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Report: Climate change causes trees to live fast, die young

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A forest in the Pyrenees Mountains in Spain. Photo: Ulf Buntgen

Once thought to be a line of defense against climate change because of their ability to store carbon, trees are instead growing fast and dying young and won’t store as much greenhouse gas over their lifespans according to research published Wednesday.

Plants and trees flourish in warmer climates, but trees that grow faster during their first 25 years tend to die much sooner than slow-growing trees found in harsh, cold conditions according to the study published in the scientific journal Nature Communications.

The findings point to a warming Earth where trees will continue to grow at accelerated rates, but the amount of carbon they will be able to store will shrink. This will have devastating consequences for carbon cycle dynamics and what amount of carbon dioxide can be pulled out of the atmosphere.

Study author Ulf Büntgen from Cambridge University’s geography department says the fast-growing response to a warmer climate is similar to how animals with a quick heart rate tend to grow faster but have shorter lives on average. [Read more…]

DNA pinpoints trees responsible for post-ice age reforestation

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There is no debate among scientists that glaciers covering large portions of North America marked the peak of the last ice age nearly 22,000 years ago, but they do disagree on the source of the trees that led to the eventual reforestation once the ice retreated. A University of Michigan study published Monday seeks to settle the dispute.

Researchers used a recently developed genetic technique to estimate the precise longitude and latitude of the surviving ancestors of today’s forest species referred to as ice-age refugia. Two broadly distributed hickory species, the bitternut and the shagbark, likely survived much farther north and closer to the ice sheet than originally believed.

Identifying the locations of glacial refugia helps scientists understand basic forest history and a key to establishing a baseline showing how fast and far tree species are able to migrate in response to climate change. Also, locating refugia helps biologists identify tree populations that may be genetically unique and important to conservation efforts.

“The traditional view is that these tree species only survived in larger refugia located farther south, where regional climate was much warmer,” University of Georgia post-doctoral research associate Jordan Bemmels said.

“Our results for bitternut hickory provide some of the strongest evidence to date that northern microrefugia existed and were important for survival of some temperate tree species throughout the ice age,” he said. [Read more…]

Urban forests, and their rural cousins, help cities mitigate climate change

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Besides their many economic and biological benefits, urban forests just make their human neighbors feel better. Photo: ncufc.org

Can innovative wood products and humans’ innate need to interact with nature help cities across the country achieve their commitments under the Paris climate accord?

More than 400 U.S. mayors and cities have signed the Paris Accords, but do they have a plan for how to accomplish the attendant goals?

Forests in their own cities and wood products from these enclaves and their rural brethren could help in a significant way.

The 2007 International Panel on Climate Change report recognized the importance of forest management: “In the long-term, a sustainable forest management strategy aimed at maintaining or increasing forest carbon stocks, while producing an annual sustained yield of timber, will generate the largest sustained mitigation benefit.”

From the trees out your office and kitchen window to the rural forest totaling around 850 million acres, or one-third of the country, the answer is a loud yes they can help.

Already, some cities are taking advantage of their backyard and boulevard forests. [Read more…]

Study: Climate change, century of fire suppression led to California megafires

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A view of the Camp Fire Tuesday Nov. 13, 2018 in Northern California. At this point, the 125,000-acre fire was only 30-percent contained after it started Nov. 8. Photo: NASA

California wildfires will become more severe in the future as warmer temperatures give way to drier summers, a decrease in the amount of snow at higher elevations despite above average rainy seasons and, possibly, because humans are too good at putting blazes out.

Improvements in suppressing forest fires, rather than letting them run their natural course, has led to forests bursting with underbrush and crowded trees, according to a study published Monday in the Proceedings of the National Academy of Sciences.

Researchers reconstructed 400 years of climate data to determine what causes wildfires in California and found many of the elements that would have pointed to a strong, wet winter would have led to a weaker wildfire season.

But that has not been the case recently as the last few years of insurmountable wildfires in California has been any indication.

[Read more…]

Not so long ago, American cities were starved for trees

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In 1919, 1,376 new Norway maples were planted along streets in Brooklyn. Photo: Department of Parks of the Borough of Brooklyn, City of New York

Many cities, in recent years, have initiated tree planting campaigns to offset carbon dioxide emissions and improve urban microclimates.

In 2007, New York City launched MillionTrees NYC, a program designed to plant 1 million new trees along streets, in parks and on private and public properties by 2017. They hit their goal two years ahead of time.

These programs are popular for a reason: Not only do trees improve the city’s appearance, but they also mitigate the urban heat island effect – the tendency for dense cities to be hotter than surrounding areas. Studies have shown that trees reduce pollutants in the air, and even the mere sight of trees and the availability of green spaces in cities can decrease stress.

But as I show in my new book, “Seeing Trees: A History of Street Trees in New York City and Berlin,” trees weren’t always a part of the urban landscape. It took a systematic, coordinated effort to get the first ones planted.

[Read more…]