Karen A. Koestner

Threats to Western United States Riparian Ecosystems: A Bibliography

This bibliography is a compendium of state-of-knowledge publications about the threats affecting western U.S. riparian ecosystems and is a companion to the website: http://www.fs.fed.us/rm/boise/AWAE/publications/bibliography.shtml#riparian. The website contains abstracts and access to many of the publications via PDFs, or it directs the readers to websites where PDFs of the publication can be viewed or obtained. The bibliography is ordered alphabetically and the type of threats discussed in each publication is highlighted. These threats include agriculture, climate change, dam construction, disease, drought, invasive species, fire, floods, flow regulation, forest harvesting, grazing, groundwater depletion, insects, mining, recreation, roads, water diversions, urbanization, and water quality.

Water yield from harvesting and thinning southwestern mountain forests: Historical experience from US Forest Service research

Subsequent to the extreme fire seasons of 2000 and 2002, extensive thinning of Southwestern mountain forests has been designated as the preferred practice to minimize the likelihood of widespread stand-replacing fires. Concurrently, historical hydrologic research been incorrectly popularized to indicate that forest canopy removal can measurably augment water yields from forested watersheds. A popular misconception has therefore arisen that these two usually incompatible goals can be achieved simultaneously on the same land. Responsible and appropriate silvicultural activities for other purposes, such as fire risk reduction, may increase water yield from upper elevation forests or improve water balance within lower elevation forests, depending on the intensity of canopy removal, tree species, latitude, elevation, and aspect. These same activities may also restore other desirable landscape characteristics and should not be directed solely at water yield. Increases in water yield will be difficult to quantify, especially at the scale of large basins, like the Salt River, that provide for large municipalities. Therefore, short term increases in water yield from forest canopy removal should be considered a serendipitous benefit if and when it occurs in conjunction with other advantageous results. BACKGROUND As a result of prolonged drought in the Western United States, a great deal of contention has developed about forest management because of drought-induced fire danger, decreased water yield from forest snowpack, and the cumulative effects of more than 100 years of fire suppression. Drought raises the fire danger in increasingly urbanized mountain forests, and (by definition) decreases water yields on which the Southwestern United States depend. Further compounding this debate is the impact prolonged fire suppression has had on these same forest stands. The purpose of this paper is to explore the inter-relationships between these three factors, and to clarify feasible multi-objective management goals. In 2002 the Rodeo-Chediski Fire burned over 200,000 ha in the Fort Apache Indian Reservation and the Apache-Sitgreaves National Forests, Arizona. This was the largest most severe fire in Arizona history with extremely high suppression and restoration costs. The fire burned at the landscape scale and impacted the watershed which provides for Phoenix, AZ—a large metropolitan area of more than three million people.