Some populations of mountain pine beetles now produce two generations of tree-killing offspring annually, dramatically increasing the potential for bugs to kill lodgepole and ponderosa pine trees, CU-Boulder researchers have found.
Because of the extra annual generation of beetles, there could be up to 60 times as many beetles attacking trees in any given year, the study found. And in response to warmer temperatures at high elevations, pine beetles also are better able to survive and attack trees that haven't previously developed defenses.
In the first half of the nineteenth century, American settlers pushed westward into the Great Plains, lured to the prairies by the agricultural promise of their dark, rich soils.
Within a century, America’s tallgrass prairies—which once stretched across more than 150 million acres, from Minnesota south to Texas and from Illinois west to Nebraska—had all but vanished under settlers’ plows. The demise of the tallgrass prairie also meant the demise of dozens of species of grasses that could grow to the height of a man, hundreds of species of flowers and herds of roaming bison.