2010-05-25_REVISION - C1981008 ‎(5)‎

• Permit No: C1981008
• IBM Index Class Name: Revision
• Doc Date: 5/25/2010
• Doc Name: Response 1 Revised Pages Section 2.04.10
• Type & Sequence: PR6
• Media Type: D
• Archive: No

Table 2.04.10 -20
Mean Herbaceous Production and Percent Composition (by dry weight)
For The Morphological Classes Encountered in Samples Of The
Swale /Drainage (IPSW) Vegetation Type
New Horizon 2 Permit Expansion Study Area, 1999
(n =50)
The willow component of the swale /drainage type occurs on shallow, slightly elevated sites that
are better - drained than areas supporting vegetation that can tolerate standing or flowing water,
and completely saturated conditions. No attempt was made to sample cover in the willow
component because of the extremely high shrub densities encountered. Qualitative evaluation
indicated that the canopy and ground cover, including litter, in the willow thickets was equal to
or greater than 100 percent. In more open areas where the willows were less dense,
quackgrass, alkali muhly and common spikerush were prevalent.
The mean density of coyote willow, the only shrub species represented, was 78 stems per
meter square. This translates to 312,000 stems per acre. The density of actual willows is
expected to be much lower. It was impossible to tell which stem went with which individual and
since willow is a clonal body individuals are in determinant. These density figures do not
represent an average density for the swale /drainage type as a whole, but only in the thickets.
A total of thirty species were found in the swale /drainage type. Graminoids dominated, with a
total of twenty species (see Table 2.04.10 -19) with ten having relative cover values of one
(Revised October 2009) 2.04.10-77
GRAMS /PLOT
PROD.
PERCENT
MORPHOLOGICAL CLASS
0.25M
LBS /ACRE
KG /HA
COMPOSITION
Perennial Graminoids
208.9
7,461
8,357
90.6
Perennial Forbs
21.7
775
868
9_4
Total
230.6
8,236
9,225
100.0
The willow component of the swale /drainage type occurs on shallow, slightly elevated sites that
are better - drained than areas supporting vegetation that can tolerate standing or flowing water,
and completely saturated conditions. No attempt was made to sample cover in the willow
component because of the extremely high shrub densities encountered. Qualitative evaluation
indicated that the canopy and ground cover, including litter, in the willow thickets was equal to
or greater than 100 percent. In more open areas where the willows were less dense,
quackgrass, alkali muhly and common spikerush were prevalent.
The mean density of coyote willow, the only shrub species represented, was 78 stems per
meter square. This translates to 312,000 stems per acre. The density of actual willows is
expected to be much lower. It was impossible to tell which stem went with which individual and
since willow is a clonal body individuals are in determinant. These density figures do not
represent an average density for the swale /drainage type as a whole, but only in the thickets.
A total of thirty species were found in the swale /drainage type. Graminoids dominated, with a
total of twenty species (see Table 2.04.10 -19) with ten having relative cover values of one
(Revised October 2009) 2.04.10-77