Flora – Part II
Do we take Owens Valley vegetation for granted?
by Sally Manning, Ph.D.
(formerly Vegetation Scientist with Inyo County Water Department)
One of the best parts of my job as Inyo County’s Vegetation Scientist was rare plant monitoring. Each spring I visited unpumped alkali meadow sites in search of two species in particular. Discovering flowers among the dense grasses, listening to birds singing and insects buzzing, watching cattle loitering nearby, smelling earth and air, looking up at magnificent mountains as an occasional white cloud drifted past…. I chuckled at the thought of getting paid to do this! Within days, however, I’d be out surveying the pumped wellfields. There, we stomped through thickets of dead and decadent shrubs while plumes of dust ascended our pant legs. We dodged tumbleweeds as branches ripped our clothes and skin, the soles of our feet burned as heat from the bare soil penetrated our boots, and it typically was deathly quiet. No chuckling here; seeing the devastation overpumping had wrought upon these former meadows, and knowing the data we collected could not adequately communicate the appalling sights, left me on the verge of tears.
Alkali meadow is a major vegetation type in Owens Valley. The first white visitors to Owens Valley commented on vast alkali meadows, spanning the valley floor as far as the eye could see (Wilke and Lawton 1976). Federal surveyors led by A. W. von Schmidt, 1855-56, noted the prevalence of grass across the valley floor. Even 75 years after completion of the LA Aqueduct, meadows were common throughout Owens Valley. In the 1980s, Los Angeles Department of Water and Power (LADWP) biologists mapped at least 70,000 acres of valley floor as dominated by California native grasses, supported by Owens Valley’s naturally shallow groundwater.
LADWP used a plant community classification scheme devised by Robert Holland in conjunction with the California Department of Fish and Game (Holland 1986). Dr. Holland used plant species as well as other features of the landscape, such as soils or geographic location, to categorize California’s diverse vegetation. Recently, there has been a trend toward plant community classifications that are purely floristic; that is, they are grouped only according to dominant species. Because the Inyo-LA Water Agreement’s vegetation classification was not purely floristic, I typically refer to alkali meadow as a “habitat,” for the reasons elaborated on in this article.
Alkali meadow is a biodiverse habitat that sustains common as well as rare species. Owens Valley alkali meadow is dominated by one or both native perennial grass species: saltgrass (Distichlis spicata) and alkali sacaton (Sporobolus airoides; nomenclature follows Hickman 1993). Both are hardy species, with roots growing to approximately two meters. Other common graminoids in alkali meadow include Leymus triticoides, Juncus balticus, Muhlenbergia asperifolia, Leymus cinereus, and, to a lesser extent, Spartina gracilis. In healthy meadow, irises, lilies, and broad-leaved herbaceous plants intermingle with the grasses. Frequently encountered species include: Anemopsis californica, Glychyrrhiza lepidota, Cordylanthus maritimus ssp. canescens, Malvella leprosa, Astragalus lentiginosus, Sisyrinchium halophilum, Crepis runcinata ssp. hallii, Sidalcea covillei, Calochortus excavates, and several species in the genus Cleomella. Native shrubs may occur in alkali meadow, including rabbitbrush (Chrysothammus nauseosus), Nevada saltbush (Atriplex lentiformis ssp. torreyi), greasewood (Sarcobatus vermiculatus), and sometimes sagebrush (Artemisia tridentata). Western Meadowlark (Sturnella neglecta), our endemic vole (Microtus californicus ssp. vallicola), a myriad of insects and spiders, and many other animals occupy and use meadows. Northern Harrier (Circus cyaneus) and Red Shouldered Hawk (Buteo lineatus) are year-round residents, breeding in Owens Valley and foraging in meadows. Cattle thrive on meadow grass, and ranching has long been a significant part of the regional economy.
Characteristics of Owens Valley alkali meadows were broadly summarized based on LADWP’s vegetation data from the 1980s (Manning 1997). Total green plant ground cover in alkali meadow averaged 38%, but ranged from 5% to 85% depending on site characteristics and site history. Soils are typically fine-grained, as opposed to rocky or gravelly. Soils vary in alkalinity (content of certain salts and pH), depending on the location, and some are very dark with organic matter. In unpumped meadow, groundwater is within approximately two meters of the surface. Shrub species account for a higher proportion of cover in meadows with lower water table. In the 1997 analysis, rabbitbrush more commonly co-occurred with saltgrass, while Nevada saltbush co-occurred with alkali sacaton. The summary results suggested that more fine-scale delineations of floristic “associations” in alkali meadow could be identified with further analysis.
In contrast to its abundance in Owens Valley, in the state of California, alkali meadow is rare (Sawyer and Keeler-Wolf 1995). Some of the species or close relatives of species that occur in alkali meadows, such as saltgrass, occur in coastal areas where their adaptations to high salinity allow them to grow. Alkali meadow similar to that in Owens Valley was probably more common in poorly-drained, low-rainfall areas of the state, such as the southern Central Valley. Drainage, water diversions, pumping, and other aspects of conversion to agriculture almost certainly reduced meadows in the Central Valley.
Currently, alkali meadow is mostly relegated to internally-draining basins in the state, including the Eastern Sierra and northeastern California. A fairly comprehensive mapping of California’s vegetation performed during the Gap Analysis Project (GAP) shows two-thirds of the state’s alkali meadow occurring in Owens Valley (Davis et al. 1998). The GAP map presents one view based on those researchers’ goals, objectives and procedures for vegetation mapping. We know, for example, that habitat that would be classified as alkali meadow also occurs in Death Valley, even though it isn’t represented on the GAP map. Regionally, within the Great Basin of the western United States, meadows are relatively uncommon in basins and valleys, and they are frequently disturbed by activities ranging from grazing to water diversions (West and Young 2000; Brussard et al. 1999). Though small in areal extent, these occasional meadows are important biologically because they harbor rare plant species and provide habitat for numerous local and migratory animal species (Deacon et al. 2007).
Because alkali meadow is so widespread in Owens Valley we may take it for granted. Unfortunately, these and other native habitats, which sustain our biotic heritage and provide largely un-quantified ecosystem services, are threatened by groundwater pumping and other water diversions intended to export water to Los Angeles. In a future article, I’ll discuss the hydrology of Owens Valley alkali meadow and how dewatering changes the habitat. Understanding how these groundwater-dependent systems work is vital to long term management of alkali meadow in California. As we struggle to resolve conflicts over the state’s limited water supply, it’s important that we learn to appropriately manage places we value. Then our descendants can count flowers while the birds sing and the cattle graze.
Brussard, P. F., D. A. Charlet, D. S. Dobkin, and others. 1998. Great Basin-Mojave Desert Region, at http://www.nwrc.usgs.gov/sandt/Great-bn.pdf [May 14, 2009] In: Mac, M. J., P. A. Opler, C. E. Puckett Haecker, and P. D. Doran. 1998. Status and trends of the nation’s biological resources. 2 vols. U. S. Department of the Interior, U. S. Geological Survey. Reston, VA.
California Department of Fish and Game. March 2009. Special animals. California Natural Diversity Database. http://www.dfg.ca.gov/biogeodata/cnddb/pdfs/SPAnimals.pdf [May 15, 2009]
California Department of Fish and Game. April 2009. State and federally listed endangered, threatened, and rare plants of California. California Natural Diversity Database. http://www.dfg.ca.gov/biogeodata/cnddb/pdfs/TEPlants.pdf [May 15, 2009]
California Native Plant Society. Inventory of rare and endangered plants, 7th edition, online http://cnps.web.aplus.net/cgi-bin/inv/inventory.cgi [May 15, 2009]
Davis, F. W., D. M. Stoms, A. D. Hollander, K. A. Thomas, P. A. Stine, D. Odion, M. I. Borchert, J. H. Thorne, M. V. Gray, R. E. Walker, K. Warner, and J. Graae. 1998. The California Gap Analysis Project–Final Report. University of California, Santa Barbara, CA. http://www.biogeog.ucsb.edu/projects/gap/gap_rep.html [May 16, 2009]
Deacon, J. E., A. E. Williams, C. D. Williams, and J. E. Williams. 2007. Fueling population growth in Las Vegas: How large-scale groundwater withdrawal could burn regional biodiversity. Bioscience. 57:688-698. doi:10/1641/B570809.
Hickman, J. C. (ed.) 1993. The Jepson manual: higher plants of California. University of California Press, Berkeley, CA.
Holland, R. F. 1986. Preliminary descriptions of the terrestrial natural communities of California. California Department of Fish and Game unpublished report.
Manning, S. J. 1997. Plant Communities of LADWP land in the Owens Valley: An exploratory analysis of baseline conditions. Inyo County Water Department report. Inyo County Water Department, Bishop, California, USA. 160 pp.
Sawyer, J. O. and T. Keeler-Wolf. 1995. A manual of California native vegetation. California Native Plant Society. 471 p.
West, N. E. and J. A. Young. 2000. Intermountain valleys and lower montane slopes. Pp. 256-284. In M. G. Barbour and W. D. Billings (eds.) North American terrestrial vegetation. 2nd ed. Cambridge.
Wilke, Philip J. and Harry W. Lawton (eds.) 1976. The expedition of Capt. J. W. Davidson from Fort Tejon to the Owens Valley in 1859. Ballena Press Publications in Archaeology, Ethnology and History No. 8. Robert F. Heizer (series ed.) Ballena Press: Socorro, NM.