Canopy position affects photosynthesis and anatomy in mature Eucalyptus trees in elevated CO2

2020 ◽  
Author(s):  
K Y Crous ◽  
C Campany ◽  
R Lopez ◽  
F J Cano ◽  
D S Ellsworth
Keyword(s):  
Elevated Co2 ◽  
Anatomical Variation ◽  
Leaf Age ◽  
Net Photosynthesis ◽  
Leaf Mass Per Area ◽  
Mesophyll Conductance ◽  
Mature Leaves ◽  
Canopy Position ◽  
Palisade Cells

Abstract 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 CO2 for up to three years. We explored these traits in relation to anatomical variation and diffusive processes for CO2 (i.e., stomatal conductance, gs and mesophyll conductance, gm) in both upper and lower portions of the canopy receiving ambient and elevated CO2. While shade resulted in 13% lower leaf mass per area ratio (MA) in lower versus upper canopy leaves, there was no relationship between leaf Nmass and canopy gap fraction. Both maximum carboxylation capacity (Vcmax) and maximum electron transport (Jmax) were ~ 18% lower in shaded leaves and were also reduced by ~ 22% with leaf aging. In mature leaves, we found no canopy differences for gm or gs, despite anatomical differences in MA, leaf thickness and mean mesophyll thickness between canopy positions. There was a positive relationship between net photosynthesis and gm or gs in mature leaves. Mesophyll conductance was negatively correlated with mean parenchyma length, suggesting that long palisade cells may contribute to a longer CO2 diffusional pathway and more resistance to CO2 transfer to chloroplasts. Few other relationships between gm 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 understanding of long-term responses to elevated CO2 in tree canopies.

scholarly journals Gradients of light availability and leaf traits with leaf age and canopy position in 28 Australian shrubs and trees

2006 ◽  
Vol 33 (5) ◽  
pp. 407 ◽  
Author(s):  
Ian J. Wright ◽  
Michelle R. Leishman ◽  
Cassia Read ◽  
Mark Westoby
Keyword(s):  
Optimal Allocation ◽  
Leaf Age ◽  
Light Availability ◽  
Leaf Traits ◽  
Leaf Angle ◽  
Leaf Mass Per Area ◽  
Evergreen Species ◽  
Plant Canopies ◽  
Eastern Australia ◽  
Canopy Position

Light availability generally decreases vertically downwards through plant canopies. According to optimisation theory, in order to maximise canopy photosynthesis plants should allocate leaf nitrogen per area (Narea) in parallel with vertical light gradients, and leaf mass per area (LMA) and leaf angles should decrease down through the canopy also. Many species show trends consistent with these predictions, although these are never as steep as predicted. Most studies of canopy gradients in leaf traits have concerned tall herbaceous vegetation or forest trees. But do evergreen species from open habitats also show these patterns? We quantified gradients of light availability, LMA, leaf N and phosphorus (P), and leaf angle along leaf age sequences and vertical canopy profiles, across 28 woody species from open habitats in eastern Australia. The observed trends in LMA, Narea and leaf angle largely conflicted with expectations from canopy optimisation models, whereas trends in leaf P were more consistent with optimal allocation. These discrepancies most likely relate to these species having rather open canopies with quite shallow light gradients, but also suggest that modelling the co-optimisation of resources other than nitrogen is required for understanding plant canopies.

scholarly journals Anatomical adjustment of mature leaves of sycamore maple (Acer pseudoplatanus L.) to increased irradiance

2022 ◽  
Author(s):  
Tomasz P. Wyka ◽  
Piotr Robakowski ◽  
Roma Żytkowiak ◽  
Jacek Oleksyn
Keyword(s):  
Late Summer ◽  
Growing Season ◽  
Leaf Mass Per Area ◽  
Acer Pseudoplatanus ◽  
Gap Formation ◽  
Mature Leaves ◽  
Acclimation Period ◽  
Leaf Tissues ◽  
Physiological Adjustments ◽  
Palisade Cells

AbstractTrees regenerating in the understory respond to increased availability of light caused by gap formation by undergoing a range of morphological and physiological adjustments. These adjustments include the production of thick, sun-type leaves containing thicker mesophyll and longer palisade cells than in shade-type leaves. We asked whether in the shade-regenerating tree Acer pseudoplatanus, the increase in leaf thickness and expansion of leaf tissues are possible also in leaves that had been fully formed prior to the increase in irradiance, a response reported so far only for a handful of species. We acclimated potted seedlings to eight levels (from 1 to 100%) of solar irradiance and, in late summer, transferred a subset of them to full sunlight. Within 30 days, the shaded leaves increased leaf mass per area and became thicker mostly due to elongation of palisade cells, except for the most shaded individuals which suffered irreversible photo-oxidative damage. This anatomical acclimation was accompanied by partial degradation of chlorophyll and a transient decline in photosynthetic efficiency of PSII (Fv/FM). These effects were related to the degree of pre-shading. The Fv/FM recovered substantially within the re-acclimation period. However, leaves of transferred plants were shed significantly earlier in the fall, indicating that the acclimation was not fully effective. These results show that A. pseudoplatanus is one of the few known species in which mature leaves may re-acclimate anatomically to increased irradiance. This may be a potentially important mechanism enhancing utilization of gaps created during the growing season.

Obstructive uropathy in the context of ureteroinguinal hernia: experience of challenges in surgical management of an unwell patient

2020 ◽  
Vol 13 (8) ◽  
pp. e235060
Author(s):  
Mitchell Egerton Barns ◽  
Arvind Vasudevan ◽  
Emma Lucy Marsdin
Keyword(s):  
Obstructive Uropathy ◽  
Anatomical Variation ◽  
Surgical Patients ◽  
Definitive Treatment ◽  
Ureteric Stent ◽  
Common Presentation ◽  
Iatrogenic Damage ◽  
Vesicoureteric Junction ◽  
Collecting System

This case exemplifies an unusual anatomical variation of a common presentation and highlights the importance of perioperative diagnosis and planning in complex surgical patients. A 72-year-old comorbid man presented to the emergency department with an infected obstructed right kidney secondary to an obstructing 12 mm vesicoureteric junction calculi. However, imaging also showed concurrent ureteroinguinal hernia associated with a 130 cm-long ureter, too long for conventional treatment with a ureteric stent. Acutely, the patient’s collecting system was decompressed via nephrostomy, but due to the rarity of this anatomical variation, definitive treatment had to be rethought to help reduce the risk of iatrogenic damage and the associated long-term complications.

scholarly journals Meteorological conditions, ozone concentration and leaf age affect gas exchange in Psidium guajava ‛Palumaʼ

Hoehnea ◽  
2017 ◽  
Vol 44 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Juliana Moreno Pina ◽  
Sérgio Tadeu Meirelles ◽  
Regina Maria de Moraes
Keyword(s):  
Gas Exchange ◽  
Ozone Concentration ◽  
Leaf Age ◽  
Psidium Guajava ◽  
Meteorological Conditions ◽  
Gas Exchanges ◽  
Mature Leaves ◽  
Young Leaves ◽  
Entire Experiment ◽  
The City

ABSTRACT This study aimed to investigate the importance of leaf age, meteorological conditions and ozone concentration (O3) on gas exchange of Psidium guajava ‛Paluma'. Saplings were grown and exposed in standard conditions in the city of São Paulo, in six periods of three months with weekly measurements in young and mature leaves. Gas exchanges were higher in young leaves for almost the entire experiment. Mature leaves showed greater reduction in gas exchange. The multivariate analysis of biotic and abiotic variables indicated that vapor pressure deficit (VPD), O3 concentration and radiation were the main variables associated with gas exchange decrease in young leaves. In mature leaves the influence of VPD is lower, but the temperature importance is higher. Moreover, the opposition between assimilation and O3 is more evident in mature leaves, indicating their greater sensitivity to O3.

scholarly journals Quantitative effects of environmental variation on stomatal anatomy and gas exchange in a grass model

2021 ◽  
Author(s):  
Tiago DG Nunes ◽  
Magdalena W Slawinska ◽  
Heike Lindner ◽  
Michael T Raissig
Keyword(s):  
Gas Exchange ◽  
Anatomical Variation ◽  
Brachypodium Distachyon ◽  
Carbon Assimilation ◽  
Light Response ◽  
Gas Analysis ◽  
Environmental Signals ◽  
Grass Model ◽  
Kinetics Of

Stomata are cellular pores on the leaf epidermis that allow plants to regulate carbon assimilation and water loss. Stomata integrate environmental signals to regulate pore apertures and optimize gas exchange to fluctuating conditions. Here, we quantified intraspecific plasticity of stomatal gas exchange and anatomy in response to seasonal variation in Brachypodium distachyon. Over the course of two years we (i) used infrared gas analysis to assess light response kinetics of 120 Bd21-3 wild-type individuals in an environmentally fluctuating greenhouse and (ii) microscopically determined the seasonal variability of stomatal anatomy in a subset of these plants. We observed systemic environmental effects on gas exchange measurements and remarkable intraspecific plasticity of stomatal anatomical traits. To reliably link anatomical variation to gas exchange, we adjusted anatomical gsmax calculations for grass stomatal morphology. We propose that systemic effects and variability in stomatal anatomy should be accounted for in long-term gas exchange studies.

Increase of photosynthesis and starch in potato under elevated CO2 is dependent on leaf age

2005 ◽  
Vol 162 (4) ◽  
pp. 429-438 ◽  
Author(s):  
María Angélica Casanova Katny ◽  
Gudrun Hoffmann-Thoma ◽  
Anton Arij Schrier ◽  
Andreas Fangmeier ◽  
Hans-Jürgen Jäger ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
Leaf Age

Photosynthetic response of geranium to elevated CO2 as affected by leaf age and time of CO2 exposure

1991 ◽  
Vol 69 (11) ◽  
pp. 2482-2488 ◽  
Author(s):  
D. W. Kelly ◽  
P. R. Hicklenton ◽  
E. G. Reekie
Keyword(s):  
Stomatal Density ◽  
Leaf Age ◽  
Net Photosynthesis ◽  
Leaf Thickness ◽  
Middle Aged ◽  
Future Studies ◽  
Structural Modifications ◽  
Young Leaves ◽  
Developmental Characteristics ◽  
Density Results

Geranium plants were grown from seed in chambers maintained at 350 or 1000 μL∙L−1 CO2. Phtopsynthesis as affected by leaf age and by leaf position was determined. Elevated CO2 enhanced photosynthesis to the greatest extent in middle-aged leaves; very young leaves exhibited little enhancement, and net photosynthesis in the oldest leaves was depressed by elevated CO2. Temporary increases in net photosynthesis (relative to leaves developed at high CO2) resulted when young leaves grown at 350 μL∙L−1 CO2 were switched to 1000 μL∙L−1 CO2. Leaves switched later in development exhibited permanent enhancement. Middle-aged leaves exhibited a temporary depression followed by permanent enhancement. Leaves developed at high CO2 and switched to low CO2 did not exhibit any photosynthetic depression relative to plants grown continuously at low CO2. Similarly, leaves developed at low CO2, switched to high CO2 for various lengths of time, and returned to low CO2 showed no photosynthetic depression. Leaves developed at low CO2 and switched to high CO2 exhibited increases in specific leaf weight and leaf thickness. The increase in leaf thickness was proportional to length of time spent at high CO2. High CO2 depressed the rate at which stomata developed but did not affect final stomatal density. Results suggest that photosynthesis at low CO2 was limited by CO2 regardless of developmental environment, whereas photosynthesis at high CO2 was limited by the developmental characteristics of the leaf. Further, both biochemical and structural modifications appear to be involved in this response. Because of the very different responses of young versus old leaves, future studies should be careful to consider leaf age in assessing response to elevated CO2. Key words: carbon dioxide, elevated CO2, photosynthesis, geranium.

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