page_title: Populus tremuloides
section_title: Dieback
hierarchical_section_title: Populus tremuloides / Ecology / Dieback
caption_attribution_description: Populus tremuloides English: Quaking Aspen, fall foliage
context_page_description: Populus tremuloides is a deciduous tree native to cooler areas of North America, one of several species referred to by the common name aspen. It is commonly called quaking aspen, trembling aspen, American aspen, mountain or golden aspen, trembling poplar, white poplar, and popple, as well as others. The trees have tall trunks, up to 25 meters tall, with smooth pale bark, scarred with black. The glossy green leaves, dull beneath, become golden to yellow, rarely red, in autumn. The species often propagates through its roots to form large clonal groves originating from a shared root system. These roots are not rhizomes, as new growth develops from adventitious buds on the parent root system.
  Populus tremuloides is the most widely distributed tree in North America, being found from Canada to central Mexico. It is the defining species of the aspen parkland biome in the Prairie Provinces of Canada and extreme northwest Minnesota.
  The quaking aspen is the state tree of Utah.
context_section_description: Beginning in the 1990s, North American scientists noticed an increase in dead or dying aspen trees. As this accelerated in 2004, a debate over causes began. No insect, disease, or environmental condition has yet been definitively identified as a cause. Trees adjacent to one another are often stricken or not. In other instances, entire groves have died.
  Many areas of the Western US have experienced increased diebacks which are often attributed to ungulate grazing and wildfire suppression. At high altitudes where grasses can be rare, ungulates can browse young aspen sprouts and prevent those young trees from reaching maturity. As a result, some aspen groves close to cattle or other grazing animals, such as deer or elk, have very few young trees and can be invaded by conifers, which are not typically browsed. Another possible deterrent to aspen regeneration is widespread wildfire suppression. Aspens are vigorous resprouters and even though the above-ground portion of the organism may die in a wild-fire, the roots, which are often protected from lethal temperatures during a fire, will sprout new trees soon after a fire. Disturbances such as fires seem to be a necessary ecological event in order for aspens to compete with conifers, which tend to replace aspens over long, disturbance-free intervals. The current dieback in the American West may have roots in the strict fire suppression policy in the United States. On the other hand, the widespread decimation of conifer forests by the mountain pine beetle may provide increased opportunities for aspen groves to proliferate under the right conditions.
  Because of vegetative regeneration by aspen, where an entire group of trees are essentially clones, there is a concern that something that hits one will eventually kill all of the trees, presuming they share the same vulnerability. A conference was held in Utah in September 2006 to share notes and consider investigative methodology.
caption: Typical yellow autumn foliage
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot S110", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "QuickTime 7.0.1", "Image DateTime": "2005:10:23 20:23:35", "Image HostComputer": "Mac OS X 10.3.9", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "9040", "Thumbnail ImageWidth": "200", "Thumbnail ImageLength": "150", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail Orientation": "Horizontal (normal)", "Thumbnail JPEGInterchangeFormat": "231", "Thumbnail JPEGInterchangeFormatLength": "8670", "EXIF ExposureTime": "1/800", "EXIF FNumber": "36/5", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2005:10:23 12:57:46", "EXIF DateTimeDigitized": "2005:10:23 12:57:46", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "309/32", "EXIF ApertureValue": "183/32", "EXIF ExposureBiasValue": "-1", "EXIF MaxApertureValue": "97349/32768", "EXIF SubjectDistance": "11/50", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire", "EXIF FocalLength": "173/32", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "1600", "EXIF ExifImageLength": "1200", "EXIF FocalPlaneXResolution": "800000/103", "EXIF FocalPlaneYResolution": "240000/31", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera"}