Lichens and air quality in Okefenokee National Wildlife Refuge: Final report

Abstract

This project on lichens and air quality in Okefenokee Refuge (NWR) was designed as a base line study of the air quality as determined by the lichens. Field work was done during November and December, 1989, when 1833 collections were made at 34 localities throughout the Okefenokee NWR in Georgia. Localities for collecting were selected to give a general coverage of the refuge and to adequately represent the total lichen flora of the refuge. Undisturbed as well as disturbed habitats were studied. While collecting at each locality, observations were made about the general health of the lichens. At some localities additional material of selected species was collected for chemical analysis. This list of species presents the first thorough listing of lichens from Okefenokee and includes 186 taxa. The lichen flora is quite diverse, with many species known from Florida and further south being present. The pondcypress trees are usually covered with Parmelia and Usnea species in addition to numerous crustose lichens. Most of the brush is covered with foliose and crustose lichens. There seems to be no obvious impoverishment of the lichen flora in any part of the the refuge. However, because there are no historical records from the refuge, there is no way to be sure some species have not already been lost. There are only a few species in the refuge that are known to be very sensitive to sulfur dioxide, but two of these are quite common in Okefenokee. The maps of the distributions of the more sensitive species do not show any significant voids that are not due to normal ecological conditions. There is no evidence of damaged or dead lichens in any area where healthy ones are not also present. The most sensitive lichen indicator technique is elemental analysis. The elemental analyses show normal levels of sulfur and other elements in the lichens and in spanish moss at all localities where they were collected. It is recommended that when new or expanded pollution sources occur near the refuge a partial restudy be done. New lichen samples should be analyzed periodically (every 5-7 years), or when additional pollution is suspected. A total restudy should be done every 10-15 years to detect any changes in the lichen flora due to air quality or climatic changes.