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| Titel |
Will elevated CO2 alter fuel characteristics and flammability of eucalypt
woodlands? |
| VerfasserIn |
Luke Collins, Victor Resco, Matthias Boer, Ross Bradstock, Robert Sawyer |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130717
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| Publikation (Nr.) |
 EGU/EGU2016-11014.pdf |
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| Zusammenfassung |
| Rising atmospheric CO2 may enhance forest productivity via CO2 fertilisation and increased
soil moisture associated with water savings, potentially resulting in increased woody plant
abundance i.e. woody thickening. Changes to vegetation structure via woody thickening,
as well as changes to vegetation properties (e.g. leaf characteristics and moisture
content), may have important implications for ecosystem flammability and fire regimes.
Understanding how elevated CO2 alters flammability and fire regimes will have
implications for ecosystem dynamics, particularly carbon sequestration and emissions. We
present data from Free Air CO2 Enrichment (EucFACE) and whole tree growth
chamber (WTC) experiments to assess the effect of elevated CO2 on fuel properties
and flammability of eucalypt woodlands. Experiments involved ambient (∼400
ppm) and elevated CO2treatments, with elevated treatments being +150 ppm and
+240 ppm at EucFACE and the WTCs respectively. We examined the response
of vegetation parameters known to influence ecosystem flammability, namely (i)
understorey vegetation characteristics (ii) understorey fuel moisture and (iii) leaf
flammability.
Understorey growth experiments at EucFACE using seedlings of two common woody
species (Hakea sericia, Eucalyptus tereticornis) indicate that elevated CO2 did not influence
stem and leaf biomass, height or crown dimensions of seedlings after 12 months exposure
to experimental treatments. Temporal changes to understorey live fuel moisture
were assessed at EucFACE over an 18 month period using time lapse cameras.
Understorey vegetation greenness was measured daily from digital photos using the
green chromatic coordinate (GCC), an index that is highly correlated with live fuel
moisture (R2 = 0.90). GCC and rates of greening and browning were not affected
by elevated CO2, though they were highly responsive to soil moisture availability
and temperature. This suggests that there is limited potential for elevated CO2 to
alter flammability due to changes in understorey fuel biomass and structure or fuel
moisture.
Leaves of Eucalyptus globulus and E. saligna grown under elevated CO2 in whole tree
growth chambers tended to be thicker than those grown under ambient CO2. Ignition delay
time was significantly increased in elevated CO2grown leaves, while total heat output and
mass loss were also reduced though effects were contingent on temperature and water
availability effects. Complementary work on the flammability of eucalypt leaves collected
from the EucFACE experiment treatments (elevated CO2 and ambient) will be discussed.
These initial investigations therefore indicate some potential for elevated CO2 to
reduce aspects of flammability of litter fuels in Australian forests and woodlands. |
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