Showing posts with label bark beetles. Show all posts
Showing posts with label bark beetles. Show all posts

Thursday, 31 January 2013

New Control Strategies for 'Bipolar' Bark Beetles


Jan. 25, 2013 — Population explosions of pine beetles, which have been decimating North American forests in recent decades, may be prevented by boosting competitor and predator beetle populations, a Dartmouth study suggests.

Bark beetles are the most destructive forest pests worldwide. Management and climate change have resulted in younger, denser forests that are even more susceptible to attack. Though intensively studied for decades, until now an understanding of bark beetle population dynamics -- extreme ups and downs -- has remained elusive.

The Dartmouth-led study, published in the January issue of the journal Population Ecology, confirmed, for the first time, that the abundance of a certain animal species -- in this case the southern pine beetle -- fluctuates innately between extremes, with no middle ground.

"That is different from most species, such as deer, warblers and swallowtail butterflies, whose populations tend to be regular around some average abundance based on food, weather, and other external factors," says Matt Ayres, a professor in the Department of Biological Sciences at Dartmouth and senior author on the paper. "They don't appear and disappear in cycles. Rather, they exist in two stable equilibrium states -- one of high abundance and the other of scarcity." Once the population pendulum swings toward the high end, it won't quickly or easily swing back.

Read on:  http://www.sciencedaily.com/releases/2013/01/130125104204.htm

Saturday, 5 January 2013

As Climate Warms, Bark Beetles March On High-Elevation Forests


Dec. 31, 2012 — Trees and the insects that eat them wage constant war. Insects burrow and munch; trees deploy lethal and disruptive defenses in the form of chemicals.

But in a warming world, where temperatures and seasonal change are in flux, the tide of battle may be shifting in some insects' favor, according to a new study.

In a report published today (Dec. 31, 2012) in the Proceedings of the National Academy of Sciences, a team of scientists from the University of Wisconsin-Madison reports a rising threat to the whitebark pine forests of the northern Rocky Mountains as native mountain pine beetles climb ever higher, attacking trees that have not evolved strong defenses to stop them.

The whitebark pine forests of the western United States and Canada are the forest ecosystems that occur at the highest elevation that sustains trees. It is critical habitat for iconic species such as the grizzly bear and plays an important role in governing the hydrology of the mountain west by shading snow and regulating the flow of meltwater.

"Warming temperatures have allowed tree-killing beetles to thrive in areas that were historically too cold for them most years," explains Ken Raffa, a UW-Madison professor of entomology and a senior author of the new report. "The tree species at these high elevations never evolved strong defenses."

Monday, 4 June 2012

Effects of Trees Killed by Bark Beetles On Wildfire

ScienceDaily (May 30, 2012) — A recent report analyzing a range of published studies on the impact of bark beetles on trees in the U.S. and Canada provides a more complete picture of the effect of this destructive insect on wildfires.
Previously published studies reported a wide variety of -- and often contradictory -- conclusions about the bark beetles' effect on fuels and wildfire. A team of researchers from the USDA Forest Service's Pacific Southwest Research and Pacific Northwest Research stations and the University of Idaho set out to identify key knowledge gaps by developing a conceptual model based on the review of 39 previously published studies. The scientists used the model to describe expected changes of fuels and fire behavior following bark beetle outbreaks.
Key findings, which appeared in the journal Forest Ecology and Management, include:
  • Bark beetle outbreaks can indeed affect fuels and fire behavior;

Friday, 30 December 2011

Bark beetles, climate change and our future

Recently, a classmate from the University of B.C. asked what I thought about Canada backing out of the Kyoto agreement, and if there was any connection between the insatiable bark beetles infesting the province’s forests and the rising temperatures on Earth.

First, trees are effectively the greatest CO2 warehouses ever created. For every metric ton of wood grown, 1.5 metric tons of CO2 is absorbed and one metric ton of oxygen is released.

Bark beetles like the mountain pine or spruce beetles and lightning-induced fires are nature’s emissaries of change. All forests must undergo a natural process of aging, facilitating regeneration — new life.

In order to fully understand what is happening in British Columbia and throughout the entire western North American continent, it is important to keep in mind that trees, insects and the climate are all inexorably linked; each plays a pivotal role in the feedback loops on nature’s gameboard.



Any change in the behaviour of one or two of these players inevitably changes all of the triumvirate’s interaction along with it. With little opportunity to adapt to new conditions, instability can cause remarkable devastation to entire ecosystems.

That instability has reverberated not only in B.C. and western North America but around the globe on every forested continent as elevated temperatures in the past 40 years of just over 0.5 degrees Celsius on average are killing mature trees by the billions.

In B.C., the mountain pine beetles have killed half the commercial forests in the last 15 years. Instead of absorbing CO2 these massive graveyards of dead trees are releasing 250 million metric tons of CO2 into the atmosphere, the equivalent of all the car and light truck emissions in Canada for five years or enough wood to build a city of eight million homes.

It doesn’t even begin to end there; the spruce beetles in the far north of the province into Yukon and Alaska have taken full advantage of warming temperatures by speeding up their life cycles, which formerly took two years and now occurs within one year.

In Kluane National Park and Reserve, Yukon spruce beetles have accomplished something never recorded in modern or past times. Since the cold ecological constraint has been removed, spruce beetles have killed over 350,000 hectares of white spruce. Before this, the largest spruce attack was a modest 247 hectares in 1977.

The long-lived, thrifty high elevation forests of white bark and limber pines of B.C. have also been decimated by mountain pine beetles because, again, the cold-temperature barrier precluding attacks is no longer in situ. Mortality in parts of northern B.C. ranges from 72 per cent to 80 per cent. These forests are crucial habitat for grizzly and black bears, and of paramount importance to retain winter snowfall, slowly release spring melt back into the water cycle and replenish the Pacific Ocean, its salmon, eagles, wolves, bears and orcas.

Death rates of white bark and limber pines across the western United States are as high as 90 per cent. The sentinels of the high country have become the tsunami sirens of global warming, showing ecologist, climatologist and physiologists that a warming world is irrevocably altering the landscape across the entire mountainous region of western North America.

It’s not just the forests that are disappearing but rather immense amounts of ice that reflect incoming solar radiation. One hundred billion metric tons of ice melted from Greenland during the blistering-warm summer of 2010. This year alone 50 per cent of Canada’s millennia-old Arctic ice shelves along the coast of Ellesmere Island vanished.

And far worse, the Southern Ocean which occupies 22 per cent of the total ocean on the globe, absorbing 40 per cent of Earth’s CO2, is acidifying so quickly (as a byproduct of absorbing rising CO2) that by 2030 the sea water will be corrosive to crustaceans, dissolving shells that the animals are making. This amplification will reverberate all the way up the food chain to the whales.

Data from the Global Carbon Project showed the carbon emissions from our planet had increased 5.9 per cent from 2009 to 2010; that’s the largest jump in any year since the Industrial Revolution.

The $17-trillion Alberta oilsands industry must spend carbon energy and precious fresh water to separate the gooey, toxic oil from the sand. Moreover, by burning this petroleum, humans will knowingly raise atmospheric CO2 levels by an astounding 150 parts per million. Earth will be uninhabitable for life as we know it.

If Australia, with its $10-trillion coke-coal industry, can ratify a carbon tax, then surely progressive Canadians can follow their lead.

We are running out of time to combat rising CO2 emissions: Earth’s forests are dying.

It’s time to embrace innovation and the cofounder of the London School of Economics, George Bernard Shaw’s dictum: “Progress is impossible without change, and those who cannot change their minds cannot change anything.”

Dr. Reese Halter is a conservation biologistat California Lutheran University in Thousand Oaks. His latest book is The Insatiable Bark Beetle.

http://www.vancouversun.com/technology/Bark%2Bbeetles%2Bclimate%2Bchange%2Bfuture/5920382/story.html
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