Leaf Response
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Leaf Response
Growth Response
Pest Interactions
Soil Response
Ozone Modeling


Leaf Surface Response

Bifacial chlorosis and bleaching of leaves were the most common foliar symptoms of O3 on paper birch (right). Premature senescence of leaves was also recorded for both aspen and birch. No symptoms were seen on sugar maple, which is O3 tolerant.

Trees in elevated CO2 + O3 had significantly less visible symptoms than did trees in elevated O3, suggesting that CO2 was compensating for the adverse O3 effects. 


Cell and Organelle-level Injuries 

Normal chloroplast of aspen leaf cells, Clone 259 in Control Treatment, showing intact thylakoid membranes and large starch grains, indicating active photosynthesis and a low number of plastoglobuli (black lipid granules).

Ozone-induced chloroplast of aspen clone 259, showing disintegration and breakdown of thylakoid membranes, accumulation of plastoglobuli (= storage sites for membrane degradation material), and a small starch grain, indicating low photosynthetic activity.

- courtesy Elina Oksanen, University of Kuopio, Finland

The Northern Forest Ecosystem Experiment (NFEE) is funded by the US Forest Service. The Aspen FACE Experiment is funded principally by the U.S. Department of Energy's Office of Biological and Environmental Research. Additional support is from the USFS Global Change Program, Michigan Technological University, the Canadian Forest Service and the USFS Northern Research Station.
For more information on this project, contact Dr. Andrew J. Burton (Michigan Technological University) at (906) 487-2566 or mailto:ajburton@mtu.edu, or Dr. Mark E. Kubiske (Northern Research Station) at (715) 362-1108 or mailto:mkubiske@fs.fed.us.
For questions or suggestions regarding this website, please contact Janet Pikkarainen at mailto:jmpikkar@mtu.edu.
Last updated: July, 2010