THE ECOLOGY OF CORTICOLOUS LICHENS: III. A SIMULATION MODEL OF PRODUCTIVITY AS A FUNCTION OF LIGHT INTENSITY AND WATER AVAILABILITY.

The article presents a study on the ecology of corticolous lichens. The study involves the use of a mathematical simulation model for predicting the productivity of epiphytic corticolous lichen in relation to the environmental conditions at Devon, England. Rates of net carbon assimilation were calculated for Parmelia caperata for a simulated time period of two years and weekly totals of net carbon assimilation were computed for lichens at each height. It was found out that the model appears to yield a calculated result which compares with the vertical distribution of P. caperata measured in the field. Moreover, the alterations in the vertical evaporation gradient are shown to have a strong effect on the vertical distribution of these species.