Mount St. Helens ash: recreating its effects on the steppe environment and ecophysiology. [Artemisia tridentata; Lupinus sulphureus]
The 18 May 1980 ash fall from Mount St. Helens was experimentally reproduced in May 1982 by applying silt-sized ash to a stand of the Artemisia tridentata/Agropyron spicatum association in south-central Washington. Compared to the adjacent control site, ash caused an immediate increase in albedo from 13% to 28%, while other parameters of the energy budget were simultaneously lowered: net radiation by approx. = 20%, soil surface temperatures by as much as 10/sup 0/C, and soil heat flux by as much as 50%. The ash's mulching action initially increased water availability and delayed leaf abscission in Artemisia tridentata (Big sagebrush) by 2 wk in summer 1982. But after summer 1982 water availability declined, while water use increased, illustrating the diverse effects of the ash. Increased reflection from the ash-covered surface increased the radiation load on plant canopies. In turn, air temperature at 0.5 m increased, latent heat flux often doubled in summer, and xylem pressure potentials decreased. Available water at the -1 m soil depth eventually decreased as much as 40%. This decrease was the result of the increase in latent heat flux and the decline in infiltration through the stratified layer created by the ash cap. In addition to allowing assessment of the effects of the 18 May 1980 ash fall on arid steppe, application of ash provided an unexpected level of precision in detecting the often subtle effects that occur when some microenvironmental parameters change while the overall macroclimate remains the same.
- Research Organization:
- Washington State Univ., Pullman
- OSTI ID:
- 7172737
- Journal Information:
- Ecology; (United States), Vol. 67:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ASHES
BIOLOGICAL EFFECTS
ENVIRONMENTAL EFFECTS
REFLECTIVITY
SOILS
AMBIENT TEMPERATURE
MOISTURE
WATER
AVAILABILITY
ARID LANDS
CANOPIES
ENERGY BUDGETS
MT ST HELENS
SOLAR RADIATION
TERRESTRIAL ECOSYSTEMS
TREES
CASCADE MOUNTAINS
ECOSYSTEMS
FEDERAL REGION X
HYDROGEN COMPOUNDS
MOUNTAINS
NORTH AMERICA
OPTICAL PROPERTIES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PLANTS
RADIATIONS
RESIDUES
STELLAR RADIATION
SURFACE PROPERTIES
USA
WASHINGTON
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)