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Soil Biology – A Primer Who is who & What do they do?. Elizabeth Sulzman, Oregon State & T. Kittel. Size, functional groups:. Important Groups of Soil Organisms. Vascular plants, mosses (autotrophs). Macroflora Microflora Macrofauna.
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Soil Biology – A Primer Who is who & What do they do? Elizabeth Sulzman, Oregon State & T. Kittel
Size, functional groups: Important Groups of Soil Organisms Vascular plants, mosses (autotrophs) • Macroflora • Microflora • Macrofauna Vascular plants (root hairs), algae, actinomycetes, bacteria, and fungi (auto- and heterotrophs) Vertebrates, arthropods, earthworms, snails… (herbivores, detritivores, predators) • Mesofauna • Microfauna Arthropods, worms (detritivores, predators) Nematodes, protazoa… (detritivores, fungivores, bacterivores, predators)
Relative Sizes Animated gif – view in slideshow mode Note ruler for scale http://commtechlab.msu.edu/sites/dlc-me/zoo/zdrr0101.html
Microflora • heterotrophs (bacteria, fungi) & autotrophs (algae, cyanobacteria) • the primary decomposers • release plant available nutrients • stabilize soil aggregates Soil bacteria Soil fungi
Aggregates held together by: Fungal hyphae Bacterial “glues” Organic matter Microflora – hyphae clay sand silt bacteria
Microfauna Amoebae Ciliate • heterotrophs; some parasitic • feed on bacteria and fungi • release plant nutrients – protozoa KEY for N Flagellate Nematode Nematode eeee!
Mesofauna Collembola (springtails) Fungus feeding mite Nematode feeding mite • heterotrophs (detritivores, predators) • feed on fungi, protozoa, nematodes, mites • important in regulating populations of everything smaller
Macrofauna • heterotrophs • shred plant material • feed on bacteria and fungi associated with organic matter Photo by Suzanne Paisley
Macrofauna – Dung Beetles • Key disposer of elephant dung • and so a protected species! (you can imagine the ‘or else’…) Amboseli National Park, Kenya Tembe Elephant ReserveKwaZulu Natal, South Africa Addo National Park, South Africa
Ecosystem Function – Soil Food Web
Ecosystem Function – Influence of soil biota on soil processes Break up O.M., mineralize and immobilize nutrients Bind aggregates, hyphae entangle particles Regulate bacterial and fungal populations Indirectly affect structure Regulate above pops.; fragment plant tissue Fecal pellets, pores Mix O.M. and mineral soil; pores; feces Fragment plant tissue
Ecosystem Function – Recall: Rate of decomposition depends on – • Physical and chemical nature of the litter material • Temperature and moisture of the soil environment • Aeration (vs. anaerobic) • The kinds and numbers of soil fauna More bugs, and more different kinds of bugs, means more decomposition