PDA

View Full Version : Twin Plagues Threaten Northern Forests


Fiddlerdave
08-23-2009, 03:44 PM
http://tinyurl.com/nwxxo4

HAINES JUNCTION, Yukon Territory (Aug. 23) A veil of smoke settled over the forest in the shadow of the St. Elias Mountains, in a wilderness whose spruce trees stood tall and gray, a deathly gray even in the greenest heart of a Yukon summer.
"As far as the eye can see, it's all infested," forester Rob Legare said, looking out over the thick woods of the Alsek River valley.

Global Warming Brings Beetles, FireRick Bowmer, AP5 photos With global warming changing the ecosystem, two new threats are emerging across the world's northern woodlands: beetles and fire. "As far as the eye can see, it's all infested," said forester Rob Legare, pictured here on Aug. 6 in Canada's Yukon Territory. According to Legare, 1 million acres of the Yukon's forest has been attacked by the tiny spruce bark beetle.

Global Warming Brings Beetles, Fire
With global warming gradually affecting the ecosystem, new elements are threatening northern forests across the world. Scientists say that with temperatures rising and land growing drier, beetles and fire are consuming these vast woodlands. "As far as the eye can see, it's all infested," forester Rob Legare, pictured here in on Aug. 6 in Canada's Yukon Territory, said. According to Legare, 1 million acres of forest there has been attacked by the spruce bark beetle.

Beetles and fire, twin plagues, are consuming northern forests in what scientists say is a preview of the future, in a century growing warmer, as the land grows drier, trees grow weaker and pests, abetted by milder winters, grow stronger.
Dying, burning forests would then only add to the warming.

It's here in the sub-Arctic and Arctic in Alaska, across Siberia, in northernmost Europe, and in the Yukon and elsewhere in northern Canada that Earth's climate is changing most rapidly. While average temperatures globally rose 0.74 degrees Celsius (1.3 degrees Fahrenheit) in the past century, the far north experienced warming at twice that rate or greater.
In Russia's frigid east, some average temperatures have risen more than 2 degrees Celsius (3.6 degrees Fahrenheit), with midwinter mercury spiking even higher. And "eight of the last 10 summers have been extreme wildfire seasons in Siberia," American researcher Amber J. Soja pointed out by telephone from central Siberia.

Along with shrinking the polar ice cap and thawing permafrost, scientists say, the warming of the Arctic threatens to turn boreal forest the vast cover of spruce, pine and other conifers blanketing these high latitudes into less of a crucial "sink" absorbing carbon dioxide and more of a source, as megatons of that greenhouse gas rise from dead, burning and decaying wood.
American forest ecologist Scott Green worries about a "domino effect."
"These things may occur simultaneously," said the researcher from the University of Northern British Columbia. "If the bark beetles kill the trees, you'll have lots of dead, dry wood that will create a really, really hot fire, and then sometimes you don't get trees regenerating on the site."

Dominoes may already be falling in western North America.
From Colorado to Washington state, an unprecedented, years-long epidemic of mountain pine beetle has killed 2.6 million hectares (6.5 million acres) of forest. The insect has struck even more devastatingly to the north, in British Columbia, where clouds of beetles have laid waste to 14 million hectares (35 million acres) twice the area of Ireland. It is expected to kill 80 percent of the Canadian province's lodgepole pines before it's finished.
Farther north, in the Yukon, the pine beetle isn't endemic yet. Here it's the spruce bark beetle that has eaten its way through 400,000 hectares (1 million acres) of woodland, and even more in neighboring Alaska, in a 15-year-old epidemic unmatched in its longevity and extent.

"It's a fingerprint of climate change," Aynslie Ogden, senior researcher for the Yukon Forest Management Branch, said in Whitehorse, the territorial capital. "The intensity and severity and magnitude of the infestation is outside the normal."
Hiking through the wild and beetle-ravaged Alsek valley, Legare, the Yukon agency's forest health expert, explained how the 6-millimeter (quarter-inch) insect does its damage.
"Usually the female bores into the tree first, followed by the male, and then they mate and they both excavate a main egg gallery which runs parallel to the wood grain," he said.

The hatched larvae, just beneath the outer bark, then feed via perpendicular galleries they bore around the tree, cutting off nutrients moving through the phloem and killing the plant. Its needles turn reddish, later gray, and eventually wind topples the dead wood.

Winter spells of minus-40-Celsius (minus-40-Fahrenheit) temperatures once killed off larvae, but those deep freezes now occur less often. And warmer summers enable some beetles to complete their reproductive cycle in one year instead of two, speeding up population growth.

Years of summer drought, meanwhile, weakened the spruces' ability to extrude sticky pitch, to trap and expel beetles. Because the snow-streaked peaks of the 5,000-meter-high (15,000-foot-high) St. Elias range block moisture from the Pacific, a mere 250 millimeters (10 inches) of precipitation falls each year. Even a slight shortfall stresses the trees.

The Yukon has experienced smaller, briefer beetle outbreaks in the past, fed by patches of fallen trees left by road construction. But "what makes this infestation different" is that climate change is a primary cause, said Legare.
As he spoke, smoke from dozens of fires, some nearby in the Yukon, some in distant Alaska, wafted over a landscape already bleak with dead forest.
In an authoritative 2007 assessment, the Intergovernmental Panel on Climate Change (IPCC), the U.N.-sponsored scientific network, cited multiple studies linking the spread of wildfires to warmer, drier conditions.

This June, in the latest such study, as early flames flared in California's wildfire season, Harvard scientists said the area burned in the western United States could increase by 50 percent by the 2050s, even under the best-case warming scenario projected by the IPCC.

In Siberia, "fire has been increasing, and there's an earlier fire season," Soja, of the U.S. National Institute of Aerospace, reported from the Sukachev Institute of Forestry in Krasnoyarsk. Her research this summer found that a warmer, drier climate appears to be stifling regrowth of burned-out areas on the Siberian forest's southern edge, turning them to grasslands.
In Canada, area burned is double what it was in the 1970s, despite greater firefighting capacity and some recent favorable weather, said Mike Flannigan, a fire researcher for the Canadian Forest Service.
He cited three key reasons: warmer temperatures are drying the forests, lengthening the fire season and generating more lightning, cause of the worst wilderness fires.

Flannigan worries, too, that future fires smoldering through the carbon-heavy peatlands that undergird much of the boreal region would pour unparalleled amounts of carbon dioxide, the main global-warming gas, into the skies, feeding an unstoppable cycle.
"The bottom line is if you get more fire, you get more emissions, which contributes to further warming, which contributes to more fires," he said in an interview from Ontario.

"The concern is that things may happen more rapidly than we anticipate. Even our most pessimistic scenarios may not be pessimistic enough."
Back here in smoky gray southwest Yukon, where things are happening, the 1,400 native Champagne-Aishihik people feel it most. The stricken forest's fallen trees are keeping them from traditional fur-trapping rounds, the streams seem warmer without thick cover overhead, and the fishing is off.
Their oral tradition tells of great change in the past, said the group's land manager, Graham Boyd. "They're now wondering what changed to have had this happen."

What's changed extends beyond Champagne-Aishihik lands to the rest of the Yukon, where forester Legare in his travels finds other insects the northern spruce engraver, the aspen leaf miner, the willow miner gaining an upper hand in unusual places in unexpected ways.

"Weird things, unprecedented things are happening," he said.
Over the top of the world in Siberia, they're girding for a surge in the highly destructive Siberian moth, a caterpillar that devours forests of pine, spruce, fir and larch.
"The moth loves warm and dry, and that's what's happening," said Nadezda M. Tchebakova, Soja's Siberian research partner. At the same time, she said from Krasnoyarsk, "the frequency and severity of fires should increase."
As the Yukon warms and burns, its foresters hope for at least an early warning on one immediate threat, the mountain pine beetle. They have set traps at the British Columbia border to alert them if the non-native insect moves northward.

"The Yukon pines probably don't have natural defenses. They may be uniquely susceptible to this pest," said ecologist Green. "Then you'll have the potential for fires in large areas of dead trees. With the needles still on them, they literally explode with fire."

Of her Yukon woodlands, Ogden said, "It's the right forest, the right climate type, and we expect the climate to warm. My sense is it" the pine beetle "is almost inevitable."

hillsidedigger
08-23-2009, 04:07 PM
Of late, many reports state that the release of methane from the Northern Seas and the tundra is being detected in rapidly increasing amounts which they say could drastically alter (for the much worse) the world's weather within as little as 10 years.

CanadaSue
08-23-2009, 05:53 PM
Interestingly, was babysitting last night & had happened to pick up Richard Preston's fine book 'Panic in Levl 4', a collection of short pieces about neat science stuff'. One section labelled 'A Death In The Forest' gave a short list of major threats to native tree species this century. An estimate of lost numbers/acreage was included. It was startling. A short list:

The Hemlock Wooly adelgid is nuking the eastern hemlock which apparently is often referred to as 'the redwood of the east'. Most of it is found in old growth, eastern rain forests... or was. Most are now dead or dying. 1904: Chestnut blight began killing almost every American chestnut on the continent. They're now functionally extinct.

Since the 1930s, we've almost lost the American elm.

Fraser firs are almost gone since the 70s, thanks to the balsma wooly adelgid.

An unknown fungal disease has killed off most wild, flowering dogwoods.

Sudden oak death is hitting California.

American beech trees are now suffering a mass die off due to an imported European fungus in an imported European insect.

In 2001 the emerald ash borere made its appearance & is ahhpily munching through many species of ash.

Sugar maples are now under attack from the Asian long horned beetle.

Preston points out, (rightly), that much of life remain undescribed & its importance to ecosystems thus, unknown. Who knows what lives in the canopies of under attack & now dying virgin forests? What will this do to insect species, birds, etc. who use these massive trees as nesting sites, sources of food, etc. What about the composition of soils, crops, etc?

It's bloody terrifying & sad.

rb.
08-23-2009, 07:40 PM
In 2001 the emerald ash borere made its appearance & is ahhpily munching through many species of ash.

My neighbourhood is currently peppered with these suckers right now. All kinds of trees marked, plastic strips around the trunk (tape?), funny looking box-kite things hanging in them.

We were on the lookout for the Asian long horned beetle when doing maple syrup. Not so worried about it now, since we've given up producing, but almost the whole 320 acres is sugar maple.

Susan4
08-23-2009, 07:53 PM
Many of the insect and disease pests in forests are invasive exotics... gypsy moth, emerald ash borer, Dutch elm disease, Chestnut blight etc. Those that are native tend to exist in the environment without catastrophic effect until something else becomes unbalanced.

The removal of fire as a disturbance regime in forests since white settlement has been such an unbalancing factor. When fire is removed, non-fire tolerant species regenerate and build the fuel load, leading to catastrophic stand-replacement conflagrations rather than low intensity ground fires.

Longer growing seasons and less winter melt in western higher elevations plug into the fire intensity as well. It is all connected, but it's not all just "eek mah hair's on fire global warming11!!11!!!"

CanadaSue
08-23-2009, 08:16 PM
Susan - I sure as shooting 'don't know trees'. I know just enough biology to realize we possibly grasp only a fraction of a percentage point of what's going on 'out there'. I have faith that systems can adapt & eventually new balances found. But I grieve the inevitable losses, ESPECIALLY the loss of that with which I'm familiar.

I miss the monarchs - I see damned few these days. We're beginning to see the first forays of emerald ash borer here & our local woods are loaded with ash - locally, I think they're pretty dominant. I live close to a stand of perhaps a dozen or so mature oaks & I'd have to drive miles to find another.

We'll adapt & so will our landscapes but transitions are ucertain times & sometimes I wonder if EVERYTHING in our lives has to be in transition at once?

Fiddlerdave
08-24-2009, 01:54 PM
I have faith that systems can adapt & eventually new balances found. The hard part is that adaptation occurs on a time scale long enough that it is hard to perceive by humans. The interim periods can be quite, uh, uncomfortable.

But I grieve the inevitable losses, ESPECIALLY the loss of that with which I'm familiar.The disappearance of our "home" ecosystems is truly heartbreaking.

Susan4
08-25-2009, 04:01 PM
The heartbreaker to me is the homogenization occurring from the introduction of exotics. I look across a midwestern landscape utterly transformed from what anything like a native ecosystem was prior to settlement. Not that pre-settlement was some magic time, we needed the land for agriculture to feed a growing nation...the trouble is what was left of the native woodlands, prairies, forests, wetlands and glades is now plagued with plant and animal species that just flat don't belong here. They take over. There's no native control to their populations. All our control efforts are spit into the wind. It's a terrible loss.:(