Mountain ecosystems. Challenges in a changing climate

Transcription

1 Mountain ecosystems Challenges in a changing climate Christian Körner Institute of Botany University of Basel, Switzerland European Conference 'Climate Change and Nature Conservation an ecological, policy and economic perspective,, Bonn 25 June 2013

2 Global Change...be realistic, not alarmistic... The Swiss Matterhorn

3 Bioclimatic belts in mountains Nival Snowline Alpine Uplands Treeline Montane Lowlands

4 The alpine and montane life zones across the globe Altitude (km) California Rocky Mts. Alps Scandi- navia Tundra Himalayas Kilimanjaro Mexico Andes Atlas New Guinea Andes Australia New Zealand Tierra del Fuego North Equator South Ch Körner (2003) Alpine plant life. Springer, Berlin

5 Elevation above sea level (m) As elevation increases, area shrinks % 1.7 % 2.7 % Global land area (outside Antarctica) Mio km 2 (=100 %) > 300 m ca. 30 Mio km 2 > 1500 m ca. 11 Mio km 2 > treeline ca. 3.6 Mio km 2 Land area per 100 m elevation steps starting from 1500 m (total = 11 Mio km 2 ). 5.1 % Fraction of land area worldwide above a given elevation (%) C Körner (2007) TREE 22: 569

6 What is a mountain? A B C? 1000 m 300 m We must abandon meters of elevation Ruggedness: 200 m of elevation in a 1.5 x 1.5 pixel = ca 2 km

7 Area of bioclimatic zones in the worldʻs s mountains M Total mountain area (16.5 Mio km 2 = 100%) G total terrestrial area outside Antarctica (134.6 Mio km 2 = 100%) Thermal belts Area M G Mio km 2 % % Nival (<3.5 C, GS <10 d) Upper alpine (<3.5 C, GS >10 d <54 d) Lower alpine <6.4 C, GS <94 d) Treeline Upper montane (>6.4 <=10 C) Lower montane (>10 <=15 C) Remaining mountain area with frost (>15 C) Remaining mountain area without frost (>15 C) Total Ch Körner et al (2011) Alpine Botany 121:73

8 H U M A N S G L O B A L C H A N G E Atmosperic chemistry Climate Land use strat. O 3 CO 2 NO x others dust temperature humidity cloud cover precipitation storms distruction of vegetation soil conversion soil losses (erosion) invasions ground sealing fragmentation of habitats extremes winter summer sum extremes temporal distribution organisms: microbes plants animals H U M A N S

9 What are the global changes which may matter in mountain ecosystems? Climatic warming (and water) N-deposition Elevated CO 2 Land use

10 ppm CO 2 Atmospheric CO 2 Climate effects Direct biological effects Indirect effects

11 No question, there is warming... Glaciers are rapidly melting in the Alps G Patzelt G Patzelt (1999) Nova Acta Leopoldina NF 81: Ch Körner

12 Climatic warming While the cold climate at high elevation had been traded as a major constraint to life, it is now believed that warming is a threat. Obviously, it cannot be both at the same time.

13 Habitat diversity is the regional driver of biodiversity a safeguard against species loss

14

15 Habitat loss due to climate warming Density of probability ( T) ( Lost (3 %) -3 cm soil temperature (270 data logger) Decrease (75 %) Current Future Increase (22 %) New Seasonal mean soil temperature ( C) D Scherrer & Ch Körner (2011) J Biogeogr 38:406

16 Longterm effects of climate warming depend on spatial resolution Surface temperature (IR) bright days and daylight hours only Spatial resolution (m 2 ) 2 K scenario habitat loss (%) 3 K scenario habitat loss (%) 4 K scenario habitat loss (%) 1 x ± ± ± x ± ± ± x ± ± ± x ± ± ± x ± ± ± 0.0 Means for three different slopes, each covering m of elevation in the Alps D Scherrer & Ch Körner (2011) J Biogeogr 38: , see also CF Randin et al (2009) GCB 15:1557

17

18 Refugia: years ago

19 Dom de Mischabel,, 4545 m, Central Swiss Alps 4505 m Outposts of life today The highest plant occurence of Europe The current flora largely survived glaciation in nunataks Ch Körner (2011) Alpine Botany 121:11

20 Saxifraga oppositifolia

21 Hourly soil temperature at -3 cm soil depth ( C) Dom 4545 m, Central Swiss Alps August 5, July 17, 2009 Maximum = 18.1 C (Aug 6, 2008) Minimum = C (Feb 15, 2009) A S O N D J F M A M J J Month in 2008/ Temperature ( C( C) Day in August 2008 Ch Körner (2011) Alpine Botany 121:11 Rel. frequency (%) Temperature during ʻgrowing seasonʼ (days with max T >3 C)

22 Microscopic organisms found in loose substrate under Saxifraga oppositifolia Oribatida mite Collembola (Thalassaphorura zschokkei) Seeds of S.oppositifolia Cleistothecium (ascomycota) Spores of arbuscular mycorrhiza (Glomeromycota) Ch Körner (2011) Alp Botany 121:11 photos by F.Oehl, Reckenholz, Switzerland

23 Season length and climate warming Ch Körner

24 Opportunistic taxa: Grow, whenever possible Soldanella pusilla Ch Körner

25 Photoperiod: Many plants follow their internal calendar irrespective of actual weather Oxyria digyna 12 h 5/10 C 16 h 5/10 C F Keller & Ch Körner (2003) Arc Antarc Alp Res 3:361 Common garden experiment in Basel Taraxacum alpinum Taraxacum officinale Ch Körner (2003) Alpine Plant Life. Springer, Berlin Ch Körner

26 Half of all alpine species exhibit photoperiod control of flowering.

27 Treelines will move

28 Rel. frequency (%) Mean 13.6 ± 0.9 Min 11.5 Max trees 20.6 ± grass Temperature ( C)

29 Relative width of tree rings (age- and site-indexed) Altitudinal distance to the outpost tree line (m) 200 years of tree growth near treeline Pinus cembra, Picea abies (Swiss and Austrian Alps) J Paulsen et al (2000) Arct Antarct Alp Res 32:14 Ch Körner

30 Areal consequences (Mio km 2 ) of an upslope shift of the treeline in response to a 1.1 and 2.2 K climatic warming, assuming the treeline has reached a new steady state. Land cover type Current K (%) +2.2 K (%) Mountain forest (+6.2) (+11.7) Lower alpine (-7.4) 0.68 (-23.5) Upper alpine and nival (-31.4) 1.03 (-54.5) Ch Körner et al (2011) Alpine Botany 121:73 Ch Körner (2012) Alpine treelines. Springer, Berlin Ch Körner

31 Species responses to climatic warming 4 Mountains may be refugia (2, 4) traps (3, 5) or a chance (6) Ch Körner

32 CO 2 -concentration (ppm) Elevated CO Photosynthesis CO 2 - saturation CO 2 -concentration (ppm) 395 ppm ' ' ' '000 Years before present 200' '000 0 Dome Concordia ice core data: Siegenthaler U et al. (2005) Science 310:1313 Vostoc ice core data: Petit JR et al. (1999) Nature 399:429 and new data Ch. Körner

33 No biomass responses of alpine grassland to 4 years of CO 2 -enrichment (Alps, Furkapass, 2500 m) Above-ground biomass (g m -2 ) CO 2 nutrient effect nutrient effect + CO 2 -N + N... irrespective of nutrition Late succession Ch Körner et al.. (1997) Acta Oecol 18:165 Ch Körner

34 Elevated CO 2 : Early succession No positive effect of elevated CO 2 on growth despite NPK-addition, some species grew less, but evapotranspiration is reduced. N Inauen et al (2012) GCB 18:985 Ch Körner

35 - Negative effect of elevated CO 2 on plant growth FACE-Glacier forefield plants, Furka, 2500 m Aboveground biomass (g d.w.) Luzula alpinopilosa Poa alpina Ranunculus Veronica glacialis alpina Ambient CO 2 Elevated CO 2 Species: p < CO 2 : p < 0.05 N: p < N +N -N +N -N +N -N +N N Inauen et al (2012) GCB 18:985 Ch Körner

36 Evapotranspiration from alpine grasslands under CO 2 -enrichment, is reduced by 3-7 % (standardized( by pretreatment ET), Swiss Alps, 2450 m CO 2 Standardized daily ET Nardus Carex Vegetation type Ambient CO 2 Elevated CO 2 CO 2 : p < % -3.2 % -6.0 % Herb rich N Inauen et al (2013) J Ecol 101:86

37 The effect of N deposition on alpine plants Swiss Alps, m, critical load 5-10 kg N ha -1 a -1 Early Late succession 100 kg N 50 kg N 25 kg N 15 kg N ha -1 a -1 Plant biomass (g m -2 ) % ** +125 % ** ± se + 27 %* + 53 %* 0 -N +N -N +N Acidic soils C Heer & Ch Körner (2002) Basic Appl Ecol 3:39 -N +N -N +N Calcareous soils E Hiltbrunner, unpubl data Ch Körner

38 NPK-fertilized Ch Körner

39 Svalbard, 79 N

40 Birdcliff Cochlearia groenlandica

41 Land use, Swiss Alps Ch Körner

42 Land use effects: Change of LAI Effect of grazing = clipping on evapotranspiration and seepage in alpine grasslands, Swiss Alps, 2450 m (2009) Weighing lysimeter (bright days) Water balance (season) Deep seepage (season) ET (mm) % -14% -2% -5% 100 As Ns As Agrostis Ns Nardus Cc Carex Cc Herb % As -48% Ns -16% -26% Cc Herb Vegetation type N Inauen et al (2013) J Ecol 101:86 Deep seepage sum (mm) % +7% +78% +11% a bc As ab c Ns Control Clipped bc c Cc bc c Herb

43 Summary Of all atmospheric change drivers, N-deposition seems to be most influencial on alpine plants (CO 2 has no effect). Warming affects tall plants (trees) much more than small (alpine) plants, except when moisture stress comes in. Photoperiodism constrains season length effects. The safest place for plant species and small animals to persist when it gets warm is mountain terrain (given sufficient height). The paradigm of alpine biota being particularly vulnerable to climatic warming needs revisiting. Effects of land use change are likely to exceed effects of climatic change.

44 New alpine research center, Swiss Alps 2440 m

45 Ch Körner