BIODIVERSITY IN ALPINE PONDS: AN INDICATOR OF CLIMATE WARMING?
Beat Oertli1 , Véronique Rosset1 & Anthony Lehmann2
University of Applied Sciences Western Switzerland EIL, hepia, Department of Nature Management, CH -1254 Jussy-Geneva, Switzerland
1
[email protected]
University of Geneva Climatic change and climate impacts research, CH - 1227 Carouge, Switzerland 2
Context Climate warming has (and will have) an impact on biodiversity worldwide (Thomas et al. 2004, Nature 411) : For example: Species distribution shifts: upwards and northwards Crocothemis erythrea
40 35 30
%
25
Coenagrion puella
20
2005
15 10
Changes in phenology
5 0 J
F
M
A
M
J
J
A
S
O
N
D
Upslope distribution shifts of species range
¾ For cold stenoterm species •
Ex.: Dragonfly A. caerulea
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)
¾ 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 treeline ecotones have been reported from North America, Scandinavia and Siberia. 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
www.wsl.ch/forschung/forschungsprojekte/treeline_ural
Upslope distribution shifts: advance of treelines
Consequence: change in biodiversity altitudinal patterns
From Gaston & Spicer 1998. Biodiversity, An Introduction.
Present trend (althought exceptions): 9Decreasing regional species richness with increasing altitude •A shift is expected in the future •On-going research focuses on the regional scale •Little is known about consequences on local diversity (e.g. ecosystem species richness)
At the local scale: increase in species number ¾ Example: Vascular plants in the High Alps (2900 to 3450 m): Plant species richness already has increased.
Mean of 362 quadrats (1 x 1 m)
12.7 species
11.4 species
¾ 43% of species expanded to new plots (5% decreased) Example: Gnaphalium supinum: from 38 plots to 112 plots
Pauli et al. 2007; Global Change Biology 13
Photo: www.flogaus-faust.de
10 years
Local scale investigated here: the pond What is a pond? Pond: a definition
www.europeandponds.org
9A small waterbody 9Size: from one metre squared to a few hectares 9Depth: from a few centimetres to many metres 9Some hold water all year round, but many go through cycles of wetting and drying 9Origin: either man-made or natural
Forel (1904): « a pond is a lake, lacking its aphotic zone » (Oertli et al. 2005, Aquatic Conservation 15)
Ponds are exceptionally numerous!
Have been forgotten in global assessments • Downing et al. (2006) have estimated their number: – > 300 millions – total surface : 1,7 millions de km2 Downing et al. 2006. Limnol.Oceanogr. 51: 2388-2397
How many ponds in Switzerland? Digital map VECTOR25 (topic « lakes » )
- 365 lakes (> 5 ha) - 32’000 ponds (size between 100 m2 and 5 ha)
Areas with highest pond density in the Swiss Alps (20 to 30 ponds /km2)
« In Hublen » (around Seebodensee), Sustenpass BE
Macun, Swiss National Park (GR)
Grimselpass , Totesee(Oberwald, Rhonegletscher, VS)
Glacier et Lapies de Tsanfleuron(Les Diablerets, Savièse-Sion, VS)
Minssieux 2009, in prep.
Natural origins in the alps ¾last glacial retreat
¾snow melting
Le Mongeron, FR
Macun, GR
¾ fluvial dynamic Arvins, GR
Ponds: models for assessing biodiversity changes Ponds as a model because: 9
Low α diversity. Small → Simple community structure (De Meester et al. 2005,
Aquat. Conserv. 15),
particularly in altitude.
9
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 large
contribution to the regional diversity. Freshwater biodiversity is particularly endangered (Dudgeon et al. 2006, Biol. Rev. 81)
9
Extremely numerous and largely distributed in the landscape: “= replicates” Two main questions on alpine pond biodiversity : 1. 2.
Are quantitative changes expected (increase in species richness)? 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 range of thermal conditions 9 Pond size: from 30 to 80’000 m2 9 Altitude: from 250 to 2800 m.asl
Switzerland
Field sampling & modelisation (GAMs) Biodiversity (species richness)
Environmental variables (15 selected from 100)
Aquatic vegetation Snails
Pond morphometry - Area
Environment - Connectivity
- Shoreline shade - Mean depth - Shoreline development
- Agriculture in watershed - % environment forested
Biology
GAMs Beetles
Climate - Mean annual air T°
- Floating/submerged vegetation coverage (%) - Fishes
Water physico-chemistry Dragonflies (adults)
Amphibia
- Conductibility - Trophy - Transparency
Others - Age
- Standardized field sampling based on the PLOCH method (Oertli et al. 2005, Aqu. Conserv.) - Modelling: GAMs. GRASP (Lehmann et al. 2003, Ecological Modelling 157)
Predictive models have been developed and used For each pond, 3 predictions for 2100:
nr 1
Increase in temperature (scenario A2) Changes in six other environmental variables:
nr 2
nr 3
+ 3.4 °C no
Proportion of agriculture in the catchment area
min
max
IN
Proportion of pond area covered by floating vegetation Proportion of pond area covered by submerged vegetation Trophic class based on P, N and conductivity
GAMs MODELS
Water transparency in summer (Snell tube) Conductivity (winter measures) (variables expected to change during this century)
OUT Predicted species richness for 2100
Predictions of potential changes in local diversity + + + (pond species richness)
+
Pond diversity will clearly increase with climate warming.
In the whole Switzerland:
87 to 104%
predictions Rosset et al. (2008) Verh Int Assoc Limnol. 30 Rosset et al. (submitted)
The increase will be particularly high in altitude. +
+
32 to 75% n = 55
+
+
77 to 136% n = 27
73 to 170% n = 15
135 to 478% n = 16
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 pond
Dragonflies: the winners and the losers in alpine ponds
Aeshna caerulea
Source of information: Swiss data bank (CSCF & CRSF) + taxonomic specialists
Thermal gradient Lowland
Mountain
Dragonflies: 7 losers (at risk of local extinction) 12% of Swiss species pool Aeshna juncea
Coenagrion hastulatum www.pbase.com/stureh
Aeshna caerulea Aeshna subarctica
Somatochlora alpestris
Leucorrhinia dubia
Somatochlora artica
Dragonflies: the winners (colonisation is soon expected) 9 species, but all other lowland species on a longer term (88% CH)
E.cyathigerum L. quadrimaculata
Aquatic vegetation: 11 losers (5%) Thermal preferences of flora species
Carex frigida
Epilobium alsinifolium
http://www.florealpes.co m
http://www.plant-identification.co.uk
Eriophorum scheuchzeri www.digitalnature.org/flora
Juncus filiformis http://edu.taivalkoski.fi
http://papounet.wifeo.com
Sparganium angustifolium Saxifraga stellaris
http://www.plant-identification.co.uk
Source of information: Swiss data bank (CSCF & CRSF) + taxonomic specialists
Aquatic beetles: 6 losers (5%) Hydroporus foveolatus
Ilybius erichsoni
-Ilybius erichsoni -Agabus lapponicus -Stictotarsus griseostriatus -Hydroporus foveolatus -Hydroporus nigellus -Hydroporus sabaudus From: www.zin.ru
Source of information: taxonomic specialists
Groups with only winners Snails
Snails and Amphibia: no cold stenotherm species
Amphibia
Thermal gradient Lowland
Mountain
Source of information: Swiss data bank (CSCF & CRSF) + taxonomic specialists
In syntheses: more winners than losers in altitude •
More colonization events than extinctions are expected. Candidates for extinctions: • A minority of the current Swiss regional species pool.
5%
0%
0%
5%
12%
95%
88% 100%
Candidates for colonizations: • The majority of the current Swiss regional species pool • They are readily available.
95% 100% From: www.countrysideinfo.co.uk
Enallagma cyathigerum
Nymphoides peltata
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 …)
Perspectives • Pond diversity constitutes an excellent sentinel system for monitoring climate warming effects at the local scale. → Should be used as a bioindicator of climate warming in long-term monitoring Ex: Swiss National Park - Monitored since 2002 !( !( !(
805
- 36 ponds - 3 streams •
806
179
!( 200
Plan de situation © MVA Grison
100
0
200 Mètres
±
On-going monitoring in the Swiss National Park
M8t
M15
M20 Robinson & Oertli 2009, eco.mont 1
Magnitude of the regional richness (Macun cirque): Compared with lowland ponds… … a particularly low richness (at species or family level)
38 len ti c t ax 17+4 a 2
7
Swiss lowland ponds
6 1
Macun ponds
1
“Thanks for your attention”
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
