Presentation on theme: "The Real Scoop on Dirt "More organization and complexity exist in a handful of soil than on the surface of all the other planets combined.” *************************************"— Presentation transcript:
The Real Scoop on Dirt "More organization and complexity exist in a handful of soil than on the surface of all the other planets combined.” ************************************* Edwin O. Wilson Harvard University SAFS
“The soil is alive and the diversity is enormous. One square foot of soil has an array of small invertebrates, mites, arachnids... hundreds, or even thousands of species, many of which are still unknown to science.” E.O.Wilson So what lives in soils?
Protozoa feed on bacteria and fungi 10 million /m 2 (3 to 20 g/m 2 ) Nematodes (round worms) feed on bacteria, fungi, protozoa and plant roots 10 million /m 2 in grassland soils, 30 million /m 2 in woodland soils Enchytraeids (pot worms) feed on dead plant material /m 2 in grassland (50-35 g/m 2 ) Tardigrades (water bears) 50 to 500 /m 2 Pauropoda 20 to 2000 /m 2 Molluscs (Slugs and Snails) feed on rotting vegetation (+ a few carnivorous species which eat other molluscs) approx. 15 /m 2 in grassland soils, 450 /m 2 in woodland soils Protozoa feed on bacteria and fungi 10 million /m 2 (3 to 20 g/m 2 ) Nematodes (round worms) feed on bacteria, fungi, protozoa and plant roots 10 million /m 2 in grassland soils, 30 million /m 2 in woodland soils Enchytraeids (pot worms) feed on dead plant material /m 2 in grassland (50-35 g/m 2 ) Tardigrades (water bears) 50 to 500 /m 2 Pauropoda 20 to 2000 /m 2 Molluscs (Slugs and Snails) feed on rotting vegetation (+ a few carnivorous species which eat other molluscs) approx. 15 /m 2 in grassland soils, 450 /m 2 in woodland soils
Symphyla feed on fungi up to 1000 /m 2 in grassland soils, 3000 /m 2 in woodland soils Isopoda (Woodlice) feed on fungi, and dead plant material 500 to 1500 /m 2 in grassland soils, 3000 /m 2 in woodland soils Diplopoda (Millipedes) feed on fungi, and dead plant material approx. 20 /m 2 in grazed grassland, 100 /m 2 in ungrazed grassland, 100+ /m 2 in woodlands Chilopoda (Centipedes) feed on insects an other soil arthropods approx. 120 /m 2 in grassland, 150+ in woodlands Aranaea (Spiders) feed on other arthropods 480 /m 2 in Moorlands, 200 /m 2 in pasture
Acari (Mites) feed on everything 100,000 to 600,000 /m 2 woodland soils Collembola (Springtails) feed on fungi and bacteria 40,000 to 70,000 /m 2 in grassland soils, /m 2 in coniferous woodland Coleoptera (Beetles) up to 2000 to 3000 /m 2 in ungrazed grasslands, considerably lower in arable soils. Hymenoptera (Ants) feed on other arthropods and plants secretions important soil movers
Today’s topics Taxonomy Aravalli, She and Garrett Archaea & the new age of microorganisms. The n-dimensional ecological niche Silvertown, J Plant coexistence and the niche. Soil food webs and crazy soil critters!
Taxonomy = naming and classifying organisms into groups that share similar characteristics Taxon = a taxonomic group or level Taxa = plural of taxon Linneaus ( ) Systema Naturae Physician - studied medicinal plants Father of taxonomy LinneausLinneaus - check this for more info on Linneaus
Linneaus’ hierarchy Imperium ("Empire") - the phenomenal world Regnum ("Kingdom") - the three great divisions of nature at the time - animal, vegetable, and mineral Classis ("Class") - subdivisions of the above, in the animal kingdom six were recognized (mammals, birds, amphibians, fish, insects, and worms) Ordo ("Order") - further subdivision of the above - the class Mammalia has eight Genus - further subdivisions of the order - in the mammalian order Primates there are four. e.g. Homo Species - subdivisions of genus, e.g. Homo sapiens. Varietas ("Variety") - species variant, e.g. Homo sapiens europaeus.
King Philip Came Over For Games Saturday Kingdom Class Order Genus Species Phylum Family Binomial nomenclature Genus species Taxonomy of Fido Note addition
The problem of common names - this fish is a: Northern pike Common Pike Great Northern Pike Jack Jackfish Northern Pickerel Pike Snake G 嚇 da (Swedish) tika obecn � (Czech) kinoje (Ojibwe) Esox lucius Look ma, I think I caught a snake …
Oh, naaaa …. its just a squirrel This is for you, Joey and John! I couldn’t resist!!
Back to taxonomy … what were those groupings anyway? It depends on who you ask … Robert Whitaker 5 kingdoms Plantae, Animalia, Protista, Fungi, Monera Karl Woese 3 domains Bacteria, Archea, Eukarya Linnaeus ’s 2 kingdoms Plantae, Animalia Ernst Haeckel - early 1900’s 3 kingdoms Plantae, Animalia, Protista Linnaeus ’s 2 kingdoms Plantae, Animalia Ernst Haeckel - early 1900’s 3 kingdoms Plantae, Animalia, Protista
The 5 Kingdoms Based on morphology, reproduction, metabolism, etc. In general, the height up the “tree” represents time
The 3 Domains Based on molecular structure of 16S or 18s subunits of ribosomal RNA BacteriaEucaryaArchea Proteobacteria Cyanoobacteria Animalia Fungi Plantae Animalia Euryarchaeota Crenarchaeota Chloroplasts Mitochondria Adapted from McGraw-Hill Pub.
X-ray crystallography image of ribosome structure University of California, Santa Cruz 16s rRNA of 3 spp. Universal Similar function Changes slowly Can be compared between organisms McGraw Hill Pub.
Dendrogram of 3 domains BacteriaEucaryaArchea McGraw-Hill Pub. And this brings us back to Aravalli, She and Garrett, Archaea & the new age of microorganisms
Why were these authors so excited? Archea are no longer just extremeophiles!!! They’re ubiquitous!!! Will this change our thinking on: how food webs work? how organisms are related? how microbial communities are organized? how soil communities are organized? IUPUI Dept. of Biology
And this brings us to the concept of an ecological niche Grinnell (1917) - the sites where organisms of a species can live Elton (1927) - the function performed by the species in the community Gause (1934) - intensity of competition determines overlap of niche Hutchinson (1957) - a region (n-dimensional hypervolume) in a multi-dimensional space of environmental factors that affect the welfare of a species
Species that need the same resources must compete They either coexist or one will die out
General theory has been - to coexist, spp. must use resources in slightly different way Time of resource use Diurnal, crepuscular, or nocturnal feeding Early or late spring nesting for owls/hawks Particular part of resource used Seeds versus nectar versus leaves of a plant Large versus small seeds Area of tree canopy used by bird spp. (MacArthur) More or less efficient use of same resource Both maples and paw paw need sunlight, but paw paw need less
So how do so many spp. of plants coexist? (Silvertown) If plants all use same few resources, why so many spp.? Two possibilities: Niche model is wrong Plant niches ARE different (we just don’t know enough to know HOW they differ) Conclusion --> differences have not been studied sufficiently Not asking the right questions (4 tests of niche separation) Studies should test all 4 of these when determining how plants use resources to see if niche model applies equally to plants One difference = mycorrhizae And that takes us right back to ……soil communities
Fig. 3. Total remaining litter mass of entire microcosms as a function of total predicted litter mass remaining. Data points represent individual microcosms either without macrofauna (open circles) or with macrofauna (i.e., millipedes, earthworms or both; solid diamonds). Hättenschwiler and Gasser 2005 Communities rule! The amount of decomposition was greater with soil macrofauna than without
Fig. 1. Litter mass of individual species predicted from monocultures of the respective species and animal treatments. (Left) Data from the three more slowly decomposing species are shown. (Right) Data from the more rapidly decomposing species. And diversity matters for tough biodegrabables! Hättenschwiler and Gasser 2005
Decomposition Nitrogen fixation Mineralization Primary production Roles of soil critters:
(Soil around plant roots) (Nitrogen!)
Thanks to Dr. Nancy Nicholson for the following images and fun facts!
Nematodes and fungi - an “inversion of the animal-eat- plant relationship” Background Nitrogen is inert in the atmosphere, so doesn’t mix with soil Nitrogen in soils is a limiting factor for plant growth Nematodes and fungi abound in healthy soils - both are essential for healthy plants because they retain nitrogen (and other nutrients) in soils once it has been captured by nitrogen-fixing bacteria The nematode - fungus relationship keeps nitrogen from going back to the atmosphere as a gas (methane)