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Soil Organisms: A Guide to Soil Biodiversity

Explore the diverse world of soil organisms, from microfauna to megafauna, and their roles in the ecosystem. Learn about mites, springtails, proturans, and more. Discover how these creatures contribute to soil health, nutrient cycling, and ecosystem balance.

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Soil Organisms: A Guide to Soil Biodiversity

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  1. Soil ORGANISMS

  2. Global Soil Biodiversity Initiative • website

  3. More useful way to classify soil organisms for our purposes: • MICROFAUNA : < 0.1 mm (WIDTH) • Bacteria, fungi, nematodes • MESOFAUNA : 0.1 – 2 mm • Springtails, pseudoscorpions, dipluran • MACROFAUNA : 2 – 20 mm • Ants, some mites, earthworms, beetles • MEGAFAUNA : > 20 mm • Moles, reptiles, badgers

  4. Mesofauna and Macrofauna

  5. arthropods • ¾ of all living organisms • Exoskeleton, jointed legs, segmented body • Insects • Crustaceans • Arachnids • Myriapoda

  6. Shredders • Microbial taxis

  7. Mites arachnids

  8. Mite Facts • 4 pairs legs • Blind; use physical and chemical sensing to navigate • 40,000 described species • Variety of food preferences (microbes, plants, some carnivorous)

  9. Extracted from one ft2 of top two inches of forest litter and soil

  10. Very persistent • Withstand 100x as much radiation as humans • Persist in an area after it becomes industrialized • Therefore can be used to determine prior vegetation type • Fossilized mite assemblages are used to reconstruct past environments

  11. Springtails (Collembola) • Arthropods • Invertebrates with external skeleton • 6 legs • Spring or hop • Furca • Eat fungal hyphae, spores and detritus • Some predatory on mites • 40,000 / m3 topsoil

  12. Can withstand freezing conditions • Have been featured on a postage stamp!

  13. Proturans • Hexapods • No antennae, no eyes • Pale or yellowish, pointed at both ends • Found in leaf litter, humus, moss, decaying wood • 700 described species

  14. Raise their back end when disturbed (like scorpions) • Eat fungal hyphae, are eaten by mites, spiders pseudoscorpions

  15. Diplurans • White or colorless hexapods • Some are dark • Elongated body • Head has pair of strings with beaded segments • Confused with earwigs but have no eyes or wings • Can regenerate lost body parts

  16. Diplurans vs. Earwigs • Some have pincers • Diplurans are not insects • Earwigs have pincers • Earwigs are insects

  17. Live in leaf litter, wood, under rocks and logs • Eat decomposing plant and animal matter; some eat nematodes and small arthropods

  18. Pseudoscorpions • Arachnids • Fused head and thorax; 11-12 segments in abdomen • Smaller head appendages are for feeding; larger ones for defense • Molt; can live 3-4 yrs

  19. Live under bark, stones, in leaf litter, caves • Have appeared on a postage stamp!

  20. Carnivorous: eat larvae, ants, mites, flies

  21. Beetles Arthropods; order Coleoptera 370,000 described species (40% of all known insect species; 30% of all known animal species) Some omnivores, some eat plants, fungi, some are carnivores Larvae (grubs)

  22. Hardened forewings cover body of beetles • Most soil beetles are brown or black • Some soil beetles are wingless

  23. Rove beetle Largest beetle family in North America Very fast and agile, are biting Carnivorous; consume more than own weight in a day Act as good “pesticides” by eating harmful root maggot flies

  24. Rove beetles

  25. Featherwing beetles • Smallest known beetles • Wings are long and are feather-shaped • Abundant on forest floor

  26. Short-winged mold beetles • Eat mold, also springtails, mites, symphylans • Have beady antennae to use in the confining passages of soil • Have short wing covers that do not restrict movement

  27. Other Macrofauna (5%) and Mesofauna(3%) CHORDATES (vertebrates) mammals, amphibians, reptiles PLATYHELMINTHES (flatworms) ASCHELMINTHES (roundworms, nematodes) MOLLUSKS (snails, slugs) ARTHROPODS : (insects, crustaceans, arachnids, myriapoda)

  28. vertebrates • Squirrels, mice, groundhogs, rabbits, chipmunks, voles, moles, prairie dogs, gophers, snakes, lizards, etc. • Contribute dung and carcasses • Taxicabs for microbes

  29. nematodes

  30. NEMATODES

  31. NEMATODES Bacteria feeder Fungal feeder

  32. Predatory Nematode

  33. Root-feeding nematodes

  34. Nematode Trappers • Fungal hyphal rings constrict when a nematode swims through.

  35. Nonsegmented, blind roundworms • > 20,000 species • Eat bacteria or fungi or plants (stylet) • And protozoa, other nematodes, algae • Specialized mouthparts • Can sense temperature and chemical changes

  36. nematode

  37. Feeding Habits Carnivores : parasites and predators Phytophages: eat above ground green plant parts, roots, woody parts Saprophages: eat dead and decaying OM Microphytic feeders: eat spores, hyphae, lichens, algae, bacteria

  38. Movement existing pore spaces, excavate cavities, transfer material to surface improve drainage, aeration, structure, fertility, granulation

  39. The divisions of the 5%: 40% bacteria and actinomycetes

  40. BACTERIA

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