PARENT SESSION
Oral Session #49: Restoration Ecology. Presiding: J. Callaway.
Wednesday, August 8, 2001. 1:00 PM to 4:30 PM. Madison Ballroom D.

In search of general principles in regeneration ecology.

Temperton, Vicky¹, Fattorini, Marzio¹, Halle, Stefan¹, ¹

ABSTRACT- Many ecosystems on earth are degraded and in need of restoration, such that a more general theory in restoration ecology allowing for the transfer of methods from one situation to another(Hobbs and Norton 1996) is required. Since 1996 our interdisciplinary research group has been studying two essentially different ecosystems, a grassland and a river, which were both heavily polluted with fertilisers until 1990. The indentification of important processes crucial to the functioning and dynamics of the systems is our goal, in order to be able to apply such generalisations to other ecosystems.One important difference we found was that recovery of the aquatic system is faster than the terrestrial system, where the soil compartment plays a crucial role in a slower regeneration process. Therefore, a conceptual model has been developed, which addresses the invasion of new species into the systems. Every new species must fit through both an abiotic and a biotic filter, and can come from one of three possible source pools: the organism bank, vegetative propagation or drift, and dispersal from the surroundings. The mesh of this two-step filter is changed by disturbance events. Experiments on the establishment of plants on the most polluted part of the grassland, indicate that changes in geomorphology rather than seed dispersal form the main limitation to regeneration. We hypothesize that the mesh of the abiotic filter remains much finer if the degradation affects physical conditions and not just species present, such that recovery time is prolonged.

KEY WORDS: ecosystem, regeneration, invasion, filter