Climate Change Group

Dr. G. Midgley (leader)

Dr. C. Musil

Dr. M. Rutherford

Dr. W. Thuiller

Mr. Les Powrie

Mr. B. Kgope

Mr. G. Hughes

Technical Staff

Mr. S. Snyders

Mr. D. de Witt

Mrs. J. Arnolds

Climate Change and Plant Biodiversity

Barney S. Kgope

South African National Biodiversity Institute,

Kirstenbosch Research Center,

Kgope@sanbi.org

Background

What is climate? - An aggregate of daily weather - whose variables interact to support life on earth.

Climate system includes processes involving - land, ocean and sea and these influence - atmosphere.

Biodiversity - variety of life on Earth - significantly influences climate.

Is the climate changing?

Previous Climate

We live on a predominantly cool-adapted planet!

Human Influence - fossil fuels

Where are we now?

UncertaintyDetectionPrediction

PolicyBehaviourTechnology

Adaptation

Climate Change Consequences

Human and animal health - e.g. heat and diseases.

Agriculture - food security (warming and drying).

Sea level rise - melting polar ice caps (potential to submerge coastal cities).

Natural ecosystems - changes in structure and function.

Water supply - decline due to potential decrease in rainfall.

South Africa and Climate Change

[PMG note: photograph not included]

5 spatially dominant biomes - SA

How did past climate change affect this region?

Climate reconstruction

6

12

15

18

0

Time (Kya)

+0.05ºC

-1.82ºC

-3.67ºC

Pollen evidence?

6

12

18

0

2

4

6

8

10

12

14

0 5000 10000 15000 20000Time (kya)

Restionaceae Ericaceae

------------ traces of both groups ----------

1

1

Shi et al (1998)

Potential Future ?

Water impacts on physiology

0.0

5.0

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15.0

20.0

25.0

30.0

20 25 30 35 40

Am

ax (

m mol

m-2

s-1

)

Amax TS

Amax GF

Amax AM

0.0

2.0

4.0

6.0

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Am

ax (

mm

ol m

-2 s

-1)

Amax CA

Amax DA

Amax AN

0.000.020.040.060.080.100.120.140.160.180.20

20 25 30 35 40

Leaf Temperature (oC)

Gs

(mo

l m-2

s-1

)

Gs CA

Gs DM

Gs AN

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20 25 30 35 40

Leaf Temperature (oC)

Gs

(mo

l m-2

s-1

)

Gs TS

Gs GF

Gs AM

Potential shift with climate change (~2050)

Potential for more species. extinction ?Aloe dichotomaAloe dichotoma

(quiver tree)(quiver tree)

Elevated and sub-ambient CO2 worksupporting mechanistic modeling

Test ideas about impacts of fire and CO2

on vegetation structure and function

[PMG note: photograph not included]

DGVM predictions for CO2 sensitivity of African mesic Savanna saplings

Simulated effects of CO2 on stem height Mesic savanna

0

1

2

3

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6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Years since burn

Ste

m h

eig

ht

(m)

180

270

360

700

Implications and testsPast contraction of woody elements with

LGM low CO2 (180ppm) – paleoecological record

Bush encroachment since the pre-industrial, and accelerating into the future with significant implications for livelihoods, ecosystem function and carbon sequestration – empirical experiments

Modelled effects of CO2 level alone on

tree success (i.t.o. LAI)using a DGVM

 Bond W.J., Midgley G.F. & Woodward, F.I. (2003) The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas. Global Change Biology 9:973-982

Bond W.J., Midgley G.F. & Woodward, F.I. (2003) What controls South African vegetation – climate or fire? South African Journal of Botany.69:1-13

Experimental tests on 3 Savanna woody species and 1 C4 grass

Plants exposed to a full range of CO2 levels viz. 180, 280, 370, 550, 700 and 1000 ppm, in Open Top Chambers

Plants - Acacia karoo, Acacia nilotica, Dichrostachys cinerea and Themeda triandra.

Acacia karroo

550 ppm180 ppm

[PMG note: photographs not included]

Acacia karoo

R2 = 0.71

0

20

40

60

80

0 250 500 750 1000

Chamber [CO2] (ppm)

shoo

t ext

ensi

on (c

m)

From pre-industrialto current CO2 levels?Trees have increased world-wide in savannas

Open savanna, S. Africa1955

Same place, 1998

(from T. Hoffmann, IPC)

[PMG note: photograph not included]

What about potential impacts of the predicted

increases in ambient temperatures?

Scale up research - biogeochemical cycles

•Long Term Ecological Research Sites

•Scale up leaf-canopy-ecosystem-regional-global

•Integrative studies

•Networks – Afri-flux

[PMG note: photograph not included]

RecommendationsSupport – Assessment of Impacts and Adaptation to

Climate Change (AIACC)Support International efforts to curb/limit greenhouse

gas emissionsKey intervention - policies promoting sustainable

management of biodiversity on private and communal land.

Expansion of protected areas an important adaptation option being implemented in SA

Increase capacity of research on climate change and sustainable development in South Africa

Science is Fun

Thank you