| Abstract: | The extensive boreal biome is little studies relative to its global importance. Its high soil moisture and low temperatures result in large below-ground reservoirs of carbon (C) and nitrogen (N). Presently, such high-latitude ecosystems are undergoing the largest temperature increases in global warming. Change in soil temperature or moisture in the large pools of soil organic matter could fundamentally change ecosystem C and N budgets. Since 1990, we have conducted treeline studies in a small (800 ha) watershed in Noatak National Preserve, northwestern Alaska. Our objectives were to (1) gain an understanding of treeline dynamics, structure, and function; and (2) examine the effects of global climate change, particularly soil temperature, moisture, and N availability, on ecosystem processes. Our intensive site studies show that the treeline has advanced into turdra during the past 150 years. Inplace and laboratory incubations indicate that soil organic-layer mineralization rates increase with a temperature change >5 degrees C. N availability was greatest in soils beneath alder and lowest beneath willow or cottongrass tussocks. Watershed output of inorganic N as NO3 was 70 percent greater than input. The high inorganic-N output likely reflects soil freeze-thaw cycles, shallow flowpaths to the stream, and low seasonal biological retention. Concentrations and flux of dissolved organic carbon (DOC) in streamwater increased during spring melt and in autumn, indicating a seasonal accumulation of soil and forest-floor DOC and a shallower flowpath for meltwater to the stream. In sum, our research suggests that treeling transitionzone processes are quite sensitive to climate change, especially those functions regulating the C and N cycles. |
| Genre: | Article |
| ProdID: | 87282 |
| Citation Author: | Stottlemyer, R.; Binkley, D.; Steltzer, H. |
| Citation Contributing Office: | Fort Collins Science Center |
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| Citation Editor: | Wilson, F. H.; Galloway, J.P. |
| Citation End Page: | 121 |
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| Citation Language: | English |
| Citation Larger Work Title: | Studies by the U.S. Geological Survey in Alaska, 2000. Professional Paper 1662 |
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| Citation Number Of Pages: | 9 |
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| Citation Phsyical Description: | p. 113-121 |
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| Citation Publisher: | U.S. Geological Survey |
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| Citation Search Results Text: | Treeline biogeochemistry and dynamics, Noatak National Preserve, northwestern Alaska; 2002; Article; Report; Studies by the U.S. Geological Survey in Alaska, 2000. Professional Paper 1662; Stottlemyer, R.; Binkley, D.; Steltzer, H. |
| Citation Start Page: | 113 |
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| Citation Year: | 2002 |
| Type: | citation/reference |
| Text: | Treeline biogeochemistry and dynamics, Noatak National Preserve, northwestern Alaska; 2002; Article; Report; Studies by the U.S. Geological Survey in Alaska, 2000. Professional Paper 1662; Stottlemyer, R.; Binkley, D.; Steltzer, H. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DOCUMENT): | http://www.fort.usgs.gov/Products/Publications/729/729.pdf |
| Date Other: | Tue, 1 Jan 2002 00:00 -0600 |
| Publisher: | U.S. Geological Survey |
