LONG-TERM TRENDS IN VARIABILITY OF PRIMARY PRODUCER COMMUNITIES IN A DYNAMIC, ARIDLAND STREAM ECOSYSTEM
Intermittent and ephemeral aridland stream ecosystems are characterized by irregular flood disturbance regimes that are highly variable among years. Flood disturbances scour stream beds, resulting in successional regrowth of primary producer communities as a function of time since flood. This study aims to understand how variability in antecedent flood conditions affects the composition and abundance of primary-producer communities over seasonal and annual timescales. Using seven-years of long-term data collected from Sycamore Creek, AZ, we examined changes in the primary-producer community, including dominant wetland plants, algae, and cyanobacteria. We evaluated how antecedent floods influenced patterns in the primary producer community. Flood discharge varied over the seven-year dataset from a maximum discharge of around 350 m^3/s in 2010. Primary producer composition and abundance varied annually as a function of among-year variation in flood events. Years with greater flood discharge magnitudes saw greater abundances of wetland plants, which varied among species. Schoenoplectus americanus experienced large increases in abundance following large flood events. Conversely, algae groups were less sensitive to flood disturbance. Our data illustrate the importance of annual variability of flood regimes on successional patterns of primary-producer communities in aridland streams.
Marina Lauck (Primary Presenter/Author), Arizona State University, email@example.com;
Nancy Grimm (Co-Presenter/Co-Author), Arizona State University, firstname.lastname@example.org;