Along with recent high-intensity forest fires, these insect outbreaks are raising concerns about the health of forests across the nation. An independent group of scientists from the Colorado Forest Restoration Institute at Colorado State University, the University of Colorado and the University of Idaho, have reached a consensus about some of the critical ecological information needed for forest management in Colorado. The group developed a report that provides forest managers and policymakers with information about different kinds of insect outbreaks occurring in Colorado forests as a basis for making decisions about how to manage forests that are going through substantial changes. This information is essential, as Colorado recently experienced severe and extensive insect outbreaks. The primary insects attacking and killing trees in Colorado forests are bark beetles and defoliators.
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Skip to Content. The forest around Grand Lake, Colo. Whole mountainsides are draped with dead trees bearing orange needles and bare branches.
The pine beetles have attacked, and people have responded with chainsaws, insecticides and anxiety about fire. Conventional wisdom suggests that decades of U. But the latest and best scientific research does not buttress conventional wisdom. The research suggests that the pine-beetle outbreaks coincide with warmer, drier years. It finds no compelling evidence that once the dead needles have fallen from the trees i. Scientists also find no evidence that this outbreak is unprecedented over time spans of several centuries, or that human fire-suppression has made western U.
Further, a team of scientists suggests that some policies and treatment options—thinning forests far from human homes, for instance—is ineffective. Thomas Veblen, a professor of distinction in geography at the University of Colorado, acknowledges the barrier of intuitive wisdom. Thomas Veblen, a professor of distinction in geography and an expert on pine beetles and forest health, cores a Douglas Fir.
But in several controlled experiments, other researchers have found that dead trees—even those bristling with dry, brittle needles—are not more likely to ignite. That dead stand of trees and a still-living stand were ignited, and both groups burned the same, Schoennagel noted. High-severity, infrequent fires are normal for boreal and high-elevation forests, she adds.
Such conclusions contradict conventional wisdom, which has driven major public policies and expenditures. At the time, Rey was endorsing an expansion of the Healthy Forests Initiative and the Healthy Forests Restoration Act, which were predicated on the belief that fire-suppression efforts of the last century have created unhealthy, unnaturally dense forests that were thus prone to wildfire.
Veblen, Schoennagel and leading experts from Colorado State University and the University of Idaho have responded to such intuitive knowledge with a rigorous assessment of research on forest-insect outbreaks and wildfire.
That report addressed common questions about forest health, fire suppression, wildfire risk and beetles. Following are some questions and answers from the report and from Veblen and Schoennagel, who discussed their research recently:. It depends, but for the most part, no. These forests burn infrequently but intensely, and there is no evidence that the wildfires have gotten worse as a result of human forest management.
At lower elevations, ponderosa-pine forests have, in some cases, become more dense. These generally lower-density forests normally experience more frequent but lower-intensity fires that tend to remove smaller trees and shrubs but leave larger trees alive.
Veblen, Schoennagel and the synthesis team note that dense stands of ponderosa pine have always existed in some places. Crown fires are not finicky; they consume fuel, dead or alive. People like green forests. Should they log or burn beetle-killed forests? It depends. Second, insect outbreaks are largely driven by climate—drought and warm temperatures. Research shows that the area of land burned by wildfire between and was six times greater than that which had burned in the previous 16 years.
That research shows that the same time period was characterized by increased spring and summer temperatures, longer fire seasons and earlier snowmelt.
As with insecticides, it makes sense to remove dead trees and other fuels near homes and offices. The synthesis report notes research showing that the heat released even from intense crown fires will not ignite wooden walls at distances of 40 meters or more. Veblen suggests a prescription.
He suggests in the wildland-urban interface, where people will live in or near wildlands, homes undergo Firewise treatment, which reduces the fuel near human structures. See www. Forest Service oversees million acres of public land. Between and , the federal agencies treated about 29 million acres. Schoennagel concurs. Thinning projects are expensive, and the wood they produce is not profitable, she says. In fact, she has led a study of 44, fire-mitigation treatments; it found that only 11 percent of the area treated was within 2.
That study was recently published in the Proceedings of the National Academy of Sciences. See sidebar. Underscoring that point, Veblen notes that fire history studies show that about 80 percent of the ponderosa-pine zone in Boulder County is naturally predisposed to burn in high severity fires similar to the Hayman Fire, which burned , acres—60, of them on one day.
Search Enter the terms you wish to search for. Other ways to search: Events Calendar Campus Map. Main menu Archive. As forests die, questionable anxieties thrive. Published: June 18, A local Colorado forest littered with trees killed by the pine beetle.
CFRI COLOSTATE EDU DOCS CFRI_INSECT PDF
My blog discusses issues and policy related to natural resources, public lands, and conservation. Excellent share! This is another wonderful story to read. Its interesting and educational.
As forests die, questionable anxieties thrive
Colorado, by Dominik. Obituary for Elaine M. The full report on forest insect, fire risk, is available at Overview. This report is a brief synthesis of the current understanding in of insect outbreaks. Population growth of the whole country. Charcoal was developed because it produces fires with colostaet heat and because direct contact of the ore with charcoal is required to produce pure copper Rostoker and otherscited in Miller a.