Fen Monitoring on the Plumas National Forest
The Sierra Cascade Province Ecology Program, Kyle Merriam and Michelle Coppoletta, have been monitoring fen ecosystems on the Plumas National Forest since 2007. Fens are unique wetlands that support many rare and endemic plant and animal species. They depend on the presence of peat-forming vegetation, which over thousands of years can accumulate thick peat bodies and serve as important regional carbon sinks. The Sierra Nevada Framework (2004) identified fen ecosystems as a key indicator habitat type. Fens have only recently been documented in many areas of the Sierra Nevada, prompting the Plumas National Forest to conduct inventory and condition assessments of fens across the forest over the past few years.
Our fen-monitoring program is designed to assist the Plumas National Forest manage and restore fen wetland ecosystems. We are currently conducting three fen-monitoring efforts:
- monitoring fenced sites on the Beckwourth Ranger District (BKRD),
- pre- and post-grazing monitoring on the BKRD, and
- Proper Functioning Condition (PFC) monitoring in the Bucks Lake Wilderness area of the Mt. Hough Ranger District.
Each of these monitoring efforts is described separately below.
Livestock currently graze many of the fens on the Plumas National Forest, but there is relatively little information about the effects of livestock use on these wetland ecosystems. To evaluate the effect of grazing on fen plant communities, we installed livestock exclosure fences at two fens, and established monitoring plots at nearby paired fens that were not fenced.
We collected species frequency data (the percentage of quadrats in which it occurs). We also recorded the percent cover of several ground cover categories, including bare ground and exposed peat, litter, open water, vegetation (basal area of plant), cow dung and hoof prints. Data were collected at both the fenced and unfenced sites prior to fencing and for three to five years after fencing.
Our preliminary analysis found that the frequency of grasses increased significantly after fencing the fens. We also found that vascular plant, bryophyte, and litter cover increased dramatically after fencing. We plan to conclude this monitoring with a final year of data collection in 2014.
Pre- and Post-grazing Monitoring
In response to requests by the Plumas National Forest Range Management Program to evaluate short-term indicators of livestock use in fen wetlands, we developed a protocol to measure several potential indicator variables, including plant, moss, litter, and exposed peat cover, as well as grazing utilization.
In 2011, we established permanent transects and collected data at six fens both prior to and after the grazing season. A second year of monitoring was conducted in 2012.
Our preliminary results suggest that many ground cover variables, such as moss cover and exposed bare peat, appear to be more sensitive to hydrology than grazing utilization. However, these data have been collected during wet spring seasons. We hope that additional monitoring will allow us to account for climatic variation and more clearly discern indicator variables that can be used to monitor the short-term effects of grazing.
The following Two Mound Fen monitoring photos highlight the early and late season in the fen.
Proper Functioning Condition (PFC) Monitoring
In 2010, 33 fens in the Bucks Lake Wilderness were assessed according to the User Guide for Assessing the Proper Functioning Condition for Fen Areas in the Sierra Nevada and Southern Cascade Ranges in California (Weixelman and Cooper 2009). The assessment found that 22 fens (67%) were functionally at risk.
In 2012, we initiated a project to monitor the condition of these fens over time, and determine if livestock grazing intensity influenced the fen indicators described in the PFC. Our monitoring measures a number of hydrologic variables that were not part of our earlier fen monitoring protocols (described above). The inclusion of hydrologic indicators should provide a more comprehensive understanding of the factors that influence fens and allow us to develop specific management recommendations. Monitoring continued in the Bucks Lake Wilderness both pre- and post-grazing in 2013. A preliminary analysis of these data has not yet been completed.
Woodsy Fen Species Composition Monitoring
Woodsy Fen is on the west side of Lake Davis on the Plumas National Forest. The Sierra Cascade ecology team, Kyle Merriam and Michelle Coppoletta and Beckwourth Ranger District Botanists, Mike Friend and Lynee Crawford, conducted this work. All species were identified within that 10-centimeter square at each meter along 25-meter transects. Four transects were within the fen and were not grazed (protected by an electric fence). The same method was conducted along four transects within the fen in areas where grazing was allowed (outside the fence).
The frequency of grasses increased significantly after fencing in Woodsy fen. Vegetation, moss and litter frequency also declined in grazed (unfenced fens) but not in fenced fens. A final year of data collection in 2014 will conclude this monitoring.