Pollinator conservation is a component of current efforts to restore plant communities infested with non-native invasive species in the Bureau of Land Management.  This article highlights the U.S. Department of the Interior's role in and commitment to pollinator conservation. Without pollinators, humans and ecosystems cannot survive. June 24-30, 2007, has been designated National Pollinator Week by the U.S. Senate (S. Res. 580) and the U.S. Department of Agriculture. Find out what’s happening during National Pollinator Week in your area or post your event at www.pollinator.org.

When past private land-use practices threatened a rare ecosystem in Colusa, Calif., one of the ways BLM’s Ukiah Field Office sought to restore native plants was through the use of pollinators.

Part of the Cache Creek Natural Area, Bear Creek supports native fishes, northwestern pond turtle and the BLM-Sensitive yellow-legged frog. It also provides habitat for tule elk, serves as a major corridor for neotropical migratory birds, and is a state “hot-spot” for dragonfly and damselfly diversity.

Yet, before BLM acquired this unique property, private land-use practices and the proliferation of invasive plants had left the area's native plants in decline.

Now BLM's Ukiah Field Office is initiating measures to restore Bear Creek's native plant communities and to enhance wildlife habitat along the riparian corridor.

BLM Battles Invasives, Works to Ensure Future of Native Plants

One of the restoration measures has been to control the massive infestation of tamarisk (Tamarix parviflora) along the seven miles of Bear Creek under BLM management. As part of this project, BLM initiated a research effort on native plant revegetation with the University of Nevada-Reno; and more recently, they entered into a cooperative agreement with UC Davis, Department of Plant Sciences. Among the objectives of this program are to:

• Develop, implement and evaluate riparian habitat restoration methods for Bear Creek;
• Fill vegetative gaps opened from tamarisk control efforts;
• Increase nectar and pollen-rich plants for area pollinators;
• Provide structure, cover, and food for a variety of birds and other wildlife;
• Restore culturally significant plants that have a long history of use by Native Americans; and
• Help ensure that declining species obtain a stronger foothold along the riparian corridor.
  

BLM Uses Native Plants to Promote Area Pollinators

To date, the BLM-Ukiah Field Office has used 20 native plants in the Bear Creek revegetation program, including trees, shrubs, and herbs. They have collected all of the materials from the riparian corridor, increased them by seed, divided root systems and cuttings, and then planted thousands of container-grown plugs at 11 sites along a 2-mile stretch of Bear Creek.

Fifteen of these plants have been recognized for their value to pollinators and are being emphasized in area plantings to enhance foraging opportunities for a wide range of flower-visiting insects.

The Challenges Ahead

BLM has been confronted with numerous biological, physical and chemical factors during the course of this program, but they are using those challenges to hone their vegetation skills. Factors affecting the program include:

• Intense winter floods that destroyed young plantings by both scouring and sediment   deposition;
• Long periods of drought that can lead to plant desiccation without adequate post-planting   irrigation;
• Bear Creek’s alkaline water chemistry, which may preclude its use as irrigation water for some species;
• Rapid changes in channel geomorphology following tamarisk control during years with peak runoff;
• Herbicide residues in the soil from tamarisk control that persist for at least two   years;
• Herbicide drift from re-treated plants onto nontarget plantings;
• Above- and below-ground herbivory from large and small mammals, i.e., gophers, voles, beaver, tule elk and cattle;
• Highly variable soil substrate and groundwater availability; and
• Invasive plants other than tamarisk that compete for productive revegetation sites, especially perennial pepperweed, tall wheatgrass, tall fescue, yellowstarthistle and summer mustard.
  

In spite of these challenges, BLM has successfully established most of the target plants, including some that are increasing on their own due to their rhizomatous habit.

The findings from BLM's work will be used to provide management recommendations for future revegetation and pollinator enhancement efforts. They continue to look for support to carry this work beyond the current two-year funding cycle.

Acknowledgements

The BLM-Ukiah Field Office is grateful to the the following organizations for the success of this program:

Wildlife Conservation Board, http://www.wcb.ca.gov/;

Rocky Mountain Elk Foundation, http://www.rmef.org/;

BLM State Office-California, http://www.blm.gov/ca/st/en.html;

UC Davis Department of Plant Sciences, http://www.plantsciences.ucdavis.edu/plantsciences/; and

California Bay-Delta Authority, http://calwater.ca.gov/, for support of this work.

For additional information on this project, contact Craig Thomsen, rangeland ecologist, Department of Plant Sciences, UC Davis, (530) 752-8810, or Gregg Mangan, Cache Creek Natural Area manager, BLM-Ukiah Field Office, (707) 468-4078, gmangan@ca.blm.gov