Morphological groups: a framework for monitoring microphytic crusts in arid landscapes

Microphytic crusts are important components of arid and semi-arid systems. They play important roles in ecosystem processes and are useful indicators of landscape health. Despite their importance, microphytic crusts and their component organisms are little understood, largely due to their small size and the difficulty in identifying them to species level. The influence of microphytic crust organisms on soils and landscapes, and their response to and recovery from perturbation is related largely by their morphology or ex ternal appearance. In this paper we examine the relationships between morph ological groups of lichens and bryophytes associated with soil crusts, and their roles in ecosystem processes in rangelands. Using published and unpub lished data we propose that the morphological group approach is a more effi cient method of monitoring soil crust organisms than one based on the tradi tional species approach. (C) 1999 Academic Press.