Recent and Holocene fire, climate, and vegetation linkages in the northern Rocky Mountains, United States of America.

详细信息   

• 作者：Power ; Mitchell James.
• 学历：Doctor
• 年：2006
• 导师：Whitlock, Cathy
• 毕业院校：University of Oregon
• 专业：Biology, Ecology.;Geography.;Paleontology.;Agriculture, Forestry and Wildlife.
• ISBN：9780542925580
• CBH：3238461
• Country：USA
• 语种：English
• FileSize：13847921
• Pages：259

文摘

The relationship between fire, vegetation, and climate in the Northern Rocky Mountains was examined for three time periods: the 20th century, the last 4000 years, and the last 13,000 years. In the last 100 years, interannual climate variations and seasonal climate anomalies were found to explain changes in yearly area burned. Climate variables were examined as composite anomalies, including: temperature, precipitation, atmospheric circulation, and surface water- and energy-balance variables. High area-burned years are characterized by (a) higher-than-average temperatures from April to September; (b) lower-than-average precipitation during June, July, and August; (c) an enhanced ridge over western North America; (d) lower-than-normal mid-tropospheric moisture; and (e) greater-than-normal sensible heat flux. Years with low area-burned are characterized by circulation anomalies that promote lower-than-average temperatures and higher-than-average precipitation.;An examination of the last 3800 years at Foy Lake in the Flathead Lake valley of northwestern Montana suggests variations in fire regime are likely a result of climate change. Fire activity was lower-than-present from 3800 to 2200 cal yr BP, and increased to present levels after 750 cal yr BP. Forest cover and charcoal influx increased between 2200 and 750 cal yr BP. Modern forest developed after 750 cal yr BP. Fire activity and forest cover decreased since Euro-American settlement.;A 13,100-year record of fire and vegetation history from Foy Lake and data from nearby sites describe the environmental changes since the retreat of glacial ice. At Foy Lake, fire activity was low during the late glacial period, was high from ca. 11,500 to 9000 cal yr BP, and was lower-than present between ca. 7500 and 2200 cal yr BP. Picea parkland was found at low elevations throughout the NRM following deglaciation. Open forests of Pinus and Pseudotsuga/Larix, developed at ca. 11,000 cal yr BP, suggesting regional warming. After ca. 4000 cal yr BP, increased Abies, Picea, and Psuedotsuga/Larix marks the onset of cooler, moister conditions. This analysis of fire, vegetation, and climate linkages on multiple time scales demonstrates the influences of short-term and long-term climate controls, vegetation responses, and disturbance frequencies on present-day ecosystems.