Model of stand photosynthesis for the wet meadow tundra at Barrow, Alaska
- San Diego State Univ., CA
A model of radiation, air temperature, and vapor density in the vegetation canopy, plant water relations, and photosynthesis, developed in the primary production research program of the U.S. Tundra Biome, IBP, is described and results for the years 1970 through 1973 presented. The model calculates daily courses of direct and diffuse solar radiation; infrared radiation; wind; air temperature and humidity; leaf temperatures; convectional and transpirational exchange by leaves, stems, and dead material; leaf H/sub 2/O content, leaf water potential; leaf resistance to H/sub 2/O loss; internal resistance to CO/sub 2/ diffusion; and net photosynthesis. Climate varied from year to year: 1970 and 1971 were similar, 1972 was relatively warm and dry, and 1973 was relatively cold and wet. Plant parameters were obtained for Carex aquatilis, Dupontia fischeri, Eriophorum angustifolium, and Salix pulchra. Leaf area indices varied by species and by year. Leaf areas of all species were lowest in 1973. Of the incoming solar radiation approximately 20% is reflected back and 32% to 53% absorbed by the canopy, increasing with leaf area index. Total seasonal vascular plant CO/sub 2/ uptake ranged from 400 to 627 g CO/sub 2/ . m/sub G//sup -2/ (subscript G refers to ground). In 1971 cuvette estimates for total seasonal vascular plant CO/sub 2/ uptake were 602 while the model predicted 627. Individual species incorporated about 4 g CO/sub 2/ . m/sub G//sup -2/ . day/sup -1/ at most. Photosynthesis increased with solar radiation, air and ground temperatures, and air vapor density and decreased with increasing infrared radiation for the sky and root resistance to water uptake.Total accumulated carbon dioxide, after subtracting growth costs of leaves, becomes positive late in the season and is highest at the lower levels. Photosynthesis seems adjusted to maximize carbon gain under the most frequent conditions but not under all conditions or extreme conditions. (auth)
- OSTI ID:
- 7227803
- Journal Information:
- Ecology; (United States), Vol. 57:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALASKA
ECOLOGY
CARBON DIOXIDE
PLANTS
BIOLOGICAL MODELS
TUNDRA
PHOTOSYNTHESIS
CLIMATES
CONVECTION
HEAT LOSSES
HUMIDITY
INFRARED RADIATION
LEAVES
PLANT STEMS
SEASONS
SIMULATION
SOILS
SOLAR RADIATION
TIME DEPENDENCE
TRANSPIRATION
UPTAKE
WATER
WIND
BIOMASS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
ENERGY LOSSES
ENERGY SOURCES
ENERGY TRANSFER
HEAT TRANSFER
HYDROGEN COMPOUNDS
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
PACIFIC NORTHWEST REGION
PHOTOCHEMICAL REACTIONS
RADIATIONS
RENEWABLE ENERGY SOURCES
SYNTHESIS
USA
510100* - Environment
Terrestrial- Basic Studies- (-1989)