Survival and reproduction of woody riparian plants is largely determined by periodic disturbances such as flood and drought. Hydrological models, incorporating greenhouse gas emission scenarios, predict that these changes will be exacerbated by climate change. Given the limited extent of aridland riparian ecosystems and likelihood of further hydrological change, an understanding of current and future effects of disturbance processes on populations of riparian plants are needed to protect breeding bird communities in the American Southwest.
To understand the effects of hydrological changes and wildfire on woody plants and riparian-nesting birds, Forest Service scientists reviewed the ecohydrology [an interdisciplinary area that draws on both ecology and hydrology] of southwestern streams and shared results from studies at the Middle Rio Grande.
Their research found that:
(1) Cottonwoods and other trees are key components of aridland riparian ecosystems.
(2) Reproduction and survival of these plants are largely determined by volume and timing of streamflows.
(3) Following alteration to natural disturbance regimes, wildfire has emerged as a threat to riparian ecosystems along streams such as the Middle Rio Grande; where nonnative plants such saltcedar recover from fire more effectively than native species. And,
(4) Cottonwood population projections indicated that sharp declines will occur as a result of climate-induced changes to streamflow and continued occurrence of wildfire.