Water and Watershed Processes
Improved knowledge of aquatic and land interactions at local and
watershed scales is essential to evaluate and design land management
alternatives for stream and watershed resources. Sixty percent of
California's water originates from small streams in the Sierra Nevada,
yet very little information is known about how these streams are
affected at the source by land management activities such as dams,
diversions, logging, etc.The quality of aquatic and riparian (near-stream)
ecosystems associated with streams is directly related to the condition
of adjacent uplands within their watersheds. The degradation of
forest streams and their associated watersheds is often the result
of non-point sources such as past timber harvesting, roads, fire
suppression, catastrophic wildfires, and atmospheric deposition.
Restoration of the Sierra Nevada's forest watersheds to historic
or desired conditions requires active management such as reintroduction
of frequent, cool fires and removal of accumulated fuel loads.
This problem area can address the multiple stressors often acting
on aquatic ecosystems in forests: tree thinning/harvesting, fire,
air pollution, climate variability, land use change, water diversion,
grazing, and roads. The land managed by the Forest Service provides
much of the source water that other organizations address once the
water gets to California's central valley and coast.
Kings River Experimental Watershed
Subproblem 1: Structure and Function of Sierra Nevada headwater streams and their associated
A suite of physical, chemical, and biological measurements is
necessary to understand how watersheds function and respond to
both natural and anthropogenic stress or disturbance. Since not
every parameter of interest can be measured, a set of characteristics
is selected to represent physical, chemical, and biological structure
and function. A good understanding of the variability in and interaction
between these characteristics is necessary to evaluate change
over time and response to management treatments.
Subproblem 2: Stream and watershed response to forest restoration.
The Sierra Nevada landscape has been altered in many ways since
the 1850s with selective timber harvesting, a century of fire
suppression, extensive domestic animal grazing, and more recently
increasing and diverse recreation. In addition, climate is changing
and restoration back to a desired historic condition may not be
entirely possible. Cause and effect experiments are necessary
to know the effectiveness of restoration practices and reduce
concerns about negative effects. Fire has been suppressed in the
Sierra Nevada for about 100 years, thus a combination of thinning
and prescribed fire is needed to efficiently move the forest condition
towards a pre-suppression condition of larger trees with a canopy
closure greater than 50% and an open understory. Desired forest
characteristics are uneven-aged stands of a patchy nature.
Subproblem 3: Forest Best Management Practices for aquatic ecosystems.
Concerns exist about negative impacts to water quality and aquatic
ecosystems from forest management and restoration activities.
100 years of fire suppression and historic land management practices
have created forests with high fuel loads and overstocked conditions.
Many small, suppressed trees exist now rather than fewer large
trees per unit area that are known to have occurred in pre-settlement
forests. Much of the information on fire effects comes from hot,
wildfire situations that result in these densely stocked contemporary
forests of the west. Usually these studies do not have before
and after data and have to use after-the-event controls. Similarly
much of the data on silviculture effects comes from severe treatments
such as clear cuts, seed-tree cuts, or shelter-wood cuts and is
predominantly from different geologic and climatic ecosystems
like the Pacific Northwest. Thus the current measures to mitigate
effects on aquatic ecosystems may be inappropriate for Sierra