PARENT SESSION
Contributed Oral Session 76: Estuary and Coastal Management
Wednesday, August 10, 8:00 AM - 11:30 AM, Meeting Room 514 A, Level 5, Palais des congrès de Montréal
Consequences of plant traits for ecosystem engineering efficiency; an ecological perspective on biophysical interactions.
Bouma, Tjeerd*,1, De Vries, Mindert2, Friedrichs, Michael3, Graf, Gerhard3, Herman, Peter1, 1 Netherlands Institute of Ecology (NIOO-CEME), Yerseke, The Netherlands2 Delft Hydraulics, Delft, The Netherlands3 University of Rostock, Rostock, Germany
ABSTRACT- Biologically mediated modifications of the environment (i.e., ecosystem engineering) has been found to significantly affect a broad range of ecosystems. Many engineers may function as keystone species. However, little is known about the benefits and costs that may be related to ecosystem engineering. We study this topic, using regularly and/or permanently submerged plant species as model system. These submerged plants are interesting because: i) hydrodynamic forces are likely to have formed a major evolutionary constraint on their growth strategies, ii) they nevertheless show a broad range of growth strategies and iii) these growth strategies determine to which extent plants are able to modify the hydrodynamic forces and thereby their environment (e.g., by enhancing sediment accretion). Our objective was to identify general patterns in how plant traits affect ecosystem engineering ability and efficiency, from a cost-benefits perspective. Our results demonstrate how shoot stiffness and spatial distribution of shoot biomass, affect species ecosystem engineering ability and efficiency. We found that i) per shoot, wave attenuation is much stronger for stiff than flexible species, but drag forces are also a larger cost in stiff species ii) per unit of biomass, wave attenuation in stands of stiff and flexible species may be comparable, iii) taking into account wave attenuation and drag forces, stiff species are more efficient ecosystem engineers than flexible species, and iv) ecosystem engineering effect strongly depends on the spatial distribution of plant biomass, and thus interacts closely with the relative advantages of clonal versus non-clonal growth strategies. In general, our results demonstrate that biophysical relations are needed to better understand the ecology of regularly and/or permanently submerged plant species.
Key words: biophysical-interactions, habitat-modification, wave-attenuation, drag