Forest mortality and climate change: The big picture

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Over the past two decades, extensive forest death triggered by hot and dry climatic conditions has been documented on every continent except Antarctica. Forest mortality due to drought and heat stress is expected to increase due to climate change. Although research has focused on isolated incidents of forest mortality, little is known about the potential effects of widespread forest die-offs. A new analysis of the current literature on this topic by Carnegie’s William and Leander Anderegg is published September 9 in Nature Climate Change.


Along with co-author Jeffrey Kane of Northern Arizona University, the Andereggs examined papers dealing with different aspects of die-off events from studies all over the world. They divided their findings into the effects on a forest community of trees and other species; on as a whole; on services forests provide to humans; and on the climate.

“This study provides a state-of-the-art overview of the many benefits forests provide to humans, from water purification to climate regulation,” said William Anderegg, “Many of these roles can be disrupted by the widespread tree mortality expected with climate change.”

They found that heat and drought, including drought-related insect infestation, can disproportionately affect some species of trees, or can hit certain ages or sizes of trees particularly hard. This can result in long-term shifts in an area’s , with the potential to trigger a transition into a different ecosystem, such as grassland. It can also impact the understory—the layer of vegetation under the treetops—as well as organisms living in the soil. More research on forest community impacts is needed, particularly on the trajectories of regrowth after forest die-off.

From an ecosystem perspective, forest die-off will also likely affect hydrological processes and . Depending on the type of forest, could be increased by the lack of tree-top interception of rainfall or decreased by evaporation due to more sun and wind exposure. Debris from fallen trees could also increase a forest’s fire risk.

Written By: PhysOrg
continue to source article at phys.org

7 COMMENTS

  1. An old friend is a rabid CC denier; it is so hard telling him he’s an idiot. Greenland ice-free? Nah! Arctic melt biggest ever? Nah! It is all (apparently) a scientific conspiracy driven by “snake oil salesmen” according to him. Mind you, although English, he is a Republican enthusiast. What to do?? 

  2. There is evidence that temperate forests are moving towards the poles as the climate warms.  There are even some plans to plant forest species to help keep pace with the shifting climate.

    http://news.nationalgeographic

    Trees Migrating North Due to Warming –
    Bruce Dorminey for National Geographic News
    February 9, 2009

    Other than the Ents of Lord of the Rings fame, trees generally aren’t known for their mobility. So news that some tree species may be headed north at an average clip of 62 miles (100 kilometers) a century may come as a surprise.

    At that rate, stands of yellow birch in the U.S., for example, may move well north of the Canadian border by the early 2100s.

    That’s the finding of a new study led by the U.S. Forest Service, which concludes that a few dozen tree species in the eastern U.S. are moving north at an unexpected rate, likely due to global warming.

    In a paper appearing this month in the journal Forest Ecology and Management, the study authors documented the northward march of 40 major tree species over 30 eastern states based on the distribution of seedlings
    versus mature trees. 

    Previous studies of plant migrations had been done using only computer simulations, or they focused on how some species are climbing up hills and mountains, said co-author Chris Oswalt, of the Forest Service’s Southern Research Station in Knoxville, Tennessee.

    By contrast, the new study looked at movement based on latitude, using a sampling of the forest service’s most recent ground-based data.

    The finding confirms a link between global warming and forest migration, said lead study author Chris Woodall, of the Forest Service’s Northern Research Station in St. Paul, Minnesota.

    “This is no longer conjecture,” he said.

    Trees on the Move

    Woodall and colleagues studied data from 15 northern species, 15 southern species, and 10 species found in both regions. They compared the latitudes of seedlings—trees less than 20 years old, on average—with those of their older counterparts.

    Eleven of the 15 northern species appear to have shifted more than 12 miles (20 kilometers), on average, from their historic ranges.

    Among the species headed north are the northern white cedar, American basswood, sugar maple, black ash, bigtooth aspen, and yellow birch.

  3. Here in BC the climate change simultaneously weakens trees and is gentler on pine beetle winter die-off. Combined they have wiped out a huge swaths of forest.  It is not just the inability of a tree to handle warm/dry conditions and inability to pick itself up to a better location causing the trouble.

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