Coping with branch excision when measuring leaf net photosynthetic rates in a lowland tropical forest
Cite this dataset
Verryckt, Lore T. et al. (2020). Coping with branch excision when measuring leaf net photosynthetic rates in a lowland tropical forest [Dataset]. Dryad. https://doi.org/10.5061/dryad.v9s4mw6rg
Abstract
Measuring leaf gas exchange from canopy leaves is fundamental for
our understanding of photosynthesis and for a realistic representation of
carbon uptake in vegetation models. Since canopy leaves are often difficult
to reach, especially in tropical forests with emergent trees up to 60
meters at remote places, canopy access techniques such as canopy cranes or
towers have facilitated photosynthetic measurements. These structures are
expensive and therefore not very common. As an alternative, branches are
often cut to enable leaf gas exchange measurements. The effect of branch
excision on leaf gas exchange rates should be minimised and quantified to
evaluate possible bias. We compared light-saturated leaf net photosynthetic
rates measured on excised and intact branches. We selected branches
positioned at three canopy positions, estimated relative to the top of the
canopy: upper sunlit foliage, middle canopy foliage, and lower canopy
foliage. We studied the variation of the effects of branch excision and
transport amongst branches at these different heights in the canopy. After
excision and transport, light-saturated leaf net photosynthetic rates were
close to zero for most leaves due to stomatal closure. However, when the
branch had acclimated to its new environmental conditions – which took on
average 20 minutes –light-saturated leaf net photosynthetic rates did not
significantly differ between the excised and intact branches. We therefore
conclude that branch excision does not affect the measurement of
light-saturated leaf net photosynthesis, provided that the branch is recut
under water and is allowed sufficient time to acclimate to its new
environmental conditions.
Methods
For methods we refer to the manuscript.
Usage notes
See info file
Funding
Research Foundation - Flanders, Award: PhD fellowship
European Research Council, Award: ERC-2013-SyG-610028 IMBALANCE-P
USR
Agence Nationale de la Recherche, Award: AnaEE-France ANR-11-INBS-0001
Agence Nationale de la Recherche, Award: Labex CEBA ANR-10-LABX-25-01