Yadvinder Malhi

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Padrões espaciais e mudanças temporais
na dinamica e biomassa de florestas
Amazônicas Resultados da rede RAINFOR
Yadvinder Malhi School of Geography and the
Environment, University of Oxford Email
ymalhi_at_ouce.ox.ac.uk
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How will Amazonian forests be affected by the
changes occurring in the 21st Century
atmosphere, and how will they affect the
atmosphere ?
Caxiuana, Brazil
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The 21st Century Atmosphere
Carbon Dioxide Temperature Rainfall
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Atmospheric carbon dioxide 1000 AD to 2000 AD
Source Intergovernmental Panel on Climate Change
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Atmospheric carbon dioxide 1000 AD to 2100 AD
Source Intergovernmental Panel on Climate Change
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Atmospheric carbon dioxide since the demise of
the dinosaurs
Source Pearson and Palmer, 2000, Nature
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Temperature
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Trends in mean temperature in tropical rainforest
regions 1975-1998
Malhi and Wright (2004), Philosophical
Transactions of the Royal Society Spatial
patterns and recent trends in the climate of
tropical rainforest regions
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Tropical land surface temperatures 1900-2100 AD
Cramer et al (2004), Philosophical Transactions
of the Royal Society
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Rainfall
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Tropical Deforestation
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Northern Bolivia, Sep 14th 2004
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West Amazonia, Sep 14th 2004
Leticia
Santa Cruz, Bolivia
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Amazon Scenarios
2000
Source D. Nepstad
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Amazon Scenarios
2010
Source D. Nepstad
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Amazon Scenarios
2020
Source D. Nepstad
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Amazon Scenarios
2030
Source D. Nepstad
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• Tropical forests and the global carbon cycle

Huanchaca, Bolivia
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Carbon Cycling by the Biosphere and OceansGt C
( billions of tons of carbon)
Atmosphere 730
Other Vegetation 1100
Tropical Vegetation 900
Oceans 38000
Lithosphere
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Carbon Cycling by the Biosphere and OceansGt C
( billions of tons of carbon)
Atmosphere 730
50
70
90
Other Vegetation 1100
Tropical Vegetation 900
Oceans 38000
Lithosphere
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Carbon Cycling by the Biosphere and OceansGt C
( billions of tons of carbon)
Atmosphere 730 (3.2 year-1)
6.4
50
90
70
Other Vegetation 1100
Tropical Vegetation 900
Oceans 38000
Lithosphere
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Carbon Cycling by the Biosphere and OceansGt C
( billions of tons of carbon)
Atmosphere 730 (3.2 year-1)
6.4
50
90
1.7
70
Other Vegetation 1100
Tropical Vegetation 900
Oceans 38000
Lithosphere
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Carbon Cycling by the Biosphere and OceansGt C
( billions of tons of carbon)
Atmosphere 730 (3.2 year-1)
6.4
50
70
90
1.7
1.7
Other Vegetation 1100
Tropical Vegetation 900
Oceans 38000
Lithosphere
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Carbon Cycling by the Biosphere and OceansGt C
( billions of tons of carbon)
Atmosphere 730 (3.2 year-1)
6.4
50
70
90
1.7
1.6?
1.6?
1.7
Other Vegetation 1100
Tropical Vegetation 900
Oceans 38000
Lithosphere
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Why would vegetation be taking up
atmospheric carbon dioxide ?
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A Modelled Estimate of the CO2 Fertilisation
Effect
1 mol C m-2 0.12 t C ha-1
Lloyd (1999), Functional Ecology
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How could the 21st century atmosphere affect the
remaining forests ?
Marajo, Brazil
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How might tropical forests respond to
atmospheric change ?
Option 1 enhanced forest growth and
dynamics Option 2 forest die-back Option 3 no
change
Kosnipata, Peru
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Option 1 enhanced forest growth and dynamics
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Option 1 enhanced forest growth and dynamics
High CO2 enhances photosynthesis, growth and root
dynamics
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Option 1 enhanced forest growth and dynamics
High CO2 improves water-use efficiency,
mitigates dry season
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Option 1 enhanced forest growth and dynamics
Rising temperatures accelerate nutrient recycling
in soil
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Option 2 forest dieback
Rising temperatures increase water stress in
canopy
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Option 2 forest dieback
Rising temperatures increase metabolic costs of
plant, increase respiration and hydrocarbon
loss and reduce biomass productivity
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Option 2 forest dieback
Persistent El-Nino like conditions reduce
rainfall in many tropical regions
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Option 2 forest dieback
Slow-growing plants are out-competed by
fast-growing, low biomass species, e.g. lianas
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Option 3 no change
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Field Studies of AtmosphericImpacts on the
Amazon Forest
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Long-term monitoring ofForest biomassForest
dynamicsForest species composition
Suriname
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The RAINFOR Project
Red Amazonica de Inventarios Forestales Rede
Amazonica de Inventarios Florestais The Amazon
Forest Inventory Network
www.geog.leeds.ac.uk/rainfor Malhi et al, An
international network to understand the biomass
and dynamics of Amazonian forests
(RAINFOR) Journal of Vegetation Science, 2002
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ATIVITIDADES DE RAINFOR

• INVENTARIOS
• FLORESTAIS
• (DE BOTANICA E
• ESTRUTURA)

• Objetivos
• Entender a variabilidade espacial
• na dinamica da floresta Amazônica.
• (ii) Estabelecer se as florestas Amazonicas
• estão mudando no tempo
• (na strutura, biomassa, composição,
• e dinamica).
• Foco em parcelas já estabelecidas.

IQUITOS, PERU, JAN 2001
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ATIVIDADES RAINFOR
2. AMOSTRA DE NUTRIENTES EM FOLHAS E SOLOS
OBJETIVO Desenvolver uma dataset
pan-Amazonica de nutrientes de solo, com
protocolos padronizados de amostra e de analise
em laboratorio.
IQUITOS, PERU, JAN 2001
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Tapajos, Brazil
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3. MEDIDA DE STRUTURA DA FLORESTA (ALOMETRIA,
INDICE DE AREA FOLIAR)
NOEL KEMPFF NATIONAL PARK, BOLIVIA, JUNE 2001
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Length of dry season
Derived from the New et al 2001 dataset
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Soils
Sources Cochrane (2003), Sombroek (2001)
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What have we found ?
New insights into the large-scale ecology of
Amazonia Evidence of changes in recent decades
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There is immense spatial variability in the
structure,dynamics and biodiversity of Amazonian
forests
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ALTA FERTILIDADE
ALTA SAZONALIDADE
Malhi et al, The above-ground coarse wood
productivity of 104 Neotropical forest plots,
Global Change Biology, in press
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Tree Growth Rates
Malhi et al, The above-ground coarse wood
productivity of 104 Neotropical forest plots,
Global Change Biology, in press
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The gradient in wood productivity probably
does NOT reflect a gradient in forest
photosynthesis
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Mercado et al, in prep
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The fraction of its photosynthesis that a
forest allocates to wood is NOT constant, but
varies threefold across our plots
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Fractional Allocation of Photosynthesis to Wood
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Fractional Allocation of Photosynthesis to Wood
Brazil
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Fractional Allocation of Photosynthesis to Wood
Ecuador
Brazil
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The Carbon Allocation of Tropical Forests
Photosynthesis 100
Leaf production 10-30 ?
Above-ground biomass 5-15
Respiration 50-70 ?
Below-ground biomass 1- 5 ?
Fine-root production 10-30 ?
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Intensive Studies of Carbon Allocation
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Photosynthesis 100
Canopy 10-30 ?
Above-ground biomass 5-15
Respiration 50-70 ?
Below-ground biomass 1- 5 ?
Fine-root turnover 10-30 ?
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Amacayacu, Colombia
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Photosynthesis 100
Canopy 10-30 ?
Above-ground biomass 5-15
Respiration 50-70 ?
Below-ground biomass 1- 5 ?
Fine-root turnover 10-30 ?
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Amacayacu, Colombia
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Photosynthesis 100
Canopy 10-30 ?
Above-ground biomass 5-15
Respiration 50-70 ?
Below-ground biomass 1- 5 ?
Fine-root turnover 10-30 ?
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Amacayacu, Colombia
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Photosynthesis 100
Canopy 10-30 ?
Above-ground biomass 5-15
Respiration 50-70 ?
Below-ground biomass 1- 5 ?
Fine-root turnover 10-30 ?
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Caxiuana, Brazil
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Amacayacu, Colombia
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Forests that grow fast, die young
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Integrated residence time of Amazon forest
biomass 55 years
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Slower growing forests have high mean
wood density, and higher biomass
Tree community ecology matters
Baker et al, Woody density drives
regional patterns of Amazon forest
biomass, Global Change Biology, 2004
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FOREST BIOMASS PER UNIT BASAL AREA
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AREA BASAL ESTA CORRELACIONADO COM DURAÇÃO DA
ESTAÇÃO SECA
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BIOMASSA AEREA
biomassa aerea viva total 91-95 Pg C (Media
315-335 t peso seco ha-1)
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The dynamics of forests appear to
have accelerated over recent decades
Kosnipata, Peru
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The forests appears to be accelerating in growth
over time
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Biomass growth rate, t / ha / year
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1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
Year
Phillips et al. (2004), Patterns and process in
Amazon tree turnover 1975-2000, Philosophical
Transactions of the Royal Society
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Florestas primarias estão acumulando biomassa e
também a taxa de acumulação e relacionado com a
fertilidade do solo.
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• A possible explanation may be that
• an external driver is accelerating forest
  productivity
• internal dynamics of the forest (allocation to
  wood, shifts in community ecology or forest
  structure) are amplifying this effect
• this in turn is accelerating tree death

Net C sink
Accelerated tree growth
Lagging accelerated tree death
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Effects on global climate
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Barro Colorado, Panama
So for the moment old growth forests appear to be
growing slightly bigger and growing and dying
much faster
Is this a good thing ?
What are the consequences for forest ecology and
biodiversity ?
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Lianas
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1990
2000
1980
Phillips et al, 2002, Nature
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Liana leaf litter fraction is increasing on Barro
Colorado Island, Panama
1985 1990 1995 2000
Wright et al. Ecology (2004)
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Fast growing trees vs. slow-growing trees
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Fast growing trees vs. slow-growing trees
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• For 18 ha of dispersed plots in old-growth forest
  in central Amazonia

• The rate of tree growth has accelerated for
  almost all tree genera since the mid-80s
  (consistent with what we are seeing across
  Amazonia)

• Many larger canopy and emergent trees, but not
  pioneer species, have increased in abundance

• Slower-growing genera (including many old-growth
  understorey trees) have declined in abundance

• The pattern is most likely explained by rising
  CO2, although other factors cannot be ruled out