2007–2008 RARE PLANT SURVEYS FREMONT CANYON CONSERVATION EASEMENT IRVINE RANCH, ORANGE COUNTY, CALIFORNIA Prepared for: THE NATURE CONSERVANCY 1400 Quail Street, Suite 130 Newport Beach, California 92660 Contact: Trish Smith (949) 263-0933 Prepared by: RICK RIEFNER & ASSOCIATES 5 Timbre Rancho Santa Margarita, California 92688 Contact: Rick Riefner (949) 322-0022 October 2009 TABLE OF CONTENTS Page EXECUTIVE SUMMARY ...............................................................................................1 I. INTRODUCTION..................................................................................................3 II. METHODS A. Approach..................................................................................................................4 B. Literature Search .....................................................................................................6 C. Field Surveys ..........................................................................................................6 III. RESULTS AND DISCUSSION A. Floristic Surveys......................................................................................................7 B. CNPS Plants.............................................................................................................8 C. Species of Local Interest in Orange County ..........................................................23 D. Invasive Plant Observations...................................................................................27 IV. RECOMMENDATIONS A. Field Surveys.........................................................................................................28 B. Management Actions.............................................................................................29 V. ACKNOWLEDGMENTS ...................................................................................31 VI. REFERENCES AND LITERATURE CITED .................................................32 TABLES 1. Summary of CNPS Plants Documented at the Fremont Canyon Conservation Easement – North Irvine Ranch 2. Summary of Species of Local Interest Documented at the Fremont Canyon Conservation Easement – North Irvine Ranch APPENDICIES A. Survey Dates and Areas Covered B. Additions to the Flora of the Fremont Canyon Conservation Easement C. Rare Plant Status Categories D. GPS Coordinates, Population Data, and Habitat Notes (Excel Spreadsheet) i TABLE OF CONTENTS Appendices continued E. Rare Plant Photographs FIGURES 1. North Irvine Ranch, Sierra Fire - Fremont Canyon Conservation Easement Boundary Map 2. CNPS Plants Map 3. Intermediate Mariposa Lily Map 4. Chaparral Bear-Grass Map 5. Species of Local Interest Map ii EXECUTIVE SUMMARY Rick Riefner & Associates conducted focused surveys for special status, special interest, and other noteworthy plant species for The Nature Conservancy within the Fremont Canyon Conservation Easement portion of the 2006 Sierra Fire area on the North Irvine Ranch, Orange County, California. The Sierra Fire burned approximately 6,000 acres of the North Irvine Ranch, including most of Fremont Canyon and portions of Gypsum Canyon. Harmsworth Associates (2001) conducted extensive biological studies and focused botanical surveys in the Fremont and SilMod Conservation Easement portions of the North Irvine Ranch (previously known as the North Ranch Policy Plan Area, NRPPA), with follow-up focused surveys for Astragalus brauntonii (Harmsworth Associates 2006) and Nolina cismontana (Harmsworth Associates 2007). However, the Sierra Fire provided new opportunities to access formerly impenetrable areas of dense chaparral or rugged terrain not surveyed previously for sensitive plants within Fremont Canyon. Surveys were conducted from April 12, 2007 through August 5, 2008. As a result, new populations for 17 taxa of interest to the California Native Plant Society (CNPS) were mapped and inventoried, which include: • Baccharis malibuensis MALIBU BACCHARIS [CNPS List 1B.1]; • Calandrinia breweri BREWER’S CALANDRINIA [CNPS List 4.2]; • Callitropsis (Cupressus) forbesii TECATE CYPRESS [CNPS List 1B.1]; • Calochortus catalinae CATALINA MARIPOSA LILY [CNPS List 4.2]; • Calochortus weedii var. intermedius INTERMEDIATE MARIPOSA LILY [CNPS List 1B.2]; • Convolvulus simulans SMALL-FLOWERED MORNING-GLORY [CNPS List 4.2]; • Dudleya multicaulis MANY-STEMMED DUDLEYA [CNPS List 1B.2]; • Lepechinia cardiophylla HEART-LEAVED PITCHER-SAGE [CNPS List 1B.2]; • Lepidium virginicum var. robinsonii ROBINSON’S PEPPERGRASS [CNPS List 1B.2]; • Lilium humboldtii subsp. ocellatum OCELLATED HUMBOLDT LILY [CNPS List 4.2]; • Microseris douglasii subsp. platycarpha SMALL-FLOWERED MICROSERIS [CNPS List 4.2]; • Nolina cismontana CHAPARRAL BEAR-GRASS [CNPS List 1B.2]; • Pentachaeta aurea subsp. allenii ALLEN’S DAISY [CNPS List 1B.1]; • Phacelia cicutaria subsp. hubbyi HUBBY’S PHACELIA [CNPS List 4.2]; • Pickeringia montana subsp. tomentosa MONTANA CHAPARRAL PEA [CNPS List 4.3]; • Pseudognaphalium leucocephalum ALLUVIAL WASH EVERLASING [CNPS List 2.2]; and • Romneya coulteri COULTER’S MATILIJA POPPY [CNPS List 4.2]. 1 Three CNPS plants were recorded for the first time for Fremont Canyon and the North Irvine Ranch, which include Convolvulus simulans, Lepidium virginicum var. robinsonii, and Phacelia cicutaria subsp. hubbyi. Fourteen taxa of local interest in Orange County were also identified, inventoried, and mapped, of which two are species of Local Concern (LC): • Calamagrostis densa SAN DIEGO REEDGRASS; and • Fritillaria biflora var. biflora CALIFORNIA CHOCOLATE LILY. Three other native species were documented that are new to the flora of Orange County: • Allophyllum divaricatum PURPLE FALSE-GILIA; • Hieracium argutum SOUTHERN HAWKWEED; and • Pholistoma racemosum SAN DIEGO FIESTA FLOWER. In addition, new locations for nine taxa thought to be scarce or uncommon in Orange County were documented, which include: • Antirrhinum multiflorum STICKY SNAPDRAGON; • Claytonia perfoliata subsp. mexicana MEXICAN MINER’S LETTUCE; • Dicentra ochroleuca FIRE HEARTS; • Ericameria cuneata var. cuneata CUNEATE-LEAVED GOLDENBUSH; • Lomatium utriculatum COMMON LOMATIUM; • Mentzelia micrantha SMALL-FLOWERED STICK-LEAF; • Muhlenbergia asperifolia SCRATCH-GRASS; • Salix lucida subsp. lasiandra YELLOW WILLOW; and • Stipa cernua NODDING NEEDLEGRASS. Information was also collected for noxious or invasive exotic plants, of which six species are established and spreading rapidly within or adjacent to Fremont Canyon, which include: • Atriplex semibaccata AUSTRALIAN SALTBUSH; • Cynara cardunculus CARDOON or ARTICHOKE THISTLE; • Emex spinosa DEVIL’S THORN; • Pulicaria paludosa SPANISH SUNFLOWER; • Silybum marianum MILK THISTLE; and • Tamarix ramosissima MEDITERRANEAN TAMARISK. Lepidium sativum (garden cress), native to the Old World, was recorded for the first time for Orange County. It does not appear to be invasive in our area. 2 2007–2008 RARE PLANT SURVEYS FREMONT CANYON CONSERVATION EASEMENT SANTA ANA MOUNTAINS, IRVINE RANCH ORANGE COUNTY, CALIFORNIA I. INTRODUCTION The 7,500-acre Fremont Canyon Conservation Easement is comprised of extremely rugged terrain located at the northwestern end of the Santa Ana Mountains on the North Irvine Ranch, Orange County, California. Fremont Canyon is bordered by the Cleveland National Forest to the east, Windy Ridge, Gypsum Canyon and the Coal Canyon Ecological Reserve to the north, Santiago Creek to the south, and Weir Canyon to the west. The Eastern Transportation Corridor (ETC) divides the easement at Blind Canyon (Figure 1). Fremont Canyon, which occupies the greater part of North Irvine Ranch, is approximately 7.5 miles-long (12 km) and extends northeast from its confluence with Santiago Creek to the easement boundary at the Cleveland National Forest. Deep canyons, narrow ridgelines, steep slopes, mesas, broad rolling hills, massive sandstone outcrops, and sheer vertical cliffs characterize the Fremont Canyon environment. Elevations range from 558 feet (170 meters) in the southwestern corner at Santiago Creek up to 2,400 feet (732 meters) at the northeastern-most corner at Fremont Ridge. Although eleven major vegetation communities have been mapped on site, chamise chaparral and southern mixed chaparral are the most extensive, which occupy over 4,700 acres of habitat (Harmsworth Associates 2001). Rock outcrops and cliffs, which are a prominent feature of the area, are comprised primarily of sandstone and unconsolidated granite (Morton et al. 1999). Soils mapped for the area are comprised of the Cieneba-Anaheim-Soper Association, which are strongly sloping to very steep, excessively drained and well drained sandy, gravelly or cobbly loams, loams, and clay loam soils (Wachtell 1978). Most soil types that make up the Cieneba-Anaheim-Soper Association are slightly to moderately acid, but the Calleguas clay loam is alkaline and calcareous (Watchell 1978). In addition, a large portion of the Fremont Canyon region is underlain by marine sandstones of the Williams Formation, which contain locally common formations of calcite (Morton et al. 1999), which is a calcium carbonate mineral. Extensive biological studies and focused botanical surveys were performed previously in Fremont Canyon from 2000 through 2006 (Harmsworth 2001, 2005, 2006, 2007). These surveys documented existing biological resources, but also identified and mapped the location of important sensitive vegetation communities and rare species occurrences, including a new grove of Tecate cypress (Callitropsis forbesii) discovered on the