Question 3 - EE2

Leaching

• Water dissolves soluble compounds (sugars, amino acids).

• Occurs early in decomposition.

• Abiotic process.

Fragmentation

• Breaks litter into smaller pieces.

• Physical drivers: Freeze–thaw, abrasion, wind.

• Biological drivers: Soil fauna (earthworms, termites, millipedes).

Chemical Alteration

• Breakdown of complex molecules.

Chemical Alteration biological drivers

Fungi, Bacteria, Protozoa, Soil Fauna

Fungi

• Decompose lignin, cellulose; dominate in forests. Mainly in the chemical alteration.

Bacteria

Prefer simple substrates; dominate in nutrient-rich soils. Mainly in the chemical alteration.

Protozoa

Stimulate turnover, taking cells popping them and using them for metabolism and excreting compounds back into the soil.

Soil Fauna

Enhance microbial access by shredding litter.

Fragmentation.

The size of the pieces of OM that things are consuming.

Big things eat big things and small things eat small things

High Carbon quality

fast decompose

Low carbon quality

slow decompose

Carbon quality

how easy it is for microbes to break down a molecule.

High quality C

Simple, Soluble, LOW C:N ration, Low lignin

Examples:

• Glucose

• Amino acids

• cellulose

Low quality C

Complex, rings, HIGH C:N, high lignin

Examples:

• Lignin

• Tannins

• Waxes

• Toxic molecules

• requires bigger enzymes

• more variety of bonds