americana) and Holboell's rockcress (Arabis holboellu). 

 Fringed sage (Anemisia frigida) is the only shrub-like 

 plant consistently present; however, it does not exceed 

 3 percent in canopy cover. (Plots 

 NHMTECLM97SC0003, NHMTECLM97SC0004] 



Sarcobatiis vermiculatus I Pascopiyrum smithtj Shrubland 



[SARVER/PASSMI] 



black greasewood / western wheatgrass shrubland 



This is a common type on the RNA, especially 

 extensive on the eastern side of the lake where it 

 occurs upslope by a matter of a few tenths of a foot or 

 more from the PASSMl alluvial flat type. These sites 

 are more salt-affected than those with Vascop^rum. 

 smithii alone. This type as found in a lacustrine setting 

 typically develops under conditions in which salts from 

 alkaline lakes are deposited by wind and water on the 

 leeward shores. The deposition process and probably 

 other habitat conditions are altered by the artificially 

 maintained water levels on Lake Mason. Black 

 greasewood (Sarcobatus vermiculatus) occupies slightly 

 raised mounds, perhaps as a result of an ensuing erosion 

 processes. Its canopy cover is low, varying between 5 

 and 20%, but the visual aspect is that of shrubland due 

 to the stature of the Sarcobatus vermiculatus relative to 

 that of the associated undergrowth. This association in 

 the RNA has been as affected by grazing as those of the 

 PASSMl type judging by the dominance of increaser 

 species, foremost among which are Japanese brome 

 (Bromus japordcus) and povertyweed {Iva axiUaris). We 

 noted a micro-patterning within this type as the dense 

 patches of Bromus japonicus seemed to have little 

 Pascopyrum smithii and conversely where tillering of P. 

 STTuthii was especially dense there was litde B. japonicus. 

 This is not a high-quality occurrence of this type due to 

 the altered environment and abundance of weeds. 

 [Plot NHMTECLM97SC00021 



Atripkx gardneri I Pascopyrum smithii Dwarf Shrubland 



[ATRGAR/ PASSMl] 



Gardner's saltsage / western wheatgrass dwarf 



shrubland 



are quite variable, including western wheatgrass 

 (Pascopyrum smithii) as usueJ dominant, meadow barley 

 (Hordeum brachyarU-herum) , foxtail barley (Hordeum 

 jubatum), bottlebrush squirreltail (Sitarxion hystrix), and 

 Nuttall's alkaligrass (Puccinellia nuttalliana) . Graminoid 

 cover is higher for the Lake Mason examples than has 

 been seen elsewhere for this association and probably 

 reflects the relatively favorable soil moisture of these 

 sites. The herbaceous component is dominated by 

 weedy species or ones that increase with disturbance, 

 including povertyweed (Iva axillaris) , clasping 

 pepperweed (Lepidium perforatum) , wild lettuce 

 (Lactuca canadensis) , and common dandelion 

 (Taraxacum officinale). The suite of weeds/increaser 

 species indicates past disturbance and decreases the 

 baseline value of these sites. [Plot 

 NHMTECLM97SC0005J 



Emergent Wetlands: We did not sample the semi- 

 permanent emergent wetlands that are part of the 

 RNA. They are dominated by hardstem bulrush 

 (Scirpus acutus) with abundant sago pondweed 

 (Potamogeton pectinatus), chara (Chara spp.), and water 

 buttercup (Ranunculiu spp.) . 



OVERALL BIODIVERSITY SIGNIFICANCE: 

 The Lake Mason RNA represents a fair example of the 

 western wheatgrass wet meadow (Pascopyrum smithii), 

 and a once common plant association, Pascopyrum 

 smithii'Nasella viridula with isolated areas in good 

 condition. There are also weed infested occurrences of 

 a less common type (PASSMl alluvial bottom) as well 

 as several associations (SARVER / PASSMl, ARTGAR 

 / AGRSMI) of more restricted occurrence also plagued 

 by weeds. We are not prepared to address the affects of 

 elevated water table levels to this low-lying RNA. In 

 comparison with MuUan Trail RNA and its 

 glaciolacustrine setting, it protects more plant 

 associations and more of the hydrological gradient, 

 though the overall ecological condition is not as high. 

 The RNA is contiguous in places with surrounding 

 grasslands connecting to the larger landscape of the 

 surrounding basin slopes. 



This association occurs as small stands that are 

 fractioiw of an acre, across salt-affected 

 alluvial/lacustrine flats on the west side of Lake Mason. 

 These sites undoubtedly have standing water during 

 spring runoff and are slow to dry given the clay soils. 

 At least one site had motded and incipiendy gleyed 

 soil, indicating an oxygen depleted condition 

 developing during extensive inundation. Canopy 

 cover of Gardner's saltsage (Atriplex gardneri) is 

 typically not greater than 20 % and usually exceeded by 

 that of a suite of graminoids whose cover contributions 



LAND USE: 



Lake Mason was intensively grazed in the past. 



Livestock grazing ceased in 1980. 



MANAGEMENT COMMENTS: 

 This RNA may be suited to study of community 

 succession and habitat values with and without 

 restoration practices. The elevated water levels may 

 affect restoration potential and efforts to simulate the 

 historical ecological drivers of grazing and fire. 



40 



