1 / 28

Soil Biology

Soil Biology. Who is down there and what do they do. Learning Objectives. List the major groups of soil organisms … Identify the roles of organisms Draw a simplified soil food web . .. Describe the conditions affecting growth… Discuss the beneficial functions …. air. water. soil. Sun.

latham
Download Presentation

Soil Biology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Soil Biology Who is down there and what do they do

  2. Learning Objectives • List the major groups of soil organisms … • Identify the roles of organisms • Draw a simplified soil food web . .. • Describe the conditions affecting growth… • Discuss the beneficial functions …

  3. air water soil Sun Producers Decomposers Consumers Humus

  4. Important Groups of Soil Organisms Size/type class e.g. and functional group/energy acquisition Vascular plants, mosses • Macroflora • Microflora • Macrofauna Vascular plants, algae, actinomycetes, bacteria, and fungi** ** Fungi are actually their own separate kingdom Vertebrates, arthropods, earthworms, snails… • Mesofauna • Microfauna Bigger arthropods, worms Nematodes, protazoa

  5. Soil Animals – micro, meso, macro

  6. Microflora Bacteria

  7. Microflora

  8. Nematodes Microfauna Protozoa 20-200 kg/ha!

  9. Mites Mesofauna Springtails

  10. Other invertebrates Mesofauna

  11. Worms Voles! Macrofauna

  12. A cup of soil contains... Bacteria Fungi* Protozoa Nematodes Arthropods Earthworms 200 billion { Microflora, or “microbes” 100,000 meters 20 million { microfauna 100,000 50,000 { macro- and mesofauna * Fungi are actually their own separate kingdom <1

  13. B – Bacteria A – Actinomycetes My – Mycorrhizae H – Saprophitic fungus N – Nematode CP – Ciliate protozoa FP – Flagellate protozoa M – Mite < 1mm 1/10 mm

  14. Fungi – tens of thousands of species • The major agent of decay in acid environs • Network of hyphae: improves soil structure • Decomposition of cellulose!!! • Can compete with higher plants for N • Gain energy from nematodes • 3 groups, yeast, mold, mushrooms • symbiotic relationships with most plants • Produce chemicals that are toxic

  15. Aggregates held together by: Fungal hyphae Bacterial “glues” Organic matter hyphae clay sand silt bacteria

  16. Bacteria – 1 billion -1 trillion/g soil (up to 20,000 spp.) • Exist in both forest and grassland soils • Most do best under high Ca2+, high pH • Do best when soil temp 20-40C (68-100F) but seldom killed by temp extremes

  17. Fungi vs. bacteria Single-celled, can form colonies Tube-like body; hyphae Rapid regeneration time (hours); can respond quickly to nutrient additions Generally slower growth rate

  18. Complex, mutually beneficial relationships bacteria fungi

  19. Microfauna Amoebae Ciliate • some parasitic • feed on bacteria and fungi • release plant nutrients – protozoa KEY for N Flagellate Nematode

  20. Microfauna • Nematodes(non-segmented, round worms) • Widely distributed in forest soils • Saprophytic and parasitic groups • Some predatory species attack tree roots and cause damage sap·ro·phyte An organism, that grows on and derives its nourishment from dead or decaying organic matter.

  21. Microfauna • Protozoa • Most abundant of all soil fauna • One-celled • Feed on bacteria • Up to 30% of all mineralized N from protozoa

  22. 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

  23. Macrofauna • shred plant material • feed on bacteria and fungi associated with organic matter Photo by Suzanne Paisley

  24. Earthworm midden

  25. Earthworms – (have gizzards!) • Probably the most important component of soil fauna (not in acid soils, not in very dry soils) • Eat OM & pass as much as 30 tons/ha of soil through their bodies (mixing horizons) each year • Promote good soil structure and aeration Great for fishing! Worm farming - Huge industry! est. wt. of worms in U.S. = 10X wt. of entire human population

  26. air water soil Sun Producers Decomposers Consumers Humus

  27. Some generalizations . . . • Forested soils more biologically diverse • Forested soils dominated by fungi • Faunal biomass (and activity) greater per ha in grasslands • Cultivated soils least diverse, less biomass, fewer organisms

More Related