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| Titel |
Assessing the contribution of leaf respiration to the carbon economy of tropical rainforest tree species |
| VerfasserIn |
Lasantha Weerasinghe, Danielle Creek, Kristine Crous, Shuang Xiang, Owen Atkin |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072162
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| Zusammenfassung |
| Tropical rainforests are among the most important biomes in terms of annual primary
productivity; hence, assessing their sensitivity to potential shifts in global and regional
temperatures patterns is a necessary step to model future local, regional, and global carbon
cycling. However, how the changes in future climate including increased temperatures in
short- and long-term basis might impact on the carbon cycling in these tropical rainforests is
little studied and remain poorly understood. Given this, this study examined the
impact of short and long term changes in temperature on leaf respiration in tropical
lowland rainforest located in Far North Queensland, Australia. We quantified how leaf
respiration responded to short-term changes in temperature and associated leaf
chemical and structural traits in 16 tropical rainforest tree species at two canopy
heights; upper and lower level of the tree canopy. Further we measured rates of
photosynthesis (A) and leaf respiration (R) both in the dark and light, and relationships
between those traits and associated leaf structural and chemical traits. Four of these
species were subsequently exposed to three different growth temperatures of 25Ë
C, 30Ë C and 35Ë C under controlled environment conditions and ability of leaf
respiration to acclimate to new temperature regimes was examined. In the field,
upper canopy leaves showed higher rates of leaf respiration in darkness and in light
than lower canopy leaves at a given set temperature (28Ë C). Moreover, at any
given leaf mass per unit area (LMA), leaf nitrogen [N] and leaf phosphorus [P]
value, rates of respiration were higher in upper canopy leaves (compared to lower
canopy leaves). The short-term temperature sensitivity of leaf respiration (Q10)
was found to be constant around 1.89 at 25Ë C irrespective of species or canopy
position.
Three out of four species subjected to different long-term growth temperatures under
control environment conditions exhibited some ability to acclimate; acclimation resulted in
homeostasis of leaf respiration measured at the prevailing growth temperatures. In
conclusion, our findings highlight the importance of canopy position in determining rates of
leaf respiration in this tropical forest, the ability of tropical rainforest species to acclimate to
changes in temperature in future warmer world, and appropriateness of current climate
models using Q10 of 2 to describe temperature sensitivity of leaf respiration for this forest
type.
Key words: Respiration, carbon cycle, acclimation, tropical rain forests |
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