Dispersal and Changes in the Local Distributions of Evernia Prunastri and Ramalina Earinacea

Summary Changes in the distributions of Evernia prunastri and Ramalina farinacea along an elm avenue have been recorded for 52 months. During this time colonization by Evernia prunastri and Ramalina farinacea has occurred over a distance of 30 m. A mathematical method is described to relate the distribution of thalli to the distance of ropagule dispersal. This method may be applicable to other situations where colonization is occurring and the source of plant propagules is known.