City forests store rainforest-levels of carbon, study finds

By Morgan Erickson-Davis
Nations are hurrying to reduce greenhouse gas emissions and slow global warming, and one way they’re going about this is by encouraging the protection of forests. Trees trap carbon in their biomass and in the soil, and it’s hoped that keeping them in the ground will keep their carbon out of the atmosphere.

Climate-focused forest conservation policies and programs tend to be focused on rainforests. Covering vast areas, rainforests have earned the moniker “lungs of the planet” for their ability to sequester carbon dioxide while producing oxygen.

But pound for pound, other types of forest give rainforests a run for their money. A hectare of mangrove, for instance, can store four times more carbon than can a hectare of rainforest. And now, new research shows that even temperate forests in cities may be able to sequester nearly as much carbon as a similarly sized area of rainforest.

The study was conducted by a team of scientists from University College London, who mapped the carbon stores of areas of tree cover in the London Borough of Camden. Their results were published recently in the journal Carbon Balance and Management.

The team used remotely sensed LiDAR (which stands for “Light Detection and Ranging”) data that provided high-resolution information about tree structure. Armed with specific numbers on the dimensions and extent of Camden’s aboveground biomass (i.e., the parts of trees that aren’t underground), the researchers were able to estimate how much carbon is contained in each pocket of urban forest.

“Urban trees are a vital resource for our cities that people walk past every day,” said lead author Phil Wilkes. “We were able to map the size and shape of every tree in Camden, from forests in large parks to individual trees in back gardens. This not only allows us to measure how much carbon is stored in these trees but also assess other important services they provide such as habitat for birds and insects.”

Their results indicate Camden’s trees contain more carbon than estimated by previous studies. And while, as a whole, the borough’s median carbon density is on the low side when compared to many natural ecosystems – roughly equivalent to subtropical steppe – its urban forests are carbon storage powerhouses. The maximum value they uncovered was in a large, 320-hectare park called Hampstead Heath. There, carbon density approaches that of tropical rainforest.

Source: City forests store rainforest-levels of carbon, study finds – Mongabay, 2018-06-29

Southeast Asian forest loss much greater than expected, with negative implications for climate

By John Sullivan, Office of Engineering Communications

Researchers using satellite imaging have found much greater than expected deforestation since 2000 in the highlands of Southeast Asia, a critically important world ecosystem.

Zhenzhong Zeng, a postdoctoral researcher at Princeton University and the lead author of a July 2 article describing the findings in Nature Geoscience, said the researchers used a combination of satellite data and computational algorithms to reach their conclusions. The report shows a loss of 29.3 million hectares of forest (roughly 113,000 square miles or about twice the size of New York state) between 2000 and 2014. Zeng said that represents 57 percent more loss than current estimations of deforestation made by the International Panel on Climate Change. He said most of the forest has been cleared for crops.

Because forests absorb atmospheric carbon, and burning forests contribute carbon to the atmosphere, loss of forests could be devastating. An accurate estimation of forest cover also is critical for assessments of climate change. Zeng also said transformation of mountainous regions from old forest to cropland can have widespread environmental impacts from soil retention to water quality in the region.

Source: Southeast Asian forest loss much greater than expected, with negative implications for climate – Princeton University, 2018-07-02

One football pitch of forest lost every second in 2017, data reveals

By Damian Carrington, Niko Kommenda, Pablo Gutiérrez and Cath Levett
Global deforestation is on an upward trend, jeopardising efforts to tackle climate change and the massive decline in wildlife.

Global tree cover losses have doubled since 2003, while deforestation in crucial tropical rainforest has doubled since 2008. A falling trend in Brazil has been reversed amid political instability and forest destruction has soared in Colombia.

In other key nations, the Democratic Republic of Congo’s vast forests suffered record losses. However, in Indonesia, deforestation dropped 60% in 2017, helped by fewer forest fires and government action.

Forest losses are a huge contributor to the carbon emissions driving global warming, about the same as total emissions from the US, which is the world’s second biggest polluter. Deforestation destroys wildlife habitat and is a key reason for populations of wildlife having plunged by half in the last 40 years, starting a sixth mass extinction.

Source: One football pitch of forest lost every second in 2017, data reveals – The Guardian, 2018-06-27

American Trees Are Moving West, and No One Knows Why


By Robinson Meyer
As the consequences of climate change strike across the United States, ecologists have a guiding principle about how they think plants will respond. Cold-adapted plants will survive if they move “up”—that is, as they move further north (away from the tropics) and higher in elevation (away from the warm ground).

A new survey of how tree populations have shifted over the past three decades finds that this effect is already in action. But there’s a twist: Even more than moving poleward, trees are moving west.

About three-quarters of tree species common to eastern American forests—including white oaks, sugar maples, and American hollies—have shifted their population center west since 1980. More than half of the species studied also moved northward during the same period.

These results, among the first to use empirical data to look at how climate change is shaping eastern forests, were published in Science Advances on Wednesday.

Source: American Trees Are Moving West, and No One Knows Why – The Atlantic, 2017-05-17

Researchers predict increasing decline of hemlock as winters warm

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.

Source: UMaine-led team predicts increasing decline of hemlock as winters warm – UMaine News – University of Maine, 2017-04-07

Will climate change affect forest ecology?

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.

Source: Will climate change affect forest ecology? – Burlington Free Press, 2017-03-12

Colorado’s wildfire-stricken forests showing limited recovery

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.

Source: Colorado’s wildfire-stricken forests showing limited recovery | CU Boulder Today | University of Colorado Boulder, 2017-01-30

Study documents tree species’ decline due to climate warming

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.

Source: Study documents tree species’ decline due to climate warming | KOMO, 2017-01-06

Why the massive Canadian boreal forest differs from the boreal forest in Northwestern Europe

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.

Source: Why the massive Canadian boreal forest differs from the boreal forest in Northwestern Europe – Phys.org

Ghost Forests: How Rising Seas Are Killing Southern Woodlands

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.

Source: Ghost Forests: How Rising Seas Are Killing Southern Woodlands by Roger Real Drouin: Yale Environment 360