BIODIVERSITY IN ALPINE PONDS: AN INDICATOR OF CLIMATE WARMING?

Beat Oertli1 , Véronique Rosset1 & Anthony Lehmann2

11 University of Applied Sciences Western Switzerland University of Applied Sciences Western Switzerland EIL, EIL, hepiahepia, Department of Nature Management, , Department of Nature Management, CH CH --1254 1254 JussyJussy--Geneva, Switzerland Geneva, Switzerland bbeat.oertlit@hesge.cheat.oertlit@hesge.ch

2 University of Geneva Climatic change and climate impacts research,

CH - 1227 Carouge, Switzerland

ContextContext

Climate warming has (and will have) an impact on biodiversityworldwide (Thomas et al. 2004, Nature 411) :

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For example:Species distribution shifts: upwards and northwards

Changes in phenology

Crocothemiserythrea

Coenagrion puella

For cold stenoterm species

• Reasons for this move: – in direct response to

increasing temperature (Parmesan & Yohe, 2003; Root et al., 2003),

– or in combination with other changes (Pounds et al., 1999; Still et al., 1999)

UpslopeUpslope distribution shifts of distribution shifts of speciesspecies rangerange

Ex.: Dragonfly A. caerulea

Evidences from several mountain systems

• In Russia, subalpine forests have shifted upwards by 60-80 m in the Southern Urals (lasts 70 years) (Moiseev & Shiyatov 2003)

• Similar up- and northward shifts of treelineecotones have been reported from NorthAmerica, Scandinavia and Siberia.

Upslope distribution shifts: advance of treelines

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Historic photographs of treelines in the Southern Ural (1929, below 1999).Source: Stepan Shiyatov

Potential increase in the elevation of the tree line, assuming a 4·5 °C rise in temperature over 100 years .Grace et al. 2002, Annals of Botany 90

ConsequenceConsequence: change in : change in biodiversitybiodiversity altitudinal patternsaltitudinal patterns

Present trend (althought exceptions):Decreasing regional species richness with increasing altitude

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n. •A shift is expected in the future

•On-going research focuses on the regionalscale

•Little is known about consequences on local diversity (e.g. ecosystem species richness)

AtAt the local the local scalescale: : increaseincrease in in speciesspecies numbernumber

Example: Vascular plants in the High Alps (2900 to 3450 m): Plant species richness already has increased.

11.4 species 12.7 species

10 years

Mean of 362 quadrats(1 x 1 m)

Pauli et al. 2007; Global Change Biology 13

43% of species expanded to new plots (5% decreased)

Example: Gnaphalium supinum: from38 plots to 112 plots

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Local scale investigated here: the pond Local scale investigated here: the pond

Pond: a definitionA small waterbodySize: from one metre squared to a few hectares Depth: from a few centimetres to many metresSome hold water all year round, but many go through

cycles of wetting and dryingOrigin: either man-made or natural

www.europeandponds.org

(Oertli et al. 2005, Aquatic Conservation 15)

Forel (1904): « a pond is a lake, lacking its aphotic zone »

What is a pond? What is a pond?

Ponds are exceptionally numerous! Ponds are exceptionally numerous!

Downing et al. 2006. Limnol.Oceanogr. 51: 2388-2397

Have been forgotten in global assessments

• Downing et al. (2006) have estimated their number:

– > 300 millions– total surface : 1,7

millions de km2

How How manymany ponds in ponds in SwitzerlandSwitzerland??

- 32’000 ponds (size between 100 m2 and 5 ha)

- 365 lakes (> 5 ha)

Digital mapVECTOR25

(topic« lakes » )

Areas with highest pond density in the Swiss AlpsAreas with highest pond density in the Swiss Alps(20 to 30 ponds /km(20 to 30 ponds /km22))

« In Hublen » (aroundSeebodensee), Sustenpass BE

Grimselpass , Totesee(Oberwald, Rhonegletscher, VS)

Macun, SwissNational Park (GR)

Minssieux 2009, in prep.

Glacier et Lapies de Tsanfleuron(Les Diablerets, Savièse-Sion, VS)

Natural origins in the alpsNatural origins in the alps

last glacial last glacial retreatretreat

Le Mongeron, FR

snowsnow meltingmelting

Macun, GR

fluvial fluvial dynamicdynamic

Arvins, GR

Ponds: Ponds: modelsmodels for for assessingassessing biodiversitybiodiversity changeschanges

Ponds as a model because:

Low α diversity. Small → Simple community structure (De Meester et al. 2005, Aquat. Conserv. 15),particularly in altitude.

High β and γ diversities (Oertli et al. 2002, Biol. Conserv. 104; Williams et al.2004, Biol.Conserv. 115; Angélibert et al. 2006, Arch. Sc. 59), i.e. with a largecontribution to the regional diversity.

Freshwater biodiversity is particularlyendangered (Dudgeon et al. 2006, Biol. Rev. 81)

Extremely numerous andlargely distributed in the landscape: “= replicates”

Two main questions on alpine pond biodiversity :1. Are quantitative changes expected (increase in species richness)?2. Are qualitative changes expected? Which would be the losers and/or winners,

i.e. the species changes in the communities?

Study sites: about 100 ponds, covering a large Study sites: about 100 ponds, covering a large range of thermal conditionsrange of thermal conditions

Switzerland

Pond size: from 30 to 80’000 m2

Altitude: from 250 to 2800 m.asl

- Standardized field sampling based on the PLOCH method (Oertli et al. 2005, Aqu. Conserv.)

Field sampling & modelisation (GAMs)

Biodiversity (species richness)

Aquatic vegetation

Snails

Beetles

Dragonflies (adults)

Amphibia

Environment- Connectivity- Agriculture in watershed- % environment forested

Environmental variables (15 selected from 100)

Pond morphometry- Area- Shoreline shade- Mean depth- Shoreline development

Water physico-chemistry- Conductibility- Trophy- Transparency

Others- Age

Biology- Floating/submerged

vegetation coverage (%)- Fishes

Climate- Mean annual air T°

GAMs

- Modelling: GAMs. GRASP (Lehmann et al. 2003, Ecological Modelling 157)

Predictive models have been developed and used

GAMsMODELS

For each pond, 3 predictions for 2100:

IN

OUT

Changes in six otherenvironmental variables:

Predicted species richnessfor 2100

+ 3.4 °C

nr1 nr2 nr3Increase in temperature(scenario A2)

no min max

Conductivity (winter measures)

Water transparency in summer (Snell tube)

Trophic class based on P, N and conductivity

Proportion of pond area covered by submerged vegetation

Proportion of pond area covered by floating vegetation

Proportion of agriculture in the catchment area

(variables expected to change during this century)

Predictions of potential changes in local diversity(pond species richness) + + + +

In the whole Switzerland:

Rosset et al. (2008) Verh Int Assoc Limnol. 30

Rosset et al. (submitted)

Pond diversity will clearly increase with climate warming.

predictions

87 to 104%

The The increaseincrease willwill bebe particularlyparticularly highhigh in altitude.in altitude.

+ + + +

n = 16n = 15

n = 55 n = 27

32 to 75% 77 to 136%

73 to 170% 135 to 478%

predictions predictions

The predicted species enrichment masks changes in species composition (and extinction events)

Colonizations: stenotherm or

eurytherm species(from lower altitudes)

Extinctions: cold stenothermal

species (=« alpine »)

Alpine pondAlpine pond

Aeshna caerulea

DragonfliesDragonflies: the winners and the losers in alpine ponds: the winners and the losers in alpine ponds

Source of information: Swiss data bank (CSCF &

CRSF) + taxonomicspecialists

MountainThermal gradient

Lowland

Dragonflies: 7 losers (at risk of local extinction)

Aeshna caerulea

Somatochlora alpestris

Coenagrion hastulatumwww.pbase.com/stureh

Leucorrhinia dubia

Aeshna juncea

Aeshna subarctica

Somatochlora artica

12% of Swiss species pool

Dragonflies: the winners (Dragonflies: the winners (colonisationcolonisation is soon expected)is soon expected)

E.cyathigerum

L. quadrimaculata

9 species, but all other lowland species on a longer term (88% CH)

Aquatic vegetation: 11 losers (5%)Thermal preferences of flora species

Source of information: Swiss data bank (CSCF & CRSF) + taxonomic specialists

Saxifraga stellaris

http://papounet.wifeo.com

Epilobium alsinifoliumhttp://www.plant-identification.co.uk

Juncus filiformishttp://edu.taivalkoski.fi

Sparganium angustifoliumhttp://www.plant-identification.co.uk

Carex frigidahttp://www.florealpes.com

www.digitalnature.org/flora Eriophorum scheuchzeri

Aquatic beetles: 6 losers (5%)

Source of information: taxonomic specialists

Ilybius erichsoni

From: www.zin.ru

-Ilybius erichsoni

-Agabus lapponicus

-Stictotarsus griseostriatus

-Hydroporus foveolatus

-Hydroporus nigellus

-Hydroporus sabaudus

Hydroporus foveolatus

Mountain

Groups with only winners

Thermal gradient

Snails

Amphibia

Lowland

Source of information: Swiss data bank (CSCF & CRSF) + taxonomic specialists

Snails and Amphibia:no cold stenothermspecies

In syntheses: more winners than losers in altitude

• More colonization events than extinctions are expected.

Candidates for colonizations:• The majority of the currentSwiss regional species pool• They are readily available.

Candidates for extinctions:• A minority of the current Swissregional species pool.

Enallagmacyathigerum

95% 100% 100%88%95%

5% 0% 0%12%5%

Nymphoides peltata

From: www.countrysideinfo.co.uk

In the reality, the pond species enrichment will be lower than predicted, but still high.

• The predictions represent a potential, i.e. the upper range of what might be the future pond diversity.

• The predicted changes will be moderated by other processes, as :

(i) physical changes (including hydrology and availability of habitats)

(ii) colonization and dispersal abilities of species(snails ≠ dragonflies)

(iii) biological interactions(competition, predation …)

PerspectivesPerspectives

• Pond diversity constitutes an excellent sentinelsystem for monitoring climate warming effects atthe local scale.

→ Should be used as a bioindicator of climatewarming in long-term monitoring

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±200 0 200100 MètresPlan de situation © MVA Grison

- 36 ponds - 3 streams

•

- Monitored since 2002

Ex: Swiss National Park

OnOn--goinggoing monitoring in the monitoring in the SwissSwiss National ParkNational Park

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Robinson & Oertli 2009, eco.mont 1

Magnitude of the Magnitude of the regionalregional richnessrichness ((MacunMacun cirque):cirque):

Swiss lowland ponds

… a particularly low richness (at species or family level)

Macun ponds

3838 lentic taxa

lentic taxa17+4

7 1

1

62

Compared with lowland ponds…

““Thanks for your Thanks for your attentionattention””

THANKS ALSO: to the “PLOCH” team (University of Geneva), to the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), to the Swiss Centre for fauna cartography (CSCF) and Swiss Centre of floristic network (CRSF), to the Federal Office for the Environment (OFEV), to many Swiss states, to HES-SO (RCSO RealTech), to the Research Commission of the Swiss National Park