Terrestrial Land Facet Components

Land facets were created by combining 3 rasters: elevation (seven 600-m bands), soil orders (11 classes) and slope (3 breaks) to produce a 270-m resolution grid. 162 land facets were created, ranging in size from over 9 million hectares in the plateaus of the Columbia Plateau to less than 1,000 hectares in steep, high elevation habitats. These 162 facets were stratified by ecoregions to produce 794 ecofacets which underlie the spatial distribution of biodiversity and the region’s biological richness.
 
Soil Order: Soil orders reflect both geology and time and are based largely on soil forming processes, including exposure to climatic factors and biological processes, as indicated by the presence or absence of major diagnostic horizons, and may reflect vegetation patterns in the western US better than geology. We used State Soil Geographic (STATSGO) soils data for the ecoregions east of the Cascade crest, and for the relatively small portions of the westside ecoregions where finer-scaled Soil Survey Geographic (SSURGO) data were not available.

Elevation Class: Elevation greatly affects vegetation pattern and distribution throughout our study area. Elevation within the study area ranges from sea level in the coastal and western ecoregions, to over 3,600 meters in the Idaho Rocky Mountains, Oregon Cascades, and California Sierras. The 600 meter elevation breaks used to create land facets are shown.

Slope Class: Slope categories were included in the Land Facet classification to help distinguish flat, high elevation deserts and plateaus from mountainous areas at similar elevations. This allowed more meaningful comparison of resilience values in different settings as high scores in topographically complex mountainous areas could not overwhelm scores in flatter plateaus. The three slope classes are: 0 – 6 degrees, 6 – 18 degrees, and slopes greater than 18 degrees.

These data are part of a land facet terrestrial resilience project created for the Pacific Northwest to identify the most resilient terrestrial sites in the Northwest U.S. that will collectively and individually best sustain native biodiversity even as the changing climate alters current distribution patterns. The central idea is that by mapping key geophysical features and evaluating them for landscape characteristics that buffer against the effects of climate change, we can identify the most resilient places in order to guide future conservation investments.  All the datasets, along with the full report containing methods and maps is available at:  http://nature.ly/resilienceNW

See a gallery of all datasets from this report on Data Basin: http://nplcc.databasin.org/galleries/e41a3ea84e78463bbf9f03ce2f8e9205

(See attached PDF of original figure)