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Success Stories

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Revegetating Mined-out Lands,Nevada

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From Mine Waste to Grassland, Arizona

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Restoring a Desert Oasis, Arizona


The Healthiest Riparian Area in North America?, NM


Restoring a Desert River, Arizona

Restoring a Desert River: Tamarisk Removal on the Upper Verde River

Healthy River-

Verde means “green” in Spanish, and the Verde River has been characterized historically by the many emerald meadows that once graced the river’s 170 mile stair step descent from Chino Valley north of Prescott, Arizona to its confluence with the Salt River, 3,500 feet lower near Scottsdale.

With headwaters just east of Paulden, Arizona the Upper Verde River comprises the first 33 miles of the 170 mile Verde River system, and most all of it crosses Prescott National Forest lands. The few remaining emerald meadows of the Upper Verde are populated mostly by sedges and play an extremely valuable role in armoring rich soils against erosion from intermittent floods.

The Upper Verde River is important to threatened, endangered and sensitive species such as native fish, including the spikedace and loach minnow. The river corridor is highly valued for recreation such as hiking, nature walking and kayaking. Quality water flow is vital to many downstream human communities within the Verde Valley and metropolitan Phoenix.

Invasive Woody Species-

Tamarisk, also known as saltcedar, is considered the worst invasive shrub impacting waterways in the Southwest. Scientific reviews note that tamarisk, allowed to expand, will dominate significant portions of riparian corridors and will negatively impact biodiversity and ecosystem functions. Tamarisk outcompetes native vegetation, causes major changes in riparian habitats, alters hydrologic and fire regimes, impacts wildlife habitats and soil biota, and consumes precious water. Tamarisk has not yet dominated the Upper Verde River ecosystem, but constitutes about 20% of the current woody plant density. Hence, a need was identified to remove and control tamarisk on the 12-mile headwater section, and restore functions and values to a native species dominated ecosystem.

Prior to 1993, woody vegetation was scant on the Upper Verde River. Streamside habitats were largely dominated by sedges and rushes, with occasional trees such as Arizona ash, walnut, and clumps of saltcedar, juniper, and other upland species. Today, the riparian habitats are comprised of dense, mixed stands of red willow, cottonwood, tamarisk, and upland woody species.

At their worst, tamarisk infestations alter the shape of the river and the way in which it functions ecologically. Channel downcutting and erosion of historical terraces are evidence of the encroachment effects of tamarisk in the floodplain. These processes lead to sedimentation and impairment of water quality. Tamarisk inhibits growth of sedges and grasses through shading. Sedges and grasses are important not only for catching and depositing sediment, but also for protecting the streambank from flood scour. Sedge-rush meadows provide diverse habitats for native wildlife and fish. Additionally, the meadows act as sponges to collect ground water, purify it and release it slowly back into the stream.

Tamarisk Removal-

Due to the difficulty of killing tamarisk root systems, trained professionals must cut stems close to the ground and immediately apply specific herbicides. In 2007 the Arizona Water Protection Fund issued a three-year grant to EcoResults Institute to administer tamarisk removal
on the upper most 12 miles of the Upper Verde River on Forest Service lands. EcoResults employed skilled technicians seasonally from the National Park Service’s Lake Mead Exotic Plant Team and Coconino Rural Environment Corps to do the work. The work was supervised by the Prescott National Forest and Rocky Mountain Research Station in accordance with stipulations of the 2004 Environmental Impact Statement for Integrated Treatment of Noxious or Invasive Weeds on the Prescott Forest. Garlon and Habitat were the herbicides used for this project.

Continued...

 

Other Success Stories

Revegetating Mined-out Lands, Nevada
From Mine Waste to Grassland, Arizona
Restoring a Desert Oasis, Arizona
The Healthiest Riparian Area in North America?, New Mexico

Open meadows can be invaded by trees that disrupt normal river functions.

 

Large tamarisk stands crowd formerly open meadow areas.

 

(1) LMEPMT crew cutting tamarisk and spraying stems with Garlon. Debris removal to uncover stems is a major work effort required to assure effective tamarisk kill and floodplain restoration. (2) One crew member records GPS data while another sprays cut tamarisks stems.

 

Same tamarisk stand shown before and after treatment.

 
 

 

 

 

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