Sierra Nevada

Ecosystem function, degradation, and restoration in wetlands of the Sierra Nevada, California

The wetlands of the Sierra Nevada were formed and are maintained by a feedback between soil, plant, and hydrologic processes. Primary production of plants builds soil organic matter and plant roots bind soil, preventing erosion during flooding. In turn, soil organic matter retains water and nutrients that support plant growth, while the hydrologic regime regulates soil organic matter decomposition, plant community makeup, and plant production. The relative stability of these interacting processes has built thick meadow soils over the past several thousand years. However, modern human impacts such as livestock grazing and water extraction have decoupled the interacting processes. Removal of plants by grazers exposes soil to water erosion and reduces production, the source of soil organic matter. Erosion gully formation and direct water extraction lower the wetland water table, speeding soil organic matter decomposition, altering plant community composition, and reducing production. Gully formation and loss of soil organic matter occur rapidly but are extremely slow to reverse by natural processes alone. Wetlands that have experienced these impacts enter alternative stable states that will not quickly return to their original configurations. In these cases, ecological restoration is necessary to repair human impacts and reestablish the stabilizing feedback of soil, plant, and hydrologic processes. This dissertation is composed of five chapters that explore wetland ecosystem function and restoration in the Sierra Nevada.
Journal Article

Wood chip soil amendments in restored wetlands affect plant growth by reducing compaction and increasing dissolved phenolics

Adding chipped wood to soil ameliorates compaction, allowing faster plant growth that is critical to successful wetland restorations. Following the filling and planting of an erosion gully in Halstead Meadow, Sequoia National Park, the tallest leaf height and maximum clone width of transplanted Scirpus microcarpus seedlings were negatively correlated with soil compaction. Plant height decreased by 9.8 cm and width decreased by 11.9 cm per MPa of soil compaction (range of 0.74–4.50MPa). We experimentally amended mineral soil in a test trench and found that every 0.10 cm3/cm3 addition of wood chips (range of 0.00–0.75 cm3/cm3) reduced compaction by 0.174MPa. Had the Halstead Meadow gully fill contained an equivalent volume of wood chips to the reference area soil organic matter content (0.64 cm3/cm3), we predict compaction would have been reduced by 1.11MPa, increasing individual transplant width spread by 36%, approximately doubling the vegetated area after two growing seasons. In a greenhouse phytometer experiment, conifer bark leachate (phenolics 211 mg/L) significantly reduced plant growth and, in the presence of added nutrients, increased the production of the enzyme polyphenol oxidase (PPO). However, phenolics concentration in bark-free conifer wood leachate (12mg/L), similar to field-sampled concentrations, did not affect plant growth or PPO production. Pure conifer bark is not recommended as a soil amendment, but the addition of low-bark-content wood chips to gully fill may be a feasible and effective means of reducing soil compaction, accelerating plant establishment, and lowering wetland restoration project costs.
Journal Article

Sierra Nevada Multi-source Meadow Polygons Compilation v.2

Resource Type: 
Compiled meadows polygons for the Sierra Nevada of California containing 18,780 meadow polygons (total area = 112,567 hectares, 278,160 acres)


ESRI ArcGIS 10 File Geodatabase


UC Davis, Center for Watershed Sciences & USDA Forest Service, Pacific Southwest Region, 2017. Sierra Nevada Multi-Source Meadow Polygons Compilation (v 2.0), Vallejo, CA, Regional Office: USDA Forest Service.2017.

Weixelman, D. A., B. Hill, D.J. Cooper, E.L. Berlow, J. H. Viers, S.E. Purdy, A.G. Merrill, and S.E. Gross. 2011. Meadow Hydrogeomorphic Types for the Sierra Nevada and Southern Cascade Ranges in California: A Field Key. Gen. Tech. Rep. R5-TP-034. Vallejo, CA. U.S. Department of Agriculture, Forest Service, Pacific Southwest Region, 34 pp.


Tim Lindemann, Dave Weixelman, Carol Clark, Stacey Mikulovsky, Qiqi Jiang, Joel Grapentine, Kirk Evans - USDA Forest Service, Pacific Southwest Region
Wes Kitlasten - U.S. Geological Survey
Sarah Yarnell, Ryan Peek, Nick Santos - UC Davis, Center for Watershed Sciences
Anna Fryjoff-Hung - UC Merced

Contact info :

Ryan Peek

Access and use limitations

This is an unofficial dataset compiled from the best available sources. The University of California, Davis (UCD) & USDA Forest Service (USFS) make no representations or warranties regarding the accuracy of data or maps. The user will not seek to hold UCD nor USFS liable under any circumstances for any damages with respect to any claim by the user or any third party on account of or arising from the use of data or maps. The user will cite UCD & USFS as the original source of the data, but will clearly denote cases where the original data have been updated, modified, or in any way altered from the original condition. There are no restrictions on distribution of the data by users.


Brief Methods:

In version 2 of the Sierra Nevada Multi-source Meadow Polygons Compilation, polygon boundaries from the original layer (SNMMPC_v1 - were updated using ‘heads-up’ digitization from high-resolution (1m) NAIP imagery. In version 1, only polygons larger than one acre were retained in the published layer. In version 2, existing polygon boundaries were split, reduced in size, or merged, and additional polygons not captured in the original layer were digitized. If split, original IDs from version 1 were retained for one half and a new ID was created for the other half. In instances where adjacent meadows were merged together, only one ID was retained and the unused ID was “decommissioned”. If digitized, a new sequential ID was assigned.


Fens of the Sierra Nevada, California, USA: patterns of distribution and vegetation

A broad sample of 79 montane fens in the Sierra Nevada revealed that underlying geology and topography exert strong control over the distribution and vegetation of these ecosystems. Distinct granodiorite, metamorphic, volcanic, carbonate and serpentine bedrock geology resulted in very different water chemistry, which had significant effects on the particular plant species found at each site. Wide-ranging values of pH (4.28–8.00) and dissolved cation concentrations (1.6–62.0 mg L-1) spanned the categories of transitional poor– rich to extremely rich fens. The vegetation of a pair of fens on carbonate bedrock and two floating mat fens was markedly different from the vegetation recorded at any other study sites. Once these outlier fens were removed from the analyses, the environmental variables that correlated most closely with the vegetation data were pH, altitude, presence of volcanic bedrock and fen slope. The measured environmental parameters explained 9.7 % of the variability in the vegetation data. Species richness was primarily (and negatively) correlated with altitude. Peat thickness (15–253 cm) was constrained in smaller catchments and on steeper slopes, and was positively correlated with soil organic matter content (16–92 %). Of the four typical fen landforms (bedrock contact, slope, spring mound and basin), sloping fens were the most common (63 % of the 79-fen sample).
Journal Article

CWS Report on Montane Meadows Released

The Center for Watershed Sciences released a new technical report Montane Meadows in the Sierra Nevada: Changing Hydroclimatic Conditions and Concepts for Vulnerability Assessment to better prepare the meadows community for ecosystem monitoring and restoration planning under future hydroclimatic conditions.

Sierra Nevada Multi-source Meadow Polygons Compilation v.1

Resource Type: 
Compiled meadows layer for the Sierra Nevada containing 17,039 meadow polygons (total area = 77,659 hectares, 191,900 acres).

ESRI ArcGIS 10 File Geodatabase

Fryjoff-Hung & Viers, 2012. Sierra Nevada Multi-Source Meadow Polygons Compilation (v 1.0), Center for Watershed Sciences, UC Davis. December 2012.

Contact info:
Joshua Viers


UC Davis compiled the “best available” meadow polygon layers into a single data layer. Data layers were collected from various agencies, individuals, and organizations. Data layer quality varied based on compilation methods and age; some layers were excluded due to poor data quality. A confidence rank (1 = low, 10 = high) was assigned to the remaining layers which were rasterized at a 10 m resolution. The layers were combined and combined raster cells with a summed rank of 2 or less were excluded. Raster cells representing open water were also excluded. A majority filter was run on the resulting remaining cells to reduce boundary heterogeneity, which replaced cell values based on the majority of the eight neighboring cells. Individual meadow polygons were created through a raster to vector conversion that treated all contiguous cells as a single part meadow feature with boundaries smoothed using the Polynomial Approximation with Exponential Kernel (PAEK) method (20 m tolerance to reduce edge complexity). Polygons with an area less than 0.4 ha (< 1 acre) were removed from the final meadow composite. Original IDs and other attributes were attached to the meadow polygons.

Due to the proprietary nature of some of the original data, and spatial imprecision, this method was used to homogenize the output of the compilation process. Original source identifiers have been maintained to migrate data between providers.

These data represent the most comprehensive spatial data on mountain meadows for the Sierra Nevada and southern Cascades. However, they are based on other available data, thus omissions are possible.

Please see the attached metadata file for more information.

Hydroclimatic alteration increases vulnerability of montane meadows in the Sierra Nevada, California

Meadow ecosystems of the Sierra Nevada (California, USA) have been maintained by the interplay of biotic and abiotic forces, where hydrological functions bridge aquatic and terrestrial realms. Meadows are not only key habitat for fishes, amphibians, birds, and mammals alike, but also provide enumerable ecosystem services to humans, not limited to regulating services (e.g., water filtration), provisioning services (e.g., grazing), and aesthetics. Across the Sierra Nevada, montane meadow ecosystems are paradoxically the most important providers of ecosystem services and the most threatened with human activity, and are at risk from a variety of threats, including hydroclimatic alteration.

Sierra Nevada Meadow Hydrology Assessment: 2012 Field Assessment. An Interim Project Report

Fryjoff-Hung, Anna and Joshua H. Viers. 2012. Sierra Nevada Meadow Hydrology Assessment: 2012 Field Assessment. An Interim Project Report to the USDA Forest Service Pacific Southwest Region (USFS PSW). University of California, Davis. 296 ppd.

Meadow Hydrogeomorphic Types for the Sierra Nevada and Southern Cascade Ranges in California

The purpose of this document is to provide a dichotomous key to meadow hydrogeomorphic types for the Sierra Nevada and Southern Cascades of California. This classification and field key uses both hydrology and geomorphology to identify fourteen meadow types. Strengths of the classification include its ability to clarify the relationship between hydrology and geomorphology and meadow function.