UC Davis Department of Plant Sciences

Meadow Conditions on National Forest Grazing Allotments

Contact Person: Dr. Leslie Roche

Project Participants: Leslie Roche, Dave Weixelman, David Lile, Matt Freitas, Kristin Oles, Anton Jackson, Anne Yost

Sampling Design

plot

Figure 3. Illustration of the design and example of the placement of permanent sample
plots installed in meadows within USFS Region 5 grazing allotments.

Across USFS Region 5 grazing allotments, key areas—meadows preferentially grazed by cattle due to high forage quantity and quality and drinking water availability—were identified for enrollment into the monitoring program. At each enrolled meadow, one to three sample plots were selected in a stratified random approach to obtain sites representative of the larger meadow vegetation complex. Each permanently marked plot consisted of three 25 m parallel transects, established five m apart (Figure 3). Along each transect, twenty 0.01 m2 quadrats were established at 1.0 m intervals. Frequency (presence/absence) of all plant species rooted within each 0.01 m2 quadrat was recorded. Rooting depth and depth to saturation are also recorded within the 10-15 m positions of each transect. Following initial establishment and baseline readings, sites are re-read at approximately 5 year intervals by USFS project teams.

Indicators of Meadow Health
Rooted frequency (Bonham 1989) data will be used to calculate a suite of indicators of meadow condition and trend, including species richness, diversity (Simpsonís and Shannon-Wiener indices), and evenness. Soil stability scores (Burton et al. 2010; Winward 2000) will also be calculated from plant functional trait groups, which are based upon life-form, life-span, plant height, growth form (clonal or not), and nitrogen fixing ability.

Grazing Management Variables
Beginning in the 1980s, there have been substantial reductions in livestock grazing pressure on national forest lands across California (Figure 1) (USDA Forest Service, Range Management, Grazing Statistical Summary).

Our project team is working to compile 102 years of annual USFS grazing records at both the forest and allotment levels across Region 5. These records will enable us to both characterize the types and trends in grazing regimes and link management changes to indicators of meadow health (see above).

Environmental Variables
For each grazing allotment enrolled in the study, we have monthly precipitation and temperature records for October 1982-September 2012. For the same period, we also have monthly snow water equivalent data projected by downscaled output from global climate models. These data will allow us to correlate indicators of meadow health to historic climatic changes, and predict changes in meadow health in response to projected climate changes.

Key covariates in these analyses will include site wetness and initial conditions, elevation, and geographic region (e.g., northern versus southern Sierra Nevada) in which the sites are embedded.

Data Analysis
In addition to providing summary statistics on meadow condition and trend across Region 5, we will use linear and generalized linear mixed model regression analyses (Rabe-Hesketh and Skrondal 2008) to test for trends in condition over time, as well as for specific relationships between meadow condition and trend, livestock management, weather and other environmental variables.

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