Variations in Isoprene Emission Capacity among Neotropical Forest Sites

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Variations in Isoprene Emission Capacity among
Neotropical Forest Sites
Peter Harley1, Pérola Vasconcellos2, Lee
Vierling3, Alex Guenther1, Jim Greenberg1,
Carlos Cleomir4, Lee Klinger
1Atmospheric Chemistry Division, National Center
for Atmospheric Research, Boulder, CO,
USA 2Departamento de Química e Meio Ambiente,
IPEN, São Paulo, SP, Brazil 3INPA Instituto
Nacional de Pesquisas da Amazônia, Manaus, AM,
Brazil 4South Dakota School of Mines and
Technology, Rapid City, SD, USA
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BVOC Emission Modeling Landcover characteristics
Hourly at 1 km2 spatial resolution
Foliage density
broadleaf tree foliage
shrub foliage
Ecoregions
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Estimating Area-averaged Isoprene Emission Rate
Area-averaged Isoprene Emission Capacity
mg C m-2 (ground) h-1
Isoprene emission rate mg C m-2 (ground) h-1
expected from a site if all leaves were at 30 oC
and receiving 1000 mmol m-2 s-1 of PAR
defined as
Adjusted by PAR and temperature algorithms
(Guenther et al. 1995)
Area-averaged Isoprene Emission Rate
mg C m-2 (ground) h-1 at a given temperature
and above-canopy PAR
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Field Enclosure Measurements
Tropical rainforests Costa Rica 50 (weighted
average) W. Amazon 40 E. Amazon 25 Congo
20 (weighted average) South China 15 (weighted
average) Tropical savannas African savannas (3
types) 5-15 (weighted) African savannas (4
types) 25-50 (weighted) Australian savannas (2
types) 55-70 (weighted average)
What fraction of woody plants emit isoprene?
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Estimating Area-averaged Isoprene Emission
Capacity
Isoprene Emission Capacity mgC g-1 (leaf dry
mass) h-1 (by Species)
Site Biomass Density g (leaf
dry mass) m-2 (ground)
biomass by species
X
X
Area-averaged Isoprene Emission Capacity mgC m-2
h-1
Simplistic Example
X X X
X X X

400 g (leaf dry mass) m2 (ground)
Total 13.2 mgC m-2 h-1
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Isoprene-emitting generain temperate vs.
tropical forests
Temperature Deciduous Forest Oak Ridge, TN
Tropical Evergreen Forest FLONA Tapajos, PA
Isoprene-emitting genus Non-emitting genus
No information
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Plant taxonomy vs. isopreneAnnonaceae
19 species within the important tropical
understory family, Annonaceae, have been sampled
for isoprene, of which only 2 have been reported
to emit. Lacking specific information about a
species within the Annonaceae, therefore, we
assume there is a 10.5 chance that it is an
isoprene emitter.
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Plant taxonomy vs. isopreneBurseraceae
10 species within the important tropical family
of canopy species, Burseraceae, have been sampled
for isoprene, of which 8 have been reported to
emit. Lacking specific information about a
species within the Burseraceae, therefore, we
assume there is an 80 chance that it is an
isoprene emitter.
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Percentage of Isoprene-Emitting Species for some
Important Tropical Tree Families
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Map of Sites for this Study
Paragominas
Tapajós Belterra
Caxiuaná
Catuaba
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Sample Tree Survey FLONA Tapajós (Km 67)
Etc., for another 2,588 lines
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Logic Tree for Assigning Isoprene Emission
Capacity
Tree Species X
Species Level Emission Information in Database?
Yes
No
Assign Emission Capacity
Genus Level Emission Information in Database?
Assign Emission Capacity
Yes
No
of Species in Family Emit Isoprene
Emitting Species/Genus 75 mgC g-1 h-1
Non-Emitting Species/Genus 0 mgC
g-1 h-1
Assign Emission Capacity
(75 mgC g-1 h-1)
/100
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Site-specific estimates of area-average isoprene
emission capacity
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LBA Field Sites (NCAR)
overlain on WWF Ecoregions
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LBA Large Scale Biosphere-Atmosphere Experiment
in Amazonia
NCAR/ACD/BAI Field Studies 1998, 1999 (2), 2000,
2001 (2)
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Global Concentration Distributions From Remote
Sensing
Palmer et al.
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BVOC Emission Modeling Environmental Conditions
BVOC Emission
Solar radiation
Temperature
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Drivers of Regional Change in Biogenic VOC
Emissions
Land-use
Physiology biological activity and stress
Landscape Emission Rate
Climate (physical and chemical)
Genetics species composition
Disturbance (.e.g., fire, flood, disease)
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Terrestrial Carbon Cycle Model
ATMOSPHERE
reactive carbon
photosynthesis
respiration
ECOSYSTEM