LIFE BaltCoast – Final Seminar

LIF

E B

altC

oast

– F

inal

Sem

inar

Department of Biology

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 [email protected]

[email protected]

28.08.12A. Wanner, S. Burmeier, J. Schwerdtfeger & K. Jensen

LIFE BaltCoast – Final Seminar

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

Conclusions(Re)IntroductionExperimental ecologyHabitatIntroduction



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)

AusblickAnsiedlungStandortÖkologieEinleitung Conclusions(Re)IntroductionExperimental ecologyHabitatIntroduction



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?




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




Strong fluctuations during the year

Several weeks of submergence in spring

Summer water level: 40 to 50 cm below ground

Burmeier & Jensen (2009)

Site conditions: groundwater levels

07-0

5

08-0

5

09-0

5

10-0

5

11-0

5

12-0

5

01-0

6

02-0

6

03-0

6

04-0

6

05-0

6

06-0

6

Date

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

Gro

undw

ater

leve

l (m

)





Site conditions: Soil parameters

pH-value ± neutral Narrow C/N-ratio Wide range of carbon and nutrient contents




L T K F R N S

0

2

4

6

8

10

Parameter

Indi

cato

r val

ue

*

*

*

* * *

*


Site conditions: Ellenberg Indicator values

Wei

ghte

d m

ean

Elle

nber

g va

lue

L- and N- values of Apium high, higher than that of the vegetation

High range of F- and N-values of the vegetation


28.08.12LIFE BaltCoast – Final Seminar



Site conditions: Summary

• Edaphic requirements rather unspecific• Characteristic factors:

– Disturbance (Grazing, mowing, wave action, camping….)

– Fluctuating water levels Habitat requirements not very specific




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)




Experimental ecology: Flooding tolerance


• Submergence by freshwater is tolerated (but: loss of vitality!)

• Submergence by saltwater (10‰) leads to death




Experimental ecology: disturbance and competition


Competition by R. repens and disturbance by mowing reduce biomass of A. repens

No interaction between factors




Experimental ecology: Establishment in the field

Closed vegetation canopyyes no

n = 25

n = 25 n = 25

n = 25

Gra

zing

yes

no




No significant differences between the groups, but

Initially higher mortality of grazed plants

Later, higher mortality of ungrazed plants


0

20

40

60

80

100

0 2 4 6 8 10

Time after transplantation (weeks)

Cum

ulat

ive

surv

ival

(%)

exposed/gap

exposed/no gap

covered/gap

covered/no gap

χ² = 1.13, df = 4, p = 0.77

0

20

40

60

80

100

0 2 4 6 8 10

Time after transplantation (weeks)

Cum

ulat

ive

surv

ival

(%)

exposed/gap

exposed/no gap

covered/gap

covered/no gap

χ² = 1.13, df = 4, p = 0.77

Experimental ecology: Establishment in the field




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!




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




Germination ecology: Temperature requirements

Germination at 5 - 35 °C Optimum at 20°C Reduction at high (and

low) temperatures





Germination ecology: Fluctuating temperatures


Seeds with primary dormancy show reduced germination at constant temperature




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





Germination ecology: Flooding tolerance


Gemination possible during flooding

Highest germination at constant conditions




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 (?)




How can we protect present populations?

• Maintain (or improve) hydrology• Maintain disturbance regime • Create gaps in autumn to enhance

autumn germination (?)




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




Establishment of new populations: Sites

Neustädter Binnensee

Hohwacht

Eichholzniederung FehmarnSundwiesen




Establishment of new populations: Experimental design

B 1

2

34

5

6

P

GPS 1GPS 2

Teich

Zaun

Kleingewässer

Hohwacht

Eichholzniederung


small water body

fence



Grazing and cover 2007C

over

[%]

Hoh

wac

ht

0

10

20

30

40

50

60

70

80

90

Eich

holz

nied

erun

g

fenced unfenced0

10

20

30

40

50

60

70

80

90

fenced unfenced fenced unfenced fenced unfenced fenced unfenced

June 2007 July 2007 August 2007 September 2007 October 2007

Cov

er o

n 25

x25

cm² [

%]

Eichholz-niederung

HohwachtJune July August Sept. October

ungrazedgrazed




Position along the hydrologic gradient

Cov

er [%

]H

ohw

acht

0

20

40

60

80

100

Eich

holz

nied

erun

g

1 2 3 4 50

20

40

60

80

100

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5


Hydrology and cover 2007C

over

on

25x2

5 cm

² [%

]

Eichholz-niederung

HohwachtJuni Juli August Sept. Oktober

1: high5: low




Plant type

Cov

er [%

]H

ohw

acht

0

10

20

30

40

50

60

70

80

90

Eic

hhol

znie

deru

ng

1 2 30

10

20

30

40

50

60

70

80

90

1 2 3 1 2 3 1 2 3 1 2 3


Plant type and cover 2007C

over

on

25x2

5 cm

² [%

]

Eichholz-niederung

HohwachtJuni Juli August Sept. Oktober

1: Seedlings

2: Runners

3: „Sods“




Cov

er o

f A

pium

repe

ns [%

]Lo

catio

n: H

owac

ht

0

20

40

60

80

100

Loca

tion:

Eic

hhol

z

0

20

40

60

80

100

Year: 2007

Loca

tion:

Neu

stad

t

grazed ungrazed0

20

40

60

80

100

Year: 2008

grazed ungrazed

Year: 2009

grazed ungrazed

Year: 2010

grazed ungrazed

Mean ± SE

Cover from 2007 to 2010C

over

on

25x2

5 cm

² [%

]

Eichholz-niederung

Hohwacht2007

ungrazedgrazed

Neustädter Binnenwasser

2008 2009 2010

not planted yet




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

ConclusionsExperimental ecologyHabitatIntroduction (Re)Introduction



Thank you for your attention!

Apium repens!







Site conditions: Soil parameters

pH-value ± neutral Narrow C/N-ratio

High range of C and nutrient contents fluctuate/deviate strongly



Germination ecology: Dormancy and light requirement

Light requirement with primary dormancy Dormancy is broken by cold stratification Stratified seeds without light requirement

for germination


Pre-treatment Light regime Incubation temperature [°C]

Germination percentage

dry storage light 15 88.60 ± 2.23darkness 15 0

light 20 91.78 ± 3.15darkness 20 0

cold stratification light 15 97.43 ± 1.29darkness 15 70.77 ± 6.28

light 20 88.57 ± 4.29darkness 20 80.42 ± 3.40


LIFE BaltCoast – Final SeminarNutzung

Dec

kung

[%]

Loka

lität

: H

ohw

acht

0

10

20

30

40

50

60

70

80

90

Loka

lität

: E

ichh

olz

WeideBrache0

10

20

30

40

50

60

70

80

90

WeideBrache WeideBrache WeideBrache WeideBrache

Grazing and cover 2008C

over

on

25x2

5 cm

² [%

]

Eichholz-niederung

HohwachtJuni Juli August Septem. Oktober

ungrazedgrazed

AusblickAnsiedlungStandortÖkologieEinleitung

09.03.09K. Jensen & S. Burmeier NNA – Wiederansiedlung von Tier- und Pflanzenarten



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




THM

(Re)Introduction of Apium repens seems possible Specific knowledge of population ecology and

habitat requirements for (re)introduction projects necessary


Documents

LIFE BaltCoast – Final Seminar