View at site 5                                                        Typical crust at site 5

Fort Irwin Study Site (FISS), in the southeast corner of Fort Irwin NTC, San Bernadino County, California, USA.  UTM 88.7645, 45.656; elevation 2220 feet.  This site is near the desert tortoise enclosures in the southwest corner of Fort Irwin NTC, northwest of Powerline Road.  Composite sample composed of subsamples from 10 composite samples in a transect that runs between the first two enclosures. Gently sloping bajada with one sizeable wash and many small channels. Algal crust almost continuous, with fair amount of lichens evident. Crust disappears on coarse sandy soils.  Date of sampling: 29 May 1998

Crust thickness not measured.

Cover summary:

Type Cover                % Cover
Shrubs                               3.0
Annuals                          14.7
Perennial grasses            0.0
Perennial forbs                0.0
Algal crust                      68.4
Bryophytes                       0.0
Lichens                              0.2
Bare Soil                            3.8
Rock                                   0.4
Gravel                                5.4
Litter                                  3.5
Cactus                                0.0

Chlorophyll a (ng/g): 2150.29
N fixation rate (mmole/n2/m2/hr):  2219.06
Soil texture class:  sand

FI6

        
           View at site 6                          Typical crust at site 6

Fort Irwin expansion site TAA2, San Bernadino County, California, USA 35º09.854' N, 116º 52.376' W, 2900 ft. elevation. Broad wash by dirt road to Montana Mine, 5.1 miles from Irwin Road. Road to Montana Mine is 10.2 miles northeast on Irwin Road past the Yermo Cut-off. Date of sampling: 9 June 1998

Dominants vascular plants at the site:  Ephedra californica, Larrea tridentata

Other common vascular plants:  Ambrosia dumosa, Bromus rubens (rare), Camissonia boothi ssp. decorticans, Chorizanthae rigida, Chorizanthae sp., Erodium cicutarium, Hymenoclea salsola, Opuntia (silver cholla?), Psorothamnus arborescens, Psorothamnus schotii, Schismus sp., Senna armata, Yucca brevifolia (rare).

Mean algal crust thickness: 8.2 mm
Mean lichen crust thickness: 17.0 mm

Cover summary:

Type Cover                % Cover
Shrubs                            7.0
Annuals                       21.9
Perennial grasses         0.0
Perennial forbs             1.6
Algal crust                   56.6
Bryophytes                    0.2
Lichens                           0.6
Bare Soil                         7.4
Rock                                0.2
Gravel                             1.4
Litter                               2.0
Cactus                             0.0