The Role of Algal Mats on Community Succession in Dunes and Dune Slacks

Different kinds of algal communities can live in dune slacks that may become temporarily flooded or remain moist throughout the year due to fluctuations in the proximity of the water table (Brown and McLachlan 1990). This chapter focuses on changes in the composition of algal communities during periods of flooding and drought, with special emphasis on the hydrological characteristics of slacks as well as on morphological and physiological factors that allow algae to survive in these stressful environments. Also discussed is the role of algae in the first stages of dune succession, when they form part of a soil community of so-called microbial mats (Belnap and Gillete 1998) as well as part of the aquatic community. In both circumstances, algae participate actively in sand stabilization and facilitate the development of several pioneer plants. Finally, changes in algal community composition are reported for the case where slacks became flooded in a tropical mobile dune system.