San Bernardino Mountains Dudleya (Dudleya abramsii ssp. affinis)

Transcription

1 San Bernardino Mountains Dudleya (Dudleya abramsii ssp. affinis) Legal Status Taxonomy State: S2.2 1 California Rare Plant Rank: 1B.2 2 Federal: U.S. Forest Service Sensitive Critical Habitat: N/A Recovery Planning: N/A San Bernardino Mountains dudleya (Dudleya abramsii ssp. affinis) is a perennial herb in the stonecrop family (Crassulaceae) (CNPS 2011). Dudleya abramsii ssp. affinis was published as a new subspecies by K.M. Nakai (1987). Dudleya abramsii is a widespread species with six subspecies currently recognized, five of which are very similar (Jepson Flora Project 2011a). There is some taxonomic uncertainty regarding the plants from Cushenbury Canyon. These plants grow on limestone and differ from most plants of San Bernardino Mountains dudleya in that they have several to many branched caudex and smaller rosettes. They resemble plants of D. a. ssp. calicola and D. a. ssp. abramsii. However, they also differ from these other subspecies in having a more simple inflorescence compared to D. a. ssp. calicola and having a different rosette leaf shape compared to D. a. ssp. abramsii. Therefore, although this population is intermediate between these three subspecies, Nakai (1987) still considers it an aberrant form of D. a. ssp. affinis (Nakai 1987; Jepson Flora Project 2011b). This is unlikely to influence the subspecies legal status because the taxonomic uncertainty appears to be limited to one known population. San Bernardino Mountains dudleya s succulent leaves are in small rosettes only 3 to 6 centimeters (1.2 to 2.4 inches) wide (Jepson Flora 1 S2: Imperiled; X.2: Imperiled. 2 1B: Rare, threatened, or endangered in California and elsewhere; X.2: Fairly threatened in California. 1

2 Distribution General Project 2011b). A full physical description of the species can be found in the original description (Nakai (1987) and the Jepson eflora (Jepson Flora Project 2011b; Nakai 1987). San Bernardino Mountains dudleya is known only from a very small area in the San Bernardino Mountains in southwest San Bernardino County (Figure SP-P28; CNPS 2011). It occurs along the western edge of the Plan Area. Only 2 of the 12 occurrences documented in the California Natural Diversity Database (CNDDB) are within the Plan Area, although there are eight additional occurrences within 5 miles of the Plan Area (CDFG 2012a). All records from the Consortium of California Herbaria (CCH) are outside of the Plan Area to the south or west (CCH 2011). Distribution and Occurrences within the Plan Area Historical Of the two occurrences of San Bernardino Mountains dudleya within the Plan Area, one is based on a collection made in 1882 at Cushenbury Springs in the Big Bear City U.S. Geological Survey (USGS) quadrangle (Figure SP-P28; CDFG 2012a). This occurrence is on private land owned by Mitsubishi Cement Corp. (formerly Kaiser Cement Company) (CDFG 2012a; Deacon 2007). Recent The one recent occurrence of San Bernardino Mountains dudleya reported in the Plan Area by the CNDDB occurs along the northeast slope of White Mountain, approximately 1.6 miles east of North Peak, on the north slope of the San Bernardino Mountains. Approximately 20 plants were observed in Ownership of the land on which this occurrence is located is unknown (CDFG 2012a). 2

3 Natural History Habitat Requirements San Bernardino Mountains dudleya grows in pebble plain or pavement habitat within pinyon and juniper woodland and upper montane coniferous forest (CNPS 2011; CDFG 2012a). San Bernardino Mountains dudleya occurs on granitic and quartzite substrates, rarely on limestone (CNPS 2011; CDFG 2012a). The two occurrences within the Plan Area do grow on limestone; the species commonly occurs on rock outcrops (CDFG 2012a). Associated species include junipers (Juniperus spp.), pines (Pinus spp.), mountain-mahogany (Cercocarpus spp.), hedgehog cactus (Echinocereus spp.), Cushenbury milkvetch (Astragalus albens), Parish s daisy (Erigeron parishii), Cushenbury buckwheat (Eriogonum ovalifolium ssp. vineum), and Cushenbury oxytheca (Acanthoscyphus parishii var. goodmaniana). San Bernardino Mountains dudleya ranges in elevation from 1,250 to 2,600 meters (4,101 to 8,530 feet) according to CNPS (2011). Although the Jepson eflora (Jepson Flora Project 2011b) cites a much higher minimum elevation of 1,800 meters (5,906 feet), CNDDB records state elevations that are more similar to the range provided by CNPS (2011): 4,200 to 8,500 feet (CDFG 2012a). Furthermore, the elevation range of occurrences within the Plan Area is narrower and is within the lower portion of the species overall elevation range, from 4,200 to 5,200 feet (CDFG 2012a). Table 1 lists primary habitat associations and parameters for the San Bernardino Mountains dudleya. Table 1. Habitat Associations for San Bernardino Mountains Dudleya Land Cover Type Pebble/pavement plain, pinyon and juniper woodland, upper montane coniferous forest Habitat Designation Habitat Parameters Supporting Information Primary Granitic and quartzite (rarely limestone) substrates; 1,250 to 2,600 meters (4,101 to 8,530 feet) elevation CNPS

4 Reproduction This perennial herb blooms from April to June according to CNPS (2011), although the Jepson eflora and the original description of the subspecies indicate a later blooming period from May to July (Jepson Flora Project 2011b; Nakai 1987). Though little information is known regarding the reproduction of this subspecies, dudleyas (Dudleya spp.) reproduce from offsets and seed. Unlike other genera in the stonecrop family, dudleyas do not propagate from individual leaf cuttings (Hodgkiss 2011). Flowers of San Bernardino Mountains dudleya are small, upright, pale yellow with red lines (Jepson Flora Project 2011b; Nakai 1987). Other Dudleya species with small upright yellow flowers are insectpollinated by bees and flies. Based on flower morphology, San Bernardino Mountains dudleya might also attract hummingbirds. Levin and Mulroy (1985) examined reproductive strategy (i.e., pollination and breeding systems) in 21 Dudleya species. They found that when maximum energy content is plotted against auto-fertility, the species fall into three groups. Dudleya abramsii might fit with the group that has moderate to high nectar production, and low autofertility (Levin and Mulroy 1985). Ecological Relationships Endemic to the pebble plains of the San Bernardino Mountains, this subspecies is associated with several other rare plants, including Cushenbury milkvetch, Parish s daisy, Cushenbury buckwheat, and Cushenbury oxytheca. Pebble plains are sparsely vegetated openings surrounded by forest with clay soils. Pebble plain habitat is found between 6,000 and 7,500 feet in elevation, and occurs only within a 92 square mile area in the San Bernardino Mountains (60 FR ). The unique combination of edaphic and climatic factors found in pebble plain habitats makes it so that several plant species are either endemic to the San Bernardino Mountains or represent disjunct occurrences of species more common elsewhere (60 FR ). Other than the habitat associations described above, little more is known about the ecological relationships of this subspecies. 4

5 Population Status and Trends Global: G3T2, Imperiled (CDFG 2012b) State: S2.2, Imperiled (CDFG 2012b) Only 2 of the 12 CNDDB occurrence records include a population size estimate. Outside the Plan Area 100 to 200 plants were estimated to occur west of the mouth of Arctic Canyon on the north slope of the San Bernardino Mountains in Within the Plan Area, approximately 20 plants were observed on the northeast slope of White Mountain in 1996 (CDFG 2012a). No additional data are available to determine its current status and population trend. Threats and Environmental Stressors San Bernardino Mountains dudleya is threatened by development, foot traffic, limestone mining, and vehicles, and is possibly threatened by non-native plants and illegal dumping (CNPS 2011). The occurrences within the Plan Area are located on private land owned by Mitsubishi Cement Corp. or the ownership is unknown (CDFG 2012a). Therefore, the populations within the Plan Area could be vulnerable to the threats listed above. Conservation and Management Activities Outside of the Plan Area, San Bernardino Mountains dudleya occurs in the San Bernardino National Forest under Forest Service management (CDFG 2012a). There is a memorandum of understanding (MOU) conservation strategy for pebble plain habitat that addresses San Bernardino Mountains dudleya, among other sensitive plant species that occur in pebble plain habitat on Forest Service land (USDA Forest Service 2005). Protection measures for the federally listed San Bernardino Mountains carbonate endemic plants may help protect this subspecies. The draft recovery plan for these species includes conservation and management of pebble plain habitat and also addresses the threat of limestone mining (USFWS 1997). 5

6 Data Characterization In general, data availability for San Bernardino Mountains dudleya is poor. Little is known regarding this dudleya s reproductive biology, ecological relationships, and population trends. Management and Monitoring Considerations Little information is known regarding San Bernardino Mountains dudleya s current status in the Plan Area. Predicted Species Distribution in Plan Area Literature Cited There are 63,893 acres of modeled suitable habitat for San Bernardino Mountains dudleya in the Plan Area. Modeled suitable habitat occurs in the western portion of the Plan Area along the edge of San Bernardino National Forest from 4,100 to 8,600 feet in elevation. Modeled suitable habitat includes woodland and forest vegetation communities with granitic and sedimentary substrates. Appendix C includes specific model parameters and a figure showing the modeled suitable habitat in the Plan Area. 60 FR Proposed Rule: Endangered and Threatened Wildlife and Plants; Proposed Endangered or Threatened Status for Seven Plants From the Mountains of Southern California. August 2, CCH (Consortium of California Herbaria) Accession results for Dudleya abramsii ssp. affinis. Accessed December 27, CDFG (California Department of Fish and Game). 2012a. Dudleya abramsii ssp. affinis. Element Occurrence Query. California Natural Diversity Database (CNDDB). Rarefind, Version 4.0 (Commercial Subscription). Sacramento, California: CDFG, Biogeographic Data Branch. Accessed February

7 CDFG. 2012b. Special Vascular Plants, Bryophytes, and Lichens List. California Natural Diversity Database (CNDDB). January Accessed. plants_and_animals.asp. CNPS (California Native Plant Society) Dudleya abramsii ssp. affinis. Inventory of Rare and Endangered Plants. Online ed. Version 8-01a. Sacramento, California: CNPS. Accessed November Deacon, M Cement Plant Celebrates 50 Years in the High Desert. Victorville Daily Press. Online ed. June 3, Accessed November 29, cement-1285-plant-community.html. Hodgkiss, R.J The Dudleya Page. The Succulent Plant Page. Last revised: November 24, Accessed December 2, dudleya.html. Jepson Flora Project. 2011a. Crassulaceae, Stonecrop Family. S. Boyd, ed. Jepson eflora [v. 1.0]. Berkeley, California: University of California. Accessed December 5, Jepson Flora Project. 2011b. Dudleya abramsii ssp. affinis. K.M. Nakai, ed. Jepson eflora [v. 1.0]. Berkeley, California: University of California. Accessed December 5, Levin, G. A., and T. W. Mulroy Floral mechanisms, nectar production, and breeding systems in Dudleya subgenus Dudleya (Crassulaceae). Transactions of the San Diego Society of Natural History 21(3): reference/74442.text Nakai, K.M Some New and Reconsidered California Dudleya (Crassulacaeae). Madroño 34(4):

8 NatureServe Dudleya abramsii ssp. affinis. NatureServe Explorer: An Online Encyclopedia of Life. Version 7.1. Arlington, Virginia: NatureServe. Last updated July Accessed December USDA (U.S. Department of Agriculture) Forest Service Land Management Plan. Part 3 Design Criteria for the Southern California National Forests: Angeles National Forest, Cleveland National Forest. Los Padres National Forest, San Bernardino National Forest, Appendix H Species Guidance Summary. September Accessed November 29, pdf. USFWS (U.S. Fish and Wildlife Service) San Bernardino Mountains Carbonate Plants Draft Recovery Plan. U.S. Fish and Wildlife Service: Portland, Oregon. 8

9 Species Range in California Utah Nevada!( Current Occurrence Point!( Historic and Unknown Occurrence Point Note: Occurrence point size graphically represents the precision level code for the data point but is not scaled geographically. Arizona!(!( Z:\Projects\CEC\j6668_DRECP\MAPDOC\MAPS\BaselineBioReport\SpeciesProfiles I January 15, Miles P a c i f i c O c e a n Sources: DRECP Species Occurrence Database (2011), CWHR (2008), CEC (2010), USGS (2010), ESRI (2010) Desert Renewable Energy Conservation Plan (DRECP) Baseline Biology Report MEXICO FIGURE SP-P28 San Bernardino Mountains Dudleya in the Plan Area (N=2)