Carbon dioxide transfer resistance as a factor in shade tolerance of tree seedlings

1970 ◽  
Vol 48 (3) ◽  
pp. 453-456 ◽  
Author(s):  
J. E. Wuenscher ◽  
T. T. Kozlowski
Keyword(s):  
Carbon Dioxide ◽  
Acer Saccharum ◽  
Net Photosynthesis ◽  
Tree Seedlings ◽  
Transfer Resistance ◽  
Quercus Velutina ◽  
Light Intensities ◽  
Quercus Species ◽  
Highly Correlated ◽  
Resistance Rates

Net photosynthesis and transpiration rates of single leaves of Quercus velutina Lam., Q. macrocarpa Michx. var. olivaeformis, and Acer saccharum Marsh. were measured at light intensities of 0.03 to 0.24 cal cm−2 min−1 (400–700 mμ). Resistance to water vapor and carbon dioxide transfer were calculated. Net photosynthesis of the Quercus species was not light saturated until light intensity was increased sufficiently to induce complete stomatal opening, indicating possible limitation of CO2 uptake at low light intensities by high CO2 transfer resistance. Rates of light-saturated net photosynthesis of all three species were highly correlated with CO2 transfer resistance.

Photosynthesis and Carbon Dioxide Transfer Resistance of Lodgepole Pine Seedlings in Relation to Irradiance, Temperature, and Water Potential

1974 ◽  
Vol 4 (2) ◽  
pp. 201-206 ◽  
Author(s):  
Gary F. Dykstra
Keyword(s):  
Carbon Dioxide ◽  
Water Potential ◽  
Environmental Conditions ◽  
Net Photosynthesis ◽  
Stomatal Resistance ◽  
Transfer Resistance ◽  
Pine Seedlings ◽  
Rate Limiting ◽  
Potential Maximum ◽  
Mesophyll Resistance

Photosynthesis and stomatal and total equivalent mesophyll resistances to CO2 transfer were measured in relation to irradiance, needle temperature, and tree water potential. Maximum rates of net photosynthesis were attained at 380 W m−2 irradiance, 20 °C needle temperature, and the highest tree water potential obtained, ca. −2.5 bars. Stomatal and total mesophyll resistances have a significant rate-limiting role when environmental conditions are less than optimum. Mesophyll resistance was larger than stomatal resistance under all environmental conditions.

Carbon dioxide biofixation byChlorella vulgarisat different CO2concentrations and light intensities

2014 ◽  
Vol 14 (5) ◽  
pp. 509-519 ◽  
Author(s):  
Barbara Clément-Larosière ◽  
Filipa Lopes ◽  
Ana Gonçalves ◽  
Behnam Taidi ◽  
Marc Benedetti ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Light Intensities

Understanding Carbon Dioxide Transfer in Direct Methanol Fuel Cells Using a Pore-Scale Model

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Nathaniel Metzger ◽  
Archana Sekar ◽  
Jun Li ◽  
Xianglin Li
Keyword(s):  
Carbon Dioxide ◽  
Pressure Drop ◽  
Gas Flow ◽  
Direct Methanol Fuel Cells ◽  
Gas Pressure ◽  
Mass Transfer Resistance ◽  
Transfer Resistance ◽  
Cell Components ◽  
Direct Methanol ◽  
Methanol Fuel Cells

Abstract The gas flow of carbon dioxide from the catalyst layer (CL) through the microporous layer (MPL) and gas diffusion layer (GDL) has great impacts on the water and fuel management in direct methanol fuel cells (DMFCs). This work has developed a liquid–vapor two-phase model considering the counter flow of carbon dioxide gas, methanol, and water liquid solution in porous electrodes of DMFC. The model simulation includes the capillary pressure as well as the pressure drop due to flow resistance through the fuel cell components. The pressure drop of carbon dioxide flow is found to be about two to three orders of magnitude higher than the pressure drop of the liquid flow. The big difference between liquid and gas pressure drops can be explained by two reasons: volume flowrate of gas is three orders of magnitude higher than that of liquid; only a small fraction of pores (<5%) in hydrophilic fuel cell components are available for gas flow. Model results indicate that the gas pressure and the mass transfer resistance of liquid and gas are more sensitive to the pore size distribution than the thickness of porous components. To buildup high gas pressure and high mass transfer resistance of liquid, the MPL and CL should avoid micro-cracks during manufacture. Distributions of pore size and wettability of the GDL and MPL have been designed to reduce the methanol crossover and improve fuel efficiency. The model results provide design guidance to obtain superior DMFC performance using highly concentrated methanol solutions or even pure methanol.

Trends in noctilucent clouds

2021 ◽  
Author(s):  
Franz-Josef Lübken ◽  
Gerd Baumgarten
Keyword(s):  
Carbon Dioxide ◽  
Water Vapor ◽  
Middle Atmosphere ◽  
Transport Model ◽  
Particle Model ◽  
Noctilucent Clouds ◽  
Middle Latitudes ◽  
Ice Particles ◽  
Highly Correlated ◽  
Ice Water

<p>Noctilucent clouds are often cited as potential indicators of climate change in the middle<br>atmosphere. They owe their existence to the very cold summer mesopause region (~130K) at mid<br>and high latitudes. We analyze trends derived from the Leibniz-Institute Middle Atmosphere<br>Model (LIMA) and the MIMAS ice particle model (Mesospheric Ice Microphysics And tranSport model)<br>for the years 1871-2008 and for middle, high and arctic latitudes, respectively.<br>Model runs with and without an increase of carbon dioxide and water vapor (from methane oxidation)<br>concentration are performed. Trends are most prominent after ~1960 when the increase of both<br>carbon dioxide and water vapor accelerates. Negative trends of (geometric) NLC altitudes are primarily<br>due to cooling below NLC altitudes caused by carbon dioxide increase. Increases of ice particle<br>radii and NLC brightness with time are mainly caused by an enhancement of water vapor.<br>Several ice layer and background parameter trends are similar at high and arctic latitudes but are<br>substantially different at middle latitudes. This concerns, for example, occurrence rates, ice water<br>content (IWC), and number of ice particles in a column. Considering the time period after 1960,<br>geometric altitudes of NLC decrease by approximately 260m per decade, and brightness increases by<br>roughly 50% (1960-2008), independent of latitude. NLC altitudes decrease by approximately 15-20m<br>per increase of carbon dioxide by 1ppmv. The number of ice particles in a column and also at the<br>altitude of maximum backscatter is nearly constant with time. At all latitudes, yearly mean NLC<br>appear at altitudes where temperatures are close to 145+/-1K. Ice particles are present nearly<br>all the time at high and arctic latitudes, but are much less common at middle latitudes. Ice water<br>content and maximum backscatter are highly correlated, where the slope depends on latitude. This<br>allows to combine data sets from satellites and lidars. Furthermore, IWC and the concentration of<br>water vapor at the altitude of maximum backscatter are also strongly correlated. Results from<br>LIMA/MIMAS agree nicely with observations.</p>

Modified Photobioreactor for Biofixation of Carbon Dioxide byChlorella vulgarisat Different Light Intensities

2015 ◽  
Vol 38 (8) ◽  
pp. 1371-1379 ◽  
Author(s):  
Gita Naderi ◽  
Moses O. Tade ◽  
Hussein Znad
Keyword(s):  
Carbon Dioxide ◽  
Light Intensities

Living long by staying small: stem layering as an adaptive life-history trait in shade-tolerant tree seedlings

2008 ◽  
Vol 38 (3) ◽  
pp. 480-487 ◽  
Author(s):  
Kerry D. Woods
Keyword(s):  
Population Dynamics ◽  
Acer Saccharum ◽  
Life Histories ◽  
Adventitious Roots ◽  
Shade Tolerance ◽  
Stem Growth ◽  
Life History Trait ◽  
Tree Seedlings ◽  
Canopy Trees ◽  
Successional Forests

Suppressed seedling banks are important in replacement dynamics in late-successional forests. However, demographic properties of seedling populations are poorly known, and there has been little attention to traits that might affect fitness in suppressed seedlings. Acer saccharum Marsh., a shade-tolerant dominant in eastern North American forests, frequently develops adventitious roots along prostrate portions of stems (“layering”). Measurements of Acer seedlings in old-growth forests in Michigan indicate that layered seedlings proportionally reduce structural allocations to older layered stem tissues, retain leaf area / height ratios of younger unlayered seedlings, and tend to survive longer. In tree seedlings, allometric consequences of normal stem growth lead to declining ratios of photosynthetic to nonphotosynthetic biomass, which potentially reduces shade tolerance and limiting age. The layering habit may defer this penalty by changing the allometry of growth. Resulting increases in life expectancy should increase chance of access to increased light and of reaching the canopy. Thus, because flowering is generally restricted to canopy trees, the tendency to layer may increase fitness. Properties of individuals in suppressed seedling banks may be selectively and ecologically important, shaping life histories and population dynamics.

scholarly journals Effect of Light Intensity and Leaf Temperature on Photosynthesis and Transpiration in Wheat and Sorghum

1970 ◽  
Vol 23 (4) ◽  
pp. 775 ◽  
Author(s):  
RW Downes
Keyword(s):  
Carbon Dioxide ◽  
Water Use ◽  
Carbon Dioxide Concentration ◽  
Leaf Temperature ◽  
High Light ◽  
Intercellular Spaces ◽  
Concentration Difference ◽  
Light Levels ◽  
Light Intensities ◽  
Water Vapour Concentration

Wheat stomata offered less resistance to water and carbon dioxide diffusion than sorghum stomata at light intensities of 0�06 and 0�26 cal cm-2 min-i (400-700 nm) but resistances were comparable at 0�46 cal cm-2 min-i. Consequently, transpiration rates were higher in wheat than in sorghum, except at the high light levels, in leaf chamber experiments described here. Rates of photosynthesis were higher in sorghum than in wheat, with the greatest difference at high light levels. This resulted in a greater efficiency of dry matter production relative to water use in sorghum. Transpiration rate increased with increased temperature in both species. Photosynthesis was independent of temperature in wheat, and in sorghum under low light conditions, but otherwise photosynthesis increased with temperature in sorghum. In both species, efficiency of water use decreased as temperature increased at all light intensities. Water vapour concentration difference between the intercellular spaces and the air was comparable in wheat and sorghum and increased with temperature. The carbon dioxide concentration difference between air and intercellular spaces was substantially greater in sorghum than in wheat and increased with leaf temperature. Maximum values were obtained at the intermediate light level in sorghum.

scholarly journals Contributions of leaf photosynthetic capacity, leaf angle and self-shading to the maximization of net photosynthesis in Acer saccharum: a modelling assessment

2012 ◽  
Vol 110 (3) ◽  
pp. 731-741 ◽  
Author(s):  
Juan M. Posada ◽  
Risto Sievänen ◽  
Christian Messier ◽  
Jari Perttunen ◽  
Eero Nikinmaa ◽  
...  
Keyword(s):  
Acer Saccharum ◽  
Photosynthetic Capacity ◽  
Net Photosynthesis ◽  
Leaf Angle

scholarly journals Mineral Elements of Subtropical Tree Seedlings in Response to Elevated Carbon Dioxide and Nitrogen Addition

PLoS ONE ◽  
2015 ◽  
Vol 10 (3) ◽  
pp. e0120190 ◽  
Author(s):  
Wenjuan Huang ◽  
Guoyi Zhou ◽  
Juxiu Liu ◽  
Deqiang Zhang ◽  
Shizhong Liu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Elevated Carbon Dioxide ◽  
Nitrogen Addition ◽  
Mineral Elements ◽  
Tree Seedlings
Sign in / Sign up

Export Citation Format

Share Document