Embed Size (px)
Citation preview
Temporal scales of climatic changes and paleodiversity patterns
in the Atlantic rainforest
Marie‐Pierre Ledru
Workshop Dimensions US‐BIOTA São Paulo A mul>disciplinary framework for biodiversity predic>on
in the Brazilian Atlan>c forest hotspot
Climate during the Quaternary
2.7 Ma
Temperature
cold warm
Maslin 2005
Quaternary and specia>on in the rainforest
Ribas 2011
Amazonia
Paleodistribu>on models
Not sa>sfying !
Atlan>c forest
Insola>on cycles
Eccentricity shape of the Earth’s orbit changes Spectral peaks at 96, 125 and 413 ka
Obliquity >lt of the Earth’s axis of rota>on Spectral peak at 41 ka
Precession Earth’s rota>onal ’s axis, spectral peak at 27 ka Earth’s orbit, spectral peak at 105 ka
Wang 2001
Precession and wet season in Northeastern Brazil
Seasonal monsoon
100 150 200 250 300 mm
15°S
0°
30°S
100 150 200 250 300 mm
15°S
0°
30°S
Ledru & Carnaval 2014
Rainfall distribu>on in December Rainfall distribu>on in June
Insolation cycles
Precession and monsoons
Braconnot et al 2008
Atlan>c rainforest
0
20
40
60
80
100
120
760
810
860
910
960
1010
1060
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130
atlan%
c forest pollen %
insola%on
W/m
2
cal x1000 yr BP
Insola%on and Atlan%c rain forest expansion phases
Ledru & Carnaval 2014
SAF
NAF
Changes in precession cycle during the rainy season
Precession and floris>c changes
Maslin et al 2005
Every 11 000 years Change in seasonality Re‐organisa>on of the forest
Ledru et al 2009
Precession and floris>c composi>on
Tree pollen frequencies
Tree pollen frequencies
Colônia SP pollen record
Insola>on cycles
Wilson 2000
insola>on and glacial cycles during the Quaternary
Paillard 1998
Earth’s energy during the Quaternary
400
500
600
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000
W/m
2
yr x 1000 before present
mid‐month insola%on 15°S for January
2.7 Ma Berger & Loutre 1991; Ledru 2014
Molecular clock in Amazonia
Ribas 2011
400
500
600
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000
W/m
2
yr x 1000 before present
0.48 0.76 1.25 1.79
2.74
0.53
Berger and Loutre 1991; Ribas 2011 ;Batalha-Filho 2013; Ledru 2014
1.17 1.56
1.85 ; 1.91; 2.02
2.24
Molecular clocks
Species richness and solar energy
Willis 2007
insola>on
Palynological Richness (number of taxa iden>fied)
The majority of diversifica>on events occur within intervals of low variability in the energy signal
Atlan>c and Amazonian rain forest specia>ons are paced with the 400 ka cycle
400
500
600
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000
W/m
2
yr x 1000 before present
0.48 0.76 1.25 1.79
2.74
0.53
Berger and Loutre 1991; Ribas 2011 ;Batalha-Filho 2013; Ledru 2014
1.17 1.56
1.85 ; 1.91; 2.02
2.24
Molecular clocks
Fischer 2011
Orbital forcing during the Holocene
Linear trend in mean seasonal amplitude in °K per 1000 yr
Linear trend in annual mean surface temperature in °K per 1000 yr
Difference between mid Holocene and present
Atlan>c forest in Nordeste
Montade 2014
Pollen record of Maranguape
5°S
0
5°N
10°N
Pacific Ocean
Atlantic Ocean
Drier
Wetter
4200 - 3700 yr BP : a Pacific / Atlantic contrasted influence on the continent
Fire in Amazonia
4.2 ka event
Holocene abrupt climate change
Lim 2014
Insola>on changes during the Holocene
Bond cycle 1500 yr
Secular scale
What would be the impact of the Bond cycles in the Atlan>c rainforest ?
Future tasks To fill a gap in our knowledge about links between Earth’s energy,
climate and specia>on we need :
*more long term and con>nuous fossil records
*to improve molecular clock chronologies
* To re define the Holocene
in this project……
