Priority Weeds
Facts About Tamarisk
- Native of Eurasia
- Introduced in the early 1800's
- Represents 80% of vegetation in the Wash
- Obligate phreatophyte
- Exhibits little diversity in height and composition
- Provides less suitable habitat for wildlife
- Increases soil salinity
Tamarisk - aka 'Saltcedar' (Tamarix ramosissima)
Introduced in the United States in the late 1800s, hundreds of thousands of acres of rivers, riparian corridors and springs have been invaded by tamarisk, outcompeting native species and altering the hydrology of the ecosystem. In the Las Vegas Wash, tamarisk has gained a foothold, representing 80 percent of the vegetation, approximately 1,500 acres.
An Aggressive Competitor
Without any natural predators in the United States, there are several ways that enable tamarisk to outcompete native plant species in the southwest. Tamarisk has the ability to transpire large quantities of water coupled with a fast growing taproot. This combination enables this weed to draw down the water table, preventing other plants' roots from reaching the soil moisture. Another competitive feature of tamarisk is its reproductive timing. It seeds earlier in the season than its competitors such as cottonwoods and willows. Without this competition from other native species, tamarisk releases million of seeds that can spread easily throughout the Wash floodplain, establishing quickly on sandbars and along the streamside. As these plants become increasingly more prevalent, there is less room for natives to establish. A copy of the Weed Wanted Poster is available courtesy of University of Nevada, Reno.
Control Program
The Las Vegas Wash Weed Partnership has ranked tamarisk third in its Top Three Hit List. Because of the extent of the infestation of the tamarisk in the Las Vegas Wash the tamarisk management program is geared for controlling the species. Tamarisk is removed in specific areas based on the revegetation program.
In 2003, approximately 1,500 acres of salt cedar were reported within the lower Las Vegas Wash, which is defined as the nine mile stretch of the Wash from Vegas Valley Drive to Lake Las Vegas. The saltcedar infestation was mapped using aerial photography and a geographic information system (GIS).
In 2007, saltcedar infestations were remapped with three goals in mind:
- Show the extent of saltcedar along the Lower Wash
- Document the reduction of acreage as a result of remove/management projects
- Determine if the saltcedar had infested new previously undocumented areas in the Lower Wash
When the remapping of the saltcedar was complete, the maps showed only 530 infested acres, a reduction of almost 1,000 acres with very few new infestations documented. LVWCC projects accounted for the removal of approximately 200 acres and residential and commercial development accounted for a reduction of about 770 acres.