February 28, 2007
GCRIO Program Overview
Our extensive collection of documents.
Archives of the
Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 2, NUMBER 7, JULY 1989
IMPACTS ON LAND AND VEGETATION
"Sensitivity of Crop Yields and Land Resource Potential to Climatic
Change in Ontario, Canada," B. Smit (Dept. Geog., Univ. Guelph, Guelph,
Ontario N1G 2W1, Can.), M. Brklacich et al., Clim. Change, 14(2),
Examines the potential implications of a climatic change corresponding to a
doubling of atmospheric concentrations of CO2 on crop production in Ontario, a
major food producing region in Canada. Crop yields and the area of land capable
of supporting specific crops would vary according to region, soil quality and
crop type. Most notable are enhanced opportunities for grains and oilseeds in
the northern regions, and diminished production of most crops in the most
"Sensitivity of Evapotranspiration in a Wheat Field, a Forest, and a
Grassland to Changes in Climate and Direct Effects of Carbon Dioxide," P.
Martin (NCAR, POB 3000, Boulder CO 80307), N.J. Rosenberg, M.S. McKenney, ibid.,
Micrometeorological and physiological measurements were used to develop
Penman-Monteith models of evapotranspiration for a wheat field in eastern
Nebraska, a forest in Tennessee, and a grassland in east-central Kansas. The
model fit the measurements well over the periods of observations. Simulation
studies show that when all climatic and plant factors are considered,
evapotranspiration estimates can differ greatly from those that consider only
temperature and can differ from the control (no climate or plant change) by
about -20 to +40%.
"Effects of CO2 Concentration on Rubisco Activity, Amount and
Photosynthesis in Soybean Leaves," W.J. Campbell (Agronomy Dept., S-215
Turner Hall, 1102 S. Goodwin Ave., Univ. Illinois, Urbana IL 61801), L.H. Allen
Jr., G. Bowes, Plant Physiol., 88(4), 1310-1316, Dec. 1988.
Plants, grown from seed in outdoor controlled-environment chambers under
natural solar irradiance, had photosynthetic rates, measured during the seed
filling stage, up to 150% greater with leaflets grown at 660 compared to 330
microliters of CO2 per liter when measured across a range of intercellular CO2
concentrations and irradiance. The amount of rubisco protein (the enzyme which
initiates C3 photosynthesis) was constant as growth CO2 concentration was
varied, and averaged 55% of the total leaflet soluble protein. Although CO2 is
required for activation of rubisco, results indicated that within the range of
CO2 concentrations used, rubisco activity was not regulated by CO2.
"Correlation of Stomatal Conductance with Photosynthetic Capacity of
Cotton Only in a CO2-Enriched Atmosphere: Mediation by Abscisic Acid?" J.W.
Radin (U.S. Dept. Agric., Western Cotton Res. Lab., Phoenix AZ 85040), W.
Hartung et al., ibid., 1058-1062.
Describes field experiments to test for the existence of a factor or
messenger, other than CO2, that coordinates variability in photosynthesis with
variability in stomatal conductance of field-grown cotton. Among individual
sunlit leaves, the photosynthetic rate (A) was significantly correlated with
stomatal conductance (g). Enriched CO2 greatly increased stomatal response to
the mesophyll metabolite abscisic acid (ABA) injected into intact leaves. The
data show no evidence for a messenger to coordinate g with A at ambient levels
of CO2, but in a CO2-enriched atmosphere ABA may function as a messenger because
the sensitivity of the system to ABA is enhanced.
Guide to Publishers
Index of Abbreviations