1. Case studies of pollen spread within a Central European Forest canopy
Martin Piringer (ZAMG),
Silvio Schüler (BFW)
Case studies of pollen spread within a Central European Forest canopy
Bundesforschungs- und Ausbildungszentrum für Wald, Naturgefahren und Landschaft
Institut für Genetik

2. Outline Site characteristics and topography of the study area
Martin Piringer et al.
Outline
Site characteristics and topography of the study area
Pollen sampling and meteorological observations
Meteorological interpretation of the time course of pollen concentrations
Results for three episode days with enhanced pollen production
Summary and conclusions

3. Site characteristics Topographic details around the lower tower
Martin Piringer et al.
Site characteristics
Topographic details
around the lower tower

4. Instrumentation on the lower tower
Martin Piringer et al.
Instrumentation on the lower tower

5. Meteorological parameters
Martin Piringer et al.
Meteorological parameters
Ultrasonic anemometers at the three levels of the tower deliver - wind direction and speed - vertical velocity - standard deviations of wind components
From sonic temperature fluctuations: - Obukhov length - friction velocity - sensible heat flux
Analog sensors: air temperature, humidity
Vapour pressure deficit: VPD = esat – ecurr

6. Phenological observations
Martin Piringer et al.
Phenological observations
all trees (487) within a radius of ~ 50 m around the tower have been identified, marked, measured and mapped (in progress)
During flowering and flushing – every 2-4 days, all trees were visually surveyed for the status of flowering and flushing
 To determine exactly which tree flowered at which day

7. Martin Piringer et al.
Pollen counts
A new vertical pollen collector which allows continuous sampling of pollen from all directions with high temporal resolution has been developed
The spore trap comprises a chamber into which air is drawn through the top of the trap with the aid of a fan.
A small part of air-stream impacts on a slowly rotating drum, which is operated by a clockwork mechanism to revolve once every seven days, every two days or every day.
The drum is covered by a transparent plastic tape, which is coated with vaseline, on which airborne particles are trapped.
The tape is replaced every week and then cut into seven sections and mounted for microscopy.
top of the trap
chamber
drum

8. Example of pollen transport to the area
Martin Piringer et al.
Example of pollen transport to the area
ECMWF backwards trajectories arriving on at 0:00 UTC (yellow),
3:00 UTC (green) and 6:00 Uhr (red)

9. All backwards trajectories 925 hPa, Norway spruce
Martin Piringer et al.
All backwards trajectories 925 hPa, Norway spruce
Trees flowering and pollen measured
on site
Trees not flowering, but pollen
measured on site

10. Meteorological analysis of measured pollen concentrations (I)
Martin Piringer et al.
Meteorological analysis of measured pollen concentrations (I)
VPD = esat – ecurr
esat = saturation vapour pressure
ecurr = actual vapour pressure

11. Meteorological analysis of measured pollen concentrations (II)
Martin Piringer et al.
Meteorological analysis of measured pollen concentrations (II)
VPD = esat – ecurr
esat = saturation vapour pressure
ecurr = actual vapour pressure

12. Dispersion of pollen: outline of method
Martin Piringer et al.
Dispersion of pollen: outline of method
Lagrange particle diffusion model LASAT
Met. Input: Time series of wind direction, wind speed, MOL, standard deviations of the wind components from the upper platform of the tower
Pollen emission rates determined via „inverse dispersion technique“
Result: Field of pollen concentrations, averaged over the hours of pollen release (assumption: all measured pollen released in situ, no advection)

13. Pollen transport: results for oak
Martin Piringer et al.
Pollen transport: results for oak

14. Pollen transport: results for Norway spruce
Martin Piringer et al.
Pollen transport: results for Norway spruce

15. Summary and conclusions
Martin Piringer et al.
Summary and conclusions
Special data set of simultaneous pollen and met. measurements at the same levels of a 36 m high tower
Advection of pollen can be explained by analysis of backwards trajectories
Vertical velocity determines pollen spread within the canopy
VPD influences pollen release; also important: stand. dev. of wind components, wind speed
Modelling pollen transport: most pollen remain within study area due to low wind speeds and good vertical mixing on pollen release days

16. Thank you very much for your attention!
Martin Piringer et al.
Thank you very much for your attention!