PARENT SESSION
Poster Session 20: Invasive Species
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

The effects of tamarisk on native floral and faunal community structure in a southern California salt marsh.

Talley, Drew^{*,1, 2}, Crooks, Jeff³, Levin, Lisa⁴, Whitcraft, Christine⁴, ¹ San Francisco Bay National Estuarine Research Reserve/SFSU, San Francisco, CA² University of California Davis, Davis, CA³ Tijuana River National Estuarine Research Reserve, San Diego, CA⁴ Scripps Institution of Oceanography, La Jolla, CA

ABSTRACT- Through their impacts on nutrient cycling, food webs, communities, and even alteration of the fundamental physical structure of habitats, exotic plant invasions have the potential to alter ecosystems across a number of spatial and temporal scales. This study tracks the history and impacts of the invasion of Eurasian trees, tamarisk (Tamarix spp.), into the high salt marsh plains of the Tijuana Estuary. This habitat has been relatively free from previous plant invasions, but the conversion of a low-lying succulent pickleweed marsh into tamarisk thickets is altering a number of community-level characteristics of the marsh. Percent cover of native vegetation is lower under tamarisk trees than in nearby control plots, but plant richness is less affected by tamarisk cover. Interestingly, the tamarisk can provide structural support for the normally low-lying marsh plant species, and maximum plant heights are often relatively high within the tamarisk canopy. Tamarisk is also affecting the resident faunal community, such as snails, birds, and insects. The mechanisms producing these changes are undoubtedly varied, and ongoing research is investigating both the roles of trophic and non-trophic (e.g., structural) interactions generating observed responses of native organisms to tamarisk. This work is also providing critical background information for ongoing work examining ecosystem responses to tamarisk eradication.

Key words: tamarix Spp., Tamarisk, Adaptive management, salt marsh