Effect of foliage spatial heterogeneity in the MODIS LAI and FPAR algorithm over broadleaf forests

Shabanov, Nikolay V.; Wang, Y.; Buermann, Wolfgang; Dong, Jing; Hoffman, Samuel M.; Smith, G. R.; Tian, Yuhong; Knyazikhin, Yuri; Myneni, Ranga B.

doi:10.1016/s0034-4257(03)00017-8

Cited by 98 publications

(50 citation statements)

References 33 publications

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“…These three variables, recollision probability, canopy interceptance and leaf absorptance, therefore, determine the partitioning of the top of canopy radiation into its absorbed and canopy leaving portions. The spectral invariant relationships have also been reported for canopy transmittance (Panferov et al, 2001;Shabanov et al, 2003) and reflectance (Disney et al, 2005;Lewis et al, 2005), suggesting that the canopy leaving radiation can further be broken down into its reflected and transmitted portions. Wang et al (2003) hypothesize that a small set of independent variables that appear in the spectral invariant relationships suffice to fully describe the law of energy conservation in vegetation canopies at any wavelength in the solar spectrum.…”

Section: Introductionmentioning

confidence: 73%

“…Smolander and Stenberg (2005), however, question the validity of the spectral invariant for canopy transmittance. They show that while the recollision probability and canopy interceptance perform well in estimating the spectral absorption of both homogeneous leaf and shoot canopies, a proposed structural parameter for separation of downward portion of the canopy leaving radiation (Knyazikhin et al, 1998;Panferov et al, 2001;Shabanov et al, 2003) can fail to predict spectral transmittance of the coniferous canopy and spectral transmittance of the leaf canopy at high LAI values. Panferov et al (2001) suggest that the spectral invariant relationship is not valid for canopy reflectance while Lewis et al (2003Lewis et al ( , 2005 and Disney et al (2005) have demonstrated its validity to describe the transformation for leaf absorptance spectrum to canopy spectral reflectance.…”

Section: Introductionmentioning

confidence: 99%

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Canopy spectral invariants for remote sensing and model applications

Huang

Knyazikhin

Dickinson

et al. 2007

Remote Sensing of Environment

137

109

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Section: Introductionmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Canopy spectral invariants for remote sensing and model applications

Huang

Knyazikhin

Dickinson

et al. 2007

Remote Sensing of Environment

137

109

View full text Add to dashboard Cite

“…The highest standard deviation of within stand PAI was approximately 0.9 despite each stand being of similar age, species, and mean PAI. The spatial heterogeneity of LAI will also contribute to the uncertainty associated with MODIS derived products (Shabanov et al, 2003) and should be considered in future studies of phenology.…”

Section: Phenology From Modis Productsmentioning

confidence: 99%

“…The biophysical and radiometric principles of using a satellitebased vegetation index or related measures (e.g., leaf area index) to detect vegetation phenology, in general, are well established (Huete et al, 2002;Rea & Ashley, 1976;Rouse et al, 1973;Shabanov et al, 2002Shabanov et al, , 2003Tian et al, 2002;Tucker, 1979;Yang et al, in press-a,b). However, much less is known about the temporal sensitivity needed to detect phenological transitions from field measurements or satellite-based vegetation products.…”

Section: Introductionmentioning

confidence: 99%

Monitoring spring canopy phenology of a deciduous broadleaf forest using MODIS

Ahl

Gower

Burrows

et al. 2006

Remote Sensing of Environment

262

154

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Climate change is predicted to alter the canopy phenology of temperate and boreal forests, which will affect carbon, water, and energy budgets. Therefore, there is a great need to evaluate remotely sensed products for their potential to accurately capture canopy dynamics. The objective of this study was to compare several products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) to field measurements of fraction photosynthetically active radiation (FPAR) and plant area index (PAI) for a deciduous broadleaf forest in northern Wisconsin in 2002. MODIS products captured the general phenological development of the canopy although MODIS products overestimated the leaf area during the overstory leaf out period. Field data suggest that the period from budburst to canopy maturity, or maximum PAI, occurred in 10 to 12 days while MODIS products predicted onset of greenness and maturity from 1 to 21 days and 0 to 19 days earlier than that from field observations, respectively. Temporal compositing of MODIS data and understory development are likely key factors explaining differences with field data. Maximum PAI estimates differed only by 7% between field derived and MODIS-based estimates of LAI. Implications for ecosystem modeling of carbon and water exchange and future research needs are discussed.

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“…Knyazikhin et al (1998b) and Panferov et al (2001) also presented a similar parameterization for the fraction of scattered radiation in canopy transmission. This parameterization was later formulated by Shabanov et al (2003) into the form…”

Section: The Recollision Probabilitymentioning

confidence: 99%

Radiative transfer, interception and scattering in coniferous forests: models and applications for production ecology and remote sensing

Smolander¹

2006

Diss. For.

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This work develops methods to account for shoot structure in models of coniferous canopy radiative transfer. Shoot structure, as it varies along the light gradient inside canopy, affects the efficiency of light interception per unit needle area, foliage biomass, or foliage nitrogen. The clumping of needles in the shoot volume also causes a notable amount of multiple scattering of light within coniferous shoots. The effect of shoot structure on light interception is treated in the context of canopy level photosynthesis and resource use models, and the phenomenon of within-shoot multiple scattering in the context of physical canopy reflectance models for remote sensing purposes.Light interception. A method for estimating the amount of PAR (Photosynthetically Active Radiation) intercepted by a conifer shoot is presented. The method combines modelling of the directional distribution of radiation above canopy, fish-eye photographs taken at shoot locations to measure canopy gap fraction, and geometrical measurements of shoot orientation and structure. Data on light availability, shoot and needle structure and nitrogen content has been collected from canopies of Pacific silver fir (Abies amabilis (Dougl.) Forbes) and Norway spruce (Picea abies (L.) Karst.). Shoot structure acclimated to light gradient inside canopy so that more shaded shoots have better light interception efficiency. Light interception efficiency of shoots varied about two-fold per needle area, about four-fold per needle dry mass, and about five-fold per nitrogen content. Comparison of fertilized and control stands of Norway spruce indicated that light interception efficiency is not greatly affected by fertilization.Light scattering. Structure of coniferous shoots gives rise to multiple scattering of light between the needles of the shoot. Using geometric models of shoots, multiple scattering was studied by photon tracing simulations. Based on simulation results, the dependence of the scattering coefficient of shoot from the scattering coefficient of needles is shown to follow a simple one-parameter model. The single parameter, termed the recollision probability, describes the level of clumping of the needles in the shoot, is wavelength independent, and can be connected to previously used clumping indices. By using the recollision probability to correct for the within-shoot multiple scattering, canopy radiative transfer models which have used leaves as basic elements can use shoots as basic elements, and thus be applied for coniferous forests. Preliminary testing of this approach seems to explain, at least partially, why coniferous forests appear darker than broadleaved forests in satellite data.Keywords: shoot structure, light interception, leaf area index, forest reflectance model, multiple scattering, photon recollision probability 4 PREFACE This work begun in 1997, when I -then a second year biology student -was working as a summer trainee for Pauline Stenberg. She had the dataset of paper II and had outlined the method described in paper I...

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Effect of foliage spatial heterogeneity in the MODIS LAI and FPAR algorithm over broadleaf forests

Cited by 98 publications

References 33 publications

Canopy spectral invariants for remote sensing and model applications

Canopy spectral invariants for remote sensing and model applications

Monitoring spring canopy phenology of a deciduous broadleaf forest using MODIS

Radiative transfer, interception and scattering in coniferous forests: models and applications for production ecology and remote sensing

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