Dr. Andrew Moldenke Dept. of Botany Oregon State University

Three thin-sectioned soils

Thin-section clear cut soil

Thin section mature forest soil

I have shown that species richness of soil arthropods is SOOO large that anyone can take a sample of forest litter (dead leaves) and soil from anywhere in the approximately 3,000 hectare Andrews Forest LTER--- and then, after identifying the arthropods, I can tell you…

what month of the year it was altitude soil moisture plant community slope face under which species of tree how old the forest trees are how long since the last fire how far from the nearest trunk

All that information (and more!) simply in a list of the relative abundance of the species

Creatures that live in the soil are very sensitive to abiotic and biotic factors therefore excellent for use as biological indicators. They have fantastic potential as indicators for determining human impacts on soil ecosystem function and for soil health.

species/m 2 individuals/m 2 forest250350,000 pasture ,000 row agriculture ,000

Indicators of change in the productive potential of soil is great but I want to talk about 2 other things today. 1. Biodiversity for its own sake. We never bother to take the time to look at these organisms, but they are some of the most fascinating animals around! WOW! FANTASTIC! 2. They don’t just passively indicate “soil health” they are key players in the cycle of plant growth and soil nutrients themselves. B.P.G.T.

Many mites

EACH and EVERY SHOVEL of forest dirt = all pictures that follow 250 spp/m 2 350,000 indivs/m % of all arthropods in most terrestrial ecosystems 120,000 little legs (Andy’s foot) 15,000 species in Oregon

So, who cares? Why study bugs in soil? What do they do? they eat and they poop 1 2

Odontodamaeus

Oppiella

Epidamaeus

Long-legged near Damaeus

Galumna open

Galumna closed

Pterochthonius

Hermanniella

Rearing mites

Small / large turtle mites

Oribatid chelicerae

Mycorrhizae

Mycorrhiza under the Electron Microscope

Isotoma

Diagrammatic springtail (Collembola)

Onychiurus

Onychiurus, high magnification

Ptiliid beetle forewing

Protura

Enchytraeid

Suctobelbella – bacterial-feeder

Cydnidae – Burrowing bug

Symphyla

Cicindelid immature

Gamasid

Uropodid

Uropodid - facial view

Polyaspidid

Cyta

Onychiurus being eaten by Labidostoma

Symphylan being eaten by Pergamasus

Pergamasus feeding (high magnification)

Pseudoscorpion

Chthoniid pseudoscorpion

Pseudoscorpion, facial view

Taracus – Skunk-spider (Opilionida)

Sclerobunus – skunk-spider

Native scorpion with young

Spider webs

Spider fangs

Callobius

Pardosa

Micro-spider, male

Antrodiaetus

Omus Cicindela

Staphylinidae

Lithobiidae

Geophilid

Centipede fangs

Ant head

Snail-feeding beetle

Snail-feeder, immature

Taracus - Opilionid

Glowworm eating millipede Millipede segments

Diapriid wasp – Diptera parasite

Rhododendron decomposition

Millipede jaws

Schematic of millipede jaw

Harpaphe mating swarm

Leaf skeletonization

Isopod

Pen-knife mite

Pen-knife mite, closed

Collohmannia nymphs

Leaf skeletonized by Collohmannia

Bacteria eaten by fungus

Soil and Plant Growth Microbial biomass (bacteria, fungi) (nutrient immobilization) In the short-term (minutes to years) the USEFUL nutrient content of soils is basically equivalent to the amount of nutrient incorporated into living microbial tissue. (Most nutrients in mineral soil are long-term resources)

Soil and Plant Growth Microbial biomass (bacteria, fungi) (nutrient immobilization) Microbes grow by producing exoenzymes that decompose the organic (+) material in the soil more bacteria more decomposition

Soil and Plant Growth Microbial biomass (bacteria, fungi) (nutrient immobilization) Nutrient availability in dead/decaying organic matter is limited by surface area for exoenzyme attack “shredding” increases surface area; therefore shredding animals (like millipedes) indirectly regulate rate of decomposition and microbial growth (example: 450x) plant biomass

Soil and Plant Growth Microbial biomass (bacteria, fungi) (nutrient immobilization) roots are completely passive for nutrient uptake shredders ?

Soil and Plant Growth Microbial biomass (bacteria, fungi) (nutrient immobilization) nutrient uptake shredders (surface area) bug poop (nutrient mineralization) nearly all nutrients mineralized by microbivory are assimilated by the remaining microbes. Surface area (microbes) surface area (roots) Plants only can assimilate nutrients released in the rhizophere Protozoa, Nematoda, Arthropoda

Anderson Millipede soil mineralization

Onion cultivation