English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Leaves are exposed to different light conditions according to their canopy position, resulting in structural and anatomical differences with consequences for carbon uptake. While these structure–function relationships have been thoroughly explored in dense forest canopies, such gradients may be diminished in open canopies, and they are often ignored in ecosystem models. We tested within-canopy differences in photosynthetic properties and structural traits in leaves in a mature  Eucalyptus tereticornis  canopy exposed to long-term elevated CO 2  for up to 3 years. We explored these traits in relation to anatomical variation and diffusive processes for CO 2  (i.e., stomatal conductance,  g  s , and mesophyll conductance,  g  m ) in both upper and lower portions of the canopy receiving ambient and elevated CO 2 . While shade resulted in 13% lower leaf mass per area ratio ( M  A ) in lower versus upper canopy leaves, there was no relationship between leaf nitrogen concentration ( N  mass ) and canopy gap fraction. Both maximum carboxylation capacity ( V  cmax ) and maximum electron transport ( J  max ) were ~18% lower in shaded leaves and were also reduced by ~22% with leaf aging. In mature leaves, we found no canopy differences for  g  m  or  g  s,  despite anatomical differences in  M  A , leaf thickness and mean mesophyll thickness between canopy positions. There was a positive relationship between net photosynthesis and  g  m  or  g  s  in mature leaves. Mesophyll conductance was negatively correlated with mean parenchyma length, suggesting that long palisade cells may contribute to a longer CO 2  diffusional pathway and more resistance to CO 2  transfer to chloroplasts. Few other relationships between  g  m  and anatomical variables were found in mature leaves, which may be due to the open crown of  Eucalyptus . Consideration of shade effects and leaf-age-dependent responses to photosynthetic capacity and mesophyll conductance are critical to improve canopy photosynthesis models and will improve the understanding of long-term responses to elevated CO 2  in tree canopies.

Canopy position affects photosynthesis and anatomy in mature Eucalyptus trees in elevated CO 2