Sierra Nevada Multi-source Meadow Polygons Compilation v.1

Joshua Viers


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


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.


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