1. Soil ORGANISMS

4. Global Soil Biodiversity Initiative
website

7. 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

8. Mesofauna and Macrofauna

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

10. Shredders
Microbial taxis

11. Mites
arachnids

12. 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)

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

14. 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

18. 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

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

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

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

24. 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

25. Diplurans vs. Earwigs Some have pincers Diplurans are not insects
Earwigs have pincers
Earwigs are insects

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

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

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

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

30. 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)

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

32. 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

33. Rove beetles

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

35. 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

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

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

38. nematodes

39. NEMATODES File name: large todes LR.jpg, 262K
Credit: Elaine R. Ingham, Oregon State University, Corvallis.

40. NEMATODES Bacteria feeder Fungal feeder
Top left is the bacterial-feeding nematode, Elaphonema.
Bottom right is a fungal-feeding nematode.
Photo credits: (for both) Elaine R. Ingham, Oregon State University, Corvallis
File names:
BFTODE
FFTODE
Fungal feeder

41. Predatory Nematode File name: predatory tode LR.jpg 254K
Credit: Kathy Merrifield, Oregon State University, Corvallis.

42. Root-feeding nematodes
Upper left is the lesion nematode, Pratylenchus.
Lower right is the root-feeding nematode, Trichodorus.
File names:
Upper Left: rootfeedingtode prat LR.jpg, 233K
Lower right: rootfeedingtode trich LR.jpg, 184K
Credits:
Upper Left: Kathy Merrifield, Oregon State University, Corvallis.
Lower right: Elaine R. Ingham, Oregon State University, Corvallis.

43. Fungal hyphal rings constrict when a nematode swims through.
Nematode Trappers
Fungal hyphal rings constrict when a nematode swims through.
Some fungi make circular rings of hyphae.
The rings constrict when a nematode swims through.
Genus of this fungi is Arthobotrys.
File name: Arthrobotrys.jpg at 265K. (Also: F-4 at 1600KB shows whole Bug Biography)
Photo credit: George L. Barron, University of Guelph, Ontario.

44. 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

45. nematode

46. 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

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

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

50. BACTERIA
Photo credit: Michael T. Holmes, Oregon State University, Corvallis
File name: PBUT

51. Bacterial biomass dominates :
grassland and agricultural landscapes
Fungal biomass dominates:
Forests

52. bacteria

53. Bacteria Abundant in rhizosphere Four FUNCTIONAL GROUPS:
Tiny (1 μm width), one-celled
Single cell division
In lab: 1 can produce 5 billion in 12 hours
(In real world limited by predators, water & food availability)
Abundant in rhizosphere
Four FUNCTIONAL GROUPS:
Decomposers
Mutualists : partner with plants
Pathogens
Chemoautotrophs

54. Some terms:
Autotrophs: can make organic compounds from inorganic compounds
Heterotrophs: feed on others to make organic compounds
Chemosynthetic: get energy from inorganic chemical reactions
Photosynthetic: get energy from sun
Aerobes: use aerobic respiration (need oxygen as electron acceptor)
Anaerobes: use inorganic or organic compounds for electron acceptor

55. Decomposers Organic chemicals in big complex chains and rings
Bacteria break bonds using enzymes they produce
Create simpler, smaller chains

56. Mutualists e.g., Nitrogen-fixing Bacteria
Nodules formed where Rhizobium bacteria infected soybean roots.
File name: Nods on Beans.jpg 277K (Also C-2 at 580K shows whole box.)
Photo credit: Stephen Temple, University of Minnesota, St. Paul. (NRCS may use this image for educational purposes.)
File name: Nods on beans

57. Root nodules

58. Chemoautotrophs Get energy from OTHER THAN CARBON compounds
From N, S, Fe, H

59. Actinomycetes Are bacteria but grow like fungi Filamentous but
video
Are bacteria but grow
like fungi
Filamentous but
morphology varies
Adaptable to drought
Important at high pH
Usually aerobic heterotrophs
Break down wide range of organic compounds
Produce geosmin (smell of “fresh soil”)

60. 40% other Microflora
Protozoa Algae Fungi

61. PROTOZOA Ciliates Amoeba Flagellates Largest of the three
Move by means of hair-like cilia
Eat other protozoa and bacteria
Amoeba
Also large
Move by means of a temporary foot (pseudopod)
Flagellates
Smallest of the three
Move by means of a few whip-like flagella.

62. Protozoa
Flagellates
Amoeba
Ciliates
Eat bacteria &
protozoa

63. protozoa Unicellular Heterotrophic Form symbiotic relationships
Eat bacteria, fungi
Form symbiotic relationships
e.g., flagellates in termite guts; digest fibers
Require water
Go dormant within cyst in dry conditions

64. Function of protozoa Make nutrients plant-available
Release excess N from the bacteria they eat
Regulate bacteria populations
Compete with pathogens

65. PROTOZOA bacteria Sand protozoa File name: Testate amoeba LR.jpg, 179K
Credit: Elaine R. Ingham, Oregon State University, Corvallis

66. Flagellate File name: vorticella prot LR.jpg, 278K
Credit: Elaine R. Ingham, Oregon State University, Corvallis.

67. Ciliate File name: ciliate2 LR.jpg 294K
Credit: Elaine R. Ingham, Oregon State University, Corvallis

68. Amoeba bacteria amoeba Photo credits:
(brown photo) No. 35 from Soil Microbiology and Biochemistry Slide Set J.P. Martin, et al., eds. SSSA, Madison, WI
(blue photo) Michael T. Holmes, Oregon State University, Corvallis. (We never used this in the Primer.)
File names:
(blue photo) AMOE
(brown photo) SSSA35
bacteria
amoeba

69. Soil-Dwelling “Vampires”
Vampyrellids
Vampyrellids are a group of amoebe that eat fungi by drilling round holes through the fungal cell wall and consumes the fluid inside.
In this picture, they attack Gaeumannomyces graminis, the fungus that causes “take-all disease” in wheat.
File name: vampraid.jpg, 451K (Also: E-4 at 1500KB, shows whole Bug Biography.)
Photo credit: Homma, Y. et al Phytopathology 69:
(Photo is in the public domain.)
Group of amoebe that drill holes in fungus and consume liquid

70. Archaea ( ar-KEY-ah) A recent discovery: 1970s Woese and Fox:
Divided bacteria into “normal” and “extremophiles” (archaeabacteria)
Changed classic “tree of life”
Bacteria
Archaea
Eukaryotes

71. Very similar to bacteria in shapes and size and reproduction
Differences:
Cell membranes contain lipids
Not chitin (like fungi)
Not cellulose (like plants)
Genes of archaea are more similar to eukaryotes than to bacteria
Can use a lot of various substances for energy

72. Importance Role in carbon cycle
Photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs
Many can survive in extreme environments (enzymes); heat, cold, salt, low pH
Many are methane-producers:
Swamp gas, cow farts
Sheer numbers:
Combined marine and soil archaea make them the most abundant organism on earth

73. Importance in Soil Role in N cycle Decomposition Ammonia oxidizers
Important anaerobic decomposers
Important in extreme environments where bacteria do not fluorish

74. algae Filamentous, colonial, unicellular Photosynthetic
Most in blue-green group, but also yellow-green, diatoms, green algae
Need diffuse light in surface horizons; important in early stages of succession
Form carbonic acid (weathering)
Add OM to soil; bind particles
Aeration
Some fix nitrogen

75. Fungi Break down OM, esp important where bacteria are less active
attack any organic residue
Most are aerobic heterotrophs
chemosynthetic: adsorb dissolved nutrients for energy

76. Grow from spores into branched hyphae
Hyphal strand divided into cells by septa that allow flow of liquids between cells
Masses of hyphae grow together in visible threads
called mycelia

77. Advantages over bacteria:
They can grow in length
Rate: 40 μm / min (bacterium travels 6 μm in its life)
Don’t need a film of water to move
Can find new food sources
Transport nutrients great distances
Produce enzymes that break down complex compounds
Can break down lignin (woody compound that binds cellulose), shells of insects, bones
Can break down hard surfaces

78. Clever, clever adaptations!
Infecting a nematode
Hypha twists back on itself and catches a nematode, hyphal cells swell and kill nematode then enter body and suck out nutrients
Oyster mushroom
Emits toxic drops from hyphal tips which touch nematode, immobilize it and hyphae enter body and remove nutrients
Trap arthropods or protozoa and digest them

81. Mycorrhizae: symbiotic absorbing organisms infecting plant roots, formed by some fungi
normal feature of root systems, esp. trees
increase nutrient availability in return for energy supply
plants native to an area have well-developed relationship with mycorrhizal fungi
Can extend the effective surface area of tree’s roots by x

83. Mycorrhizal structure
Mycorrhizae
Tree root
Photo credit: Randy Molina, Oregon State University, Corvallis.
File name: M4 Fungi LR.jpg, 328K
Fungal hyphae
Mycorrhizal structure

84. Ectomycorrhizal
Endomycorrhizal
Grow close to root surfaces
Hardwoods and conifers
Penetrate and grow inside roots
Vegetables, annuals, grasses, shrubs, perennials, softwoods

85. Ectomycorrhizae
Photo Credit: USDA, Forest Service, PNW Research Station, Corvallis, Oregon.
File name: Ectomy~1

86. Arbuscular Mycorrhizae (AM)
File name: VAM LR.jpg 205K
Photo Credit: Elaine R. Ingham, Oregon State University, Corvallis.

87. Higher fungi have basidium : club-shaped structure , bearing fruiting body
toadstools, mushrooms, puffballs, bracket fungi

88. Fungi and Soil Quality Decompose carbon compounds
Improve OM accumulation
Retain nutrients in the soil
Bind soil particles
Food for the rest of the food web
Mycorrhizal fungi
Compete with plant pathogens
Photo credit: No. 48 from Soil Microbiology and Biochemistry Slide Set J.P. Martin, et al., eds. SSSA, Madison WI.
File name: SSSA48

89. 12% Earthworms
(Macrofauna: > 1 cm long) ANNELIDS

90. earthworms Some 7000 species 3 categories:
Epigeic (leaf litter/compost dwelling )
Endogeic (topsoil or subsoil dwelling )
Anecic (deep burrow drillers)

91. Giant Benefits to soil Move air in and out of soil
Castings are rich in available nutrients
Produce 10 lbs / yr

92. 1 acre good garden soil: 2-3 million
1 acre forest soil: 50,000