Black Oak- White Oak Forest

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Black Oak- White Oak Forest
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Manistee National Forest
Outwash plain dominated by Jack Pine to the
west Northern hardwood forest to the east
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Land Form

• Kamic Hills
• Formed by
• Wisconsin
• Glaciation approx.
• 8000-9000 years
• ago

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Parent Material

• Ice contact material
• Derived from outwash
• stratified drift laid down
• by previous Illinoian
• glaciation (128,000 yrs.
• ago)

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Ecosystem overview
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Northern Oak Relationships
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Soil Profile
Oe/i/a2-0 cm intact and partially decomposed
Quercus rubra, Acer rubrum, Q. alba leaves
abrupt smooth boundary.   A 0-3 cm black (7.5 YR
2.5/1) loamy sand, weak fine subangular blocky
structure very strongly acid abrupt smooth
boundary.   E 3-6 cm dark gray (7.5YR 4/1)
loamy sand weak medium subangular blocky
structure very strongly acid, abrupt smooth
boundary.   BS1 6-14 cm brown. (7.5YR 4/4)
sand single grain moderately acid diffuse
smooth boundary.   BS2 14-26 cm strong brown
(7.5YR 5/8) sand single grain moderately acid
diffuse smooth boundary.   C 26 cm dark
yellowish brown (10YR 5/8) sand single grain
moderately acid.
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Soil Profile
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Soil Texture
Group sand silt clay In lab In situ
Fine Young Entisols 91.15 3.64 5.21 sand loamy sand
Duripan Duripan 90.93 5.56 3.51 sand loamy sand
Bt Boys 76.94 17.40 5.60 loamy sand loamy sand
Average 86.34 8.87 4.77    
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Bulk Density, AWC and OM

• Bulk Density
• 1.08 g/cm3
• Available Water Content
• 0.23 cm3 H2O/ cm3 soil
• Organic Matter Content
• 2.06

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Soil pH, CEC base saturation
Base Saturation 13
pH Using H2O 4.62 Using CaCl2 3.46
CEC (cmolc/ kg) 1.19

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Soil Profile Summary

• Soil Texture Sand (76-91)
• Silt (3-17)
• Clay (3-5)
• - Affects Db and AWC
• Lowest CEC and base saturation
• Non-calcareous acidic
• Soil horizons shallow and not well
• developed

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Soil Profile Summary

• Texture Sand (90-92)
  Clay (3.5) Silt ( 5-5.5)
  Non-calcareous Acidic Well-developed forest
  floor Soil Horizons shallow not very
  developed

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Plant Profile
Predominant Overstory plants Quercus alba,
Quercus rubra, Acer rubrum Understory plants
included Pinus Strobus, Sassafras albidum,
Hamamelis virginiana Groundcover plants
included Pteridium aquilinum, Carex
Pensylvanica,
Gaylussacia bacata
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Plant Factors Influencing Soil

• Slow Decomposition
• Nutrient Poor Litter
• High Content of Organic Acids

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NO and NH Nutrient Pools
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Nitrogen Exchange

• Nitrogen is often a limiting factor in the
  productivity of terrestrial ecosystems.
• Microbial activity fixes organic nitrogen into
  forms that are available to plants
• plants use fixed nitrogen to manufacture organic
  compounds,
• N returns to the microbes tied in organic
  compounds forming plant litter

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Nitrogen Exchange

• N cycling is controlled by
• Litter production, above and below ground
• Litter chemical composition
• Microbial community numbers and types
• Temperature and moisture affecting the activity
  of microorganisms

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Role of Organic Matter (Carbon)

• Carbon supplied by plant litter limits microbial
  growth
• Amount of N released during decomposition
  reflects the quality of organic matter

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The Connection

• Plant and microbial activity within terrestrial
  ecosystems is tightly linked through the exchange
  of C and N

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Chemistry

• N is released from OM by heterotrophic soil
  organisms (bacteria,fungi, actinomycetes) in the
  form of ammonia
• R-NH3 H2O ? R-OH NH4
• Ammonia can then be assimilated by plants,
  participate in ion exchange reactions or

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Chemistry

• it can be oxidized by chemoautotropic bacteria
  to form nitrate
• 2 steps
• NH4 11/2 O2 ? NO2- H2O 2H
• NO2- 1/2O2 ? NO3-

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Nitrifying Bacteria

• Only 3 genera carry out the first step, and
  only 1 genera carry our the second
• All nitrifying bacteria are
• strictly anaerobic and
• intolerent of low soil pH
• Thus, their activity is restricted in acidic
  conditions like the northern oak ecosystem

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N and C Exchange in the Northern Oak Ecosystem

• Microbial biomass is very small
• Thus, so is the specific microbial respiration
  rate, indicating the relative efficiency of the
  microbial community to convert organic C to
  biomass. (higher less efficient)

site microbial biomass spec resp
units ?g C/g mg/g/d
NH 117.09 215.04
NO 20.84 556.34
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N and C Exchange in the Northern Oak Ecosystem

• The low biomass of microorganisms contributes to
  a small amount nitrogen produced.
• The acidity of the site may contribute to the
  very low amount of nitrate.

site incub NH4 incub NO3-
units ug N/g soil
NH 31.67 27.35
NO 23.27 0.32
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N and C Exchange in the Northern Oak Ecosystem

• The ratio of C respired to N mineralized
  indicates the litter quality of a site.
• A high ratio indicates a good substrate for
  microbial growth, but little N released where it
  can be assimilated for plants.

Site C respiredN mineralized
NH 7.16
NO 11.11
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How does it all fit together?

• Fire from west burns through NO forest
• burn? quick release loss of nutrients
• Vegetation response to /100yr disturbance
• Less nutrients in oak litter ? slow decomp.
• Canopy less dense ? site drier than NH
• Less water ? less weathering of soil