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Title: Biomass and toxicity responses of poison ivy (Toxicodendron radicans) to elevated atmospheric CO2

item MOHAN, JACKIE - Harvard University
item Ziska, Lewis
item SCHLESINGER, W - Duke University
item THOMAS, RICHARD - West Virginia University
item Sicher Jr, Richard
item GEORGE, KATE - University Of Maryland
item CLARK, JAMES - Duke University

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2006
Publication Date: 6/13/2006
Citation: Mohan, J.E., Ziska, L.H., Schlesinger, W.H., Thomas, R.B., Sicher Jr, R.C., George, K., Clark, J.S. 2006. Biomass and toxicity responses of poison ivy (Toxicodendron radicans) to elevated atmospheric CO2. Proceedings of the National Academy of Sciences. 103(24):9086-9089.

Interpretive Summary: Since the start of the industrial revolution, humans have poured a lot of carbon dioxide (CO2) into the atmosphere. In addition to being the principle greenhouse gas, CO2 is also the source of carbon for photosynthesis, and giving plants more CO2 makes them grow more. However, not all plants are "good", some plants are undesirable. We call these plants weeds. Some weeds are undesirable because of their effect on human health. One such weed is poison ivy (Toxicodenron radicans). ARS scientists, working with scientists at Duke and Harvard, have been able to demonstrate that the expected rise in atmospheric CO2 is likely to both stimulate the growth of poison ivy, and also to increase its toxicity. The information will be of interest to farmers who contend with poison ivy as a weed, but also to healthcare workers, and other plant scientists.

Technical Abstract: Contact with poison ivy (Toxicodendron radicans) is one of the most widely-reported ailments at United States’ poison centers, and this plant has been introduced throughout the world. Approximately 80% of humans develop dermatitis upon exposure to the carbon-based active compound, urushiol. It is not known how poison ivy might respond to increasing concentrations of atmospheric carbon dioxide (CO2), but previous work done in controlled growth-chambers shows that other vines exhibit large growth enhancement from elevated CO2. Rising CO2 is potentially responsible for increased vine abundance that is inhibiting forest regeneration and increasing tree mortality around the world. In this six-year study at the Duke University Free-Air CO2 Enrichment (FACE) experiment, we show that elevated atmospheric CO2 in an intact forest increases photosynthesis, water-use efficiency, growth, and population biomass of poison ivy. Further, high-CO2 plants produce a more allergenic form of urushiol. This work suggests Toxicodendron taxa will become more abundant and more "toxic" in the future, potentially affecting global forest dynamics and human health.