Chapter 22: Decomposition & Nutrient Cycling


A generalized model of nutrient cycling



Retranslocation or reabsorption nutrients.........







Decomposing organisms are categorized into groups based on size and function
Microflora: bacteria and fungi
Invertebrate detritivores
Microfauna and microflora



Bacteria are the dominant decomposers of dead

 animal matter



Fungi are the major decomposers of plant matter







Results of a litterbag experiment in central Virginia.

Looks at decomposition of fallen leaves.





Organic matter decomposes at different rates




The carbon form available affects the consumption (or decomposition) rates:
Cellulose and hemicellulose



     C9H10O2, C10H12O3, C11H14O4




An experiment that studied rate of carbon decay in straw found the following........

Variation in rates of decay of different classes of carbon compounds




















Nutrients in Organic Matter Are Mineralized During Decomposition



If the nitrogen content of the litter material is high, then mineralization may exceed the rate of immobilization from the onset of decomposition









Mulch vs. Compost vs. Humus




The rhizosphere