1. Ecology of Apium repens
University of Hamburg
Ecology of Apium repens
Germination and survival of Apium repens in „coastal conditions“
Antonia Wanner, Sandra Burmeier, Jan Schwerdtfeger & Kai Jensen
WG Applied Plant Ecology, Biocentre Klein Flottbek, University of Hamburg
LIFE BaltCoast – Final Seminar
Department of Biology

2. Outline Apium repens: Who is it? Biology Distribution and threat
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Outline
Apium repens: Who is it?
Biology
Distribution and threat
Guiding questions
Habitat requirements
Hydrology
Soil conditions
Experimental ecology
Interspecific competition
Field: Herbivory and vegetation gaps
Germination, dormancy, dispersal
(Re)Introduction: Establishment of new populations
Experimental design
Establishment success
Conclusions

3. In Schleswig-Holstein only one recent population!
Ausblick
Ansiedlung
Standort
Ökologie
Einleitung
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Apium repens: Who is it?
Characteristics
Perennial, evergreen Umbellifer
10-30 cm height
Reproduction by seeds and runners
Threat and protection status
Has always been rare
Pronounced decline in the last decades
Listed in Annex II & IV of the Habitats Directive, Red Lists (D and SH: 1 = threatened with extinction), legally protected in D
Range
in Europe from GB to Portugal
Germany: 4 main areas of distribution
In Schleswig-Holstein only one recent population!
(Status in 2006) 3

4. Guiding questions Is Apium repens rare due to
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Guiding questions
Is Apium repens rare due to
…specific habitat requirements?
…low competitive ability?
…narrow regeneration niche?
…dispersal limitation?
How can we protect present populations?
(How) can we establish new populations? 4

5. Site conditions: Hydrology, soil parameters
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Site conditions: Hydrology, soil parameters
Hydrology: Groundwater levels
Fehmarn, Sundwiesen
Groundwater logger, 1 year
Soil parameters
20 populations in Northern Germany
pH, carbon content, macro nutrients
Ellenberg Indicator values
85 vegetation relevés from Northern Germany
Weighted means of the vegetation vs. Apium repens 5

6. Site conditions: groundwater levels
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Site conditions: groundwater levels
Strong fluctuations during the year
Several weeks of submergence in spring
Summer water level: 40 to 50 cm below ground
Burmeier & Jensen (2009) 6

7. Site conditions: Soil parameters
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Site conditions: Soil parameters
pH-value ± neutral
Narrow C/N-ratio
Wide range of carbon and nutrient contents
Burmeier & Jensen (2009) 7

8. Site conditions: Ellenberg Indicator values
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Site conditions: Ellenberg Indicator values
L- and N- values of Apium high, higher than that of the vegetation
High range of F- and N-values of the vegetation
Weighted mean Ellenberg value
Burmeier & Jensen (2009)
LIFE BaltCoast – Final Seminar 8

9. Site conditions: Summary
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Site conditions: Summary
Edaphic requirements rather unspecific
Characteristic factors:
Disturbance (Grazing, mowing, wave action, camping….)
Fluctuating water levels
Habitat requirements not very specific 9

10. Experimental ecology: competition, establishment
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Experimental ecology: competition, establishment
Apium repens under „coastal conditions“? Flooding and salinity tolerance
Water regime: fresh vs. brackish water (10‰)
Submergence: 0, 2, 4, 8, 2x2 weeks
Disturbance and interspecific competition
Disturbance regime: mowing vs. control
Competition with Ranunculus repens
Establishment in the field
Transplant experiment on the island Fehmarn
Vegetation gaps (yes/no) and herbivory (yes/no) 10

11. Experimental ecology: Flooding tolerance
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Experimental ecology: Flooding tolerance
Submergence by freshwater is tolerated (but: loss of vitality!)
Submergence by saltwater (10‰) leads to death
Burmeier & Jensen (2009) 11

12. Experimental ecology: disturbance and competition
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Experimental ecology: disturbance and competition
Competition by R. repens and disturbance by mowing reduce biomass of A. repens
No interaction between factors
Burmeier & Jensen (2009) 12

13. Experimental ecology: Establishment in the field
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Experimental ecology: Establishment in the field
Closed vegetation canopy
yes no
yes
n = 25
n = 25
Grazing no
n = 25
n = 25 13

14. Experimental ecology: Establishment in the field
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Experimental ecology: Establishment in the field
No significant differences between the groups, but
Initially higher mortality of grazed plants
Later, higher mortality of ungrazed plants
Burmeier & Jensen (2009) 14

15. Flooding, competition: Summary
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Flooding, competition: Summary
Apium repens under „coastal conditions“?
Very tolerant to submergence,
but not by salt water (long-term)
Competition:
Apium repens depends on disturbances
 Low competitive ability! 15

16. Experimental ecology: Germination & dispersal
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Experimental ecology: Germination & dispersal
Temperature requirements
Thermogradient-Incubator
7 levels of temperature (from 5 °C to 35 °C)
Dormancy and light requirements
Stratification (cold-wet treatment, yes/no), light (yes/no)
Constant vs. fluctuating temperature (15, 20, 5/15, 10/20 °C)
Flooding tolerance of germination
4 flooding regimes + control
1 x 0,5; 1 x 1; 1 x 2; 2 x 1 weeks
Dispersal ecology: Seed bank, seed buoyancy 16

17. Germination ecology: Temperature requirements
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Germination ecology: Temperature requirements
Germination at °C
Optimum at 20°C
Reduction at high (and low) temperatures
Burmeier & Jensen (2008) 17

18. Germination ecology: Fluctuating temperatures
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Germination ecology: Fluctuating temperatures
Seeds with primary dormancy show reduced germination at constant temperature
Burmeier & Jensen (2008) 18

19. Germination ecology: Dormancy and light requirement
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Germination ecology: Dormancy and light requirement
Light requirement with primary dormancy
Dormancy is broken by cold-wet stratification
Stratified seeds do not need light for germination
Burmeier & Jensen (2008) 19

20. Germination ecology: Flooding tolerance
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Germination ecology: Flooding tolerance
Gemination possible during flooding
Highest germination at constant conditions
Burmeier & Jensen (2008) 20

21. Regeneration ecology: Summary
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Regeneration ecology: Summary
Cold-wet statification or light is required for germination
Also germinate during or after flooding
 Germination requirements not highly specific
Seed bank:
Viable seeds were found in the top soil (-5/-10 cm depth)
 at least short-term persistent seed bank
Dispersal:
Seeds can float > 50 days (in the greenhouse), but sink with heavy rainfall
sites mostly near small (vernal) water bodies
 short-distance dispersal by water (also ramets)
Seed production limited (?)
Dispersal limition (?) 21

22. How can we protect present populations?
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
How can we protect present populations?
Maintain (or improve) hydrology
Maintain disturbance regime
Create gaps in autumn to enhance autumn germination (?) 22

23. Establishment of new populations
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Establishment of new populations
3 Sites close to the island of Fehmarn
Eichholzniederung (EH), Hohwacht (HW), Neustädter Binnensee (NB)
Planting in 2007 (EH, HW) and 2008 (NB)
Experimental design
Creation of small water bodies in large-scale grazing landscapes
Grazing (yes/no)
Each 3 transects along a hydrological gradient
3 „plant types“ (seedlings, runners, sods)
Planting of 200 individuals per site
Monitoring
Monthly monitoring between May and October 2007 to 2010 23

24. Establishment of new populations: Sites
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Establishment of new populations: Sites
Eichholzniederung
Fehmarn
Sundwiesen
Hohwacht
Neustädter Binnensee 24

25. Establishment of new populations: Experimental design
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Establishment of new populations: Experimental design
Hohwacht
small water body
Kleingewässer
fence
Eichholzniederung 25

26. Grazing and cover 2007 Cover on 25x25 cm² [%] Hohwacht
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Grazing and cover 2007
June 2007
July 2007
August 2007
September 2007
October 2007
June
July
August
Sept.
October
Hohwacht
Cover on 25x25 cm² [%]
Eichholz-niederung
ungrazed
grazed 26

27. Hydrology and cover 2007 Cover on 25x25 cm² [%] Hohwacht
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Hydrology and cover 2007
June 2007
July 2007
August 2007
September 2007
October 2007
Juni
Juli
August
Sept.
Oktober
Hohwacht
Cover on 25x25 cm² [%]
Eichholz-niederung
1: high
5: low 27

28. Plant type and cover 2007 Cover on 25x25 cm² [%] Hohwacht
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Plant type and cover 2007
June 2007
July 2007
August 2007
September 2007
October 2007
Juni
Juli
August
Sept.
Oktober
Hohwacht
Cover on 25x25 cm² [%]
Eichholz-niederung
1: Seedlings
2: Runners
3: „Sods“ 28

29. Cover from 2007 to 2010 Cover on 25x25 cm² [%] Hohwacht
Conclusions
(Re)Introduction
Experimental ecology
Habitat
Introduction
Cover from 2007 to 2010
2007
2008
2009
2010
Hohwacht
Eichholz-niederung
Cover on 25x25 cm² [%]
Neustädter Binnenwasser
not planted yet
ungrazed
grazed 29

30. Conclusions Is Apium repens rare due to
Experimental ecology
Habitat
Introduction
(Re)Introduction
Conclusions
Is Apium repens rare due to
…specific habitat requirements? No
…low competitive ability? Yes
…narrow regeneration niche? No
…dispersal limitation? Probably
How can we protect present populations?
 Maintain hydrology and disturbances
(How) can we establish new populations?
Yes, we can…. (sometimes)
With seedlings, runners or sods
With appropriate hydrology and disturbance regime 30

31. Thank you for your attention!
Conclusions
Experimental ecology
Habitat
Introduction
(Re)Introduction
Thank you for your attention!
Apium repens!
A. Wanner, S. Burmeier, J. Schwerdtfeger & K. Jensen
LIFE BaltCoast – Final Seminar

32. Site conditions: Soil parameters
pH-value ± neutral
Narrow C/N-ratio
High range of C and nutrient contents fluctuate/deviate strongly
Burmeier & Jensen (2009) 32

33. Germination ecology: Dormancy and light requirement
Light requirement with primary dormancy
Dormancy is broken by cold stratification
Stratified seeds without light requirement for germination
Burmeier & Jensen (2008) 33

34. NNA – Wiederansiedlung von Tier- und Pflanzenarten
Ausblick
Ansiedlung
Standort
Ökologie
Einleitung
K. Jensen & S. Burmeier
NNA – Wiederansiedlung von Tier- und Pflanzenarten
Grazing and cover 2008
Hohwacht
Juni
Juli
August
Septem.
Oktober
Cover on 25x25 cm² [%]
Eichholz-niederung
ungrazed
grazed 34

35. Summary Site conditions
Conclusions
Experimental ecology
Habitat
Introduction
(Re)Introduction
Summary
Site conditions
Strong fluctuations of groundwater levels, submergence in spring
pH close to 7; narrow C/N-ratio; otherwise unspecific
Competition, disturbance, flooding tolerance
Low competitive ability, depends on disturbances
tolerant against flooding of freshwater
Germination ecology
Germination requirements: primary dormancy, stratification, light requirement, temperature fluctuations, temperature range comparable to other species of Central European wetlands, but:
Germination possible also submerged
Establishment of new populations
Impact of management/grazing/mowing, hydrology and year on establishment success
Plant type not relevant 35

36. THM (Re)Introduction of Apium repens seems possible
Conclusions
Experimental ecology
Habitat
Introduction
(Re)Introduction
THM
(Re)Introduction of Apium repens seems possible
Specific knowledge of population ecology and habitat requirements for (re)introduction projects necessary 36