Ecosystem engineers activate plant-mycorrhizal mutualism in salt marshes

DALEO, P.; FANJUL, E.; MENDEZ CASARIEGO, A.; SILLIMAN, B.; BERTNESS, M.D.; IRIBARNE, O.

Ecology Letters

Año: 2007 vol. 10 p. 902 - 908

1461-023X

Theory predicts that ecosystem engineers should have their most dramatic effects whenthey enable species, through habitat amelioration, to live in zones where physical andbiological conditions would otherwise suppress or limit them. Mutualisms betweenmycorrhizal fungi and plants are key determinants of productivity and biodiversity inmost terrestrial systems, but are thought to be unimportant in wetlands because anoxicsediments exclude fungal symbionts. Our field surveys revealed arbuscular mycorrhizalassociations on salt marsh plant roots, but only in the presence of crabs that oxygenatesoils as a by-product of burrowing. Field experiments demonstrate that fungalcolonization is dependent on crab burrowing and responsible for nearly 35% of plantgrowth. These results highlight ecosystem engineers as ecological linchpins that canactivate and maintain key mutualisms between species. Our findings align salt marsheswith other important biogenic habitats whose productivity is reliant on mutualismsbetween the primary foundation species and micro-organisms.