaho and Columbia University have calculated how much of the increased scope and intensity of Western wildfires can be attributed to human-caused climate change and its effects. They state that, since 1979, climate change is responsible for more than half of the dryness of Western forests and the increased length of the fire season. Since 1984, those factors have enlarged the cumulative forest fire area by 16,000 square miles, about the size of Massachusetts and Connecticut combined, they found.