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Illinois Plant Communities

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13 lined ground squirrel Hispid pocket mouse. Unaffected by grazing. White-footed deer mouse. Influence of Fire. Native American Fires ... – PowerPoint PPT presentation

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Title: Illinois Plant Communities


1
Illinois Plant Communities Prairie Ecosystems
2
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3
Primary Production
  • Grasses occur in two basic forms - sod (or turf)
    grasses form a thick mat - bermuda grass, blue
    grass
  • bunch grasses grow in distinct clumps - little
    bluestem, prairie dropseed
  • sod grasses usually grow vegetatively with short
    rhizomes, stolons or runners and are very
    effective in resisting water or wind erosion
  • bunch grasses reproduce vegetatively by tillers -
    shoots which arise from the crown - basal portion
    of plant, atop the roots - may have up to 100 or
    more tillers in a single clump of grasses like
    little bluestem

4
Sod grass vs. bunch grass
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6
Grass Tillers
7
Grass Tillers in a Sod Grass
8
Grass Rhizomes
9
Rhizomes and Tillers Stabilizing Soil
10
Primary Production
  • Gross primary production (GPP) is the total
    amount of energy fixed by a plant or plant
    community
  • Net primary production - is the amount of energy
    stored or biomass produced - it is GPP minus
    energy burned in respiration
  • NPP GPP - R

11
Ecosystem Production
  • Gross Ecosystem Production (GEP) - is total
    energy fixed in ecosystem
  • Net ecosystem production (NEP) is total amount of
    energy stored or biomass produced by all
    organisms in ecosystem - producers, consumers,
    decomposers - or GEP - ecosystem respiration (ER)
    the respiration of all plants, consumers and
    decomposers
  • NEP GEP - ER

12
Photosynthesis
13
Prairie Productivity
  • Estimates of production of aboveground biomass
    range from 200 to 570 grams of carbon per square
    meter per year for a tallgrass prairie

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16
Prairie Productivity
  • In prairies 2 to 4 times the amount of
    aboveground biomass occurs as biomass below
    ground
  • Prairie plants produce extensive root systems -
    big bluestem roots reach down 2 m switchgrass
    roots reach down 3.7 m forbs such as leadplant
    and dotted gayfeather have much deeper roots -
    reaching down 5 m
  • A student of Weaver's measured the length of root
    material in the top 10 cm of a 0.5 square meter
    plot and found 21.5 km of big bluestem root 38.7
    km of little bluestem 18.3 km of needlegrass
    176.7 km of Kentucky bluegrass

17
Prairie Productivity contd
  • For most praire plants, 80 of the root biomass
    occurs in the top 25 cm of soil
  • Further complicating the picture is that many
    grasses reproduce by rhizomes - the rhizomes
    anchor the plant, take up some water and
    nutrients, store food, and produce aerial shoots
    - rhizomes usually occur in the top 10 to 20 cm
    of the soil

18
Prairie Productivity
  • In prairies belowground biomass of 685 to 1900 g
    C per square meter per year
  • Thus total yearly production in tallgrass
    prairies combining aboveground and belowground
    biomass appears in the 800 to 2400 g C per square
    meter per year range
  • This is in comparison to 3500 g C per square
    meter for an Iowa cornfield

19
Influence of grazing
20
East African Grasslands
21
Grazing in East Africa
22
Compensatory Growth
  • Grazing seems to stimulate plants to engage in
    compensatory growth (to replace lost plant
    material) and to reallocate resources within the
    plant
  • Compensatory growth may occur due to enhanced
    photosynthesis more efficient light use due to
    reductions in mutual shading hormonal changes
    causing an increase in tillering leaf cell
    division and leaf cell expansion reduced rate of
    leaf senscence nutrient recycling accompanying
    herbivory (excretion releases nutrients) some
    stimulatory effect of herbivore saliva (this idea
    about cow slobber is very controversial)

23
Grazing in Illinois Prairies
  • Illinois tallgrass prairie plants vary in
    response to grazing - ability to withstand
    grazing depends upon several factors
  • 1. possession of rhizomes
  • 2. capacity for production of lateral shoots
  • 3. small height and erectness of growth habit
  • 4. lateness of seed germination and spring
    growth
  • 5. slow growth rate
  • 6. lateness of elevation of stem apex above
    minimum point of grazing

24
Decline with Grazing
Indian grass Willow aster
25
Increase with Grazing
Sideoats grama Common Yarrow
26
Highly invasive after grazing
Downy Brome (cheatgrass) Canada Thistle
27
Eastern Meadowlark Dickcissel Increase with
moderate grazing
28
Grasshopper sparrow Only found in grazed areas
29
Savannah sparrow Declines with grazing
30
LeContes Sparrow Bobolink Unaffected by
grazing
31
Decline with grazing
Prairie Vole Short-tailed shrew
32
Unaffected by grazing
Thirteen-lined ground squirrel White-footed deer
mouse
33
Influence of Fire
34
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35
Native American Fires
Meadows Burning by George Caitlin - 1832
36
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38
Decline with spring fires
  • Kentucky Bluegrass
  • Bicknells Sedge

39
Increase with spring fires
  • Canada Wild Rye
  • Prairie Dropseed

40
Fire Effects
  • If fire is followed by adequate precipitation,
    biomass production will increase in the next 2 to
    3 years following the fire if precipitation is
    less than adequate, biomass production will
    decrease
  • Species richness of plants usually increases in
    burned compared to unburned areas - species
    richness also increases when fire is combined
    with grazing - so fire and grazing both act to
    limit growth by competitive dominants and allow
    competitively inferior species to increase

41
Increase with fire -Prairie Grasshoppers
42
Decrease with fire
  • Beetles
  • Leafhoppers
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