USGS Home Contact USGS Search USGS

Maps, Imagery, and Publications Hazards Newsroom Education Jobs Partnerships Library About USGS Podcasts/RSS

Saltcedar, Russian-olive Invade Western Riparian Ecosystems

In the arid and semi-arid Southwest, essential habitat for wildlife is often found in streamside or riparian ecosystems, whose importance for wildlife cover, migration routes, water, and food is critical because such habitat makes up less than 1 percent of the southwestern landscape.

USGS Scientists survey vegetation and other habitat characteristics at 500 long-term USGS stream gaging stations to better understand how non-native plants invade riparian areas

Unfortunately, these unique and important habitats are being invaded by non-native plants, such as saltcedar and Russian-olive, which are replacing native streamside vegetation and changing ecosystems and waterways. In large areas of west Texas, New Mexico, Arizona, Colorado, Utah, Nevada, and southern California, salt cedar is now the dominant riparian species. This change has resulted in loss of biodiversity, degradation of bird habitat, decreased channel conveyance, increased water loss, and loss of recreational opportunities.

To better understand these invasions, USGS scientists from the Midcontinent Ecological Science Center are examining the environmental factors that make riparian ecosystems more susceptible to non-native plants. At 500 randomly selected long-term USGS stream gauging stations in 17 western states, scientists are relating the abundance of native and non-native woody riparian plants to the timing and magnitude of stream flow, channel geometry, salinity, and climate.

On experimental plots, scientists are also comparing seedling germination and survival among native cottonwood and non-native saltcedar and Russian-olive. Together, these data will help identify the factors influencing the current distribution of native and non-native plants and will help managers predict the spread of non-native species to new locations.

"Our work provides an interdisciplinary approach to solving riparian issues by combining hydrology, plant ecology, and fluvial geomorphology," said USGS hydrologist Jonathan Friedman. "We hope to eventually be able to predict the susceptibility of riparian habitats to saltcedar and Russian-olive invasions by looking at specific site characteristics."

Results from this study will improve management decisions regarding invasive plants and reservoir operations, control efforts, grazing, and native species restoration.