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Published on: August 29, 2019
Does canopy mean nitrogen concentration explain variation in canopy light use efficiency across 14 contrasting forest
Mikko Peltoniemi1, Minna Pulkkinen, Pasi Kolari
1Department of Forest Sciences, FI-00014 University of Helsinki, Finland. mikko.peltoniemi@metla.fi
Tree Physiology
|February 11, 2012
Summary
Plant canopy nitrogen concentration significantly correlates with maximum light use efficiency (LUE), impacting gross primary production (GPP) across all light levels. Further data is needed to integrate this finding into GPP models.
Area of Science:
- Ecology
- Plant Physiology
- Ecosystem Science
Background:
- Light use efficiency (LUE) in plant canopies varies spatially, partly due to species differences.
- Canopy nitrogen concentration ([N]) is a potential driver of this spatial variation in LUE.
- Current models often link nitrogen's effect on photosynthesis to high light conditions, not maximum LUE across all light levels.
Purpose of the Study:
- To estimate maximum LUE at 14 forest sites using eddy-covariance data.
- To examine the dependency of maximum LUE on canopy nitrogen concentration ([N]).
- To investigate the potential incorporation of the maximum LUE-[N] relationship into gross primary production (GPP) models.
Main Methods:
- Estimated maximum LUE, defined as GPP/aPPFD under optimal conditions before light saturation.
- Analyzed the correlation between maximum LUE and canopy mean [N] across 14 forest sites.
- Assessed the impact of including the [N]-maximum LUE relationship on GPP model accuracy.
Main Results:
- Maximum LUE was higher in deciduous/mixed forests than coniferous forests.
- A significant positive correlation was found between maximum LUE and canopy mean [N].
- This correlation persisted across different daily photosynthetic photon flux density (PPFD) levels.
Conclusions:
- Maximum LUE shows a linear correlation with canopy nitrogen concentration.
- Gross primary production (GPP) is positively influenced by [N] even at low PPFD.
- More extensive data is required to refine GPP models incorporating the LUE-[N] relationship.
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