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U.S. Forest Service


Assessing Proper Functioning Condition for Fen Areas in the Sierra Nevada and Southern Cascade Ranges

Alkali Fen. Alkali Fen, Plumas National Forest. Photo by Catie and Jim Bishop.

Fens are an important and unique wetland type. Fens support a large number of rare plant species. Many of the species have the main ranges of their distribution far to the north in Alaska and Canada with their southernmost range in California or Rocky Mountain fens. Larger animals like deer and livestock graze in this type of wetland. Fens are important as sites of groundwater discharge and are good indicators of shallow aquifers. Vegetation in all wetlands plays an important role in recycling nutrients, trapping eroding soil, and filtering out polluting chemicals such as nitrates. In addition, fens figure prominently in nearly all scenarios of CO2-induced global change because they are a major sink for atmospheric carbon.

Proper Functioning Condition

Proper Functioning Condition (PFC) provides a checklist and supporting science to help rate the condition of fens in the Sierra Nevada and Southern Cascades of California. This system is being used in California to assess fens.

Fens are threatened by groundwater alteration, land use, and exotic plant species. Water diversions, ditches, and roads have a substantial impact on fens. Livestock management can affect fens by trampling, compacting peat, creating bare areas in the fen or in adjacent uplands, altering hydrologic conditions and initiating erosion and gully formation. Off-highway vehicle use can negatively affect fens by exposing soil and bare peat, creating channels in fens that act as a water diversion and compact soil. Invasion of nonnative plant species is apparent in some fens in the Sierra Nevada. Such species include timothy (Phleum pretense), Canada thistle (Circium arvense), and dandelion (Taraxacum officinale).

Grazing impacts to fen on the eastide of Meathouse Meadow. Grazing impacts to fen on the eastide of Meathouse Meadow, Tahoe National Forest. Photo by Susan Urie.

Field Assessment

The term “Proper Functioning Condition” is used to describe both the assessment process and the on the ground condition for fens. The field assessment is designed to be conducted by an interdisciplinary team with journey-level expertise in botany, range, and soils, or hydrology. The field assessment provides a consistent approach for assessing the physical functioning of fens through the conservation of hydrology, vegetation, and soil and landform attributes. This can provide information about whether a fen area is physically functioning in a manner that will allow the maintenance or recovery of desired values over time.

On-the-ground Condition

The on-the-ground condition refers to how well the physical processes are functioning. This is the state of resiliency that will allow continued development of the fen. Generally, a fen in a physically non-functioning condition will not provide quality habitat conditions. A fen that has recovered to a proper functioning condition either would be providing quality habitat conditions, or would be moving in that direction if recovery is allowed to continue.

Qualitative Assessment Method Checklist

The PFC field assessment involves a qualitative assessment method checklist. It is based upon a consistent approach balancing hydrology, vegetation, and soil and erosion attributes and processes to assess the condition of a fen. A checklist is used that synthesizes information to determine the overall health of an area of fen.

The checklist conclusion will be a rating of Proper Function Condition (highest), Functional at Risk, or Nonfunctional. For Functional at Risk, a trend of upward, downward, or not apparent can also be rated. A question is also asked in the checklist conclusion, “Are factors contributing to unacceptable conditions outside the control of the manager?” If the answer is yes, then what are those factors? Are they flow regulations, mining activities, upstream channel conditions, channelization, road encroachment, oil field water discharge, augmentation flows, or other (specify)? Some of the items may be quantitatively measured to further support the PFC condition rating.

The U.S. Forest Service 2004 Sierra Nevada Forest Plan Amendment Record of Decision states that a desired future condition of fens is at the Proper Functioning Condition level. The checklist has also been adapted from the Bureau of Land Management Proper Functioning Condition checklist for lentic areas.