SHRUB COMMUNITIES OF THE
LAHONTAN SANDS
James A. Young
Robert R. Blank
Thomas Lugaski
ABSTRACT
there are extensive areas of sand that are generally stabilized with vegetation and appear to be a fossil delta
of the Humboldt River corresponding to the deltas of the
Truckee, Carson, and Walker Rivers. North of this delta
in Silver State Valley and spilling across the Bloody Run
Mountains to the northeast and the Sombrero Peak area
to the southwest are extensive areas of active sand fields
that have been interpreted as representing an earlier-age
Humboldt River delta. The validity of this interpretation
remains to be proven.
The species diversity of the shrub component of the
plant communities occupying areas of sand, thought to
be sediments from pluvial Lake Lahontan, is considerably
greater than on adjacent lake plain soils. Big sagebrush
(Artemisia tridentata) is a major component of these plant
communities even though they are located below the sagebrush zone. The species that compose the plant communities on the sands change from the lower edge of the
sagebrushlbunchgrass zone to the depths of the Carson
Desert. Species of saltbush (Atriplex) and horse brush
(Tetradymia) are the most constant members of these
shrub communities.
MACROENVIRONMENTAL SETIING
Most of the sand deposits in the Lahontan Basin are
below the elevation that is normally considered the limit
of.distribution for big sagebrush (Artemisia tridentata)
plant communities growing on residual-alluvial soils.
This level is roughly 8-10 inches (20-25 em) of precipitation and 4,100 ft (1,230 m) elevation. Many of the sand
deposits support basin big sagebrush plant communities,
but the vegetation on adjacent lacustrinal soils on the
lake plains or beach ridges will seldom be dominated
by big sagebrush plants. The occurrence of the sands
allows big sagebrush to extend its range to lower elevations, into much more atmospherically dry areas than
where the species is normally capable of growing. The
lake plain soils are derived from very-fine-textured material that was capable of remaining in suspension in the
lake waters for prolonged periods (Young and others
1986). These soils have very slow permeability rates
with the moisture from limited precipitation events often
evaporating from the surface before it can enter the soil
profile. Also, the lake sediments are often saline/alkaline.
If groundwater reaches the soil surface, soluble salts are
often deposited on the soil surface in crust (Young and
Evans 1980). If groundwater does not reach the soil surface on a regular basis, the lake plain soils tend to have
high salt content near the surface and become increasingly salty with depth.
In contrast, the sands are highly permeable, are readily leached of soluble salts, and readily give up moisture
to plants in comparison to the fine-textured sediments.
The sands may be capable of retaining only a fraction
of the soil moisture that the fine-textured sediments are
theoretically capable of retaining, but their permeability,
freedom from salt concentrations, and more available
moisture content results in more effective environments
for plant growth. Even a very thin veneer of sand seems
to greatly increase the potential oflake plain environments to support plant growth. We suggest that relatively thin veneers of sand may result in moisture being
perched on the surface of buried lake plain soils and protected from evaporation by the sand deposit.
INTRODUCTION
The Lahontan sands are a fairly diverse group of sandtextured sediments that are considered to have originated
as a result of deposition in pluvial Lake Lahontan that
occupied northwestern Nevada during periods of the
Pleistocene. The sands are thought to be erosional products of at least partially glacial-fed rivers that drained
from the eastern slopes of the Sierra Nevada and from
the higher mountains of the interior of the Great Basin.
Running from north to south on the trans-Sierra, the rivers are: (a) the Susan, which fed the Honey Lake embayment of Lahontan; (b) the Truckee, which originated in
the Lake Tahoe basin; (c) the Carson; (d) the Walker;
and (e) the Humboldt, which was the only major river
that rose in the interior of the Great Basin to feed Lake
Lahontan.
The sands were apparently initially deposited in deltas
where the rivers reached the deep-water portions of the
lake. The Truckee River flows in a steep-walled canyon
for a considerable distance below the maximum lake level
and currents apparently were sufficient to keep most
sediments moving until the canyon opened to what is now
the Carson Desert near Fernley, NV. This canyon effect
was more or less apparent for the Carson and Walker
Rivers. The deltas of the Truckee, Carson, and Walker
Rivers coa1esce in the western Carson Desert. There are
two distinct deltas located near Winnemucca, NV, that
may represent different age events on the Humboldt
River. In the Humboldt River valley west of Winnemucca
Paper presented at the Symposium on Cheatgrass Invasion, Shrub
Die-Off, and Other Aspects of Shrub Biology and Management, Las Vegas,
NV, April 5-7, 1989.
James A. Young and Robert R. Blank are Range and Soil Scientists,
U.S. Department of Agriculture, Aricultural Research Service, Reno, NV
89512. Thomas Lugaski is Lecturer in Geology, Mackay School of Mines,
University ofNevada, Reno, NV 89507.
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This file was created by scanning the printed publication.
Errors identified by the software have been corrected;
however, some errors may remain.
Bottom of Basins
community species become more frequent in the dune
communities. Littleleafhorsebrush (Tetradymia glabrata) is the first of the interspace species to mix with the
big sagebrush, followed by shadscale <A-triplex confertifolia) and in the bottom of the basin black greasewood (Sarcobatus vermiculatus). The interspace shrub community
reflects the same sequence with the bottom of the basin
having the interspace between dunes occupied by relatively pure stands of black grease wood.
There is a third level of dunes (at least in Silver State
Valley) that reflects a more stable land surface. The size
of the three dune systems is 49 to 65ft (15 to 20m) for the
active dunes, 5 to 10ft (1.5 to 3m) for the secondary
dunes, and 1.6 to 3.3 ft (0.5 to 1.0 m) for the third-level
dune systems. The third-level system is characterized by
repetitive, relatively monospecific communities dominated
by spiny hopsage (Grayia spinosa), shadscale, or black
greasewood. Apparently, these three levels of dune stability do not represent successional stages, because the fields
they characterize are physically separated. The structure
of the dunes suggests they represent different erosional
events, with different scales to the wind parameters that
produced the fields.
There is a limit to how far the adaptation of big sagebrush can be stretched. In the lower elevation portions
of the Carson Desert it is replaced with Bailey grease wood
and other shrubs of the chenopod family. Greasewood is
more characteristic of salt desert environments even
though the soluble salt content of the sands remains low.
Desert Mountains
There are several isolated mountains in the southwestern portion of the Carson Desert where Lahontan sands
have been driven up and sometimes over the mountain
ranges by winds. The mountain ranges extend above the
maximum level of Lake Lahontan and during pluvial
periods were islands in the lake system. Apparently due
to the orthographic-induced aridity of the location of the
mountains they do not support big sagebrush on residualalluvial soils even at their higher elevations. Lahontan
sands enhance the potential of these environments for the
growth of shrubs.
SPECIFIC SHRUB COMMUNITIES
Humboldt Delta
The following characterizations of shrub communities
of the Lahontan sands should not be considered the final
word in such classification, but represent the results of
detailed reconnaissance-level investigations.
The modern delta of the Humboldt River extends from
the prominent sill in the valley floor west of the town of
Winnemucca, downstream almost to Mill City. In contrast
to Silver State Valley, the modern delta is almost totally
stabilized sand dunes with only infrequent active dunes.
The aspect of the current delta has a light gray cast
from the presence of hairy horsebrush (Tetradymia comosa) plants along the crest of the dunes. These dunes
are in the 5 to 10 ft (1.5 to 3.0 m) size class. The slopes
of the dunes are vegetated with big sagebrush, littleleaf
horsebrush, fourwing saltbush, rubber rabbitbrush, and
black greasewood plants. The interspaces among the
dunes often have the lake plain sediments exposed and
support black greasewood or shadscale communities.
These interspace communities are nearly species specific
depending on the distance to the water table (Young and
others 1986).
Silver State Valley
.···
The largest field of active sand in the Lahontan basin
is loc.ated northwest of Winnemucca, NV, in the south end
of Silver State Valley. This sand may represent a fossil
delta of the Humboldt River or it may be a product of the
Quinn River system and the northern Black Rock Desert.
On the flanks of the Slumbering Hills and Bloody Run
Mountains, among the extremely active dunes of this
field, Artemisia tridentata/Oryzopsis hymenoides communities occur. The most constant, subdominant shrub in
these communities is rubber rabbitbrush (Chrysothamnus
nauseosus), which apparently occurs in two forms in these
communities, one of which is preferred by browsing animals. A second semi woody species with high constancy
is buckwheat (Eriogonum kearneyi).
The first woody species to become established on the
active dunes at this site is fourwing saltbush (Atriplex
canescens). These shrubs are very robust specimens and
apparently are the gigas form of this species (Stutz and
others 1915).
In the center of the sand fields at Silver State Valley
the plant communities are dependent on the dune height
and stability. The huge, active dunes are largely bare
of vegetation, except for occasional patches ofrabbitbrush
and sagebrush. Lower, more stable dunes have big sagebrush on the upper portions of the dune and more drouttolerant or salt-tolerant species in the interspace. As
you descend to the center of the valley the interspace
Long Valley Delta
Long Valley Creek was a tributary of the Honey Lake
embayment of pluvial Lake Lahontan and the sandtextured delta of this stream is located to the northeast
of the town of Doyle, CA. The sand occurs in the lee of
the Turtle Mountain extension of the Fort Sage Mountain
complex. Rather than forming dune fields, the sands form
cones extending down from the ridge over which it has
been driven from the Long Valley delta. The plant community growing on these sands is the basic big sagebrush
community found in Silver State Valley complete with
buckwheat. This community is enriched with the presence of such species as antelope bitterbrush (Purshia
tridentata) and green ephedra (Ephedra viridis).
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Flanigan
CONCLUSIONS
Flanigan, NV, is located to the northeast across Honey
Lake Valley from the Fort Sage sand area. This is a
much more arid environment than the Doyle area, which
receives trailing precipitation from the Sierra Nevada.
The sands at Flanigan occur in long, parallel ridges
rather than crescent dunes. The ridges apparently are
moving from the northwest to the northeast and arealmost perpendicular to bar and beach features of Lake
Lahontan. The dominant vegetation is again big sagebrush and associated species, but the more mesic species
such as bitterbrush are gone compared to the Doyle-Fort
Sage location. The presence of Nevada dalea (Dalea polyadenia) attests to the lack of precipitation at this site.
The presence of sand on the lake plain ofpluvial Lake
Lahontan increased the diversity of shrubs that form
plant communities in these arid environments. Indian
ricegrass (Oryzopsis hymenoides) is a constant understory
dominant in all of these communities. The widespread
occurrence of big sagebrush underlines the ecologic amplitude of this species and causes speculation as to the evolutionary status of the forms that occupy the sand field
environments.
REFERENCES
Stutz, H. C.; Melby, J. M.; Livingston, G. K. 1975. Evolutionary studies of Atriplex canescens. American Journal
of Botany. 67: 236-248.
Young, J. A.; Evans, R. A., eds. 1980. Physical biological
and cultural resources of the Gund Research and demonstration ranch Nevada. ARM-W-11. Agric. Reviews
and Manuals. Oakland, CA: U.S. Department of Agriculture, Science and Education Administration. 72 p.
Young, J. A.; Evans, R. A.; Roundy, B. A.; Brown, J. A.
1986. Dynamic landforms and plant communities in
a pluvial lake basin. Great Basin Naturalist. 46: 1-21.
Desert Queen Valley
,;:'··
'.
..
This site lies in the lee of the Hot Springs Mountains
in the northern Carson Desert. The sand apparently has
been eroded from the delta of the Truckee River located
to the southwest. This was the deep-water portion of
Lake Lahontan.
The Desert Queen site is apparently too dry for big
sagebrush. The dominant shrub is Bailey greasewood.
The sands occur in a very large field with dune height
limited to less than 1.6 ft (0.5 m). Littleleafhorsebrush,
shadscale, and fourwing saltbush occur in this community, making them the most constant species on sand
across the basin. Nevada ephedra (Ephedra nevadensis)
and winterfat (Ceratoides lanata) are also components of
this community.
~·.
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