HR: 16:55h
AN: H34A-04    [Abstracts]
TI: Using Mechanistic Studies to Model Riparian Tree Establishment Under Environmental Flow Scenarios on Regulated Rivers
AU: * Stella, J C
EM: stella@esf.edu
AF: Dept. of Forest and Natural Resources Management, SUNY College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210, United States
AU: Battles, J J
EM: jbattles@nature.berkeley.edu
AF: Dept. of Environmental Science, Policy and Management, University of California, Berkeley, 137 Mulford Hall, Berkeley, CA 94720, United States
AU: McBride, J R
EM: jrm@nature.berkeley.edu
AF: Dept. of Environmental Science, Policy and Management, University of California, Berkeley, 137 Mulford Hall, Berkeley, CA 94720, United States
AU: Orr, B K
EM: bruce@stillwatersci.com
AF: Stillwater Sciences, 2855 Telegraph Ave., Berkeley, CA 94705, United States
AB: In the Central Valley of California, pioneer cottonwood and willow species dominate the near-river forests. Historically, seedling recruitment for these disturbance-adapted species coincided with spring floods. Changes in flow timing and magnitude due to river regulation have decreased the success of seedling cohorts and contributed to the decline of these riparian tree populations. In order to address gaps in our understanding of these species and potential restoration strategies, we field-calibrated a conceptual model of seedling recruitment for the dominant pioneer woody species, Populus fremontii, Salix gooddingii, and S. exigua. We conducted experiments to identify seedling desiccation thresholds and seed longevity, used field studies to measure seedling competition and seasonal seed release patterns, and modeled interannual differences in dispersal timing using a degree-day model. These studies were integrated into a recruitment model that generates annual estimates of seedling density and bank elevation based on inputs of seasonal river discharge, seed dispersal timing, and seedling mortality from desiccation. The model predictions successfully captured interannual and species-level patterns in recruitment observed independently throughout a 20-km reach of the lower Tuolumne River from 2002-04. The model correctly predicted that seedling densities were highest in 2004 and lowest in 2003, and that S. exigua recruitment would be less extensive than for the two tree species. This work shows promise as both a quantitative approach linking hydrology, climate and plant community dynamics, and as a process-based framework for guiding flow releases and other management actions to restore riparian tree population along Central Valley rivers.
DE: 1808 Dams
DE: 1813 Eco-hydrology
DE: 1820 Floodplain dynamics
DE: 1851 Plant ecology (0476)
DE: 1860 Streamflow
SC: Hydrology [H]
MN: 2007 Fall Meeting