|We watch the water.|
|photo courtesy of S. Brown & C. Klingler|
by Sally Manning, Ph.D.
(Dr. Manning recently retired from a long tenure as Inyo County Water Department Research Scientist--Vegetation.)
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 Dr. R. 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 2 m. 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 2 m 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 Owens Valley probably was 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 unquantified 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.
Further information for the references cited in this article appears in the main section of this page under "Literature cited." For more information on sensitive species that occur in association with Owens Valley alkali meadow, see the CNPS inventory of rare and endangered plants and the DFG's list of state and federally listed endangered, threatened, and rare plants of California for information on plants and this informative pdf from the DFG on "special animals" for more about sensitive animal species.
by Daniel Pritchett, Conservation Chair of the local Bristlecone Chapter of the California Native Plant Society
Paiutes living in the Valley when the first Europeans arrived were well-acquainted with the native flora and had developed extensive irrigation systems in several areas to propagate food plants (Sauder 1994).
Surveyor A.W. von Schmidt, one of the first Europeans to record observations, did not share the Paiutes’ appreciation of the native flora. In 1855 he wrote that “on a general average the country forming the Owens Valley is worthless to the White Man.”
On the other hand, only four years later (1859), Captain J.W. Davidson of the U.S. Army evaluated the valley quite differently: “Every step now taken shows you that nature has been lavish of her stores. The Mountains are filled with timber, the valleys with water, and the meadows of luxuriant grass. Some of the meadows contain, at a moderate estimate, ten thousand acres every foot of which can be irrigated” (Sauder 1994).
Recent visitors from better-watered parts of the world have been known to dismiss the vegetation in the Owens Valley as “a bunch of weeds” while some long-time local residents still describe the Owens Valley’s extensive shrub lands simply as “sagebrush.”
Ecologists describe vegetation in terms of both physiographic features of the environment in which it occurs and particular associations of species. Some of the characteristic types of Owens valley vegetation are listed below:
These occur along the Owens river and streams flowing from the Sierra Nevada. Important tree species include Populus fremontii (Fremont cottonwood), Salix gooddingii (Goodding’s black willow), Salix laevigata (red willow) and, along a few streams, Quercus kelloggii (black oak). Common shrubs include Salix exigua (Coyote willow) and Rosa woodsii (wood rose). Leymus triticoides (beardless wildrye) is a common grass, and rushes and sedges are abundant as well. Tamarix ramosissima (tamarisk, or salt cedar), a non-native shrubby tree, has invaded many riparian areas in the Owens Valley and is the object of ongoing eradication efforts. Riparian forest communities statewide are classified as “very threatened” by the California Natural Diversity Database (Sawyer and Keeler-Wolf 1995).
These occur in high water table areas on the valley floor. Two native grasses are characteristic of alkali meadows: Sporobolus airoides (sacaton) and Distichlis spicata (saltgrass). The meadows are home to several endangered species such as Calochortus excavatus (Inyo County star tulip) and Sidalcea covillei (Coville’s checkerbloom). Alkali meadows themselves are classified as “very threatened” by the California Natural Diversity Database (Sawyer and Keeler-Wolf 1995). Alkali shrub communities are typically dominated by such plants as Atriplex lentiformis ssp. torreyi (Nevada saltbush), Chrysothamnus nauseosus (rabbitbrush), Sarcobatus vermiculatus (greasewood), and Suaeda moquinii (inkweed). When subject to such anthropogenic stresses as groundwater pumping and cattle grazing alkali meadows are vulnerable to invasion by shrubs and conversion to alkali shrub communities.
These occur on the broad bajadas and alluvial fans which descend from canyon mouths of the Sierra Nevada and the White and Inyo Mountains. Common species include Atriplex confertifolia (shadscale), Ephedra nevadensis (Nevada ephedra), and Eriogonum fasciculatum (California buckwheat). At the northern end of the valley there are large stands of Coleogyne ramosissima (blackbrush) as well as such Great Basin species as Artemisia tridentata (sagebrush) and Purshia tridentata (bitterbrush). In the southern half of the valley Mojave Desert species such as Larrea tridentata (creosote bush) and Ambrosia dumosa (burro bush) occur.
In arid environments water is often a limiting factor for plant growth. There are two basic strategies plant species have evolved for dealing with water stress: 1) drought tolerance and 2) drought evasion.
Drought tolerant plants have developed strategies to maximize their efficiency in use of water. This allows them to thrive in areas where moisture is not adequate for most species to survive at all. Alluvial fans and slopes of desert mountains are characteristic landforms for drought tolerant species. Some local examples are shadscale and creosote bush.
Drought evasive plants, on the other hand, have developed strategies to maximize growth in areas where a reliable supply of water is available. They out-compete drought tolerant species where water is abundant but don't occur at all where it is not and so evade drought entirely. They typically occur along rivers and streams and in areas where groundwater is close to the surface.
Groundwater dependent vegetation (GDV) is the phrase used in the LTWA and its technical appendix (aka the Green Book) to describe vegetation composed of drought evasive species. Management of GDV is one of the primary concerns of the LTWA because GDV is vulnerable to water table drawdowns caused by groundwater pumping.
In the Owens Valley, GDV originally covered large areas of the valley floor, as well as narrow strips along streams coming down from the Sierra and isolated patches surrounding springs. Much of the original acreage of meadow was cleared for agriculture and for construction of the towns.
For more information about vegetation of the Owens Valley floor, contact the Inyo County Water Department at www.inyowaterdept.org. An overview of vegetation in the White and Inyo Mountains is available in Hall (1991). Plant lists for certain parts of the Owens Valley such as the Alabama Hills and the Bishop Creek watershed are available from the Bristlecone Chapter of the California Native Plant Society (www.bristleconecnps.org).
References for Daniel Pritchett's article (above):
Hall, C.A., Jr. (Ed.) 1991. Natural History of the White-Inyo Range Eastern California. California Natural History Guides: 55. University of California Press. Berkeley.
Sauder, R.A. 1994 The lost frontier: water diversion in the growth and destruction of Owens Valley agriculture. University of Arizona Press. Tucson.
Sawyer, J. O. and T. Keeler_Wolf. 1995. A manual of California vegetation. California Native Plant Society, Sacramento, Calif.
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.