Transcript Slide 1
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/m2 individuals/m2 250 350,000 pasture 30-60 100,000 row agriculture 5-10 2 - 20,000 forest 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/m2 350,000 indivs/m2 120,000 little legs (Andy’s foot) 70-80% of all arthropods in most terrestrial ecosystems 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 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 Cicindela Omus 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) ? shredders roots are completely passive for nutrient uptake Soil and Plant Growth Microbial biomass (bacteria, fungi) (nutrient immobilization) shredders (surface area) nearly all nutrients mineralized by microbivory are assimilated by the remaining microbes. bug poop (nutrient mineralization) Protozoa, Nematoda, Arthropoda nutrient uptake Surface area (microbes) surface area (roots) Plants only can assimilate nutrients released in the rhizophere Anderson Millipede soil mineralization Onion cultivation