HR: 11:35h
AN: H42A-06    [Abstracts]
TI: Hierarchical controls on patterns of habitat and species diversity in river networks
AU: * Beechie, T
EM: tim.beechie@noaa.gov
AF: NOAA Fisheries, NW Fisheries Science Center 2725 Montlake Blvd. E., Seattle, WA 98112, United States
AU: Pess, G
EM: george.pess@noaa.gov
AF: NOAA Fisheries, NW Fisheries Science Center 2725 Montlake Blvd. E., Seattle, WA 98112, United States
AB: Patterns of habitat heterogeneity and species diversity in river networks are constrained by a nested hierarchy of physical controls. Large-scale, long-term controls set bounds for habitat and biological expression, whereas short-term and smaller-scale processes determine conditions at a point in time. At the river basin scale, geologic and topographic controls constrain reach attributes such as channel slope and channel confinement, which in turn constrains finer scale habitat structure. Overlain on this geologic template are down-valley trends in relative sediment supply that cause a systematic shift in channel-floodplain dynamics. At the reach-scale, channel slope is a primary control on habitat types (e.g., pools, riffles, ponds) in single thread channels, but local bed load and wood supply influence local habitat diversity. In floodplain reaches, diversity of habitat types is controlled mainly by the rate of lateral channel movement and floodplain turnover, which decrease down-valley with decreasing bed load supply. These controls drive two important aspects of environmental complexity, which in turn drive biological diversity in river networks: diversity of patch ages, and diversity of patch types. Ecological theory suggests that floodplain forest communities will be most diverse in floodplain reaches with intermediate rates of floodplain turnover, and reach-level aquatic communities will be most diverse in mid-network where habitat heterogeneity is highest.
DE: 0410 Biodiversity
DE: 1820 Floodplain dynamics
DE: 1825 Geomorphology: fluvial (1625)
DE: 1856 River channels (0483, 0744)
DE: 1879 Watershed
SC: Hydrology [H]
MN: 2007 Fall Meeting