Use of Ecoregions, Hydrologic Unit Codes (HUCs), and Marine Protection Study Regions as the Planning Units for the State Wildlife Action Plan Update

As mentioned in the last newsletter, California has the most biological diversity of any state in the nation. This diversity is supported by the many unique habitats which evolved from the combination of our geology, topography and climate. Because of our diversity, characterizing the state becomes difficult, especially when describing natural resources. Consequently, State and federal wildlife and land-management agencies have divided the state into practical management jurisdictions based roughly on the distribution of biological resources. For instance, the California Biodiversity Council designated regions based on agency management jurisdictions combined with ecological features of the landscape. For the SWAP-2005, the plan development team took a similar approach to that of the Biodiversity Council, and used their boundaries with some minor adjustments, to develop regional conservation recommendations.

For the SWAP-2015 update, three separate sets of geographic units (or scales) will be used to identify priority conservation targets (species, habitats, and ecosystems that are the focus of conservation strategies), assess threats to those targets, and develop strategies to conserve those targets. USDA ecoregions (see Figure 1) will be used as the biogeographic units to assess threats and develop strategies for the terrestrial targets of the SWAP. The National Hydrography Dataset (NHD), at the HUC 4 scale (Figure 2), will be used for aquatic targets. CDFW’s Marine Life Protection Act study regions will be used for the marine targets (Figure 3).

California EcoregionsFigure 1: Ecoregions of California (USDA 1994)

Hydrolic Units MapFigure 2. Hydrologic Units overlaid on Ecoregion boundaries (USGS)

Marine Protection AreasFigure 3. Marine Protection Study Regions

The SWAP 2015 Update process will also need to address cross-boundary issues that may not be captured within the individual ecoregion or watershed planning unit or within the state borders. In addition, there may be other issues that require coordination among teams to ensure similar outputs. Examples include addressing anadromy; addressing single species targets that use multiple habitat types or different habitat types during different life-stages either within or across ecoregions/HUCs; and addressing habitat or species targets that may shift across ecoregions/HUCs, or state borders as a result of climate change. The ecoregion/HUC teams will coordinate across boundaries as they develop the steps in the process (e.g. assess threats, develop strategies).