Oak Hickory on Coarse Textured Kamic Soils

1. Oak Hickory on Coarse Textured Kamic Soils Stinchfield Woods, MI Jennifer Austin Joshua Berk Knox Erin Uloth Jennifer Dowdell Presentation for Soil Properties and Processes

2. Parent Material Topography pH Water Availability Temperature Vegetation Aboveground Carbon N pools Quantity and Quality Soil Microbial Activity Forest Floor Carbon CO2 Quantity and Quality Quantity & Quality Soil Organic Matter Belowground Carbon

3. The differences in soil parameters observed at our four sites can be chiefly explained as influence of: • Parent Material • Chemistry – Calcareous, high nutrient (cation) availability  acts as a pH buffer • Texture – Sandy to Loam  Influence low to moderate water holding capacity for plant use • Topography – Ice-Contact Kettles and Kames • Temperature – Slope, N/S Aspects, Position on slope  Solar energy input • Water Availability – Slope position, N/S Aspects  loss/gain H2O, litter accumulation (OM)

4. The differences in soil parameters observed at our four sites can be chiefly explained as influence of (continued): • Temperature • Vegetation – Global trends driven by growing season length • Vegetation • Temperature – More vegetation insulates soil from sun (& evapotranspiration) • Water– More vegetationincreased transpiration

5. Parent Material Topography pH Water Availability Temperature Vegetation Aboveground Carbon N pools Quantity and Quality Soil Microbial Activity Forest Floor Carbon CO2 Quantity and Quality Quantity & Quality Soil Organic Matter Belowground Carbon

6. Soil Diagnostics Texture Field Results: Loam and loamy sand Lab results: Silt 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 characteristics. Relationship with other sites… particularly Mixed Oak.

7. Available Water Content OM contributes to aggregate formation. OM was 3-4% by weight. AWC ranged from 0.18 cm3 H2O/cm3 to 0.37 cm3 H2O/cm3 (mid-range compared to other sites). Vegetation confirms this: Quercus velutina Quercus alba Carya glabra and ovata Carex pensylvanica Contrasts with the Mixed Oak site…

8. Cation 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. Oak Hickory: 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 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.

9. Parent Material Topography pH Water Availability Temperature Vegetation Aboveground Carbon N pools Quantity and Quality Soil Microbial Activity Forest Floor Carbon CO2 Quantity and Quality Quantity & Quality Soil Organic Matter Belowground Carbon

10. Influences on Microbial Data What do these communities prefer, and how do these main influences play out at Stinchfield?

11. Microbial Data • NW top: major outlier, discounted from analysis • Predictions: • High efficiency correlated with high C:N ratio • pH/AWC/temp correlated with respiration rates • Low OM correlated with high respiration rates or low C inputs (aboveground C) Recall: OM=Input-Microbial Activity (Respiration)

12. Microbial Data: Trends • A few notes… • Specific Respiration: well correlated with C:N • N Availability: well correlated with pH • C:N ratio: variable across site

13. How did our predictions fare? • High efficiency correlated with high C:N ratio? • No! The opposite of expected! • pH/AWC/temp correlated with respiration rates? • Complex interaction of these factors; AWC might be a driver • Low OM correlated with high respiration rates OR low C inputs (aboveground C)? • OM and respiration rates do not necessarily correlate… so let’s see if the story is complete with biomass analysis. C/N Specific Respiration

14. Correlations and Hypotheses • Does Microbial Biomass correlate with: • Depth of A: not really (r of 0.6 with slope of 0) • OM%: No (r of 0.5 with slope 0) • AWC: No (r of 0.5 with slope 0) • pH: Yes (r of >0.7) BUT NEGATIVELY! • But Remember: We only have 3 data points!!

15. Parent Material Topography pH Water Availability Temperature Vegetation Aboveground Carbon N pools Quantity and Quality Soil Microbial Activity Forest Floor Carbon CO2 Quantity and Quality Quantity & Quality Soil Organic Matter Belowground Carbon

16. 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?

17. Above Grnd C - Forest Floor C… Where did all the C go? • 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 microbial respiration of C to CO2 Account for the difference? YES!! 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

18. Oak-Hickory Summary • AWC increases as texture becomes loamy and OM content increases • Vegetation suggests OH a drier site • Calcareous Parent Material leads to high base saturation • Specific Respiration correlates with C:N ratio • Mildly acidic & well-drained encourages microbial activity • BA not a good measure of AG Carbon • FF Carbon not correlated with AG Carbon across our 4 sites – good indicator of microbial respiration

19. Unknowns • What drives respiration rates? • What is the main driver for site productivity? • Why is efficient respiration related to higher quality sites?