Do severe wildfires make forests in the western United States more susceptible to future bark beetle outbreaks?
The answer, in a study published Monday (Nov. 7, 2016) in the Proceedings of the National Academy of Sciences, is no. By leading to variability in the density and size of trees that grow during recovery, large fires reduce the future vulnerability of forests to bark beetle attacks and broad-scale outbreaks.
“Fire creates a very heterogeneous landscape,” says study co-author Kenneth Raffa, professor of entomology at the University of Wisconsin-Madison. “Beetles can only reproduce in an individual tree once, so they take advantage of this patch of trees and that patch of trees as they become available, but when the number and size of trees vary a lot, it’s hard for a large outbreak to develop.”
Read more at: http://phys.org/news/2016-11-variable-tree-growth-forests-future.html#jCp
There are killing machines on the loose in California and the entire Western region.
They’re found in packs and look for the weak but they’re not the scary predator you’d imagine. In fact, they’re about the size of a rice grain.
They’re called bark beetles.
A June 2016 Cal Fire report stated the ongoing drought in combination with the tiny insects are responsible for killing about 66 million trees in California since 2010. That’s up from 29 million trees in 2015 and 3.3 million in 2014, according to the report.
Invasive insects cause at least $77 billion in damage every year, according to a study released Tuesday that says this figure is “grossly underestimated” because it covers only a fraction of the globe.
Climate change is on track to boost the area affected by nearly 20 percent before mid-century, the authors reported in the journal Nature Communications.
Canvassing more than 700 recent scientific studies, researchers looked at the impact of non-native species on goods and services, healthcare and agricultural output.
Most of these studies applied to North America and Europe, which means the devastation wrought by crop-chomping and disease-carrying bugs from afar has not been adequately measured, the authors said.
The most destructive of the insects canvassed was the Formosan subterranean termite, which lives in huge colonies and feasts on wooden structures and living trees.
Pine trees in California forests will die out and give way to brush and chaparral, forestry experts warn, unless agencies undertake what one analyst called a “massive effort” to reduce fuels and replant trees. Otherwise, the conversion to chaparral could further increase risk of wildfires and affect the state’s water supply.
A U.S. Forest Service survey, released in June, revealed that 66 million trees—mostly pine species—have died in the southern Sierra alone, due to bark beetle infestations, drought, wildfire and climate change. One question now, experts say, is what will replace those dead trees.
“We know in the Sierra and Sequoia national forests east of Fresno, the beetles have killed at least 85 percent of the entire pine vegetative type and at least 20 percent of the mixed conifer type, which is pine and fir,” said Steve Brink, California Forestry Association vice president of public resources. “By the end of this summer, essentially 100 percent of the pine type will be dead in the Sierra and Sequoia national forests, and you are going to have a massive conversion to chaparral.”
New Brunswick is on the brink of another spruce budworm outbreak and the forestry industry — the largest in the province — is doing everything in its power to prevent massive defoliation like that of the 1970s.
But to control the insect’s population, the province is banking on a different approach than the intensive aerial spraying of the past, according to the research scientist with the Canadian Forest Service.
“We’re trying to do a very surgical targeted, very small areas, instead of treating half the province, which happened during the previous outbreak,” said Johns.
Scientists together with the industry have started treating several hot spots in New Brunswick in the face of a looming epidemic.
An insect responsible for the loss of much of the eastern United States Appalachian region’s hemlock trees has found its way into Michigan. The hemlock woolly adelgid poses a threat to the state’s valuable hemlock stands. A call to action by citizens may be the most realistic path to further detection and control.
Justin Whitehill is hopeful that “we will eventually be able to produce EAB-resistant ash trees by borrowing from other ash trees that have natural resistance. Applying modern genomic technologies to conventional tree-breeding methods has the potential to preserve not only a single species, but a whole genus that is being impacted worldwide.”
Paul Merten has spent nearly a decade chasing down a killer in the Southern Appalachians, armed with no more than a pocket knife and measuring tape.But recently the entomologist with the U.S. Forest Service in Asheville, N.C., has been homing in on the tiny, yet lethal pest with what he hopes is a secret weapon — parasitoids, also known as wasps.Merten and Haywood County Community College forestry student Caroline McGough were deep in the woods on the Appalachian Trail slicing across the North Carolina-Tennessee border last week, unleashing parasitoids in a science fiction-like attack on the emerald ash borer.
Researchers here are hatching a plan to stop the woolly adelgid. A 1-acre plot of forest is the site of a budding insectary, a farm in the trees of the predator beetle Laricobius nigrinus that has been shown in some cases to kill the adelgid.
California has suffered more than 5,000 wildfires this year, and we’ve only reached the beginning of the season. Just last week, more than 10,000 firefighters were battling blazes throughout the state – fires largely fueled by already-dead, dry trees.
But many of those trees aren’t dying of old age. They were killed by one tiny culprit: the bark beetle.