Soil arthropods, invertebrate animals with exoskeletons, including ants, termites and millipedes, munch their way through plant litter that ends up as the nutrient rich soil upon which complex terrestrial life depends. Most of us, though, are likely only dimly aware of the essential roles arthropods play in maintaining ecosystems. We are more apt to regard arthropods as pests, and thus with a vague annoyance, or in a fearful context. Termites, for example, are likely far better recognized for the terror they instill in homeowners, than for the fact that they process up to 60% of plant debris. This is no small feat, and it is worth understanding the critical role arthropods play as either plant litter ‘transformers’ or ‘ecosystem engineers’.
As ‘transformers’, arthropods ingest plant debris and excrete it back into the environment. Their feces contain the now disintegrated matter, with a significantly higher surface area than before, which enhances further degradation by microorganisms able to convert this organic material into even simpler inorganic substances for plant nutrition.
Arthropod soil ‘engineers’, present in areas such as coniferous forests where earthworms are rare, are not nearly as well recognized as their earthworm counterparts for their role in soil structure. Arthropods in such areas burrow through the soil and transport materials, necessary for the mixing of organic and mineral fragments and to promote porosity, essential for multiple critical aspects of soil, including aeration, water retention, and root penetration.
To learn more about the wide diversity and abundance of soil arthropods and the roles they play in ecosystem maintenance, see: ‘Role of Arthropods in Maintaining Soil Fertility‘ by Thomas W. Culliney of the USDA-APHIS, now online in the current issue of Agriculture.