Oak Hickory on Coarse Oak Hickory on Coarse Textured Kamic SoilsTextured Kamic Soils

Stinchfield Woods, MIStinchfield Woods, MI

Jennifer AustinJoshua Berk KnoxErin UlothJennifer Dowdell

Presentation for Soil Properties and Processes

Belowground

Carbon

Aboveground Carbon

Soil Organic Matter

Soil Microbial ActivityForest Floor

Carbon

N pools

CO2

pHWater

Availability

Quantity and Quality

Temperature

Quantity and Quality

Quantity & Quality

Vegetation

TopographyParentMaterial

The differences in soil parameters observed at our four sites can The differences in soil parameters observed at our four sites can be chiefly explained as influence of:be chiefly explained as influence of:

Parent MaterialParent Material

Chemistry – Calcareous, high nutrient (cation) availabilityChemistry – Calcareous, high nutrient (cation) availability

acts as a pH bufferacts as a pH buffer

Texture – Sandy to Loam Texture – Sandy to Loam

Influence low to moderate water holding capacity for plant useInfluence low to moderate water holding capacity for plant use

TopographyTopography – Ice-Contact Kettles and Kames – Ice-Contact Kettles and Kames

Temperature – Slope, N/S Aspects, Position on slope Temperature – Slope, N/S Aspects, Position on slope

Solar energy inputSolar energy input

Water Availability – Slope position, N/S Aspects Water Availability – Slope position, N/S Aspects

loss/gain Hloss/gain H22O, litter accumulation (OM)O, litter accumulation (OM)

The differences in soil parameters observed at The differences in soil parameters observed at our four sites can be chiefly explained as our four sites can be chiefly explained as

influence of (continued):influence of (continued):

TemperatureTemperature Vegetation – Global trends driven by growing season Vegetation – Global trends driven by growing season

lengthlength VegetationVegetation

Temperature – More vegetation insulates soil from sun Temperature – More vegetation insulates soil from sun (& evapotranspiration)(& evapotranspiration)

Water– More vegetationWater– More vegetationincreased transpirationincreased transpiration

Belowground

Carbon

Aboveground Carbon

Soil Organic Matter

Soil Microbial ActivityForest Floor

Carbon

N pools

CO2

pHWater

Availability

Quantity and Quality

Temperature

Quantity and Quality

Quantity & Quality

Vegetation

TopographyParentMaterial

Soil DiagnosticsSoil Diagnostics

TextureTexture

Field Results: Field Results: Loam and loamy sandLoam and loamy sand

Lab results: Lab results: Silt loam to loamy sandSilt loam to loamy sand

The surface area created by texture and structure contributes to available water content and base saturation. ORGANIC MATTER will also play a pivotal role in these The surface area created by texture and structure contributes to available water content and base saturation. ORGANIC MATTER will also play a pivotal role in these characteristics. characteristics.

Relationship with other sites… particularly Mixed Oak. Relationship with other sites… particularly Mixed Oak.

Available Water ContentAvailable Water Content

OM contributes to aggregate formation. OM contributes to aggregate formation. OM was 3-4% by weight. OM was 3-4% by weight.

AWC ranged from 0.18 cmAWC ranged from 0.18 cm33 H H22O/cmO/cm33 to 0.37 cm to 0.37 cm33 H H22O/cmO/cm33 (mid-range (mid-range compared to other sites).compared to other sites).

Vegetation confirms this: Vegetation confirms this: Quercus velutinaQuercus velutinaQuercus albaQuercus albaCarya glabra Carya glabra andand ovata ovataCarex pensylvanica Carex pensylvanica

Contrasts with the Mixed Oak site…Contrasts with the Mixed Oak site…

Cation Exchange Capacity/ Base SaturationCation Exchange Capacity/ Base Saturation

CEC is determined in part by clay minerology, OM content, and cation concentration from parent material. OM contributes 30-90% of total CEC.CEC is determined in part by clay minerology, OM content, and cation concentration from parent material. OM contributes 30-90% of total CEC.

Oak Hickory:Oak Hickory:

Stinchfield parent material is calcareous and our results confirm that it has a high base saturation. 95-99 %Stinchfield parent material is calcareous and our results confirm that it has a high base saturation. 95-99 %

CEC ranges from 3.83 cmol/kg to 8.94 cmol/kg. The site that has the highest CEC, NW slope, also has the highest OM and is CEC ranges from 3.83 cmol/kg to 8.94 cmol/kg. The site that has the highest CEC, NW slope, also has the highest OM and is significantly different in texture: Loam. Higher clay content leads to a higher potential to attract and absorb cations.significantly different in texture: Loam. Higher clay content leads to a higher potential to attract and absorb cations.

Contrasted with Mixed Oak ecosystem… same base saturation but different CEC.Contrasted with Mixed Oak ecosystem… same base saturation but different CEC.

Belowground

Carbon

Aboveground Carbon

Soil Organic Matter

Soil Microbial ActivityForest Floor

Carbon

N pools

CO2

pHWater

Availability

Quantity and Quality

Temperature

Quantity and Quality

Quantity & Quality

Vegetation

TopographyParentMaterial

Influences on Microbial DataInfluences on Microbial Data

Neutral pH:Neutral pH: GoodGood

Ample moisture:Ample moisture: ModerateModerate

Warmer temperatures:Warmer temperatures: GoodGood

Ample carbon (food)Ample carbon (food) Good?Good?

What do these communities prefer, and how What do these communities prefer, and how do these main influences play out at do these main influences play out at

Stinchfield?Stinchfield?

Microbial DataMicrobial Data

NW top: major outlier, discounted from NW top: major outlier, discounted from analysisanalysis

Predictions:Predictions: High efficiency correlated with high C:N ratioHigh efficiency correlated with high C:N ratio pH/AWC/temp correlated with respiration ratespH/AWC/temp correlated with respiration rates Low OM correlated with high respiration rates or Low OM correlated with high respiration rates or

low C inputs (aboveground C)low C inputs (aboveground C)

Recall: OM=Input-Microbial Activity (Respiration)Recall: OM=Input-Microbial Activity (Respiration)

Microbial Data: TrendsMicrobial Data: Trends

NE Mid 4 6.620 23.000 264.540 1.480 0.044 22.520 6.42 0.28 4.03%NW Bottom 3 5.185 40.631 916.000 1.102 0.016 36.879 5.84 0.37 4.90%

NW Top 2 0.932 37.000 5319.800 0.317 0.008 15.630 5.74 0.32 4.40%SW Top 1 5.400 26.400 530.660 0.873 0.001 30.240 5.53 0.18 3.03%

N Nit (g N/m2/d)

Ratio C Resp/N

Min pH (H20)Site # OM (%)AWC (cm3 H2O/cm3)

Microbial Biomass (gC/m2)

Microbial Resp

(µg/g/d)

Specific Resp

(µg/g/d)N Min (g N/m2/d)

A few notes…

•Specific Respiration: well correlated with C:N

•N Availability: well correlated with pH

•C:N ratio: variable across site

How did our predictions fare?How did our predictions fare?

High efficiency correlated with High efficiency correlated with high C:N ratio? high C:N ratio?

No! The opposite of expected!No! The opposite of expected! pH/AWC/temp correlated with pH/AWC/temp correlated with

respiration rates?respiration rates? Complex interaction of these Complex interaction of these

factors; AWC might be a driverfactors; AWC might be a driver Low OM correlated with high Low OM correlated with high

respiration rates OR low C inputs respiration rates OR low C inputs (aboveground C)?(aboveground C)?

OM and respiration rates do not OM and respiration rates do not necessarily correlate… so let’s necessarily correlate… so let’s see if the story is complete with see if the story is complete with biomass analysis.biomass analysis.

20

22

24

26

28

30

32

34

36

38

40

0 200 400 600 800 1000

C/N

Specific Respiration

Correlations and HypothesesCorrelations and Hypotheses

Does Microbial Biomass correlate with:Does Microbial Biomass correlate with: Depth of A: Depth of A: not reallynot really (r of 0.6 with slope of 0) (r of 0.6 with slope of 0) OM%: OM%: NoNo (r of 0.5 with slope 0) (r of 0.5 with slope 0) AWC: AWC: NoNo (r of 0.5 with slope 0) (r of 0.5 with slope 0) pH: pH: YesYes (r of >0.7) BUT NEGATIVELY! (r of >0.7) BUT NEGATIVELY!

But Remember: We only have But Remember: We only have 3 data points!!3 data points!!

Belowground

Carbon

Aboveground Carbon

Soil Organic Matter

Soil Microbial ActivityForest Floor

Carbon

N pools

CO2

pHWater

Availability

Quantity and Quality

Temperature

Quantity and Quality

Quantity & Quality

Vegetation

TopographyParentMaterial

Site #

Aboveground Carbon

Mg* ha-1

Aboveground Nitrogen

kg N* ha-1

Forest Floor Carbon

Mg* ha-1

Forest Floor

Nitrogen kg N*ha-1

Microbial Biomass Mg*ha-1

Soil Carbon

Mg*ha-1

Soil Nitrogen kg N*ha-1

Basal Area

NE Mid 4 102 207.1 13 86.4 0.0007 45.5 1356 20NW Mid 3 246.4 536.8 7.7 50 0.0005 57.3 1404 38.6NW Top 2 83.4 167.3 7.3 47.6 0.0009 59 1609.2 50SW Top 1 80 150 9.5 0.06 0.0005 30.1 1193 18

Tues Mean 127.9 265.3 9.4 46 0.0007 48 1390.6 31.7Mon. Mean 141.6 302.2 8.7 56.7 54.5 1362.6

We learned that:We learned that:• BA not a good measure of AG carbon:

• Site #2: highest BA, but 2nd lowest Aboveground (AG) C & N. (difference due to DBH distribution)

• The AG Carbon is 2.6 times what is in the soil.

• F.Floor C NOT correlated with AG C across the 4 sites.

It varied from 3 to 12 % of AG C. .. So …

Why Not?Why Not?

Microbial BM does NOT account for the “missing” C: and:

Soil carbon accounts for only 40% on average of the “missing” C. Flux vs Pools: OM accumulation :10kg/ha*yr -> 5780 years to accumulate

wow!

Does the Does the microbial respirationmicrobial respiration of C to CO of C to CO2 2 Account for the difference?Account for the difference?

YES!! YES!! r=.903!!r=.903!!

As Resp declines, the ratio of FF to AG (controling for %OM) increases.

With less microbial respiration, more FF C builds up per unit AG C

Above Grnd C Above Grnd C -- Forest Floor C… Forest Floor C… Where did all the C go?Where did all the C go?

Oak-Hickory SummaryOak-Hickory Summary

AWC increases as texture becomes loamy and OM AWC increases as texture becomes loamy and OM content increasescontent increases

Vegetation suggests OH a drier siteVegetation suggests OH a drier site Calcareous Parent Material leads to high base Calcareous Parent Material leads to high base

saturationsaturation Specific Respiration correlates with C:N ratioSpecific Respiration correlates with C:N ratio

Mildly acidic & well-drained encourages microbial activity Mildly acidic & well-drained encourages microbial activity BA not a good measure of AG CarbonBA not a good measure of AG Carbon FF Carbon not correlated with AG Carbon across our FF Carbon not correlated with AG Carbon across our

4 sites – good indicator of microbial respiration4 sites – good indicator of microbial respiration

UnknownsUnknowns

What drives respiration rates?What drives respiration rates? What is the main driver for site productivity?What is the main driver for site productivity? Why is efficient respiration related to higher Why is efficient respiration related to higher

quality sites?quality sites?