1. Coupling Solid-Aqueous-Gas Phases Of Carbon And
Nitrogen Across Topographic Gradients And
Extreme Weather Events
Rodrigo Vargas
Department of Plant and Soil Sciences
University of Delaware
CoPI: Shreeram Inamdar
Collaborators: Angelia Seyffeth, Jinjun Kan, Josep Barba
Students: Sandra Petrakis, Daniel Warner
Contact: rvargas@udel.edu
AFRI and NIWQP PD meeting
October 12-13, 2016
Washington, D.C.

2. Overall goal:
To understand how weather variability (especially extreme weather
events) influences the key ecosystem processes of nutrient and soil GHG
fluxes in ex-urban forests.
Approach:
- In situ field measurements across topographic gradients
- Experiment of extreme water pulses on soils
- Automated measurements of multiple soil GHG

3. Motivation
Hurricane Matthew (2016)
Hurricane Sandy (2012)

4. (Dhillon and Inamdar 2013)
(Vargas 2012)

5. Conceptual diagram of how
topographic position will
influence GHG fluxes, soil
water content, C and N pools,
and variance. The size of the symbol represents the relative magnitude of the variable

6. - In situ field measurements across topographic gradients
Fairhill State Park, MD

7. - In situ field measurements
CO2 (Emissions):
• Soils => 64%
• CWD => 8%
• Stems =>28%
CH4 (Consumption):
• Soils => 99%
• CWD => 1%
• Stems =>-4%
(Werner et al. in review)

8. - In situ field measurements
(Werner et al. in review)

9. - In situ field measurements
2015 2015
Werner et al (in preparation)

10. - In situ field measurements
Werner et al (in preparation)

11. - Experiment of extreme water pulses on soils
Petrakis et al (in review)
Location Name Soil texture
Upslope Upland Forest Site 1 Sandy loam
Mid-slope Upland Forest Site 2 Loam
Wetland Wetland Loamy sand
Creek Creek Sand
244% for CO2 (Creek)
>5x104 % for CH4 (Wetland)
>5x104 % for N2O (Forest)

12. - Experiment of extreme water pulses on soils
Petrakis et al (in review)
Creek soil contributed the most to a 20-
year global warming potential
Forest Site contributed the most to the
100-year GWP (53.7%) as a result of large
N2O emissions.

13. Petrakis et al (in preparation)
- Automated measurements of multiple soil GHG

14. - Automated measurements of multiple soil GHG
Petrakis et al (in preparation)

15. - Concluding remarks