Climate change and plant extinction

Transcription

1 Climate change and plant extinction Andrew D. Friend Laboratoire des Sciences du Climat et de l Environnement (LSCE) Gif-sur-Yvette Friday, 9 February, extinction «cessation of existence of a species or group of taxa, reducing biodiversity» Dodo, Mauritius, extinct <1700 Passenger pigeon, N. America, extinct 1901 Golden Toad, last seen 15 May, 1989, Costa Rica 2

2 extinction only 1/1000 of all species are still alive (i.e. almost all species that have ever existed are now extinct - extinction is normal) but, over time, biodiversity has increased 3 numbers of species: Kingdom described estimated total Bacteria 4,000 1,000,000 Protoctists 80, ,000 Animals 1,320,000 10,600,000 Fungi 70,000 1,500,000 Plants 270, ,000 TOTAL 1,744,000 ca. 14,000,000 4

3 Plant evolution Source: Elizabeth Anne Viau 5 plant evolution > diversity 500 mya to land more CO 2, nutrients, and light But: problems (drivers of evolution) Intense competition for light Elevated display of foliar elements Water stress Cuticle, stomata, extensive roots, phenology, tracheids, herbaceous Fire Herbaceous habit Limited N supply (competition from microbes) Leaf structure and display Symbiotic N-fixation, NO 3 - use Freezing Deciduous Protective compounds Herbivory Grass habit, protective compounds, elevated display Photorespiration C4 photosynthesis Followed by evolution of decomposing organisms Bacteria, fungi, soil fauna 6

4 plant diversity 7 Extinction rates Extinctions over past 400 years: 337 vertebrates 389 invertebrates 90+ plants mammals and birds: 0.5 extinctions/yr Geological rate? spp. average lifespan = 4 million yr 10 million spp. therefore, 10/4 = 2.5 extinctions/yr So, now (10000/15) is x background rate 8

5 Why important: plant metabolites Antimicrobial Antifungal Antiviral Chemotherapy Taxol (from Pacific yew tree) Vincristine (from Madagascar periwinkle) 9 Why important: food crops New Species New Genes drought tolerance salttolerance 10

6 Reasons for extinctions: Global Temperature Trends habitat destruction agriculture, logging, development exploitation invasion climate/environmental change 11 Credit: NASA 12

7 13 Future??? 14

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9 future extinctions: 15-37% of land plants and animals lost by 2050 due to climate change (1-2+ C) (Thomas et al., 2004) 17 Calculating risks from climate change Niche-based models «niche» = ecological space relates spp. distribution to climate «climate envolope» future climate scenario > spp. move, or die? depends on amount of climate change dispersal 18

10 Vegetation distribution : potential natural vegetation (BIOME4; Kaplan et al., 2003) 19 Whittaker (1975): climate envelopes 20

11 Almond-leaved willow 21 climate parameters precipitation mean annual winter summer temperature mean annual minimum growing degree days soil moisture temperature with migration 2050 rainfall now critically endangered Without migration 22

12 2% EX 22% CR Proportion of species classified according to the IUCN Red List assessment under two extremes assumptions about species migration. EX, extinct; CR, critically endangered; EN, endangered; VU, vulnerable; LR, lower risk. Predictions for source: Thuiller et al., Climate change threats to biodiversity in Europe. PNAS 102, Estimated percentage of species loss and turnover. Upper extreme, upper quartile, median, lower quartile, and lower extreme are represented for each box. source: Thuiller et al., Climate change threats to biodiversity in Europe. PNAS 102,

13 main causes: species loss rates growing-degree days moisture availability >80% loss northcentral Spain Cevennes Massif Central 25 Relationships between the percentage of species loss and anomalies of moisture availability and growing-degree days. The colours correspond to different climate change scenarios. source: Thuiller et al., Climate change threats to biodiversity in Europe. PNAS 102,

14 Regional projections of the residuals from the multiple regression of species loss against growing-degree days and moisture availability. Red colours indicate an excess of species loss; grey colours indicate a deficit. Gray: hot and dry tolerant species RED: specialized species marginal habitats source: Thuiller et al., Climate change threats to biodiversity in Europe. PNAS 102, Spatial sensitivity of plant diversity in Europe ranked by biogeographic regions. Mean percentage of current species richness (Left) and speciesloss(center) and turnover (Right) by environmental zones under the A1-HadCM3 scenario. source: Thuiller et al., Climate change threats to biodiversity in Europe. PNAS 102,

15 conclusions Considerable risks to biodiversity from climate change in Europe Greatest vulnerability in mountain regions Least vulnerability in southern Mediterranean and Pannonian regions Transition zone key for plant-species conservation in a changing climate 29 avoiding mass extinctions avoid climate change reduce emissions move plants design reserves 30

16 it is said: «we re sitting at the edge of a mass extinction» Root et al. (2003) BUT, is that really true??? 31 32

17 big unknown: direct effect of CO

18 plants need: light warmth water nutrients CO 2 nitrogen phosphorus, etc. 35 plants grow better with more CO 2 especially at higher temperatures! 36

19 CO 2 supply and transpiration conductance data: beech (Forstreuter, 1998) CO 2 2xCO 2 A net g leaf E leaf RH data: beech +26% -40% -29% -19% (Friend & Leith) ++N +158% +65% +48% +10% 37 increased CO 2 : increased photosynthesis reduced evapotranspiration increased leaf area increased growth rate reduced heat stress reduced moisture stress all especially at higher temperatures! 38

20 how to build a model (1) : fundamental growth processes Rosa hybrida L. photosynthesis responses LI-6400 data model A/Ci responses at 10 and 20 C. B, A/Ci responses at 30 and 40 C. C, TemperatureresponseatthreeCa levels (µbar). D, Light response at Ca of 350 µbar at 25 C. Relative humidity was maintained around 50 %. A/Ci responses at two incident PAR levels (70 and 200 µmol m 2 s 1) at 25 C. B, Light response at Ca of 1000 µbar at 25 C. C, Temperature response at three Ca levels under incident PAR of 200 µmol m 2 s 1. D, Light response of leaves of different age (30, 68 and 180 d after unfolding) at ambient CO2 (350 µbar) at 25 C. Relative humidity was maintained around 50 %. source: Kim & Leith, what limits plant growth? term: Net Primary Production (NPP) basically, growth rate 40

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22 43 Potential climate limits to plant growth derived from long-term monthly statistics of minimum temperature, cloud cover, and rainfall potential climate limits: water (red), sunlight (green), temperature (blue) Nemani et al., Science June 6 th

23 NPP increases: Figure 16. Trends in NPP computed using the PEM, driven by AVHRR NDVI. 45 Woody encroachment Invasion of woody plant species into savannas and grasslands Widespread globally Why? Land use: grazing, fire suppression? Climate, exotic species, rising CO2 also implicated Increase C storage Detrimental for grazing 1903 vs 1941, Santa Rita range, AZ ( arch/biblio1.html) 46

24 MOD15_BU LAI and FPAR: 1- and 4-km, monthly 47 spatial pattern of greening Analyses of pixel-based persistence indices from GIMMS (v1) NDVI data for the period 1981 to 1999 indicate that: About 61% of the total vegetated area between 40N-70N in Eurasia shows a persistent increase in growing season NDVI over a broad contiguous swath of land from Central Europe through Siberia to the Aldan plateau, where almost 58% (7.3 million km 2 ) is forests and woodlands. North America, in comparison, shows a fragmented pattern of change, notable only in the forests of the southeast and grasslands of the upper Midwest. From Zhou et al., (JGR, 2001) 48

25 Future Dynamics of C Sink Mechanisms 1. Are the sink mechanisms permanent features? 2. Will they increase in strength? Sink Strength Sink Strength time time 3. Will they saturate? 4. Will they disappear? Sink Strength Sink Strength time time 49 need to build: process-based, mechanistic computer models of plant growth and environmental responses... 50

26 major science questions Physiological processes Controls on plant distribution and production Responses to forcings, past, present and future Climatechange Increasing[CO 2 ], [O 3 ], Ndep Land use and Management Roles of terrestrial ecosystems for Climate Biogeochemistry 51 key processes in vegetation models Photosynthesis Respiration Stomatal conductance Nutrient uptake Partitioning and growth Phenology Reproduction Competition Herbivory, fire, and disease Mortality 52

27 how to build a model (1) : fundamental growth processes rubisco carboxylation capacity photosynthesis (Farquhar model) RuBP regeneration chlorophyll [CO 2 ] [O 2 ] A Vmax min C + K i * ( C Γ ) i ( 1+ O / K ) J ; 4 * ( C Γ ) i ( C + 2Γ ) = * c i Michaelis-Menten constants o i Photorespiration compensation point Michaelis-Menten kinetics V = V max [ S] [ S] + K m Photosynthesis (umol m -2 s -1 ) Photosynthesis CO2 concentratation (mmol m -3 ) Modélisation de la végétation, lundi 24 avril, CEREGE 53 how to build a process-based vegetation model : fundamental growth processes CO 2 photosynthesis CO 2 respiration litter production C, N, P N, P nutrient uptake 54

28 how to build a model (1) : fundamental growth processes partitioning G C =f T xc l /M T light (Phyt) G N,P(f,r) =G C(f,r) xn,p l /C l G N,P(w) =0.1G N,P N l /C l P l /C l meristem control water (Β D ) 55 how to build a model (4) : biological interactions and dynamics competition, space and temporal dynamics large variation in methods big-leaf, NPP horizontal vertical gap model individual-based statistical 56

29 how to build a model (5) : forcing physical environment many approaches prescribed monthly, daily, hourly weather generator PBL coupling Mesoscale coupling GCM coupling 57 what models tell us : climate change impacts Hybrid DGVM 1990s 2080s 58

30 FEEDBACKS... Coupled vegetation/climate global leaf canopy CO 2 fluxes canopy C-flux canopy C-flux change ( ) gc/m 2 /day gc/m 2 /day (annual total flux = 121 PgC/yr) (flux change = +47%; climate only: -9%) 59 60

31 state of knowledge: highly uncertain Many European species could be threatened by climate change. Under the assumption of no migration, more than half of the species...become vulnerable or committed to extinction by Thuiller et al. (2005) The CO 2 -induced global warming extinction hypothesis claims...many species of plants and animals will not be able to migrate either poleward in latitude or upward in elevation fast enough to avoid extinction as they try to escape the stress imposed by the rising temperature....[but, in fact] the ranges of most of earth s plants will likely expand if the planet continues to warm, making plant extinctions even less likely than they are currently. Idso (2003) 61 lots more work to do... HYBRID6 GPT(NPP) GPT NLEVs NLEVt BREVs BREVt BRDDt C3g C4g BRCDt moss NLCDt 62

32 FIN 63