Publication Type:Journal Article
Year of Publication:2004
Authors:Fogel, B. N., Crain, C. M., Bertness M. D.
Journal:Journal of Ecology
Keywords:ecosystem engineering, facilitation, habitat modification, physical stress, reductive potential, salt marsh ecology, species diversity, Triglochin maritima, waterlogging

1. Ecosystem engineers can influence other organisms indirectly by modifying their physical habitat and are common in all natural communities. We examined the mechanisms underlying the effects of engineering by seaside arrowgrass, Triglochin maritima (Juncaginaceae), in a northern New England forb panne. Within these waterlogged areas, T. maritima creates elevated rings that support high plant cover compared with nearly bare adjacent substrate.

2. The influence on vegetation patterns of ring height and facilitation by neighbouring vegetation were examined in the field with T. maritima rings (elevation + vegetation), experimentally lowered rings (vegetation only), artificially raised mud (elevation only) and bare mud. Transplants of four perennial species, along with naturally occurring seedlings, were followed to assess plant performance. We also monitored edaphic conditions, seed dispersal and plant cover in experimental plots over two growing seasons.

3. All transplanted species showed increased success in raised treatments (in which the substrate showed an increase in reductive potential and a decrease in waterlogging) while there was no significant relationship to the presence of neighbouring vegetation. Seed supply, however, was enhanced by both ring elevation and the presence of neighbours.

4. A glasshouse experiment to test the response of T. maritima to waterlogging showed an increased production of shallow roots, suggesting a mechanism that may contribute to ring formation.

5. Our results indicate that community consequences of engineering by T. maritima are predominantly due to raised ring formation that ameliorates waterlogging stress and thereby promotes increased species diversity. Consequently, T. maritima may be an important target species for conservation, as sea level rise is expected to increase waterlogging stress in marshes.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith