02808nas a2200253 4500008004100000245012900041210006900170300001400239490000700253520197600260653002602236653001702262653002502279653002002304653002402324653002302348653002202371653002402393653001702417100002402434700002302458700002302481856005002504 2004 eng d00aCommunity level engineering effects of Triglochin maritima (seaside arrowgrass) in a salt marsh in northern New England, USA0 aCommunity level engineering effects of Triglochin maritima seasi a589–5970 v923 a

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.

10aecosystem engineering10afacilitation10ahabitat modification10aphysical stress10areductive potential10asalt marsh ecology10aspecies diversity10aTriglochin maritima10awaterlogging1 aFogel, Benjamin, N.1 aCrain, Caitlin, M.1 aBertness, Mark, D. uhttps://juncaginaceae.myspecies.info/node/578