THE established method of defining the plethora of soil bugs is based on their size.
But, as soil biologist Damian Bougoure points out, size doesn't tell us much about what they do.
The biggest are macrofauna, including worms, beetles and ants.
"These are the prime movers or ecosystems engineers and they move bug food deeper into the profile," Damian said.
A little smaller are the mesofauna, or the litter transformers, which include, for example, mites and springtails.
"They are the teeth of the soil's digestive tract and contribute to recycling residues," Damian said.
Then there are two groups, the microfauna and microflora, which form the microfood web. They feed on the organic matter and each other, secreting enzymes to break down these residues.
The microfauna include protozoa and nematodes and they "do a little bit of the bumping and grinding".
The microflora are the smallest and include bacteria, fungi, viruses, actinomycetes and archea.
However, bug food, or soil carbon, is not uniformly distributed in soils.
"The first hot spot is the decomposing residue where there are heaps of bacteria," Damian said. "Then there is the dirt that sticks on plant roots or the rhizosphere.
"This is really important because it contains a lot of chemicals the plants are secreting and bugs love it."
The third hotspot was the macroaggregates.
"Where you have soil aggregation you have a hot spot for soil biology," Damian said.
