Productive Ecosystem

Well Developed Soil

Radrick Forest: A Mixed Oak Ecosystem

Outline

I. Re-introduction to Radrick ForestSoil characteristics:I. PhysicalII. ChemicalIII. BiologicalIV. Synthesis: How do the factors above

combine to influence soil formation and ecosystem development?

Glacial History of Michigan

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0.2

0.4

0.60.8

1

1.2

1.4

AWC Bulk Density

(cm3 H2O/cm3 soil) (g/cm3)

Mixed OakOak-HickoryN. HardwoodsBlack Oak/White Oak

Soil typeMixed Oak Loam

Oak-Hickory Sandy LoamN. Hardwoods Loamy Sand

Black Oak/White Oak Sand

Soil Formation

Why does Radrick have well developed soil?

•Climate

•Glacial History

•Parent Material

Chemical properties of the mixed oak ecosystem

pH (DI water) pH (CaCl2) CEC (cmolc/kg) % Base Saturation

Mixed Oak 6.14 5.71 8.57 0.99

Oak Hickory 4.98 4.19 10.78 0.99

Northern Hardwoods 4.50 3.11 4.03 0.93

Black Oak/White Oak

3.50 2.63 1.90 0.13

Comparison graph for pH and CEC

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2

4

6

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pH (H20) pH (CaCl2) CEC(cmolc/kg)

Mixed Oak

Oak-Hickory

NorthernHardwoodBlack Oak/WhiteOak

Why do we see these differences?

• Parent material may explain the north/south data

• But, OH and MO share the same parent material, so we look to weathering and %organic matter

• These play into soil texture; MO is the most clayey of the sites.

• The MO profile is highly developed and has a strong buffering capacity.

Radrick Forest Microbial Carbon Utilization Compared to Other Ecosystems

• Mixed Oak has relatively high levels of microbial biomass compared to other ecosystems;•But total microbial activity is not much different;

Microbial Activity in Four Michigan Forest Ecosystems

MO

MO

OH

OH

NH

NH

NO

NO

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

180.00

MO 154.92 20.76

OH 91.50 23.21

NH 126.57 22.94

NO 40.93 12.43

Avg Microbial biomass(μgC/g)

Avg Microbial respiration(μg/g/d)

Relative Proportions of the number of

microorganisms

Fungi?%

Bacteria?%

Actinomycetes?%

Discussion of Microbial Activity in Radrick Forest:What factors explain why MO has high microbial biomass, but low activity?•Composition of microbial community?

-A higher proportion of actinomycetes would tend to result in lower respiration, but unlikely to account for the higher biomass. -A high proportion of bacteria would account for a higher biomass, but not for the low activity.-A higher presence of fungi would account for the higher biomass, and possibly into lower respiration, if C is incorporated in building biomass rather than respired.

Other Potential Factors:•Presence of organic matter?

–Radrick forest has a moderate level of soil organic matter.• Soil physical characteristics?

–The more clayey texture of the MO system would tend to reduce gaseous diffusion, causing locally increased CO2 levels, thus slowing respiration rates even with a high microbial biomass.

• Soil chemical characteristics?– The overall pH is moderate, and not particularly conducive to fungi. But poor diffusion could create microzones with high CO2 concentrations, and low pH.

It may explain

It may explain

It may explain

It may explain

Radrick Forest Mineralization and Nitrification Compared to Other Ecosystems

• Mixed Oak has a high rate of N Mineralization compared to other ecosystems;•Efficiency of MO

Microbial Activity in Four Michigan Forest Ecosystems

MO

MO

MO

OHOH

OH

NHNH

NH

NONO

NO

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

MO 5.51 1.71 3.91

OH 1.35 0.06 17.13

NH 3.74 1.88 6.19

NO 1.02 0.02 12.18

Avg Net NMineralization

(μg N/g/d)

Avg Net Nitrification (μg N/g/d)

Ratio of C respired to N mineralized

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50

100

150

200

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300

350

Biom

ass

(Mg/

ha)

Mi neral Soi l 35. 8 91. 9 29. 5 12. 6Forest Fl oor 11. 5 6. 5 7. 2 7. 2Aboveground 269. 2 226. 4 245. 2 182. 8

MO OH NH NO

Radrick forest has: highest above ground biomass highest litter production intermediate soil organic matter

*High decomposition rate Near neutral PH,

Sufficient soil moisture Good aeration and Relatively warm climate High litter quality

Why does Radrick forest not have the highest soil organic matter?

* Relatively lower allocation to root and n nutrient-rich ecosystem

Low High

Nitrogen Availability

Standing RootBiomass

Percent of TotalNPP Allocated toRootRoot Mortality

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500

1000

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3000

3500

4000

4500

Nitr

ogen

Poo

l (k

g/ha

)

Mi neral Soi l 3501. 9 1718. 4 2382. 8 1221. 1Forest Fl oor 154. 7 42. 2 88. 2 54. 1Aboveground 582. 2 486. 3 572. 6 404. 3

MO OH NH NO

Why is the soil OM in Radrick forest such a big pool of N?

• 1. Clayey soil with high CEC large amount of inorganic N is bound

• 2. Contain some species with nutrient-rich tissue higher litter quality. (N concentration in forest floor = 1.35%)

(even higher than NH??)• 3. High microbial biomass can

be part of the pool

SpeciesRelative

Dominance (%)

Leave N concentrat

ion(%)

Branch N concentrat

ion(%)

Blake Oak (Quercus velutina)

8.5 1.19 0.39

Red Maple (Acer rubrum)

13.1 2.29 0.59

Sassafras (Sassafras albidum)

15.0

Bitternut Hickory (Carya cordiformis)

25.2 1.31 0.45

Red Oak (Quercus rubra)

33.4 1.23 0.42

Shagbark Hickory (Carya ovata)

1.2 1.31 0.45

Black Cherry (Prunus serotina)

3.6 2.11 0.48

Effect of high nitrification:Negatively charged nitrate ions are not adsorbed by the negatively charged colloids, so it leaches out of the ecosystem easily.

Soil NO3- Without Incubation (ug N / cm3 soil)

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1.4

MO OH NH NO

ug N/cm3

Soil NH3+ Without Incubation (ug N / cm3 soil)

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5

10

15

20

25

30

35

40

MO OH NH NO

ug N/cm3

Radrick Forest has highest aboveground biomass, faster nutrient uptake

Soil: *Fine texture *Calcareous parent material *High water availability *High PH *High CEC

Climate:Relatively warm and humid

High Above ground biomass

High quality of both above- and below- ground litter

Large soil microbial community

High rate of decomposition and mineralization

Fast uptake

Low leaching

Low fire frequency

Nutrient tightly bound within the ecosystem

Thanks!!