FRACTAL GEOMETRY AND ECOLOGY OF LICHENS

Abstract

From a morphological point of view lichens are usually classified in three life-forms: foliose, crustose and fruticose. In this paper we consider one lichen for each of them [a foliose (Parmelia tiliacea), a crustose (Rhizocarpon geographicum) and a fruticose (Cladonia mediterranea) lichen], and by direct measurement we show that these samples have fractal geometry and we detemine their fractal dimensions and fractality ranges. On the basis of these results, we then discuss the possible ecological causes that could have selected these geometries and that should be considered in a realistic mathematical model of growth.