Threat Assessments on California Rangelands

Critical Habitat: Change in the percentage of watershed area with critical habitat from 2010 to a future time period

Example Critical habitat Map

These maps display the change in the proportion of watershed area that contains critical habitat from 2010 to a future time period for three IPCC-SRES scenarios – A1B, A2 and B1. Future time periods displayed include 2040, 2070 and 2100. Watershed boundaries are from the 8-digit Watershed Boundary Dataset (http://water.usgs.gov/GIS/huc.html). Critical habitat is defined as critical priority conservation areas mapped in the California Rangeland Conservation Coalition's focus area map (http://www.carangeland.org/focusarea.html). Priority conservation areas were defined by The Nature Conservancy as privately-owned rangelands that have high biodiversity value and require conservation action in the next 2-10 years (TNC, 2007).

Future change in priority conservation areas was based on land use-land cover (LULC) change maps generated for each scenario by the U.S. Geological Survey's probabilistic LULC model, FOREcasting SCEnarios of land-use change (FORE-SCE) ( http://www.usgs.gov/climate_landuse/land_carbon/LULC.asp). The LULC classification scheme of the scenarios closely follows the National Land Cover Database (NLCD) (http://www.mrlc.gov/) and includes broad classes such as cropland, hay/pasture, development, grassland, shrubland, forest and wetlands.

Change in priority conservation areas was defined to occur if areas mapped as either forest, grassland, shrubland or wetland were converted to one of the following classes: developed, logging, mining, cropland or hay/pasture.

The maps display the change in the proportion of watershed area that contains critical habitat and is calculated as:

ΔH = [(Hx – H2010)/A]*100

Where:

  • ΔH = change in percentage of watershed area that contains critical habitat
  • Hx = area of critical habitat at time x
  • H2010 = area of critical habitat in 2010
  • A = watershed area

Reference

The Nature Conservancy (TNC). 2007. California Rangeland Conservation Coalition Biological Prioritization of Rangelands: Approach and Methods. Available online at: http://www.carangeland.org/images/Appraoch_and_Methods.pdf.