BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Poa secunda | Sandberg Bluegrass 



GENERAL BOTANICAL CHARACTERISTICS : 
Sandberg bluegrass is a shallow-rooted, cool-season perennial
bunchgrass.  Growth form ranges from small tufts with only one or two
culms to large tussocks up to 1 foot (0.3 m) in diameter [66].  Sandberg
bluegrass is relatively short lived, and its populations tend to
fluctuate with annual weather conditions [20].


RAUNKIAER LIFE FORM : 
   Chamaephyte


REGENERATION PROCESSES : 
Sandberg bluegrass regenerates by tillering and by seed.  Plants are
pollinated by wind or are self-fertile.  Sandberg bluegrass can also
produce viable seed without pollination (facultative apomixis)
[18,28,35,41].  Sandberg bluegrass produces significant amounts of seed
in most years.  In the laboratory, fifty percent germination was
obtained from fresh seed after a 3-month afterripening period [64].


SITE CHARACTERISTICS : 
Sandberg bluegrass occurs on flats and ridgetops, slopes, meadows, and
open timberline.  It grows well in rich clay loam soils but most often
inhabits shallow, rocky, or sandy soils.  It is the characteristic grass
of the scablands of eastern Washington and Oregon [56,66].  It is
usually found on well-drained soils.  Sandberg bluegrass is fairly
shallow-rooted and is favored over deeper-rooted perennials in areas
receiving frequent light rains or where soil moisture is otherwise
limited [34,50].  In intermountain grassland of northeastern Nevada,
Sandberg bluegrass-dominated communities occurred on the driest sites
[46].  In southeastern Washington cheatgrass-Sandberg bluegrass
communities, Sandberg bluegrass generally dominated north-facing slopes,
while cheatgrass dominated south-facing slopes [44].  In southern Idaho,
Sandberg bluegrass was found to decrease on periodically flooded
streambanks [54].


SUCCESSIONAL STATUS : 
Sandberg bluegrass occurs in open sun to partial shade.  In fallow
fields in western Montana, it returned 7 years after plowing [69].
Sandberg bluegrass tends to persist with fire and/or grazing.  In the
absence of fire in sagebrush (Artemisia spp.) steppe, it may be shaded
out by sagebrush [1,65,69].  Sandberg bluegrass succession in plant
communities other than sagebrush steppe is poorly documented, but it is
likely that with canopy closure, Sandberg bluegrass becomes shaded out
in any plant community in which it occurs.


SEASONAL DEVELOPMENT : 
Sandberg bluegrass completes spring growth earlier than many other
perennial grasses.  Because it is a shallow-rooted species, it must
complete growth and seed production before available soil moisture has
been depleted on summer-dry ranges [10].

In eastern Washington, Sandberg bluegrass has two periods of maximum
leaf height:  midwinter and May.  Leaves begin growing in fall as soon
as rains begin.  Soaking rains are not necessary; light showers are
sufficient to initiate growth.  The decline in growth after midwinter
may be due to autosenescence of fall leaves.  Spring leaves generally
reach maximum development late in the season.  Cessation of growth
coincides with depletion of soil moisture in the top 4 inches (10 cm) of
soil.  Sandberg bluegrass roots appear to be active in the temperature
range of 42 to 59 degrees Fahrenheit (5.5-15 deg C) [19].

The following data were collected from 1941 to 1947 on the upper Snake
River Plain of Idaho at 5,500 feet (1,676 m) elevation.  Average
precipitation was 10 inches (254 mm).  The average date of snowmelt
during this period was March 30 [10].
       
                                    Average Date
                           ______________________________
                           P. secunda       P. nevadensis

Growth starts                 3/30               3/30
Flower stalks appear          4/27               5/6
Heads fully out               5/15               6/3
Flowers in bloom              6/5                6/18
Seed ripe                     6/26               7/9
Dissemination starts          6/30               7/15
Dissemination over            7/25               8/8
Plant drying                  5/23               6/30
Plant dried                   7/9                8/9

Related categories for Species: Poa secunda | Sandberg Bluegrass