Climate change and plant extinction

1

1

Climate changeand plant extinction

Andrew D. FriendLaboratoire des Sciences du Climat

et de l’Environnement (LSCE)Gif-sur-Yvette

Friday, 9 February, 2007

2

extinction

« cessation of existence of a species or group of taxa, reducing biodiversity »

Golden Toad, lastseen 15 May, 1989,Costa Rica

Passenger pigeon,N. America,extinct 1901

Dodo, Mauritius,extinct <1700

2

3

extinction

only 1/1000 of all species are still alive(i.e. almost all species that have everexisted are now extinct - extinction isnormal)

but, over time, biodiversity hasincreased…

4

numbers of species:Kingdom described estimated totalBacteria 4,000 1,000,000Protoctists 80,000 600,000Animals 1,320,000 10,600,000Fungi 70,000 1,500,000Plants 270,000 300,000

TOTAL 1,744,000 ca. 14,000,000

3

5

Plant evolution

Source: Elizabeth Anne Viau

6

• 500 mya to land– more CO2, 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, NO3

- 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

plant evolution > diversity

4

7

…plantdiversity

8

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 100-200x background rate

5

9

Why important: plant metabolites

• Antimicrobial• Antifungal• Antiviral• Chemotherapy

– Taxol (from Pacificyew tree)

– Vincristine (fromMadagascar periwinkle)

10

Why important: food crops• New Species• New Genes

– drought tolerance– salt tolerance

6

11

Reasons for extinctions:

• habitat destruction– agriculture, logging, development

• exploitation• invasion• climate/environmental change

Global Temperature Trends

12

Credit: NASA

7

13

14

Future???

8

15

16

9

17

future extinctions:

• 15-37% of land plants and animals lost by 2050 due to climate change (1-2+ °C) (Thomas et al., 2004)

18

Calculating risksfrom 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

10

19

Vegetation distribution : potential natural vegetation(BIOME4; Kaplan et al., 2003)

20

Whittaker (1975): climate envelopes

11

21

Almond-leaved willow

22

now

climate parameters

• precipitation– mean annual– winter– summer

• temperature– mean annual– minimum– growing degree days

• soil moisture

2050

rainfall

tem

pera

ture

Withoutmigration

with migration

criticallyendangered

12

23

source: Thuiller et al., 2005. Climatechange threats to biodiversity inEurope. PNAS 102, 8254.

Proportion of species classified according to the IUCN Red Listassessment under two extremes assumptions about species migration.EX, extinct; CR, critically endangered; EN, endangered; VU, vulnerable;LR, lower risk. Predictions for 2080.

22% CR

2% EX

24


Estimated percentage of species loss and turnover. Upper extreme, upperquartile, median, lower quartile, and lower extreme are represented foreach box.

13

25

species loss rates

• main causes:– growing-degree days– moisture availability

• >80% loss– northcentral Spain– Cevennes– Massif Central

26


Relationships between the percentage of species loss and anomalies ofmoisture availability and growing-degree days. The colours correspond todifferent climate change scenarios.

14

27


Regional projections of the residuals from the multiple regression of speciesloss against growing-degree days and moisture availability. Red colours indicatean excess of species loss; grey colours indicate a deficit.

RED:specialized speciesmarginal habitats

Gray:hot and drytolerant species

28


Spatial sensitivity of plant diversity in Europe ranked by biogeographic regions.Mean percentage of current species richness (Left) and species loss (Center)and turnover (Right) by environmental zones under the A1-HadCM3 scenario.

15

29

conclusions

• Considerable risks to biodiversity fromclimate 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

30

avoiding mass extinctions

• avoid climate change• reduce emissions• move plants• design reserves

16

31

it is said:

• « we’re sitting at the edge of a massextinction » Root et al. (2003)

BUT, is that really true???

32

17

33

big unknown: direct effect of CO2

34

18

35

plants need:

• light• warmth• water• nutrients

– CO2

– nitrogen– phosphorus, etc.

36

plants grow better

• with more CO2

• especially at higher temperatures!

19

37

cond

ucta

nce

CO2

data: beech (Forstreuter, 1998)

2xCO2

++N

+26% -40% -29%

+158% +65% +48%

Anet gleaf Eleaf data: beech(Friend & Leith)

RH

-19%

+10%

CO2 supply and transpiration

38

increased CO2:

• increased photosynthesis• reduced evapotranspiration• increased leaf area• increased growth rate• reduced heat stress• reduced moisture stress• all especially at higher temperatures!

20

39

source: Kim & Leith, 2003

how to build a model (1) : fundamental growth processes

photosynthesis responsesRosa hybrida L.

○ data – model

A/Ci responses at 10 and 20 °C. B, A/Ci responses at 30 and 40 °C. C, Temperature response at three Ca levels (µbar). D, Light response at Ca of350 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 underincident 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 wasmaintained around 50 %.

LI-6400

40

what limits plant growth?

• term: Net Primary Production (NPP)– basically, growth rate

21

41

42

22

43

44

Potential climate limits to plant growth derived from long-termmonthly statistics of minimum temperature, cloud cover, and rainfall

Nemani et al., Science June 6th 2003

potential climate limits:water (red), sunlight (green), temperature (blue)

23

45

NPP increases:

Figure 16. Trends in NPP 1981-1999 computed using the PEM, driven by AVHRR NDVI.

46

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(http://ag.arizona.edu/research/archer/research/biblio1.html)

24

47

MOD15_BU LAI and FPAR: 1- and 4-km, monthly

48

spatial pattern of greening

From Zhou et al., (JGR, 2001)

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 km2) 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.

25

49

1. Are the sink mechanisms permanent features?

time

Sink

St r

eng t

h

3. Will they saturate?

time

Sink

St r

eng t

h

2. Will they increasein strength?

time

Sink

St r

eng t

h

4. Will they disappear?

timeSi

nk S

t ren

g th

Future Dynamics of C Sink Mechanisms

50

need to build:

• process-based, mechanistic computer models of plant growth and environmentalresponses...

26

51

major science questions• Physiological processes• Controls on plant distribution and production• Responses to forcings, past, present and

future– Climate change– Increasing [CO2], [O3], Ndep– Land use and Management

• Roles of terrestrial ecosystems for– Climate– Biogeochemistry

52

key processes invegetation models

• Photosynthesis• Respiration• Stomatal conductance• Nutrient uptake• Partitioning and growth• Phenology• Reproduction• Competition• Herbivory, fire, and disease• Mortality

27

53


photosynthesis(Farquhar model)

( )( )

( )( )

Γ+Γ−

++Γ−

=*

**

max

24;

/1min

i

i

oici

i

CCJ

KOKCCVA

carboxylationcapacity

RuBPregeneration

[CO2][O2]

Photorespirationcompensationpoint

Michaelis-Mentenconstants

Michaelis-Mentenkinetics

rubi

sco chlorophyll

Modélisation de la végétation,lundi 24 avril, CEREGE

Photosynthesis

-20

-10

0

10

20

30

40

50

0 20 40 60 80 100

CO2 concentratation (mmol m-3)

Phot

osyn

thes

is (u

mol

m-2

s-1

)

[ ][ ] mKSSVV+

= max

54

CO2

photosynthesisCO2

respiration

how to build a process-based vegetation model : fundamental growth processes

nutrientuptake

N, P

litter production

C, N, P

28

55

GC=fTxCl/MT

meristemcontrol

water (ΒD)

light (Phyt)

GN,P(f,r)=GC(f,r)xN,Pl/Cl

GN,P(w)=0.1GN,P


partitioning

Nl/ClPl/Cl

56

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

29

57

how to build a model (5) : forcing

physical environment

many approaches

•prescribed•monthly, daily, hourly

•weather generator•PBL coupling•Mesoscale coupling•GCM coupling

58

1990s

2080s

what models tell us : climate change impacts

Hybrid DGVM

30

59

Coupled vegetation/climate global leaf canopy CO2 fluxes

gC/m2/daygC/m2/day

canopy C-flux canopy C-flux change (2070-1860)

(annual total flux = 121 PgC/yr) (flux change = +47%; climate only: -9%)

FEEDBACKS...

60

31

61

state of knowledge:highly uncertain

• Many European species could be threatened by climatechange. Under the assumption of no migration, more than half of the species...become vulnerable or committed to extinction by 2080. Thuiller et al. (2005)

• The CO2-induced global warming extinction hypothesisclaims...many species of plants and animals will not beable 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 willlikely expand if the planet continues to warm, makingplant extinctions even less likely than they are currently. Idso (2003)

62

lots more work to do...

HYBRID6 GPT(NPP)

GPT

NLEVs NLEVt BREVs BREVt BRDDt C3g C4g BRCDt moss NLCDt

32

63

FIN

Documents

Climate change and plant extinction