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The importance of micrometeorological variations for photosynthesis and transpiration in a boreal coniferous forest

Schurgers, Guy LU ; Lagergren, Fredrik LU ; Mölder, Meelis LU and Lindroth, Anders LU (2015) In Biogeosciences 12(1). p.237-256
Abstract
Plant canopies affect the canopy micrometeorology, and thereby alter canopy exchange processes. For the simulation of these exchange processes on a regional or global scale, large-scale vegetation models often assume homogeneous environmental conditions within the canopy. In this study, we address the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy level while applying the within-canopy distributions of these driving variables. The simulation model showed good agreement with eddy... (More)
Plant canopies affect the canopy micrometeorology, and thereby alter canopy exchange processes. For the simulation of these exchange processes on a regional or global scale, large-scale vegetation models often assume homogeneous environmental conditions within the canopy. In this study, we address the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy level while applying the within-canopy distributions of these driving variables. The simulation model showed good agreement with eddy covariance-derived gross primary production (GPP) estimates on daily and annual timescales, and showed a reasonable agreement between transpiration and observed H2O fluxes, where discrepancies are largely attributable to a lack of forest floor evaporation in the model. Simulations in which vertical heterogeneity was artificially suppressed revealed that the vertical distribution of light is the driver of vertical heterogeneity. Despite large differences between above-canopy and within-canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biogeosciences
volume
12
issue
1
pages
237 - 256
publisher
Copernicus Publications
external identifiers
  • wos:000347960800015
  • scopus:84920997141
ISSN
1726-4189
DOI
10.5194/bg-12-237-2015
language
English
LU publication?
yes
id
929dea92-c245-4043-9d49-a402be126244 (old id 5063107)
date added to LUP
2015-02-24 11:59:48
date last changed
2017-10-01 03:30:36
@article{929dea92-c245-4043-9d49-a402be126244,
  abstract     = {Plant canopies affect the canopy micrometeorology, and thereby alter canopy exchange processes. For the simulation of these exchange processes on a regional or global scale, large-scale vegetation models often assume homogeneous environmental conditions within the canopy. In this study, we address the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy level while applying the within-canopy distributions of these driving variables. The simulation model showed good agreement with eddy covariance-derived gross primary production (GPP) estimates on daily and annual timescales, and showed a reasonable agreement between transpiration and observed H2O fluxes, where discrepancies are largely attributable to a lack of forest floor evaporation in the model. Simulations in which vertical heterogeneity was artificially suppressed revealed that the vertical distribution of light is the driver of vertical heterogeneity. Despite large differences between above-canopy and within-canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration.},
  author       = {Schurgers, Guy and Lagergren, Fredrik and Mölder, Meelis and Lindroth, Anders},
  issn         = {1726-4189},
  language     = {eng},
  number       = {1},
  pages        = {237--256},
  publisher    = {Copernicus Publications},
  series       = {Biogeosciences},
  title        = {The importance of micrometeorological variations for photosynthesis and transpiration in a boreal coniferous forest},
  url          = {http://dx.doi.org/10.5194/bg-12-237-2015},
  volume       = {12},
  year         = {2015},
}