The Behaviour of Populations of the Marsh Gentian (Gentiana pneumonanthe): A Modelling Approach

(1) The marsh gentian (Gentiana pneumonanthe) is a plant of limited geographical distribution, whose abundance in Britain has been reduced by loss of habitat and changes in land management. (2) A computer model (MGEN) is described that allows relationships between gentians and the associated heathland vegetation to be examined. (3) Simulations produced by the model illustrate the role of periodic disturbances of the habitat and variations in yearly climate on both the overall performance and survival of individual populations. (4) Operation of the model demonstrates the requirement for greater detail regarding establishment, consideration of spatial relationships, and allowance for immigration and establishment of new, or replacement populations. (5) Simulations produced by the model suggest management options for the marsh gentian to survive on heathlands.