Presented at the 3rd ICOS Science Conference in Prague, Czech Republic, 11-13 Sep 2018.

1. „Flooding-induced N2O and CH4 fluxes
from soil to tree level”
Thomas Schindler (1), Ülo Mander (1), Katerina Machácová
(2), Iuliia Burdun (1), Dmitrii Krasnov (3), Gert Veber (1), and
Kaido Soosaar (1)
(1) University of Tartu, Institute of Ecology & Earth Sciences, Department of
Geography, Tartu, Estonia; (2) Lab. of Ecological Plant Physiology, Global
Change Research Institute CAS, Brno, Czech Republic, (3) Department of
Plant Physiology, Estonian University of Life Sciences, Tartu, Estonia
In a nutshell
- Jul/Aug 2017 - FluxGAF
- Doctoral SummerSchool
- complex field experiment on bio-
geo-chemical processes
- Two weeks artificial Flooding
- Flooded Spot + Control Spot
- Stem heights: 0 / 80 / 170 cm
- Automatic soil chambers (8+4)

2. Hypothesis
Extreme Climate Events
 Flooding or heavy rain effect on
forest ecosystem processes
Hypothesis :
Pulsing water level resp. water
saturated soil
(I) increases N2O/CH4 flux, (N2O
caused by soil NO3- reduction),
(II) but flux decreases over tree height,
(III) Further, the process is not daytime –
related.

3. Methods
11 days: 55 … 70 m³ water / day
http://www.freeworldmaps.net/europe/estonia/map.html
Grey Alder Forest Site:
Flooding Plot: 40x40m
Control Plot: 20x20m

4. Methods
170cm
80cm
0cm
Flood Plot Control Plot
Soil 8 autom. chambers 4 autom. chambers
Stems 9 trees 3 trees
Additionally:
- piezometer (water level, autom. 30min interval),
- soil moisture / temperature sensors (1min interval)

5. Volumetric
water
content –
main
driver!!!
Control plotFlooded plot
Drivers

6. (I) N2O Fluxes – Soil and Stem (0 cm)
Flux increased at Flooding Plot
Soil Tree Stem

7. (I) N2O Fluxes – Soil and Stem (0 cm)
Flux increased at Flooding Plot
Soil Tree Stem

8. (I) N2O Fluxes – Soil and Stem (0 cm)
Flux increased at Flooding Plot
Soil Tree Stem

9. (I) CH4 Fluxes – Soil and Stem (0 cm)
Significantly more CH4
during the post flooding
Soil Tree Stem

10. (I) CH4 Fluxes – Soil and Stem (0 cm)
Significantly more CH4
during the post flooding
Soil Tree Stem

11. Stem Fluxes at 0 / 80 / 170 cm height
N2O CH4

12. Stem Fluxes at 0 / 80 / 170 cm height
N2O CH4

13. Tree Stem Fluxes at Night
Nighttime:
Similar pattern !
Increase during flooding,
Decrease over height.
But lower values (apprx. 50%)

14. Tree Stem Fluxes at Night
Nighttime:
Similar pattern !
Increase during flooding,
Decrease over height.
But lower values (aprx. 50%)

15. To Conclude
1. fluxes increased significantly during flooding
period (N2O) and immediately after (CH4)
2. Stem fluxes decreased over height
3. Stem fluxes at nighttime: similar pattern (but
lower values)
4. Higher fluxes in flooding time coherent to higher
groundwater levels and NO3-
Our results show that stem fluxes, especially during
extreme weather events such as flooding or heavy
rain, significantly contribute to forest C and N cycles
and must be included in relevant models.
„Flooding-induced N2O and CH4 fluxes
from soil to tree level”
FluxGAF Forest at Night

16. Acknowledgment
Contact me:
Thomas.Schindler@ut.ee
This study was supported by the
Ministry of Education and Science of
Estonia (SF0180127s08 grant), the
Estonian Research Council (IUT2-16)
and the EU through the European
Regional Development Fund
(ENVIRON and EcolChange Centres of
Excellence, Estonia) and the European
Social Fund (Doctoral School of Earth
Sciences and Ecology).

17. BACKUP

18. NO3- and N2O during Flooding
Decreasing NO3-
Assumption:
N2O produced by denitrification
→ Microbiological Analysis needed
(perspective)