SGER: Early Responses of an Experimental Marsh Ecosystem to Varied Topographic Heterogeneity

San Diego State University Foundation, San Diego CA

Investigators

Abstract

Multi-scale, vertical, and horizontal topographic heterogeneity is a critical property of wetland ecosystems. The lack of topographic heterogeneity in restored systems could be a key constraint on their progress toward structural and functional equivalency with undisturbed sites. This project will test the role of heterogeneity in the progress of ecosystem restoration. We hypothesize that topographic heterogeneity enhances the development of restored wetlands and predict that ecosystem structure and function will develop much more rapidly where topographic heterogeneity is added. We will test this hypothesis using an 8-ha "model marsh" in the Tijuana River National Estuarine Research Reserve in San Diego County, CA. To maximize scientific benefits, the site was designed as a large-scale, replicated experiment. This one-of-a-kind project has tremendous potential to advance restoration science due to its state-of-the-art design, replicated treatments, and large scale. Over time, the replicated cells are expected to diverge in structure and function, as tidal creek morphology and marsh surface elevations respond to erosion and sedimentation; colonization by vegetation and invertebrates (including founder effects/chance establishments); use by fish; and landscape position (distance along the tidal channel that feeds all three creek networks). Chance establishments by plant seeds and invertebrates brought into the system by tidal water could be particularly important. We will collect critical baseline data as we document early conditions at the model marsh, and assess changes in structure, function, and variability during marsh development. Such early information will strengthen our ability to predict and model the viability of other wetland restoration projects.