 |
| Titel |
Disentangling the drivers of coarse woody debris behavior and carbon gas
emissions during fire |
| VerfasserIn |
Weiwei Zhao, Guido R. van der Werf, Richard S. P. van Logtestijn, Jurgen R. van Hal, Johannes H. C. Cornelissen |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121408
|
| Publikation (Nr.) |
 EGU/EGU2016-120.pdf |
|
|
|
|
|
| Zusammenfassung |
| The turnover of coarse woody debris, a key terrestrial carbon pool, plays fundamental roles in
global carbon cycling. Biological decomposition and fire are two main fates for dead wood
turnover. Compared to slow decomposition, fire rapidly transfers organic carbon from the
earth surface to the atmosphere.
Both a-biotic environmental factors and biotic wood properties determine coarse wood
combustion and thereby its carbon gas emissions during fire. Moisture is a key inhibitory
environmental factor for fire. The properties of dead wood strongly affect how it burns either
directly or indirectly through interacting with moisture. Coarse wood properties vary between
plant species and between various decay stages. Moreover, if we put a piece of dead wood in
the context of a forest fuel bed, the soil and wood contact might also greatly affect their fire
behavior.
Using controlled laboratory burns, we disentangled the effects of all these driving factors:
tree species (one gymnosperms needle-leaf species, three angiosperms broad-leaf species),
wood decay stages (freshly dead, middle decayed, very strongly decayed), moisture content
(air-dried, 30% moisture content in mass), and soil-wood contact (on versus 3cm above the
ground surface) on dead wood flammability and carbon gas efflux (CO2 and CO released in
grams) during fire. Wood density was measured for all coarse wood samples used in our
experiment.
We found that compared to other drivers, wood decay stages have predominant positive
effects on coarse wood combustion (for wood mass burned, R2=0.72 when air-dried and
R2=0.52 at 30% moisture content) and associated carbon gas emissions (for CO2andCO (g)
released, R2=0.55 when air-dried and R2=0.42 at 30% moisture content) during fire. Thus,
wood decay accelerates wood combustion and its CO2 and CO emissions during fire, which
can be mainly attributed to the decreasing wood density (for wood mass burned,
R2=0.91 when air-dried and R2=0.63 at 30% moisture content) as wood becomes more
decomposed.
Our results provide quantitative experimental evidence for how several key abiotic and
biotic factors, especially moisture content and the key underlying trait wood density, as well
as their interactions, together drive coarse wood carbon turnover through fire. Our
experimental data on coarse wood behavior and gas efflux during fire will help to improve the
predictive power of global vegetation climate models on dead wood turnover and its feedback
to climate. |
|
|
|
|
|
|