Lack of belowground mutualisms hinders Pinaceae invasions

NUÑEZ, M. A., HORTON T. R. & SIMBERLOFF, D.

ECOLOGY

Año: 2009 vol. 90 p. 2352 - 2359

0012-9658

Why particular invasions succeed and others fail is not well understood. Therole of soil biota has been proposed as important. However, the role of mutualists has receivedmuch less attention than that of pathogens. Here we report that lack of adequate ectomycorrhizal fungi hinders invasion by exotic Pinaceae on Isla Victoria, Argentina, by reducing both the probability of establishment and growth of invading individuals. More than one hundred exotic tree species were introduced to this island ca. 80 years ago, but invasive trees are found in high densities only in areas adjacent to plantations. With a series of greenhouse and field experiments we found lower mycorrhizal colonization levels and few fungal species far from original plantings, and key fungal mutualists are confined to areas near plantations, probably owing to dispersal limitations. Low inoculum levels far from the plantations are retarding the invasion. Our experiments indicate that positive interactions belowground can play a key but underappreciated role in invasion dynamics.