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Consequences of fire on aquatic nitrate and phosphate dynamics in Yellowstone National Park

Author(s): James A. Brass, Vincent G. Ambrosia, Philip J. Riggan, Paul D. Sebesta
Year Published: 1996

Airborne remotely sensed data were collected and analyzed during and following the 1988 Greater Yellowstone Ecosystem (GYE) fires in order to characterize the fire front movements, burn intensities and various vegetative components of selected watersheds. Remotely sensed data were used to categorize the burn intensities as: severely burned, moderately burned, mixed burn, lightly burned, and unburned. Water samples were then collected in six streams, under various burn conditions, for the next five years. Those samples, collected twice a day, for the summer months following snow melt, were analyzed with a Dionex ion chromatograph in order to determine the chemical concentrations of nitrates (NO3) and phosphates (PO4) in the streams. Those nitrate and phosphate levels were compared to a reference stream (unburned) in order to determine the change in chemical concentrations under various burning conditions. Our results indicate that stream nitrate remains high, even after five years of ecosystem recovery. Nitrate levels, found in various burn conditions, ranged from 2.6 to 33 times greater than our reference, unburned stream concentrations. Phosphate concentrations exhibited similar conditions with levels 2.0 to 29 times greater than background levels. These results indicate that burn intensities regulate stream water nitrate and phosphate concentrations; that aquatic ecosystem alterations are of much longer duration than previously thought; and that remotely sensed data can be used effectively to predict burn intensities which relate to watershed chemical changes that will affect aquatic conditions.

Citation: Brass, James A.; Ambrosia, Vincent G.; Riggan, Philip J.; Sebesta, Paul D. 1996. Consequences of fire on aquatic nitrate and phosphate dynamics in Yellowstone National Park. In: Greenlee, Jason M., ed. The ecological implications of fire in Greater Yellowstone, proceedings of the second biennial conference on the Greater Yellowstone Ecosystem. 1993 September 19-21; Yellowstone National Park. Fairfield, WA: International Association of Wildland Fire. p. 53-57.
Topic(s): Fire Effects, Ecological - First Order, Fire Intensity / Burn Severity, Ecological - Second Order, Water, Fire Regime
Ecosystem(s): Subalpine wet spruce-fir forest, Subalpine dry spruce-fir forest, Montane wet mixed-conifer forest, Montane dry mixed-conifer forest, Riparian woodland/shrubland
Document Type: Conference Proceedings
NRFSN number: 11990
FRAMES RCS number: 14995
Record updated: May 10, 2018