BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Artemisia arbuscula ssp. arbuscula | Gray Low Sagebrush 



GENERAL BOTANICAL CHARACTERISTICS : 
Gray low sagebrush is a dwarf, low-spreading, evergreen shrub of
irregular form which grows up to 20 inches (5 dm) in height, with a
crown spread of 16 to 32 inches (4-8 dm) [2,50].  The fibrous portion of
the root system is shallow and fairly extensive, which allows good water
absorption [60].  Gray low sagebrush may fix nitrogen [21].  It closely
resembles black sagebrush and is frequently misidentified in the field
[8,62].

Gray low sagebrush can endure drought and prolonged spring flooding
[63].  


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Gray low sagebrush reproduces by seed [52,69].  It does not resprout;
layering occurs infrequently [43,58].  In laboratory tests, stem
cuttings of gray low sagebrush failed to root [26].  The lightweight
seed ripens from late October to November and is then dispersed by wind.
Cleaned seed averages 980,000 per pound (2,160/g) [2,42,69].  Under
laboratory conditions, seed from Oregon germinated in 17 days at 72
degrees Fahrenheit (22 deg C) [10].  Seed from California germinated on
many soil types under a wide temperature range [60].


SITE CHARACTERISTICS : 
Gray low sagebrush typically occurs on dry, rocky slopes and ridges in
mountainous terrain or on harsh sites in dry foothills or plateaus
[6,62].  It often grows in a near monoculture but can occur as islands
in open stands of ponderosa pine (Pinus ponderosa) or white fir (Abies
concolor), or in foothills pine (P. sabiniana)-California black oak
(Quercus kelloggii), and western juniper communities [35,51,69].  Gray
low sagebrush grows well on the coldest and driest woodland sites in
desert ranges of the Great Basin [44].

The distribution of gray low sagebrush is largely determined by edaphic
factors [27,72]; it apparently grows best on dry, shallow, rocky, and
often alkaline soils [2,53].  Gray low sagebrush typically occupies
sites with soils less than 13 inches (33 cm) to an impermeable clay B
horizon, or if deeper, with 30 percent or more gravel and cobbles in the
horizon [54,72].  Unfractured bedrock is often present 13 inches (33 cm)
or less below the surface on low sagebrush sites [27].  Gray low
sagebrush grows in glacial tills, hardpans 10 to 15 inches (25-38 cm)
deep, well-developed argillic horizons, and on moderate to strongly
developed clay derived from basaltic parent materials [23,53].  Gray low
sagebrush grows on dolomite, sandstone, and granitic soils of
California's White Mountains, although growth is relatively poor on the
dolomitic soils [60].  In many areas, surface soils are highly eroded
[69].  Gray low sagebrush sites are characterized by large amounts of
bare ground and exposed surface rock.

The claypan soils, which are typical of most low sagebrush sites, often
flood in spring and dry to a hard, sun-baked crust by mid to late summer
[68].  Root-zone aeration is poor in many areas due to the development
of a perched water table in spring and winter [72].  The shallow,
fibrous root system of gray low sagebrush allows good growth on poorly
aerated soils [44].  Extreme tolerance of drought may control the
distribution of this species in some areas [73].  Annual precipitation
at gray low sagebrush sites ranges from 7 to 18 inches (18-46 cm) [53].

The elevational range of gray low sagebrush is from 2,300 to more than
11,500 feet (700-3,500 m) [73].  In the Intermountain region, gray low
sagebrush grows most commonly at lower elevations but may be found above
10,000 feet (3,050 m) on warmer and drier sites [48].  In parts of
Idaho, gray low sagebrush grows in distinct high and low elevation zones
[43].  Upper elevational limits are imposed by low air and soil
temperatures and a short growing season [60].  Elevational ranges are as
follows [21,45,60,63,72]:

                    feet            meters
 
        CA     10,000-12,800     3,050-3,904
        CO      7,000- 8,000     2,134-2,439
        ID      6,200- 9,100     1,890-2,774
        MT      4,500- 7,700     1,372-2,347
        NV      5,902- >8,852    1,800- >2,700
        OR      3,000- 9,000       914-2,743
        UT      4,500- 8,000      1,372-2,439
        WY      5,100- 8,600      1,555-2,621



SUCCESSIONAL STATUS : 
Gray low sagebrush occurs in late succession in a number of drier
sagebrush-grassland and forest habitat types.  It is a dominant shrub
over large areas of middle to high elevation terrain in the
Intermountain West [54].  Gray low sagebrush is also well represented in
the early successional stages of many big sagebrush communities and is
an early pioneer species in some old streambottoms [3].  The very dry,
rocky soils of some sites may prevent the establishment of big
sagebrush, allowing gray low sagebrush to persist as a dominant in these
topoedahic climax communities [73].


SEASONAL DEVELOPMENT : 
New growth of gray low sagebrush begins in May, with the formation of
young heads in July [2].  General flowering dates are as follows [21]:

  Earliest Date     Latest Date     State

      May            September        CO
      July           August           MT
      August         September        UT
      June           October          WY

Phenology may vary by phenotype as well as by geographic area.  Eckert
[22] reported that in Oregon, a small-headed form blooms from August to
September, whereas a large-headed form flowers during July and August.
Seed matures from late August through October, and ripens by October or
November [2,63].

Related categories for Species: Artemisia arbuscula ssp. arbuscula | Gray Low Sagebrush