300 



P. W. Flanagan and F. L, Bunnell 



8 600 



20 40 60 80 100 110 120 130 140 150 

 Time, hrs 



.500 



C 



I 400 

 « 300 



<L) 



tr 



^ 200- 



■5 100- 



e 



3 



o 







■\°c 



Cumulotive 

 Respiration, 



^^r- 



j^i}' 



4 





Weight 



60 



50 



40 ^ 



o 



30_ c 



, o" E 



-t- H20i;.2 



u 



10^ ? 



10 20 30 40 50 60 70 80 90 100 

 Time, hrs 



FIGURE 9-3. Respiration and growth (wet 

 weight) of a common tundra soil fungus. Myceli- 

 um sterilium BIS, at 10° and -I °C, growing on a 

 mineral salt medium containing a known amount 

 of glucose. Vertical bars represent the standard 

 errors fn = 6). (After Flanagan and Bunnell 

 1976.) 



respiration was measurable using individual fungi were -6.5 °C and 

 + 48°C. Some psychrophilic fungi were present. Corresponding with the 

 temperature gradient, there is a general increase in psychrophilic fungi 

 from the phyllosphere (5.5%) to the litter (7.5%) and into the soil 

 (15.6% of the mycoflora). Even among psychrophilic forms, however, 

 growth of most organisms was not measurable below -3°C. At 0°C the 

 psychrophiles cultured on potato extract broth did produce measurable 

 growth; average growth rate of four psychrophiles at 0°C was 3.6 mg g"' 

 day"'. Fungi from other Alaskan sites, Eagle Summit and Prudhoe Bay, 

 showed similar responses (Flanagan and Scarborough 1974), leading to 

 the conclusion that both bacteria and fungi in tundra are capable of 

 growth and respiration at subzero temperatures. These observations sup- 

 port hypothesis one. 



