A habitat matrix conceptual model for stream periphyton

Abstract

In this paper we suggest a conceptual model for the evaluation of periphyton communities in unshaded temperate streams based on the primary habitat variables of flood disturbance, nutrient resource supply and invertebrate grazing. The core of this model is a classification of 35 periphyton taxa into four main functional groups based on the C-S-R life history strategies of Grime. Possible successional trajectories following system-wide disturbances under different nutrient supply regimes are also discussed. The interaction of disturbance and nutrient supply on species membership, productivity and accrual time results in a predicted gradient from low biomass in frequently disturbed, unenriched habitats to high biomass in infrequently disturbed, enriched habitats. This prediction is verified empirically using literature data. Herbivory can strongly modify such periphyton responses to disturbance and resource supply. However, these grazing effects could vary greatly depending on the dominant invertebrate grazer and their total abundance, which inturn, is also sensitive to changes in disturbance and nutrient resource supply. This interaction is also discussed. The conceptual model complements other more general habitat templet and dynamic equilibrium concepts in ecology.