Planning for Shrub Establishment on Former Crop Lands in the Carrizo Plain Using Fine Scale VegCAMP and CNPS Data to Find Reference Sites and ID Target Plant Species Dave Hacker

Why we are talking about shrubs Topaz Incidental Take Permit (ITP) required 12,140 acres of mitigation land “allscale (Atriplex polycarpa), California ephedra (Ephedra californica), and/or other perennial shrub species appropriate to the HM lands where the native shrub cover has been removed or adversely altered by livestock grazing, fire, farming, or other anthropogenic causes” Why we are talking about shrubs

ITP Conditions use of a reference site to determine target shrub cover and species OR, if not available, establishing 15-20% perennial shrub cover on 50% of the mitigation lands within 10 years of acquisition

More Back Story California Valley Solar Ranch—9,157 acres, same shrub requirements Topaz ITP mitigation lands owned by CDFW CVSR ITP mitigation lands owned by solar project owner

Why do we want Shrubs? A mosaic of grasslands and shrublands provides a more diverse prey base for kit foxes, which can buffer against fluctuations in prey base and habitat functions due to stochastic events, and to allow spatial partitioning between SJKF and coyotes, which may reduce predation on kit foxes.1 Shrub cover associated with persistent San Joaquin antelope squirrel (State Threatened species) populations. 1. Nelson, Julia L., B.L Cypher, C.D. Bjurlin, and S. Creel. 2007. Effects of habitat on competition between kit foxes and coyotes. J. Wildlife Management. 75(5):1467-1475.

Birds (e.g. LeConte’s thrasher) perch sites nest sites Pronghorn fawning cover late season forage Birds (e.g. LeConte’s thrasher) perch sites nest sites prey and forage diversity Reptiles shade for thermoregulation = more time to forage on hot days cover from predators and photographers more insect diversity Photo of LeConte's thrashers from http://data.prbo.org/apps/cplcth/.

Have lots of this low diversity grassland Want more of this mix of grassland and shrubland

Sought Reference Areas for CDFW-Owned Lands (Topaz Mitigation Lands) Example at San Andreas fault scarp where full suite of listed species occurs in shrub/grassland mosaic.

We wanted reference sites to tell us which areas might be suitable for shrub establishment, which shrub species the area could support, target shrub cover, and approximate patch size.

The California Native Plant Society (CNPS) and CDFW’s Vegetation Classification and Mapping Program (VegCAMP) produced a fine-scale vegetation data set and map for the nearby Carrizo Plain National Monument (federal lands) and the Carrizo Plain Ecological Reserve (adjoining state lands) in 2013 (Stout et al. 2013 and unpublished CDFW data). Includes plant comms to alliance level % cover by species area of each comm. disturbance levels and more attributes Used full spatial extent of data (the whole National Monument) as the reference site Vegetation Data

Soils Precipitation Natural Resource Conservation Service soil map unit data—found types that occurred both within extent of veg data and the mitigation lands. Precipitation model data (30-year normals) was also available in 0.64 km2 pixels from the PRISM Climate Group at Oregon State University (PRISM Climate Group 2013). Used only qualitatively, did not extract values from spatial data (i.e. I just looked at the values to see if they were close).

In ArcMap GIS, intersected vegetation with soils Gave us polygons with all vegetation data per soil type

veg alliance or macrogroup Plant Comms. by Soil Type, with Precipitation (mm) Overlay veg alliance or macrogroup precipitation soil map unit #

Example vegetation data for 311 Yeguas-Pinspring Complex, 2-9% slopes.

Results 12 of the 17 mitigation land soil types were found in the reference area. Five of the mitigation land soil types (next slide) supported extensive shrublands in the reference area and within the target precipitation range, comprising 37,348 acres of reference site.

Atriplex polycarpa alliance in reference area occurred on all five soil types common between reference and mitigation areas.

4,432 acres, or 11.9%, of the reference area was mapped as Atriplex polycarpa alliance The Ephedra californica alliance was abundant in four of the five soil types and covered a total of 1,541 acres. Other shrub alliances found in some soils in much lesser, but still considerable extents, were, in order of abundance, Ericameria linearifolia – Isomeris arborea and Eriogonum fasciculatum. More Results

Reference sites provided evidence that 4,572 acres (38%) of the soil map units on the mitigation lands would likely support Atriplex polycarpa and/or Ephedra californica. Establishing 520 acres of Atriplex polycarpa alliance with 14% shrub cover on the mitigation lands would replicate the proportion found in the reference area Ephedra californica, Ericameria linearifolia – Isomeris arborea and Eriogonum fasciculatum alliances were also found and would likely be appropriate for some of the mitigation lands soil types. Conclusions

Mitigation area soil types which support extensive shrub communities in the reference area.

The extent of the mapped shrub alliances should not be equated with the extent of shrubs because reference area grasslands and forb lands with 1-5% shrub cover were mapped as non-shrub communities. Similarly, the minimum map unit in the vegetation data was 1 acre, so patches smaller than one acre were not reflected in the results. i.e. shrubs occur in more areas than were mapped Discussion

Discussion Most areas with shrubs showed no sign of mechanical disturbance when visited and/or none was noted in the CNPS/VegCAMP data. Atriplex polycarpa has recolonized some of the former crop lands in the reference area, apparently where washes have transported seed from higher slopes that escaped cultivation.

Some of the soil types where no shrub lands were found were the same type as where shrubs were extensive, but in lesser slope classes. In general, the lesser slope classes were farmed for longer and could have therefore been more subject to shrub eradication. The lack of shrubs in the lower slope classes may be a result of past land use rather than unsuitability for shrubs. More areas of the mitigation lands may be able to support shrubs than just the areas for which good reference sites were found. Discussion

Atriplex polycarpa established on test plot on Yeguas-Pinspring complex, 0-2% slopes, Diefenderfer property (CVSR ITP mitigation lands)