USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Research Topics Water and Watersheds

About this Research:
Participating Programs
Contributing Scientists and Staff
Study explores stream nitrogen concentrations

For the first time, a collaborative study [] has compared water quality trends in forested streams across the country that are largely undisturbed by land use or land cover changes. The study draws on 559 years of stream nitrate and 523 years of stream ammonium data from 22 streams in 7 experimental forests across the country. The study found that even near-pristine forested streams are subject to change.

Southern Sierra Critical Zone Observatory

The Kings River Experimental Watersheds hosts the Southern Sierra Critical Zone Observatory--a National Science Foundation effort to gain a better understanding of the zone of earth where "rock meets life." The critical zone extends from the tops of the trees to the groundwater and covers the entire earth where there is land. Download the video created by a UA Flandrau Science Center team to introduce the motivation and science involved in the National Critical Zone Observatory research program.

Kings River Experimental Watersheds (KREW)

Soil Characterization

Characterizing the variation in soils that occur on KREW watersheds is important to understand watershed condition, changes in ecosystem processes, and changes that might be seen in stream conditions. The treatments that will be implemented on KREW are known to have impacts on soils and their structure. The use of heavy machinery and creation and/or maintenance of skid trails during logging operations can compact soils and increase erosion. Prescribed fire treatments alter the nutrient availability of soils, and have the potential to leave upper layers hydrophobic, which increases overland flow and erosion. Understanding how these treatments impact soils can contribute to the implementation, where necessary, of lower-impact management by the Forest Service and other agencies. For specifics concerning soil characterization see the KREW Study Plan (Hunsaker et al. 2004).

Soil Grid

Under Construction

Soil Pits

At selected points on the existing 150-m grid, soil profiles are prepared by digging a pit one meter deep and analyzing the vertical horizon. These are the same grid points where vegetation plots are located. From each horizon, a core is taken to determine bulk density, and samples are taken for nutrient analysis and soil moisture content. At randomly-selected points 10m or more from the soil pit, three satellite samples of the O horizon layer and mineral soil are collected for analysis. Around the center of the soil pit, a 0.1-hectare, circular plot is used to measure large woody debris and live woody vegetation. In 2003, 40 grid points were selected to begin sampling; resulting data will be analyzed to refine the design and more thoroughly sample the soil on KREW. Ultimately, sampling will occur once during the pre-treatment period, and once, immediately following treatment. For a further description of field methods and laboratory analysis, see KREW Study Plan (Hunsaker et al. 2004).

Last Modified: Jun 21, 2013 08:30:09 PM