California Freshwater Conservation Blueprint - TNC [ds2790]

Conservation scientists have adapted conservation planning principles designed for protection of habitats ranging from terrestrial to freshwater ecosystems. We applied current approaches in conservation planning to prioritize California watersheds for management of biodiversity using the Zonation software. For all watersheds, we compiled data on the presence/absence of herpetofauna and fishes; observations of freshwater-dependent mammals, selected invertebrates, and plants; maps of freshwater habitat types; measures of habitat condition and vulnerability; and current management status. We analyzed species-distribution data to identify areas of high freshwater conservation value that optimized representation of target taxa on the landscape and leveraged existing protected areas. The resulting priority network encompasses 34% of the area of California and includes greater than or equal to10% of the geographic range for all target taxa. High-value watersheds supported non-target freshwater taxa and habitats, and focusing on target taxa may providebroad conservation value. Most of the priority conservation network occurs on public lands (69% by area), and 46% overlaps with protected areas already managed for biodiversity. A significant proportion of the network area is on private land and underscores the value of programs that incentivize landowners to manage freshwater species and habitats. The priority conservation areas encompass more freshwater habitats/ha than existing protected areas. Land use (agriculture and urbanization), altered fire regimes, non-nativefish communities, and flow impairment are the most important threats to freshwater habitat in the priority network, whereas factors associated with changing climate are the key drivers of habitat vulnerability. Our study is a guide to a comprehensive approach to freshwater conservation currently lacking in California. Conservation resources are often limited, so prioritization tools are valuable assets to land and water managers.

The analysis was conducted using 6th field hydrologic code subwatersheds (HUC12s) as the basic planning unit. Base HUC12 layer provided by UC Davis Center for Watershed Sciences.

Attributes of interest:

• c_abf75_rnk - Zonation rank results for an optimization run on a combined set of fish and herp targets using the added benefit function algorithm. Rank indicates the order of removal in the optimization run - high values indicate late removal and therefore high conservation value.

• c_abf75_prp - Zonation prop results for an optimization run on a combined set of fish and herp targets using the added benefit function algorithm. One minus Prop indicates the minimum percentage of range included in the solution for all targets.

• fnd75 - values = 1 indicate those HUCs forced to be included in the priority network due to the coverage of existing GAP status 1,2 protected areas within the HUC. Must have at least 75% areal coverage or 75% of perennial streams in HUC in a GAP 1,2 protected area

• cva75 - values = 1 indicate those HUCs included as priority conservation areas. Equivalent to a selection of c_abf75_prp greater than or equal to 0.9, or the network of HUCs which encompass at least 10% of the range of all targets in the Zonation optimization

• cond_index - The composite habitat condition index, or the sum of rank-normalized habitat condition scores for factors identified in our analysis as best representing the variability of habitat condition in priority conservation areas. High values indicate impaired habitat condition; low values indicate less impairment. The composite habitat condition index is comprised of metrics related to the extent of floodplain development,fire-regime condition class, proportion of fish community consisting of non-natives, dam-related flow impairment, and artificial drainage of wetlands and hydric soils.

• threat_index - The composite threat index, or the sum of rank-normalized vulnerability scores for factors identified in our analysis as best representing the variability of threats to priority conservation areas. High values indicate high vulnerability; low values indicate less vulnerability. The composite vulnerability index is comprised of metrics related to average temperature change, land-conversion risk, runoff change, baseflow change, and snow water-equivalent change.

• cons_strat - A generalized conservation strategy for priority conservation areas based on habitat condition index and vulnerability index scores.