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Vegetation
of the Owens Valley has been studied, classified, and described
in many ways.
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).
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| photo by Mike Prather |
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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).
--Daniel
Pritchett, Conservation Chair of the local
Bristlecone Chapter of the
California Native Plant Society
Literature Cited
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.
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