THE GROUND CREW
Right beneath our feet there is a world of living organisms that most people have never seen. In a typical forest or grassland community the soil surface is covered by one or two inches of humus, a complex mixture of organic matter in various stages of decay. This layer of humus is teeming with a fascinating variety of living organisms that play important roles in soil fertility and nutrient cycling. These soil dwellers represent all trophic levels: herbivores, carnivores, omnivores, and decomposers. Their foods include roots, seeds, fungi, dead wood, and decaying leaves. They may be predators, parasites, or saprophytes. This soil community is a microcosm that illustrates the complex ecological interactions among living organisms. Its diversity is astonishing -- 15 to 20 major taxonomic groups can usually be collected in a single square-foot sample of humus, with populations of some species exceeding one million individuals per acre.
- Build a Berlese Funnel and use it to extract arthropods from a sample of forest soil, compost, or ground cover.
- Use a simple identification key to learn who's who among soil-dwelling arthropods.
- Extrapolate from random samples to calculate population density, create ecological pyramids, and compare various indices of ecological diversity.
Animal Diversity in the Soil Community
- Aschelminthes -- nematodes, roundworms
- Annelida -- earthworms, segmented worms
- Araneae -- spiders
- Acarina -- ticks, mites
- Opiliones -- harvestmen, daddylonglegs
- Isopoda -- pillbugs, sowbugs, woodlice
- Diplopoda -- millipedes, thousand leggers
- Chilopoda -- centipedes, hundred leggers
- Collembola -- springtails
- Archeognatha -- bristletails
- Thysanura -- silverfish
- Orthoptera -- grasshoppers, crickets
- Isoptera -- termites
- Blattodea -- cockroaches
- Dermaptera -- earwigs
- Thysanoptera -- thrips
- Hemiptera -- true bugs
- Homoptera -- leafhoppers, planthoppers, aphids
- Psocoptera -- barklice
- Neuroptera -- lacewings, antlions, aphislions
- Hymenoptera -- ants, wasps
- Coleoptera -- beetles, weevils
- Lepidoptera -- moths
- Diptera -- flies
- Siphonaptera -- fleas