Microflora Activities and Decomposition 319 



IOOf: 



80 



60 



<:7> 



c 



E 



1) 



40 



ZO- 



IC 



8 

 6h 



I 2 3 



Time, yrs 



FIGURE 9-11. Percentage of ethanol-soluble and 

 ethanol-insoluble compounds remaining in decom- 

 posing Carex aquatilis (A,, A) and Eriopiiorum an- 

 gustifolium (m, o). Percentages are based on weight 

 per unit area. (After Bunnell et al. 1977b.) 



illustrated by many decomposing substrates (Surges 1958, Minderman 

 1968, Satchell 1974). 



Here we address the manner in which the phenomenon of substrate 

 "quality" represented in the function gresp by the single coefficient Oj 

 can be related to substrate chemistry more directly. In accordance with 

 earlier workers different constituents are assumed to have their own 

 chemical-specific rates of decomposition. In addition the decomposition 

 rate of each chemical constituent is assumed to be a function of the tem- 

 perature and moisture-dependent respiration rate of the microflora, and 

 thus changes seasonally or even daily. The observed decomposition rate 

 of a substrate is assumed to be the sum of the temperature-moisture- 

 chemical-specific rates of utilization times the amount of each chemical 

 constituent present. Observed rates of decomposition thus change with 

 the meteorologically induced changes in rates of microbial respiration 

 and the changing capacity of the substrate to provide energy to the mi- 

 crobial population. 



As developed by Minderman (1968), the decay rate of a substrate 

 can be expressed as: 



(dY/dt) = I {dy,/dt) 



i= 1 



(dY/dt) = I -k,y^ 



i= 1 



where Y = total weight of the decomposing substrate 



