Table A .--Calculated mass of organic veserve in a cold desert 



shrub ecosystem 



'■ Root ■ Other ' Total 

 (cm. ) :_ ; ; 



g./m.'^ 



Aboveground^ 240 240 

 Below ground 



0-30 631 244 875 



30-60 380 38 . 418 



60-90 177 13 190 



90-120 36 2 38 



>120 11 <1 n_ 



Total 1,235 538 1,772 



■•■Maxiraum height of shrubs is about 30 cm. Occasional grasses 

 and annual weeds reach 45 cm. Total depth of vegetal layer, 

 therefore, about 170 cm. : 35 cm. aboveground, 135 cm. below ground. 



Aboveground Accumulation and Productivity 



About a third of the mass of 240 g./m.^ of organic material above the ground was 

 unattached litter. Of the mapped shrubs, 35 percent were completely dead, and half of 

 the crown cover of the living shrubs was dead. As we noted earlier, part of the wood 

 of living stems is dead and weathered; so the total living perennial aerial part of the 

 biomass probably constitutes no more than 35 g./m.^ of the total accumulated organic 

 matter above the ground. The accumulation of top-derived material includes an addi- 

 tional 162 g. sorted out from the underground samples. Therefore, the total accumula- 

 tion from aerial parts is about 400 g./m.^ compared to the 1,370 g./m.^ we estimate to 

 have accumulated from underground parts. 



Hutchings and Stewart (1953) reported the average annual productivity of air-dry 

 green matter in 20 pastures near our study area to be 219 lb. /acre (24.5 g./m.^). 

 During the 12 years of their study, the productivity ranged from 75 to 468 lb. /acre 

 (8.4 to 52.5 g./m.^]. We believe that their average value can be applied with some 

 modification to our site. From Hutchings and Stewart's unpublished field data we 

 determined the yields of two of the closest pastures (both lightly grazed) to be 25.3 

 g./m.^. Ungrazed plots within the pastures have had yields similar to the pasture 

 yields in the fewer years they were sampled. Several other ungrazed areas in the same 

 kind of community in the same valley and in other valleys of western Utah and eastern 

 Nevada have average yields-"^ (3, 4, or 5 years) that range from 13.6 to 44.3 g./m.^; 

 average for all was 24.4 g./m.. 



Although these productivity data are not from the immediate site of our standing 

 crop data, they are really more useful to our purpose than just 1 or 2 years' productiv- 

 ity determination on the site. This is because as organic matter accumulates over 

 several years, productivity ought properly to be expressed as an average over several 

 years, especially where its annual variation is as broad as it is on this desert. 



■^Unpublished data in the files of Intermountain Forest and Range Experiment Station. 



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