Betancourt thinks that we are on the verge of a new spate of tree migrations. Dead trees now abound on Utah’s landscape, and Dr. With long-term warming, however, other species can move in from lower elevations or further south. When the drought abates, the resident tree species typically return. Droughts trigger bark beetle infestations, wildfires, and tree dieoffs, opening up niches for regeneration. Packrat 7000 year old Middenĭroughts figure prominently in Dr. Geological Survey, who uses these packrat middens and tree rings to reveal past plant migrations, these recent advances by Utah’s two pinyon pines followed the Medieval Climate Anomaly, a period from 900 to 1300 AD marked by warming in Europe and severe drought in Utah. We know this from radiocarbon dates on pinyon pine needles taken from ancient nest heaps of packrats preserved in caves. Across Utah, two-needle pinyon leaped over the Uintas to Flaming Gorge. A thousand years ago, one-needle pinyon hopped from the Raft River Mountains in Utah to City of Rocks, Idaho. The past provides us with lessons about plant migrations. If these are the first signs of climate change, even longer growing seasons will trigger not just earlier blooms but also northward plant migrations. Our average onset of Spring now comes a week earlier across the West. In the late 1970’s, springtime in the American West warmed abruptly by 2 degrees Fahrenheit in the valleys, double that higher up. Tales of the Packratĭownload file | Play in new window | Duration: 3:01 | Recorded on August 27, 2009 Introduction, Tom Higham, Radiocarbon Laboratory, University of Waikato, New Zealand Ĭopyright © 2009 Ken ColeOne of the best storytellers in Utah’s national parks is not a ranger, but the lowly packrat. Pack Rat Middens, Colorado Plateau in Land Use History of North America, Ken Cole, USGS/Northern Arizona University, Packrat Middens: The Last 40,000 Years of Biotic Change, University of Arizona Press, 1990 Text: Julio Betancourt USGS and Jim Cane, Bridgerland Audubonīetancourt, Julio L., Thomas R. The Legacy of Early Grazing on Utah’s Rangelands This is Linda Kervin for Bridgerland Audubon Society. Like Aesop’s fables, this cautionary lesson of the packrat’s ecological tale remains clear and relevant today. Despite curtailed grazing in subsequent decades at Capitol Reef and Glen Canyon, packrats show us that the flora still has not recovered. We know that palatable plant species and those susceptible to trampling suffered declines, because they are absent from middens from that time period. Beginning 150 years ago, vast herds of sheep and cattle tromped and chewed their way across the unfenced rangelands of Utah in numbers unimaginable today. Ken and colleagues then carefully translated these packrats’ stories by identifying and counting the plant fragments in these fossil nests.Īt both Capitol Reef and Glen Canyon, old packrat nests revealed pre-settlement plant communities that were rich in diverse grasses, wildflowers and shrubs. As controls, they also collected nests from mesa tops inaccessible to livestock. By carbon-14 dating, the nest ages are known to span the last 10,000 years. Ken and colleagues sampled old packrat nests around Glen Canyon National Recreation Area and Capitol Reef National Park. Ken Cole with the US Geological Survey is a fluent translator of the packrat’s stories. Protected in a desert cave or rock crevice and preserved by a rat’s own urine, this heap is a detailed and accurate time capsule of the past local flora. The midden is a heap of leaves, twigs, seeds and fruits the packrat discards outside its nest. Their stories of past plant communities are written in their middens. Download file | Play in new window | Duration: 2:51 | Recorded on November 1, 2012Ĭopyright © 2009 Ken ColeOne of the best storytellers in Utah’s national parks is not a ranger, but the lowly packrat.
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