A worldwide research effort to study the effects of elevated carbon dioxide and ozone on trees is underway in Wisconsin. Long-term effects are being studied with the aid of outdoor laboratories known as Free Air Carbon dioxide Enrichment (FACE) — a series of tubes forming a ring around clusters of aspen, birch and maple trees. The tubes inject elevated CO2, ozone or a combination of CO2 and ozone into the atmosphere around the trees. Nearly 60 researchers from seven countries are cooperating on the research. We all know higher ozone levels are detrimental to our plants. There is much talk about increased greenhouse gases, primarily increased CO2, and how it will affect living things. Among the questions being addressed: “Will elevated CO2 alleviate ozone, drought and/or low fertility stress? Will elevated CO2 increase plant growth? Will insect and disease pressure change with changing CO2 and ozone concentrations?” After several years, there are a few knowns: increased CO2 increases tree growth; increased ozone stunts tree growth; increased CO2 and ozone at the same time can cancel out each other's affects; increased CO2 increases some insect and disease pressure and delays normal autumn leaf fall, possibly causing increased winter dieback. There is variability among the three species — the maple is less tolerant and birch more tolerant to changes in atmospheric gases. Other FACE Experimental stations are located in Duke Forest, Duke University, N.C., (pine); Oak Ridge, Tenn., (sweetgum); Mercury, Nev., (desert ecosystems); and Switzerland (ryegrass & clover), to name a few.