PARENT SESSION
Oral Session #32: Testing Ecological Theory in Restoration Practice.
Presiding: C. Brown
Tuesday, August 6. 8:00 AM to 11:30 AM. Grand Ballroom West, Radisson.

Ecological theory and invasive species in salt marsh restoration.

Grosholz, Edwin^*,1, Levin, Lisa², Neira, Carlos², ¹ University of California, Davis, CA, USA² University of California, San Diego, La Jolla, CA

ABSTRACT- Of the many obstacles to success of many restoration projects are non-native species that invade newly restored habitat. Older ecological theory predicted that more diverse systems would be less invasible than less diverse ones, all else being equal. Thus, restoration projects should increase native diversity in order to minimize subsequent invasion by non-native species. However, it is now clear that there are several important exceptions to this pattern. A more recent idea suggested that certain invasive species may facilitate the subsequent invasion of other non-natives, resulting in a positive feedback dubbed invasional meltdown. We show that this is occurring as the result of the Spartina hybrid invasion in San Francisco Bay, CA. By creating structure in a naturally unvegetated habitat, we show that Spartina alters light levels, water flow and sedimentary processes. As a result, we show that the Spartina hybrid decreases invertebrate diversity and increases in the relative abundance of exotic species. The lesson for restoration in these heavily invaded intertidal, estuarine habitats is to remove this invasive plant, which we predict will be more successful than simply focusing on native diversity per se.

KEY WORDS: restoration, invasive species, Spartina, invertebrate