February 28, 2007
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Global Climate Change Digest
A Guide to Information on Greenhouse Gases and Ozone Depletion
Published July 1988 through June 1999
FROM VOLUME 8, NUMBER 5, MAY 1995
OF GENERAL INTEREST: BIOLOGICAL IMPACTS
Effects of Ambient Ozone and Climate Measured on Growth of Mature Forest Trees,"
S.B. McLaughlin (Environ. Sci. Div., Oak Ridge Natl. Lab., Oak Ridge TN 37831),
D.J. Downing, Nature, 474(6519), 252-254, Mar. 16, 1995.
Reports a five-year study of serial changes in stem circumference of 28
mature loblolly pine (Pinus taeda L.) trees, that has defined a rough
ozone response threshold and quantified short- and longer-term components of
growth responses to varying ozone and climate variables. Episodic alterations of
stem growth are directly related to ozone exposure combined with low soil
moisture and high air temperature. Future ozone effects on forests are likely to
be influenced by climate change and by projected increases in regional ozone
pollution in industrialized countries.
Potential Effects of Increased Atmospheric Carbon Dioxide (CO2),
Ozone (O3), and Ultraviolet-B (UV-B) Radiation on Plant Diseases," W.J.
Manning (Dept. Plant Pathol., Univ. Massachusetts, Amherst MA 01003), A. V.
Tiedemann, Environ. Pollut., 88(2), 219-245, 1995.
Very little is known about the actual impacts of climate change factors on
disease epidemiology in plants. Increased CO2 could increase plant
canopy size and density, with resulting greater biomass and higher microclimate
relative humidity. This could promote diseases such as rusts, mildews, leaf
spots and blights. Plants weakened through ozone could be more susceptible to
necrotrophic pathogens; ozone is unlikely to directly affect fungal pathogens.
Increased UV-B could lead to increased disease resistance through increased
production of flavinoids, but reduced net photosynthesis, and premature ripening
and senescence, could result in variable reactions to disease.
Change: Modelling the Potential Responses of Agro-Ecosystems with Special
Reference to Crop Protection," J. Goudriaan (Dept. Theoretical Production
Ecol., Wageningen Agric. Univ., POB 430, 6700 AA Wageningen, Neth.), J.C.
Zadoks, ibid., 215-224.
Although climate change can affect potential yields, little is known about
its ability to modify the effects of pests, diseases, and weeds. If climate
change causes a gradual shift of agricultural regions, crops and associated
pests, diseases and weeds will migrate together, though perhaps at different
rates. Increases in atmospheric CO2 and UV radiation are not likely
to have large effects. Makes cautionary remarks to avoid jumping to conclusions.
Climate Change on Grassland Production and Soil Carbon Worldwide," W.J.
Parton (Natural Resour. Ecol. Lab., Colorado State Univ., Ft. Collins CO 80523),
. .and SCOPEGRAM Group Members (c/o D.O. Hall, Div. Life Sci., King's Coll.,
London W8 7AH, UK), Global Change Biology, 1(1), 13-22, Feb.
Modeling was done under two different climate change scenarios for 31
temperate and tropical grassland sites using the CENTURY model. The net effect
of climate change and CO2 was an increase in net primary production
in mesic and dry savanna regions, with little or no change in cold desert steppe
or humid tropical regions. Detecting statistically significant change in plant
production would require a 16% change because of high year-to-year variability
in plant production. Most predicted changes in plant production are less than
"Climate of the
21st Century," L. Bengtsson (M. Planck Inst. Meteor., Bundestr. 55, D-20146
Hamburg, Ger.), Agric. & Forest Meteor.,
72(1-2), 3-29, Dec. 1994.
Primarily a review of how GCMs predict climate change. Concludes with
results of possible changes in vegetation estimated by the response of a biome
model, which indicates minor changes in vegetation. There is a small
north-eastward movement of vegetation zones over Europe and North America.
Climate Change: Are Passive Greenhouses a Valid Microcosm for Testing the
Biological Effects of Environmental Perturbations?" A.W. Kennedy (Marine
Lab., CSIRO, POB 20, North Beach, Perth WA 6020, Australia),
Global Change Biology, 1(1), 29-42, Feb. 1995.
Challenges the assumption of many studies that "passive"
greenhouses (those not requiring artificial power input to create treatment
conditions) provide a sufficiently controlled micro-environment for climate
change research. Greenhouses modify temperature, moisture, light, gas
composition, snow cover, and wind speed in a complex and interactive manner.
However, the relationship between modification and forecast conditions of
climate change is poor, and interpretation of biological responses and
extrapolation to predictive models is unreliable. Suggests amendments to the
methodology used in greenhouse experiments to overcome criticisms of artifact
and lack of rigor.
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