Seasonal water limitation exerts a strong ecological filter on stream communities in semiarid regions. For first year riparian willow and poplar tree seedlings, desiccation from rapidly declining river flows can limit reproduction, especially on rivers in which flow regulation and land conversion have limited the amount of area available for recruitment. We investigated survivorship of first-year riparian seedlings to simulated river stage declines, focusing on the three dominant species in California’s heavily regulated San Joaquin Basin: Fremont cottonwood, Goodding’s black willow, and sandbar willow. Seedlings grown in mesocosms were subjected to water table decline rates typical in spring on unregulated and regulated rivers. We compared species’ differences in survival time and fit the empirical data to accelerated failure time models that predicted time until death as a function of drawdown rate, initial seedling size, and maternal line.
Stella, J.C., J.J. Battles, J.R. McBride, and B.K. Orr. 2010. Riparian seedling mortality from simulated water table recession, and the design of sustainable flow regimes on regulated rivers. Restoration Ecology 18(S2):284-294.