Ozone-Induced Symptoms on Vegetation within the Moosehorn National Wildlife Refuge in Maine

Abstract

During 1998–2000 and 2002–2004, field surveys were conducted within the Moosehorn National Wildlife Refuge, located in northeastern Maine, to determine if ozone-induced symptoms occurred on refuge vegetation. Foliar symptoms were observed on ozone-sensitive bioindicators during each survey year, but the incidence (percentage) of plants exhibiting symptoms was generally low and varied among species and years. Refuge plants that exhibited symptoms included Fraxinus spp. (ash), Populus spp. (aspen), Corylus cornuta (beaked hazelnut), Prunus serotina (black cherry), Prunus pensylvanica (pin cherry), Apocynum androsaemifolium (spreading dogbane), and a viburnum tentatively identified as Viburnum nudum var. cassinoides (withe-rod). Data from the nearest US EPA ozone-monitoring site, located 113 km southwest of the refuge in Acadia National Park, ME, revealed that ambient SUM60 ozone levels during survey years ranged from approximately 17,900 ppb-hrs in 2000 to more than 40,000 ppb-hrs in 1998. Therefore, the threshold level of SUM60 ozone capable of inducing symptoms on sensitive vegetation within this refuge and Class-I Wilderness area is less than 18,000 ppb-hrs, and may be as low as 10,000 ppb-hrs. The results of these surveys can be used by the US Fish and Wildlife Service when making air-quality management decisions, including those related to the review of Prevention of Significant Deterioration permits, and might serve as input into formulating more stringent National Ambient Air Quality Standards for ozone.