Impact of Ozone on terrestrial vegetation

Articles by: Fuhrer J

SC/Biology 4095 Presentation

Topic: Impact of Ozone on vegetation

Enriched O3 in atmosphere = visible signs of injury (discolouration) within few hours/days
First signs of photochemical air pollution in 1940s in L.A and N.E.
Large scale experiments in:
US (National Crop Loss Assessment Network)
Europe (European Open-Top Chamber Program)

Ozone Flux into terrestrial plants

Tropospheric Ozone Impacts

How ozone in the lowest part of the atmosphere has altered temperatures over the past 100 years. The contribution of a single air pollutant/greenhouse gas towards the warming of specific regions in the world.

Factors affecting ozone transfer on land

Air conductivity/Atmospheric resistance affected by:

§Wind Speeds

§Atmospheric stability

§Surface roughness

Diffusive and Stomatal resistance affected by:

§Air water vapor deficit

§Soil moisture deficit

§Physiological status of plant

Effects on biomass distribution and terrestrial plant growth

§Ozone stress affects biomass distribution (Carbon and nutrients)

§Species with high growth rate = more sensitive to ozone stress

§Agriculture: Prefer to shift biomass allocation from reproduction to vegetative parts

§Harvest Index declines with increasing Ozone acting against plant breeding efforts

Ozone causes a shift in biomass distribution

Shift in allocation between aboveground parts

§Chronic Ozone stress: decrease in biomass allocation to roots

§Decline in proportion of root to shoot mass

§Decline in root mass = decline in shoot light use efficiency

§Plants more susceptible to:

Drought

Nutrient deficiency

Trees (Wind Throw)

Effect on Terrestrial Plant Communities

§Competition in communities for nutrients

§Presence of Ozone = Disadvantage to sensitive species

§Change in competitive balance

§Change in composition of genetic structure

§Selection of tolerant genotypes response to high ozone stress

§Future generations more tolerant to higher ozone amounts.

§Lower Genetic Diversity

Exposure-Response Relationships in Wheat and Small trees in Europe

§Method: Open-top exposure chambers (OTC)

§Quantitative relationship: Ozone and measureable ozone effects

§Small change in environment: Manipulate Ozone levels

§Linear function: determine level of ozone at which negative effects occur

§Results: sufficient decline in stem growth with increasing ozone for wheat, spruce and beech.

Risk analysis and Conclusions

§Need better methods to assess and estimate ozone uptake by plants

§Relate Ozone uptake to plant growth and yield

§Need longer durational studies to better understand long term effects

§High levels of Ozone highly affect terrestrial plants in Northwest and south Europe as well as USA.

§Dry soil and air conditions reduce the risk of significant negative effects on crop yield.

References

§Fuhrer J. 2002. Ozone Impacts on Vegetation. Ozone: Science and Engineering: The Journal of the International Ozone Association. 24(1): 69-74.

§Fuhrer J, Endtner V, Bungener P, Nassbaum S and Grub A. 1997. Interspecific differences in ozone tolerance. Breefing for a multifunctional agriculture. 97(1): 191-194.

§FuhrerJ, Skarby L and Ashmore M. 1997. Critical levels for ozone effects on vegetation in Europe. Environment and Pollution. 97(1): 91-106

§Fuhrer J and Achermann B. 1999. Critical levels for Ozone, Level II. Forest and Landscape. 111-114.

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