Management Guidelines to Reduce Endangered Species Conflicts from Salt Cedar Control at Reclamation Water Projects

Project ID: 9331
Principal Investigator: Susan Broderick
Research Topic: Invasive Species
Funded Fiscal Years: 2005, 2006 and 2007
Keywords: None

Research Question

* How do wildlife species respond to various types and scales of salt cedar control measures?

This research quantifies the effects on representative avian, mammalian, and insect communities across a wide range of salt cedar control measures (including herbicide, mechanical, prescribed burning, and biocontrol) in four western river systems. The purpose of the research is to develop management guidelines that would be implemented by Reclamation resource managers conducting salt cedar control programs to prevent adverse impacts to threatened and endangered (T&E) and other special-status species habitat.

Need and Benefit

Salt cedar (_tamarisk_) control projects are being implemented on rivers and reservoirs throughout the arid Western United States at an unprecedented rate as Reclamation and other management entities seek to liberate additional water. However, little information is available on how wildlife species respond to salt cedar control methods (herbicide, mechanical, prescribed burning and biocontrol), or on the potential for adverse impacts to T&E and special-status species such as the southwest willow flycatcher, yellow-billed cuckoo and bell's vireo, as well as many other riparian species that are watch-listed or are state species of concern.

Data and management guidelines developed from this research would provide Reclamation resource managers with the knowledge and tools to implement salt cedar control projects on Reclamation water projects that are designed to protect and enhance T&E species habitat. This will prevent or reduce the risk of Reclamation's water facilities receiving violation notices under Federal or State laws and potential interruption, reduction or elimination of water or power deliveries. Additionally, this research facilitates and uses a wide array of collaborative partnerships that will benefit Reclamation by expanding the number of sites and management methods, as well as providing additional funding for data collection and analysis. Entities such as the Socorro Soil and Water Conservation District, Save our Bosque Task Force, Bureau of Land Management (BLM) and National Park Service (NPS) recognize the need for data on wildlife responses to salt cedar control measures and guidelines designed to prevent unintended adverse impacts and to enhance habitat.

These management guidelines would initially be developed for Reclamation water projects on the Pecos River at Brantley Dam, Canadian River at Sanford Dam, Rio Grande upstream of Elephant Butte Reservoir and the Arkansas River at Pueblo Dam. The knowledge obtained from this research could be readily expanded to water projects on the Colorado, the Platte and other western rivers with extensive areas of salt cedar infestations that can potentially impact Reclamation's water and power deliveries.

Reclamation has pioneered efforts to include wildlife monitoring in its salt cedar leaf beetle release projects (biocontrol). Useful data are being obtained on wildlife responses to salt cedar biocontrol; and these efforts need to continue, particularly when leaf beetle herbivory is now beginning to effect large areas of salt cedar. However, little or no information is available from any source on wildlife responses to large-scale aerial herbicide applications with products such as Arsenal, large and small scale mechanical control measures, and large and small scale prescribed burning. No effort has been made to comprehensively analyze wildlife responses to a wide range of salt cedar control measures across a wide range of scales (large to small) across a wide range of riparian conditions.

The consequences of proceeding with large-scale vegetation control measures with little or no knowledge of impacts to riparian wildlife communities is subjecting Reclamation to the risk of causing unintended adverse impacts to species that are already listed as threatened or endangered; or pushing at-risk species such as yellow-billed cuckoos and bells vireos, that are now only candidate species or species of concern, to becoming listed species.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Independent Peer Review

The following documents were reviewed by qualified Bureau of Reclamation employees. The findings were determined to be achieved using valid means.

Butterfly assemblages associated with invasive tamarisk (Tamarix spp) Sites: Comparisons with Tamarisk Control and Native Vegetation Reference Sites (final, PDF, 1.5MB)
By Mr. S. Mark Nelson and Richard Wydoski
Publication completed on July 31, 2013

We studied butterfly assemblages at six types of riparian landscapes in five different watersheds in the southwestern US. Sites included a mix of saltcedar, native and saltcedar-treated. Significant differences were found between sites. The assumption that tamarisk removal is sufficient to recover sensitive species were not true in the cases we examined. Results support the importance of reinstating stream-flow regimes & suggest active restoration is needed to restore sensitive wildlife spp.

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Last Updated: 6/22/20