Studies of Growth Rates of Corticolous Lichens on Long Island, New York

The growth rates of several corticolous lichens particularly Parmelia sulcata, P. caperata, and Lecanora caesiorubellawere determined by a tracing method on acetate sheets. Rates similar to those determined by other workers for related lichens were detected. Climate was found to have a strong effect on the annual growth rates. The slow rate of growth of lichen thalli has drawn the interest of many workers. Until recently, most studies were done on saxicolous species and few concerned bark lichens. The present investigation of lichens growing on oaks was part of a general study of the lichen vegetation of Long Island. The data here are admittedly only a very small addition to a growing body of growth rate information which we hope will some day allow us to understand better the autecology and community dynamics of lichens.