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Articles 1 - 13 of 13
Full-Text Articles in Physical Sciences and Mathematics
Gas Exchange Measurements In The Unsteady State, Aaron J. Saathoff, Jonathan Mark Welles
Gas Exchange Measurements In The Unsteady State, Aaron J. Saathoff, Jonathan Mark Welles
School of Natural Resources: Faculty Publications
Leaf level gas exchange is a widely used technique that provides real-time measurement of leaf physiological properties, including CO2 assimilation (A), stomatal conductance to water vapour (gsw) and intercellular CO2 (Ci). Modern open-path gas exchange systems offer greater portability than the laboratory-built systems of the past and take advantage of high-precision infrared gas analyzers and optimized system design. However, the basic measurement paradigm has long required steadystate conditions for accurate measurement. For CO2 response curves, this requirement has meant that each point on the curve needs 1–3 min and a full response curve …
Parallel Seasonal Patterns Of Photosynthesis, Fluorescence, And Reflectance Indices In Boreal Trees, Kyle R. Springer, Ran Wang, John A. Gamon
Parallel Seasonal Patterns Of Photosynthesis, Fluorescence, And Reflectance Indices In Boreal Trees, Kyle R. Springer, Ran Wang, John A. Gamon
School of Natural Resources: Faculty Publications
Tree species in the boreal forest cycle between periods of active growth and dormancy alter their photosynthetic processes in response to changing environmental conditions. For deciduous species, these changes are readily visible, while evergreen species have subtler foliar changes during seasonal transitions. In this study, we used remotely sensed optical indices to observe seasonal changes in photosynthetic activity, or photosynthetic phenology, of six boreal tree species. We evaluated the normalized difference vegetation index (NDVI), the photochemical reflectance index (PRI), the chlorophyll/carotenoid index (CCI), and steady-state chlorophyll fluorescence (FS) as a measure of solar-induced fluorescence (SIF), and compared these …
Parallel Seasonal Patterns Of Photosynthesis, Fluorescence, And Reflectance Indices In Boreal Trees, Kyle R. Springer, Ran Wang, John A. Gamon
Parallel Seasonal Patterns Of Photosynthesis, Fluorescence, And Reflectance Indices In Boreal Trees, Kyle R. Springer, Ran Wang, John A. Gamon
School of Natural Resources: Faculty Publications
Tree species in the boreal forest cycle between periods of active growth and dormancy alter their photosynthetic processes in response to changing environmental conditions. For deciduous species, these changes are readily visible, while evergreen species have subtler foliar changes during seasonal transitions. In this study, we used remotely sensed optical indices to observe seasonal changes in photosynthetic activity, or photosynthetic phenology, of six boreal tree species. We evaluated the normalized difference vegetation index (NDVI), the photochemical reflectance index (PRI), the chlorophyll/carotenoid index (CCI), and steady-state chlorophyll fluorescence (FS) as a measure of solar-induced fluorescence (SIF), and compared these …
Productivity, Absorbed Photosynthetically Active Radiation, And Light Use Efficiency In Crops: Implications For Remote Sensing Of Crop Primary Production, Anatoly A. Gitelson, Yi Peng, Timothy J. Arkebauer, Andrew E. Suyker
Productivity, Absorbed Photosynthetically Active Radiation, And Light Use Efficiency In Crops: Implications For Remote Sensing Of Crop Primary Production, Anatoly A. Gitelson, Yi Peng, Timothy J. Arkebauer, Andrew E. Suyker
School of Natural Resources: Faculty Publications
Vegetation productivity metrics such as gross primary production (GPP) at the canopy scale are greatly affected by the efficiency of using absorbed radiation for photosynthesis, or light use efficiency (LUE). Thus, close investigation of the relationships between canopy GPP and photosynthetically active radiation absorbed by vegetation is the basis for quantification of LUE. We used multiyear observations over irrigated and rainfed contrasting C3 (soybean) and C4 (maize) crops having different physiology, leaf structure, and canopy architecture to establish the relationships between canopy GPP and radiation absorbed by vegetation and quantify LUE. Although multiple LUE definitions are reported in the literature, …
On The Spatial Heterogeneity Of Net Ecosystem Productivity In Complex Landscapes, Ryan E. Emanuel, Diego Andrés Riveros-Iregui, Brian L. Mcglynn, Howard E. Epstein
On The Spatial Heterogeneity Of Net Ecosystem Productivity In Complex Landscapes, Ryan E. Emanuel, Diego Andrés Riveros-Iregui, Brian L. Mcglynn, Howard E. Epstein
School of Natural Resources: Faculty Publications
Micrometeorological flux towers provide spatially integrated estimates of net ecosystem production (NEP) of carbon over areas ranging from several hectares to several square kilometers, but they do so at the expense of spatially explicit information within the footprint of the tower. This finer-scale information is crucial for understanding how physical and biological factors interact and give rise to towermeasured fluxes in complex landscapes. We present a simple approach for quantifying and evaluating the spatial heterogeneity of cumulative growing season NEP for complex landscapes. Our method is based on spatially distributed information about physical and biological landscape variables and knowledge of …
Modeling Whole-Tree Carbon Assimilation Rate Using Observed Transpiration Rates And Needle Sugar Carbon Isotope Ratios, Jia Hu, David J. P. Moore, Diego Andrés Riveros-Iregui, Sean P. Burns, Russell K. Monson
Modeling Whole-Tree Carbon Assimilation Rate Using Observed Transpiration Rates And Needle Sugar Carbon Isotope Ratios, Jia Hu, David J. P. Moore, Diego Andrés Riveros-Iregui, Sean P. Burns, Russell K. Monson
School of Natural Resources: Faculty Publications
• Understanding controls over plant–atmosphere CO2 exchange is important for quantifying carbon budgets across a range of spatial and temporal scales. In this study, we used a simple approach to estimate whole-tree CO2 assimilation rate (ATree) in a subalpine forest ecosystem.
• We analysed the carbon isotope ratio (δ13C) of extracted needle sugars and combined it with the daytime leaf-to-air vapor pressure deficit to estimate tree water-use efficiency (WUE). The estimated WUE was then combined with observations of tree transpiration rate (E) using sap flow techniques to estimate ATree. …
Scaling Up Of Co2 Fluxes From Leaf To Canopy In Maize-Based Agroecosystems, Timothy J. Arkebauer, Elizabeth A. Walter-Shea, Mark A. Mesarch, Andrew E. Suyker, Shashi Verma
Scaling Up Of Co2 Fluxes From Leaf To Canopy In Maize-Based Agroecosystems, Timothy J. Arkebauer, Elizabeth A. Walter-Shea, Mark A. Mesarch, Andrew E. Suyker, Shashi Verma
School of Natural Resources: Faculty Publications
Carbon dioxide fluxes are being measured in three maize-based agroecosystems in eastern Nebraska in an effort to better understand the potential for these systems to sequester carbon in the soil. Landscape-level fluxes of carbon, water and energy were measured using tower eddy covariance systems. In order to better understand the landscape-level results, measurements at smaller scales, using techniques promoted by John Norman, were made and scaled up to the landscape-level. Single leaf gas exchange properties (CO2 assimilation rate and stomatal conductance) and optical properties, direct and diffuse radiation incident on the canopy, and photosynthetically active radiation (PAR) reflected and …
Photosynthetic Response Of Soybean To Twospotted Spider Mite (Acari: Tetranychydae) Injury, Adeney De Freitas Bueno, Regiane Cristina Oliveira De Freitas Bueno, Paul David Nabity, Leon George Higley, Odair Aparecido Fernandes
Photosynthetic Response Of Soybean To Twospotted Spider Mite (Acari: Tetranychydae) Injury, Adeney De Freitas Bueno, Regiane Cristina Oliveira De Freitas Bueno, Paul David Nabity, Leon George Higley, Odair Aparecido Fernandes
School of Natural Resources: Faculty Publications
The twospotted spider mite Tetranychus urticae Koch is a common pest on soybean plants. To clarify plantarthropod interaction on mite-soybean system, leaf fluorescence, photosynthetic responses to variable carbon dioxide levels, and chlorophyll content were evaluated. Significant photosynthetic rate reduction was observed due to stomatal limitation. Stomatal closure was the major plant physiological response. As a consequence, there was reduction in photosynthetic rates. Surprisingly, plants did not show chlorophyll content reduction associated with photosynthetic impairment. No differences in fluorescence data indicate that T. urticae injury did not impair the function of light harvesting and photoelectron transport. These results showed that T. …
Ecophysiology Of Two Native Invasive Woody Species And Two Dominant Warm-Season Grasses In The Semiarid Grasslands Of The Nebraska Sandhills, Kathleen D. Eggemeyer, Tala Awada, David A. Wedin, F. Edwin Harvey, Xinhua Zhou
Ecophysiology Of Two Native Invasive Woody Species And Two Dominant Warm-Season Grasses In The Semiarid Grasslands Of The Nebraska Sandhills, Kathleen D. Eggemeyer, Tala Awada, David A. Wedin, F. Edwin Harvey, Xinhua Zhou
School of Natural Resources: Faculty Publications
Populations of Pinus ponderosa and Juniperus virginiana are expanding into semiarid Sandhills grasslands in Nebraska. To evaluate the physiological basis of their success, we measured the seasonal course of leaf gas exchange, plant water status, and carbon isotope discrimination in these two native trees and two native C4 grasses (Schizachyrium scoparium and Panicum virgatum). Compared to the trees, grasses had higher net photosynthetic rates (Anet) and water use efficiency (WUE) and more negative predawn and midday water potentials (Ψ) in June and July. While leaf Ψ and rates of leaf gas exchange declined for all …
Ecophysiology Of Two Native Invasive Woody Species And Two Dominant Warm-Season Grasses In The Semiarid Grasslands Of The Nebraska Sandhills, Kathleen D. Eggemeyer, Tala Awada, David A. Wedin, F. Edwin Harvey, Xinhua Zhou
Ecophysiology Of Two Native Invasive Woody Species And Two Dominant Warm-Season Grasses In The Semiarid Grasslands Of The Nebraska Sandhills, Kathleen D. Eggemeyer, Tala Awada, David A. Wedin, F. Edwin Harvey, Xinhua Zhou
School of Natural Resources: Faculty Publications
Populations of Pinus ponderosa and Juniperus virginiana are expanding into semiarid Sandhills grasslands in Nebraska. To evaluate the physiological basis of their success, we measured the seasonal course of leaf gas exchange, plant water status, and carbon isotope discrimination in these two native trees and two native C4 grasses (Schizachyrium scoparium and Panicum virgatum). Compared to the trees, grasses had higher net photosynthetic rates (Anet) and water use efficiency (WUE) and more negative predawn and midday water potentials (Ψ) in June and July. While leaf Ψ and rates of leaf gas exchange declined for all …
Photosynthesis And Stomatal Conductance Related To Reflectance On The Canopy Scale, S. B. Verma
Photosynthesis And Stomatal Conductance Related To Reflectance On The Canopy Scale, S. B. Verma
School of Natural Resources: Faculty Publications
No abstract provided.
Modeling Canopy Photosynthesis: Scaling Up From A Leaf To Canopy In A Temperate Grassland Ecosystem, S. B. Verma
Modeling Canopy Photosynthesis: Scaling Up From A Leaf To Canopy In A Temperate Grassland Ecosystem, S. B. Verma
School of Natural Resources: Faculty Publications
No abstract provided.
Simultaneous Determination Of Short-Period Photosynthesis And Evapotranspiration (Horticulture And Forestry Progress Report No. 91), Norman J. Rosenberg
Simultaneous Determination Of Short-Period Photosynthesis And Evapotranspiration (Horticulture And Forestry Progress Report No. 91), Norman J. Rosenberg
School of Natural Resources: Faculty Publications
No abstract provided.