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Stith T. Gower - One of the best experts on this subject based on the ideXlab platform.
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Leaf area index measurements of Boreal forests: Theory, techniques, and L
2020Co-Authors: Jing M. Chen, Stith T. Gower, Paul Steven Plummer5, M Rich, John M. NormanAbstract:Abstract. Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LA1 estimates are required in studies of ecophysiology, atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LA1 values obtained by several research teams using different methods for a broad spectrum of Boreal forest types in support of the international Boreal EcosystemAtmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI-2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LA1 from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LA1 of Boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LA1 falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LA1 estimates available for Boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LA1 measurements
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net primary production and carbon allocation patterns of Boreal forest ecosystems
Ecological Applications, 2001Co-Authors: Stith T. Gower, Olga N Krankina, R.j. Olson, Michael J Apps, Sune Linder, Chuankuan WangAbstract:The three objectives of this paper were: to summarize net primary production (NPP) and carbon allocation patterns for Boreal forests, to examine relationships between climatic and biological variables and NPP, and to examine carbon allocation coefficients for all Boreal forests or types of Boreal forests that can be used to estimate NPP from easily measured components of NPP. Twenty-four Class I stands (complete NPP budgets) and 45 Class II Boreal forest stands (aboveground NPP [NPPA] and budget only) were identified. The geographic distribution of the Class I stands was not uniform; 46% of the stands were from two studies in North America, and only one stand was from the important larch forests of Eurasia. Total (above- and belowground) net primary production (NPPT) ranged from 52 to 868 g C·m−2·yr−1 and averaged 424 g C·m−2·yr−1. NPPA was consistently larger for deciduous than for evergreen Boreal forests in each of the major Boreal regions, especially for Boreal forests in Alaska. Belowground net prima...
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net primary production and carbon allocation patterns of Boreal forest ecosystems
Ecological Applications, 2001Co-Authors: Stith T. Gower, Olga N Krankina, R.j. Olson, Michael J Apps, Sune Linder, Chuankuan WangAbstract:The three objectives of this paper were: to summarize net primary production (NPP) and carbon allocation patterns for Boreal forests, to examine relationships between climatic and biological variables and NPP, and to examine carbon allocation coefficients for all Boreal forests or types of Boreal forests that can be used to estimate NPP from easily measured components of NPP. Twenty-four Class I stands (complete NPP budgets) and 45 Class II Boreal forest stands (aboveground NPP [NPPA] and budget only) were identified. The geographic distribution of the Class I stands was not uniform; 46% of the stands were from two studies in North America, and only one stand was from the important larch forests of Eurasia. Total (above- and belowground) net primary production (NPPT) ranged from 52 to 868 g C·m−2·yr−1 and averaged 424 g C·m−2·yr−1. NPPA was consistently larger for deciduous than for evergreen Boreal forests in each of the major Boreal regions, especially for Boreal forests in Alaska. Belowground net prima...
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measurements of leaf orientation light distribution and sunlit leaf area in a Boreal aspen forest
Agricultural and Forest Meteorology, 1998Co-Authors: Christopher J. Kucharik, John M. Norman, Stith T. GowerAbstract:A new instrument called a Multiband Vegetation Imager (MVI) (Kucharik et al., 1997), which uses a 16-bit charge-coupled device (CCD) camera and filter exchange mechanism to capture 2-band (visible and near-infrared) image pairs of plant canopies, has been used to measure the light distribution over sunlit leaves and indirectly infer leaf area index (LAI), sunlit LAI and leaf angle distribution (LAD) in a Boreal aspen (Populus tremuloides) forest during the Boreal Ecosystem‐ Atmosphere Study (BOREAS). One purpose of this study is to demonstrate that by combining MVI measurements with numerical Monte Carlo simulations of forest canopy architecture, the LAD and sunlit LAI of aspen can be obtained indirectly. Our results show that this Boreal aspen stand exemplifies an erectophile LAD, with a mean leaf inclination angle near 708 .W e also find that the values of the measured and modeled sunlit leaf area in aspen do not change dramatically for typical northern Boreal latitude solar zenith angles (i.e. 30‐708). A major problem with determining the sunlit LAI is deciding what range of light intensities constitute a sunlit leaf because penumbra create a smooth continuum of light intensities over sunlit and shaded leaves in the canopy. Therefore, we show that the upper and lower limits can be placed on sunlit LAI values in aspen by using different leaf illumination threshold levels to determine sunlit and shaded LAI in the canopy. Typically, sunlit LAI values in aspen (LAIa3.3) range between 0.8‐1.0 at a 708 sun zenith angle and 1.1‐1.6 at a 308 sun zenith angle. Monte Carlo simulations and MVI measurements suggest that canopy sunlit leaf area estimates are possible from below the canopy at modest LAI values ( 5.0). Since a substantial fraction of the total sunlit leaf area can be viewed from below the canopy in aspen (40‐60% of the total sunlit LAI), a representative light distribution can be measured and used to quantify the canopy leaf angle distribution. # 1998 Elsevier Science B.V. All rights reserved.
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leaf area index of Boreal forests theory techniques and measurements
Journal of Geophysical Research, 1997Co-Authors: Jing M. Chen, John M. Norman, Stith T. Gower, Paul M Rich, Steven PlummerAbstract:Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LAI estimates are required in studies of ecophysiology, atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LAI values obtained by several research teams using different methods for a broad spectrum of Boreal forest types in support of the international Boreal Ecosystem-Atmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI-2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LAI from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LAI of Boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LAI falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LAI estimates available for Boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LAI measurements.
Jing M. Chen - One of the best experts on this subject based on the ideXlab platform.
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Leaf area index measurements of Boreal forests: Theory, techniques, and L
2020Co-Authors: Jing M. Chen, Stith T. Gower, Paul Steven Plummer5, M Rich, John M. NormanAbstract:Abstract. Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LA1 estimates are required in studies of ecophysiology, atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LA1 values obtained by several research teams using different methods for a broad spectrum of Boreal forest types in support of the international Boreal EcosystemAtmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI-2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LA1 from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LA1 of Boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LA1 falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LA1 estimates available for Boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LA1 measurements
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Leaf area index measurements
2014Co-Authors: Jing M. Chen, L Paul, Steven PlummerAbstract:Abstract. Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LA1 estimates are required in studies of ecophysiology, atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LA1 values obtained by several research teams using different methods for a broad spectrum of Boreal forest types in support of the international Boreal Ecosystem-Atmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI-2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LA1 from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LA1 of Boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LA1 falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LA1 estimates available for Boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LA1 measurements. 1
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compact airborne spectrographic imager casi used for mapping biophysical parameters of Boreal forests
Journal of Geophysical Research, 1999Co-Authors: Jing M. Chen, J R Miller, J Freemantle, Sylvain G Leblanc, Sara Loechel, C L Walthall, Kris A Innanen, Peter H WhiteAbstract:During the Boreal Ecosystem-Atmosphere Study (BOREAS), which took place in Saskatchewan and Manitoba in 1994, the Compact Airborne Spectrographic Imager (CASI) acquired images of Boreal forests. In this paper we present results of radiometric and geometric analysis of the CASI data for developing algorithms for retrieving leaf area index (LAI) and crown closure of the Boreal forest. The images of over 30 sites, composed of black spruce, jack pine, and aspen stands, were acquired on different days and locations with various solar illumination and view geometries. The geometrical-optical model, named "4-Scale" (Chen and Leblanc, 1997, 1316 -1337), was used to correct the images to a common solar zenith angle (358) and a common view angle (nadir). The 4-Scale model is also used for radiometric analysis based on spectral signatures of leaves and the background (moss, grass, and soil) acquired using various field and laboratory techniques. The red reflectance of all three cover types decreased with increasing LAI as expected. Similar but weaker decreasing trends were found in the near-infrared (NIR) band for conifer stands in contrast to previous findings for cropland and grassland. No significant NIR response to LAI was found for aspen stands. It is shown from 4-Scale that as LAI increases, the crown and ground shadow fractions of conifer forests increase, while the sunlit background fraction decreases and the sunlit crown fraction increases. The large change in the shadow fractions is the major factor controlling the behavior of red and NIR signals. Since Boreal forests have abundant green moss and understory as the background, there is only a small difference in optical properties between the overstory and the background. The increases in the shadow fractions with LAI help strengthen the response of optical measurements to changes in LAI, providing a key mechanism for remote information retrieval. The implications of these findings on formulating/selecting vegetation indices and inversion models are discussed in this paper. Relationships of crown closure with CASI measurements are also included in the analysis.
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leaf area index of Boreal forests theory techniques and measurements
Journal of Geophysical Research, 1997Co-Authors: Jing M. Chen, John M. Norman, Stith T. Gower, Paul M Rich, Steven PlummerAbstract:Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LAI estimates are required in studies of ecophysiology, atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LAI values obtained by several research teams using different methods for a broad spectrum of Boreal forest types in support of the international Boreal Ecosystem-Atmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI-2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LAI from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LAI of Boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LAI falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LAI estimates available for Boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LAI measurements.
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seasonal change in understory reflectance of Boreal forests and influence on canopy vegetation indices
Journal of Geophysical Research, 1997Co-Authors: J R Miller, Jing M. Chen, Richard A Fournier, Peter H White, D R Peddle, Greg Mcdermid, Paul Shepherd, Irene Rubinstein, J Freemantle, Raymond SofferAbstract:One objective of the Boreal Ecosystem-Atmospheric Study (BOREAS) is to increase our understanding of the nature of canopy spectral bidirectional reflectance in the visible/near-infrared regimes for open canopies typical of Boreal forest stands. For such stands, the need to characterize the reflectance of the sunlit and shaded vegetated understory is critical. These variables are subject to temporal variability due to differences in species phenology and foliar display as well as diurnal and seasonal changes in solar illumination through a seasonally varying upper canopy foliar area. To provide for this need, a multiteam field effort was mounted to measure the nadir midday understory reflectance for the flux tower sites during 1994 BOREAS field campaigns between February and October, specifically during the winter focused field campaign (FFC-W), the spring thaw focused field campaign (FFC-T), and the three intensive field campaigns (IFC-1, IFC-2, and IFC-3) between June and September, which sample vegetation phenological change. This was accomplished by measuring at near-solar noon the sunlit and shaded nadir reflectance of the understory along a surveyed leaf area index (LAI) transect line at each flux tower site. Site-to-site comparisons of understory reflectance spectra reveal stand differences that become more significant as the season progresses. Mean midday understory reflectance spectra were observed to be remarkably consistent over the season for young jack pine stands, followed by somewhat increased variability for mature jack pine, and significant seasonal variability for black spruce stands. Derived vegetation indices for understories are generally consistent with extrapolations of previous relationships of canopy spectral vegetation indices (VIs) versus leaf area index to zero LAI. Inclusion of these “zeroLAI” understory-derived indices significantly enhance the correlation in the linear VI-LAI relationships.
John M. Norman - One of the best experts on this subject based on the ideXlab platform.
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Leaf area index measurements of Boreal forests: Theory, techniques, and L
2020Co-Authors: Jing M. Chen, Stith T. Gower, Paul Steven Plummer5, M Rich, John M. NormanAbstract:Abstract. Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LA1 estimates are required in studies of ecophysiology, atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LA1 values obtained by several research teams using different methods for a broad spectrum of Boreal forest types in support of the international Boreal EcosystemAtmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI-2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LA1 from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LA1 of Boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LA1 falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LA1 estimates available for Boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LA1 measurements
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measurements of leaf orientation light distribution and sunlit leaf area in a Boreal aspen forest
Agricultural and Forest Meteorology, 1998Co-Authors: Christopher J. Kucharik, John M. Norman, Stith T. GowerAbstract:A new instrument called a Multiband Vegetation Imager (MVI) (Kucharik et al., 1997), which uses a 16-bit charge-coupled device (CCD) camera and filter exchange mechanism to capture 2-band (visible and near-infrared) image pairs of plant canopies, has been used to measure the light distribution over sunlit leaves and indirectly infer leaf area index (LAI), sunlit LAI and leaf angle distribution (LAD) in a Boreal aspen (Populus tremuloides) forest during the Boreal Ecosystem‐ Atmosphere Study (BOREAS). One purpose of this study is to demonstrate that by combining MVI measurements with numerical Monte Carlo simulations of forest canopy architecture, the LAD and sunlit LAI of aspen can be obtained indirectly. Our results show that this Boreal aspen stand exemplifies an erectophile LAD, with a mean leaf inclination angle near 708 .W e also find that the values of the measured and modeled sunlit leaf area in aspen do not change dramatically for typical northern Boreal latitude solar zenith angles (i.e. 30‐708). A major problem with determining the sunlit LAI is deciding what range of light intensities constitute a sunlit leaf because penumbra create a smooth continuum of light intensities over sunlit and shaded leaves in the canopy. Therefore, we show that the upper and lower limits can be placed on sunlit LAI values in aspen by using different leaf illumination threshold levels to determine sunlit and shaded LAI in the canopy. Typically, sunlit LAI values in aspen (LAIa3.3) range between 0.8‐1.0 at a 708 sun zenith angle and 1.1‐1.6 at a 308 sun zenith angle. Monte Carlo simulations and MVI measurements suggest that canopy sunlit leaf area estimates are possible from below the canopy at modest LAI values ( 5.0). Since a substantial fraction of the total sunlit leaf area can be viewed from below the canopy in aspen (40‐60% of the total sunlit LAI), a representative light distribution can be measured and used to quantify the canopy leaf angle distribution. # 1998 Elsevier Science B.V. All rights reserved.
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leaf area index of Boreal forests theory techniques and measurements
Journal of Geophysical Research, 1997Co-Authors: Jing M. Chen, John M. Norman, Stith T. Gower, Paul M Rich, Steven PlummerAbstract:Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LAI estimates are required in studies of ecophysiology, atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LAI values obtained by several research teams using different methods for a broad spectrum of Boreal forest types in support of the international Boreal Ecosystem-Atmosphere Study (BOREAS). These methods include destructive sampling and optical instruments: the tracing radiation and architecture of canopies (TRAC), the LAI-2000 plant canopy analyzer, hemispherical photography, and the Sunfleck Ceptometer. The latter three calculate LAI from measured radiation transmittance (gap fraction) using inversion models that assume a random spatial distribution of leaves. It is shown that these instruments underestimate LAI of Boreal forest stands where the foliage is clumped. The TRAC quantifies the clumping effect by measuring the canopy gap size distribution. For deciduous stands the clumping index measured from TRAC includes the clumping effect at all scales, but for conifer stands it only resolves the clumping effect at scales larger than the shoot (the basic collection of needles). To determine foliage clumping within conifer shoots, a video camera and rotational light table system was used. The major difficulties in determining the surface area of small conifer needles have been largely overcome by the use of an accurate volume displacement method. Hemispherical photography has the advantage that it also provides a permanent image record of the canopies. Typically, LAI falls in the range from 1 to 4 for jack pine and aspen forests and from 1 to 6 for black spruce. Our comparative studies provide the most comprehensive set of LAI estimates available for Boreal forests and demonstrate that optical techniques, combined with limited direct foliage sampling, can be used to obtain quick and accurate LAI measurements.
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carbon distribution and aboveground net primary production in aspen jack pine and black spruce stands in saskatchewan and manitoba canada
Journal of Geophysical Research, 1997Co-Authors: Stith T. Gower, Christopher J. Kucharik, John M. Norman, Jason G Vogel, S J Steele, T K StowAbstract:The objectives of this study are to (1) characterize the carbon (C) content, leaf area index, and aboveground net primary production (ANPP) for mature aspen, black spruce, and young and mature jack pine stands at the southern and northern Boreal Ecosystem-Atmosphere Study (BOREAS) areas and (2) compare net primary production and carbon allocation coefficients for the major Boreal forest types of the world. Direct estimates of leaf area index, defined as one half of the total leaf surface area, range from a minimum of 1.8 for jack pine forests to a maximum of 5.6 for black spruce forests; stems comprise 5 to 15% of the total overstory plant area. In the BOREAS study, total ecosystem (vegetation plus detritus plus soil) carbon content is greatest in the black spruce forests (445,760–479,380 kg C ha−1), with 87 to 88% of the C in the soil, and is lowest in the jack pine stands (68,370–68,980 kg C ha−1) with a similar distribution of carbon in the vegetation and soil. Forest floor carbon content and mean residence time (MRT) also vary more among forest types in a study area than between study areas for a forest type; forest floor MRT range from 16 to 19 years for aspen stands to 28 to 39 years for jack pine stands. ANPP differs significantly among the mature forests at each of the BOREAS study areas, ranging from a maximum of 3490 to 3520 kg C ha−1 yr−1 for aspen stands to 1170 to 1220 kg C ha−1 yr−1 for jack pine stands. Both net primary production (NPP) and carbon allocation differ between Boreal evergreen and deciduous forests in the world, suggesting global primary production models should distinguish between these two forest types. On average, 56% of NPP for Boreal forests occurs as detritus and illustrates the need to better understand factors controlling aboveground and below-ground detritus production in Boreal forests.
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carbon distribution and aboveground net primary production in aspen jack pine and black spruce stands in saskatchewan and manitoba canada
Journal of Geophysical Research, 1997Co-Authors: Stith T. Gower, Christopher J. Kucharik, John M. Norman, Jason G Vogel, S J Steele, T K StowAbstract:The objectives of this study are to (1) characterize the carbon (C) content, leaf area index, and aboveground net primary production (ANPP) for mature aspen, black spruce, and young and mature jack pine stands at the southern and northern Boreal Ecosystem-Atmosphere Study (BOREAS) areas and (2) compare net primary production and carbon allocation coefficients for the major Boreal forest types of the world. Direct estimates of leaf area index, defined as one half of the total leaf surface area, range from a minimum of 1.8 for jack pine forests to a maximum of 5.6 for black spruce forests; stems comprise 5 to 15% of the total overstory plant area. In the BOREAS study, total ecosystem (vegetation plus detritus plus soil) carbon content is greatest in the black spruce forests (445,760–479,380 kg C ha−1), with 87 to 88% of the C in the soil, and is lowest in the jack pine stands (68,370–68,980 kg C ha−1) with a similar distribution of carbon in the vegetation and soil. Forest floor carbon content and mean residence time (MRT) also vary more among forest types in a study area than between study areas for a forest type; forest floor MRT range from 16 to 19 years for aspen stands to 28 to 39 years for jack pine stands. ANPP differs significantly among the mature forests at each of the BOREAS study areas, ranging from a maximum of 3490 to 3520 kg C ha−1 yr−1 for aspen stands to 1170 to 1220 kg C ha−1 yr−1 for jack pine stands. Both net primary production (NPP) and carbon allocation differ between Boreal evergreen and deciduous forests in the world, suggesting global primary production models should distinguish between these two forest types. On average, 56% of NPP for Boreal forests occurs as detritus and illustrates the need to better understand factors controlling aboveground and below-ground detritus production in Boreal forests.
T K Stow - One of the best experts on this subject based on the ideXlab platform.
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carbon distribution and aboveground net primary production in aspen jack pine and black spruce stands in saskatchewan and manitoba canada
Journal of Geophysical Research, 1997Co-Authors: Stith T. Gower, Christopher J. Kucharik, John M. Norman, Jason G Vogel, S J Steele, T K StowAbstract:The objectives of this study are to (1) characterize the carbon (C) content, leaf area index, and aboveground net primary production (ANPP) for mature aspen, black spruce, and young and mature jack pine stands at the southern and northern Boreal Ecosystem-Atmosphere Study (BOREAS) areas and (2) compare net primary production and carbon allocation coefficients for the major Boreal forest types of the world. Direct estimates of leaf area index, defined as one half of the total leaf surface area, range from a minimum of 1.8 for jack pine forests to a maximum of 5.6 for black spruce forests; stems comprise 5 to 15% of the total overstory plant area. In the BOREAS study, total ecosystem (vegetation plus detritus plus soil) carbon content is greatest in the black spruce forests (445,760–479,380 kg C ha−1), with 87 to 88% of the C in the soil, and is lowest in the jack pine stands (68,370–68,980 kg C ha−1) with a similar distribution of carbon in the vegetation and soil. Forest floor carbon content and mean residence time (MRT) also vary more among forest types in a study area than between study areas for a forest type; forest floor MRT range from 16 to 19 years for aspen stands to 28 to 39 years for jack pine stands. ANPP differs significantly among the mature forests at each of the BOREAS study areas, ranging from a maximum of 3490 to 3520 kg C ha−1 yr−1 for aspen stands to 1170 to 1220 kg C ha−1 yr−1 for jack pine stands. Both net primary production (NPP) and carbon allocation differ between Boreal evergreen and deciduous forests in the world, suggesting global primary production models should distinguish between these two forest types. On average, 56% of NPP for Boreal forests occurs as detritus and illustrates the need to better understand factors controlling aboveground and below-ground detritus production in Boreal forests.
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carbon distribution and aboveground net primary production in aspen jack pine and black spruce stands in saskatchewan and manitoba canada
Journal of Geophysical Research, 1997Co-Authors: Stith T. Gower, Christopher J. Kucharik, John M. Norman, Jason G Vogel, S J Steele, T K StowAbstract:The objectives of this study are to (1) characterize the carbon (C) content, leaf area index, and aboveground net primary production (ANPP) for mature aspen, black spruce, and young and mature jack pine stands at the southern and northern Boreal Ecosystem-Atmosphere Study (BOREAS) areas and (2) compare net primary production and carbon allocation coefficients for the major Boreal forest types of the world. Direct estimates of leaf area index, defined as one half of the total leaf surface area, range from a minimum of 1.8 for jack pine forests to a maximum of 5.6 for black spruce forests; stems comprise 5 to 15% of the total overstory plant area. In the BOREAS study, total ecosystem (vegetation plus detritus plus soil) carbon content is greatest in the black spruce forests (445,760–479,380 kg C ha−1), with 87 to 88% of the C in the soil, and is lowest in the jack pine stands (68,370–68,980 kg C ha−1) with a similar distribution of carbon in the vegetation and soil. Forest floor carbon content and mean residence time (MRT) also vary more among forest types in a study area than between study areas for a forest type; forest floor MRT range from 16 to 19 years for aspen stands to 28 to 39 years for jack pine stands. ANPP differs significantly among the mature forests at each of the BOREAS study areas, ranging from a maximum of 3490 to 3520 kg C ha−1 yr−1 for aspen stands to 1170 to 1220 kg C ha−1 yr−1 for jack pine stands. Both net primary production (NPP) and carbon allocation differ between Boreal evergreen and deciduous forests in the world, suggesting global primary production models should distinguish between these two forest types. On average, 56% of NPP for Boreal forests occurs as detritus and illustrates the need to better understand factors controlling aboveground and below-ground detritus production in Boreal forests.
Christopher J. Kucharik - One of the best experts on this subject based on the ideXlab platform.
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measurements of leaf orientation light distribution and sunlit leaf area in a Boreal aspen forest
Agricultural and Forest Meteorology, 1998Co-Authors: Christopher J. Kucharik, John M. Norman, Stith T. GowerAbstract:A new instrument called a Multiband Vegetation Imager (MVI) (Kucharik et al., 1997), which uses a 16-bit charge-coupled device (CCD) camera and filter exchange mechanism to capture 2-band (visible and near-infrared) image pairs of plant canopies, has been used to measure the light distribution over sunlit leaves and indirectly infer leaf area index (LAI), sunlit LAI and leaf angle distribution (LAD) in a Boreal aspen (Populus tremuloides) forest during the Boreal Ecosystem‐ Atmosphere Study (BOREAS). One purpose of this study is to demonstrate that by combining MVI measurements with numerical Monte Carlo simulations of forest canopy architecture, the LAD and sunlit LAI of aspen can be obtained indirectly. Our results show that this Boreal aspen stand exemplifies an erectophile LAD, with a mean leaf inclination angle near 708 .W e also find that the values of the measured and modeled sunlit leaf area in aspen do not change dramatically for typical northern Boreal latitude solar zenith angles (i.e. 30‐708). A major problem with determining the sunlit LAI is deciding what range of light intensities constitute a sunlit leaf because penumbra create a smooth continuum of light intensities over sunlit and shaded leaves in the canopy. Therefore, we show that the upper and lower limits can be placed on sunlit LAI values in aspen by using different leaf illumination threshold levels to determine sunlit and shaded LAI in the canopy. Typically, sunlit LAI values in aspen (LAIa3.3) range between 0.8‐1.0 at a 708 sun zenith angle and 1.1‐1.6 at a 308 sun zenith angle. Monte Carlo simulations and MVI measurements suggest that canopy sunlit leaf area estimates are possible from below the canopy at modest LAI values ( 5.0). Since a substantial fraction of the total sunlit leaf area can be viewed from below the canopy in aspen (40‐60% of the total sunlit LAI), a representative light distribution can be measured and used to quantify the canopy leaf angle distribution. # 1998 Elsevier Science B.V. All rights reserved.
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carbon distribution and aboveground net primary production in aspen jack pine and black spruce stands in saskatchewan and manitoba canada
Journal of Geophysical Research, 1997Co-Authors: Stith T. Gower, Christopher J. Kucharik, John M. Norman, Jason G Vogel, S J Steele, T K StowAbstract:The objectives of this study are to (1) characterize the carbon (C) content, leaf area index, and aboveground net primary production (ANPP) for mature aspen, black spruce, and young and mature jack pine stands at the southern and northern Boreal Ecosystem-Atmosphere Study (BOREAS) areas and (2) compare net primary production and carbon allocation coefficients for the major Boreal forest types of the world. Direct estimates of leaf area index, defined as one half of the total leaf surface area, range from a minimum of 1.8 for jack pine forests to a maximum of 5.6 for black spruce forests; stems comprise 5 to 15% of the total overstory plant area. In the BOREAS study, total ecosystem (vegetation plus detritus plus soil) carbon content is greatest in the black spruce forests (445,760–479,380 kg C ha−1), with 87 to 88% of the C in the soil, and is lowest in the jack pine stands (68,370–68,980 kg C ha−1) with a similar distribution of carbon in the vegetation and soil. Forest floor carbon content and mean residence time (MRT) also vary more among forest types in a study area than between study areas for a forest type; forest floor MRT range from 16 to 19 years for aspen stands to 28 to 39 years for jack pine stands. ANPP differs significantly among the mature forests at each of the BOREAS study areas, ranging from a maximum of 3490 to 3520 kg C ha−1 yr−1 for aspen stands to 1170 to 1220 kg C ha−1 yr−1 for jack pine stands. Both net primary production (NPP) and carbon allocation differ between Boreal evergreen and deciduous forests in the world, suggesting global primary production models should distinguish between these two forest types. On average, 56% of NPP for Boreal forests occurs as detritus and illustrates the need to better understand factors controlling aboveground and below-ground detritus production in Boreal forests.
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carbon distribution and aboveground net primary production in aspen jack pine and black spruce stands in saskatchewan and manitoba canada
Journal of Geophysical Research, 1997Co-Authors: Stith T. Gower, Christopher J. Kucharik, John M. Norman, Jason G Vogel, S J Steele, T K StowAbstract:The objectives of this study are to (1) characterize the carbon (C) content, leaf area index, and aboveground net primary production (ANPP) for mature aspen, black spruce, and young and mature jack pine stands at the southern and northern Boreal Ecosystem-Atmosphere Study (BOREAS) areas and (2) compare net primary production and carbon allocation coefficients for the major Boreal forest types of the world. Direct estimates of leaf area index, defined as one half of the total leaf surface area, range from a minimum of 1.8 for jack pine forests to a maximum of 5.6 for black spruce forests; stems comprise 5 to 15% of the total overstory plant area. In the BOREAS study, total ecosystem (vegetation plus detritus plus soil) carbon content is greatest in the black spruce forests (445,760–479,380 kg C ha−1), with 87 to 88% of the C in the soil, and is lowest in the jack pine stands (68,370–68,980 kg C ha−1) with a similar distribution of carbon in the vegetation and soil. Forest floor carbon content and mean residence time (MRT) also vary more among forest types in a study area than between study areas for a forest type; forest floor MRT range from 16 to 19 years for aspen stands to 28 to 39 years for jack pine stands. ANPP differs significantly among the mature forests at each of the BOREAS study areas, ranging from a maximum of 3490 to 3520 kg C ha−1 yr−1 for aspen stands to 1170 to 1220 kg C ha−1 yr−1 for jack pine stands. Both net primary production (NPP) and carbon allocation differ between Boreal evergreen and deciduous forests in the world, suggesting global primary production models should distinguish between these two forest types. On average, 56% of NPP for Boreal forests occurs as detritus and illustrates the need to better understand factors controlling aboveground and below-ground detritus production in Boreal forests.
