LIFE BaltCoast – Final Seminar

1. 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 antonia.wanner@uni-hamburg.de kai.jensen@uni-hamburg.de LIFE BaltCoast – Final Seminar Department of Biology

2. Introduction Habitat Experimental ecology (Re)Introduction Conclusions Outline • Apiumrepens: Who isit? • Biology • Distribution andthreat • Guidingquestions • Habitat requirements • Hydrology • Soilconditions • Experimental ecology • Interspecificcompetition • Field: Herbivoryandvegetationgaps • Germination, dormancy, dispersal • (Re)Introduction: Establishment ofnewpopulations • Experimental design • Establishment success • Conclusions

3. Apium repens: Who is it? Einleitung Introduction Ökologie Habitat Experimental ecology Standort Ansiedlung (Re)Introduction Ausblick Conclusions In Schleswig-Holstein only one recent population! (Status in 2006) • Characteristics • Perennial, evergreenUmbellifer • 10-30 cm height • Reproductionbyseedsandrunners • Threatandprotectionstatus • Hasalwaysbeen rare • Pronounceddecline in the last decades • Listed in Annex II & IV ofthe Habitats Directive, Red Lists (D and SH: 1 = threatenedwithextinction), legallyprotected in D • Range • in Europe from GB to Portugal • Germany: 4 mainareasofdistribution

4. Guiding questions Introduction Habitat Experimental ecology (Re)Introduction Conclusions • IsApiumrepensrare due to • …specifichabitatrequirements? • …lowcompetitiveability? • …narrowregenerationniche? • …dispersallimitation? • Howcanweprotectpresentpopulations? • (How) canweestablishnewpopulations?

5. Site conditions: Hydrology, soil parameters Introduction Habitat Experimental ecology (Re)Introduction Conclusions • 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

6. Introduction Habitat Experimental ecology (Re)Introduction Conclusions 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)

7. Introduction Habitat Experimental ecology (Re)Introduction Conclusions Site conditions: Soil parameters • pH-value ± neutral • Narrow C/N-ratio • Wide rangeofcarbonandnutrientcontents Burmeier & Jensen (2009)

8. Introduction Habitat Experimental ecology (Re)Introduction Conclusions 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 28.08.12

9. Introduction Habitat Experimental ecology (Re)Introduction Conclusions Site conditions: Summary • Edaphicrequirementsratherunspecific • Characteristicfactors: • Disturbance(Grazing, mowing, waveaction, camping….) • Fluctuatingwaterlevels • Habitat requirements not veryspecific

10. Experimental ecology: competition, establishment Introduction Habitat Experimental ecology (Re)Introduction Conclusions • 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)

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

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

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

14. Introduction Habitat Experimental ecology (Re)Introduction Conclusions 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)

15. Flooding, competition: Summary Introduction Habitat Experimental ecology (Re)Introduction Conclusions • Apiumrepensunder „coastalconditions“? • Very tolerant tosubmergence, • but not bysaltwater(long-term) • Competition: • Apiumrepensdepends on disturbances •  Low competitiveability!

16. Experimental ecology: Germination & dispersal Introduction Habitat Experimental ecology (Re)Introduction Conclusions • 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

17. Germination ecology: Temperature requirements Introduction Habitat Experimental ecology (Re)Introduction Conclusions • Germination at 5 - 35 °C • Optimum at 20°C • Reduction at high (and low) temperatures Burmeier & Jensen (2008)

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

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

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

21. Regeneration ecology: Summary Introduction Habitat Experimental ecology (Re)Introduction Conclusions • Cold-wetstatificationor light isrequiredforgermination • Also germinateduringor after flooding •  Germination requirements not highlyspecific • Seedbank: • Viableseedswerefoundin the top soil (-5/-10 cm depth) •  atleast short-term persistent seedbank • Dispersal: • Seedscanfloat> 50 days (in thegreenhouse), but sink withheavy rainfall • sitesmostlynearsmall (vernal) waterbodies •  short-distancedispersalbywater (also ramets) • Seedproduction limited (?) • Dispersallimition (?)

22. Introduction Habitat Experimental ecology (Re)Introduction Conclusions How can we protect present populations? • Maintain (orimprove) hydrology • Maintaindisturbanceregime • Create gaps in autumntoenhanceautumngermination (?)

23. Establishment of new populations Introduction Habitat Experimental ecology (Re)Introduction Conclusions • 3 Sites closetotheislandof Fehmarn • Eichholzniederung (EH), Hohwacht (HW), Neustädter Binnensee (NB) • Planting in 2007 (EH, HW) and 2008 (NB) • Experimental design • Creationofsmallwaterbodies in large-scalegrazinglandscapes • Grazing (yes/no) • Each 3 transectsalong a hydrologicalgradient • 3 „plant types“ (seedlings, runners, sods) • Plantingof 200 individuals per site • Monitoring • Monthlymonitoringbetween May andOctober 2007 to 2010

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

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

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

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

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

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

30. Conclusions Introduction Habitat Experimental ecology Conclusions (Re)Introduction • IsApiumrepensrare due to • …specifichabitatrequirements? No • …lowcompetitiveability? Yes • …narrowregenerationniche? No • …dispersallimitation? Probably • Howcanweprotectpresentpopulations? •  Maintainhydrologyanddisturbances • (How) canweestablishnewpopulations? • Yes, wecan…. (sometimes) • Withseedlings, runnersorsods • Withappropriatehydrologyanddisturbanceregime

31. Introduction Habitat Experimental ecology Conclusions (Re)Introduction Apium repens! Thank you for your attention! A. Wanner, S. Burmeier, J. Schwerdtfeger & K. Jensen LIFE BaltCoast – Final Seminar 28.08.12

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)

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)

34. Grazing and cover 2008 Einleitung Ökologie Standort Ansiedlung Ausblick K. Jensen & S. Burmeier NNA – Wiederansiedlung von Tier- und Pflanzenarten 09.03.09 Hohwacht Juni Juli August Septem. Oktober Cover on 25x25 cm² [%] Eichholz-niederung ungrazed grazed

35. Summary Introduction Habitat Experimental ecology Conclusions (Re)Introduction • 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

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