Microflora Activities and Decomposition 301 



0.6 



0.4 



Psychrophiles and 



Cold Tolerant Mesophiles 



£ 

 ^O.Z 



E 

 o 



0.4 



0.2 



Psychrophilic 

 Thermotolerant * — 4 — u 



-♦M.S. 



iT.c. 



10 15 20 

 Temperoture , 



25 



30 35 



40 



FIGURE9-4. Fungal growth 

 responses to temperature 

 among several different ster- 

 ile forms (M.S.), Chryso- 

 sporium pannorum (C.p.), 

 Cladosporium herbarum 

 (C.h.), and Trichosporiella 

 cerebriformis (T.c.) grow- 

 ing in liquid potato dextrose 

 extract. Vertical bars repre- 

 sent the standard errors (n 

 = 8). (Flanagan, unpubl.) 



Growth rates of fungi are not always closely coupled with rates of 

 respiration (Figure 9-3), especially in the senescing phase of growth or at 

 low temperatures (-3 °C) when growth has ceased but respiration is still 

 measurable. The relationship between respiration and temperature can 

 be either linear or exponential, depending on the isolate. Furthermore, 

 certain fungi, e.g. CCS, may show an exponential relationship between 

 respiration and temperature while the relationship of growth to tempera- 

 ture is linear, or the reverse may be the case as with Cladosporium herb- 

 arum (cf. Figures 9-2 and 9-4). Therefore no one specific organism or 

 randomly collected group of organisms will emulate completely the 

 response of respiration or growth to temperature found among field 

 populations. 



Summing individual rates of respiration (cf. growth) for the major 

 fungal species shows an average Qio (ratio of the rates at 10 ° and °C) of 

 3.6. The measured Qio for respiration of total litter over the same tem- 

 perature range is between 3.8 and 4. Temperature fluctuations decrease 

 and temperatures are generally lower with depth. According to the se- 

 cond hypothesis it is expected that with increasing depth microorganisms 

 would show flatter and more linear responses to temperature for their 

 various biological activities. A linear rather than exponential response to 



