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Title: Rising atmospheric carbon dioxide and potential impacts on the growth and toxicity of poison ivy (Toxicodendron radicans)

item Ziska, Lewis
item Sicher, Richard

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2007
Publication Date: 7/1/2007
Citation: Ziska, L.H., Sicher Jr, R.C., George, K., Mohan, J.E. 2007. Rising atmospheric carbon dioxide and potential impacts on the growth and toxicity of poison ivy (Toxicodendron radicans). Weed Science. 55(4)288-292.

Interpretive Summary: Carbon dioxide stimulates the growth of plants, but different types of plants respond differently. Some plants that could respond to carbon dioxide include plants that affect people's health. For example, poison ivy can induce a skin rash in two out of three people who come into contact with it for the first time. In this experiment we examined how poison ivy could respond to increases in carbon dioxide using concentrations of carbon dioxide that existed in 1950, the current level of carbon dioxide, and the projected level of carbon dioxide for the years 2050 and 2090, respectively. We found that carbon dioxide stimulated the growth of poison ivy with the largest relative increase occurring between 1950 and today. In addition, we found that as carbon dioxide increased, the production of urushiol, the oil in poison ivy that causes a rash, increased as well. Overall, these results indicate that the growth and survivability of poison ivy is likely to increase as carbon dioxide increases in the atmosphere. These data will be of interest to climatologists, health care providers, pharmaceutical companies, scientists, and policy makers.

Technical Abstract: Because of its ability to induce contact dermatitis, the establishment and spread of poison ivy (Toxicodendron radicans (L.) Kuntze) is recognized as a significant public health concern. In the current study, we quantified potential changes in the biomass and urushiol content of poison ivy as a function of incremental changes in global atmospheric carbon dioxide concentration [CO2]. We also examined the rate of new leaf development following leaf removal to simulate responses to herbivory as functions of both [CO2] and plant size. The experimental CO2 values (300, 400, 500 and 600 umol mol-1) corresponded approximately to the concentration that existed during the middle of the 20th century, the current concentration, and near and long-term projections for this century (2050 and 2090), respectively. Over a 250-day period, increasing [CO2] resulted in significant increases in leaf area, leaf and stem weight, and rhizome length relative to the 300 umol mol-1 baseline, with the greatest relative increase occurring from 300 to 400 umol mol-1. Because of the stimulatory effect of [CO2] on leaf biomass, the amount of urushiol produced per plant increased significantly for all [CO2] above the 300 umol mol-1 baseline. Significant increases in the rate of leaf development following leaf removal were also observed with increasing [CO2]. Overall, these data confirm earlier, field-based reports on the CO2 sensitivity of poison ivy, but emphasize its ability to respond to even small (ca 100 umol mol-1) changes in [CO2] above the mid 20th century carbon dioxide baseline. This would suggest that its rate of spread, its ability to recover from herbivory, and its production of urushiol, may be enhanced in a future, higher CO2 environment.