Vegetation - Pismo State Beach and Oceano Dunes SVRA [ds2944]

Vegetation types in the study area are classified as vegetation alliances defined by their dominant or co-dominant species, following the classification system in A Manual of California Vegetation, Second Edition (MCV2) (Sawyer et al. 2009). However, coastal dune vegetation types are under-represented in the MCV2 because these areas have not been well studied (Keeler-Wolf, pers. comm., to S. Little June, 2012). Therefore, portions of the study area also contain dominant plants that do not have an MCV2 corresponding alliance. As a result, District staff and their consultants created unique alliances to describe the alliances not classified by MCV2, and these are referred to as District alliances in this report. Vegetation mapping was conducted during the week of September 10 through 14, 2012 by a team of seven individuals representing biologists from the District, TRA Environmental Sciences, Inc. (TRA), and independent consultants. District biologists independently continued vegetation mapping in subsequent weeks and completed the effort in December 2012.Mapping was conducted by teams of two biologists. Vegetation was mapped in the following areas: vegetation islands, Maidenform, Oso Flaco Lake and Creek, portions of the Phillips 66 leasehold, and North and South Oso Flaco. Aerial base maps, acquired from the National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center (2011), were used for vegetation mapping. A checklist of common plant species in the study area, developed by District biologists, was also used to aid in documenting plants observed in the study area. The mapping methodology used was consistent with Sawyer et al. (2009). Each mapping unit was mapped as one vegetation alliance only (i.e., different vegetation layers were never mapped separately as different alliances in the same mapping unit). In areas dominated by shrubland species where dominant species of two or more shrubland alliances were present in the same mapping unit, the unit was mapped as the shrubland alliance corresponding with the dominant shrub species. Likewise, in areas dominated by herbaceous species where dominant species of two or more herbaceous alliances were present in the same unit, the unit was mapped as the herbaceous alliance corresponding to the most dominant herbaceous species. In addition, the following methods were used in those locations where dominant species from both shrubland and herbaceous alliances were present in the same mapping unit:In areas of higher than 20 percent total vegetative cover, the unit was mapped as the shrubland alliance if shrubs had at least 10 percent cover, even if total cover of herbs was higher than that of shrubs. If shrubs covered less than 10 percent and herbaceous vegetation was dominant, the unit was mapped as the herbaceous alliance. In areas of less than 20 percent total vegetative cover, the unit was mapped as the shrubland alliance even if shrubs were less than 10 percent cover if shrubs were evenly distributed across the area. If shrubs were less than 2-5 percent cover and unevenly distributed, the unit was mapped as the herbaceous alliance.Vegetation alliance boundaries were sketched onto 11 x 17-inch base maps. All distinctive vegetation types were mapped in the field regardless of size. Plant species observed in each area mapped were checked off on the checklist of common plant species or added to the list, if necessary. Observations likely did not include every plant species present in the study area (e.g., fall annuals that were not present when mapping took place would not have been detected). During vegetation mapping one team member sketched the vegetation alliances while the other completed the species checklist. All species detected are listed in Appendix A.Once on-site work was completed, field maps were georeferenced and digitized using ArcGIS 10.1. Vegetation alliance outlines were digitized to produce vector data representing hand-drawn polygons. Desktop mapping was performed at different scales appropriate to the variable scales of each field map. This process was started by CDPR staff and completed by TRA. Quality assurance and quality control were provided by CDPR biologists.