1. Dynamics of the Northern Hardwood Ecosystem Yuqiong Hu, Jeff Plakke, Sharon Shattuck, Erin Wiley

2. Introduction: Field Review -Moraine deposits composed of old outwash plains -Abrupt, hilly topography -higher latitude and elevation cooler temperatures -Sandy soil -Well-developed profile -Bh horizon -Overstory dominated by Acer saccharum -Many mesic indicators Conclusion: Most important factors influencing this site are topography and climate. Topography leads to fire suppression and climate influences soil moisture.

3. Results: Physical Properties Average texture, based on Textural Triangle= Sand AWC= 0.14 cm^3 H 2 O/cm^3 soil

4. Results: Chemical Properties pH –Water pH: 5.31 –CaCl2 pH: 4.66 Organic Matter: –Organic Matter: 3.26% –Organic Carbon: 1.63% CEC and Base Saturation –CEC: 3.87 cmol charge per kilogram –Base Saturation: 96.4%

5. Results: Biological Properties Microbial Biomass and N- Mineralization Northern Hardwoods Aeolian Ant Farm ξ Ped ZeplinAverage Microbial Biomass g C/M ² 6.9418.9210.6512.17 Specific Microbial Respiration Rate mg/g/d395.55129.38264.85263.26 Net Nitrogen Mineralization g N/m²/d0.1750.090.3440.203 Net Nitrification g N/m²/d0.0790.0040.1820.088 Ratio of C respired to N mineralized ug C/ug N15.7325.548.20916.493

6. Results: Biological Properties Biomass and Nitrogen Pools

7. Discussion: Physical Properties Texture Sandy texture (87% sand) –Cannot hold moisture well low surface area: volume ratio –Because parent material and texture are similar to Northern Oak site, there must be another driver for ecosystem development

8. Discussion: Physical Properties Available Water Content (AWC) AWC Relatively low, but higher than site on similar parent material. Why? –Physiography and Climate Parent material= sand Higher elevation, higher latitude influences snowmelt –Lower Solar Penetration due to high Basal Area –Organic Matter Field evidence: –Presence of Bh horizon in soil profile indicates organic matter breakdown.

9. Discussion: Chemical Properties pH and Organic Matter pH: What controls it? –Litter quality –Microbial activity (because pH is acidic, fungi are primary decomposers in this ecosystem) –Parent Material (soil buffering capacity) Organic Matter –Low in soil compared to O.M. pool in overstory; indicates high rate of decomposition –Increases water-holding capacity –Field evidence: Bh horizon indicates high amount of O.M. in system

10. Discussion: Chemical Properties CEC and Base Saturation CEC and Base Saturation –CEC somewhat low due to parent material Sand= low CEC Higher than site on similar parent material due to higher O.M. content –Base Saturation: Indication of large nutrient pool Lack of Fire Young, relatively unweathered Parent Material

11. Discussion: Biological Properties Microbial Activity and Nitrogen Cycling –Litter Production high + litter accumulation low = high Microbial Biomass -“look up, look down” –Litter Quality is high = high C:N ratio –N mineralization = NH 4 +  lots of “Goodies” –Nitrification is high Nitrobacter spp. NH 4 +  NO 3 - Potential for nutrient loss through leaching NO 3 - (highly mobile, sandy soils, water movement) after a disturbance (decreased plant uptake).

12. Discussion: Biological Properties Biomass and Nutrient Pools Aboveground Biomass is highest “look up…” –drives N mineralization and Nitrification through litter decompostion Belowground Nitrogen Pool is Highest Forest floor is lowest for both “…look down.” = high rate of decomposition. “what about the roots?”

13. Climate snowpack evapotranspiration moisture Rate of microbial activity Litter quality Plant community Nutrient pool Litter Quantity DISCUSSION & SYNTHESIS:

14. Topography Disturbance Regime Nutrient Pool Plant community Litter quality Rate of Microbial Activity pH DISCUSSION & SYNTHESIS: Litter quantity

15. Questions?