Ozone-Induced Stipple on Plants in the Cape Romain National Wildlife Refuge, South Carolina

Abstract

During 1996–1998 and 2002–2003, field surveys were conducted within the Cape Romain National Wildlife Refuge, located on the Atlantic coast of South Carolina, to determine if refuge vegetation exhibited foliar symptoms (stipple) induced by ambient ozone. Foliar stipple was observed on Rhus copallina (Winged Sumac), Sapium sebiferum (Chinese Tallowtree), and Vitis sp. (wild grape). Grape had the greatest frequency of stippled plants, followed by Winged Sumac and Chinese Tallowtree. Chinese Tallowtree produced the most classic ozone-induced stipple, and may have the most potential as a useful ozone-sensitive bioindicator. Percentage of plants with ozone-induced symptoms varied among species and years. The threshold value of CUM60 ambient ozone needed to induce symptoms on ozone-sensitive plants in the refuge was estimated to be approximately 9000 ppb-hrs.