TY - JOUR ID - barnes1992 AU - Barnes, J. D. AU - Balaguer, L. AU - Manrique, E. AU - Elvira, S. AU - Davison, A. W. TI - A Reappraisal of the Use of Dmso for the Extraction and Determination of Chlorophylls-a and Chlorophylls-B in Lichens and Higher-Plants UR - ://WOS:A1992HR32900001 DO - 10.1016/0098-8472(92)90034-y T2 - Environmental and Experimental Botany PY - 1992 SN - 0098-8472 VL - 32 IS - 2 SP - 85-100 AB - The use of DMSO for the extraction and determination of chlorophylls a and b in lichens and higher plants was reevaluated. Because of differences between the absorption spectra of pure chlorophylls a and b in DMSO and 80% acetone, formulae to calculate the individual concentrations of chlorophyll a, chlorophyll b and total (a + b) chlorophyll in pigment extracts were redetermined for specific use with DMSO. In lichens, the problem of chlorophyll degradation resulting from the presence of acidic lichen substances was specifically addressed. Repeated washing of thalli with carbonate-saturated 100% acetone followed by extraction in DMSO containing PVP(i) minimized the conversion of chlorophylls to phaeophytin during extraction of chlorophylls from lichens for which the content of lichen substances was characterized. In lichens containing significant quantities of acidic compounds, the modified DMSO assay proved superior to 80% acetone for the extraction and determination of chlorophyll a and b concentrations. In a range of higher plants, determinations of chlorophyll a and b concentrations were virtually identical when the modified DMSO assay was compared with the traditional method of chlorophyll extraction using 80% acetone. Moreover, DMSO extracts could be cold-stored for up to 7 days with no significant loss of chlorophylls a or b, or changes in the a/b ratio. Potential eco-physiological applications of the modified DMSO assay, which eliminates the necessity for grinding plant material and centrifuging plant extracts, are discussed. KW - dimethylsulfoxide dmso, dimethyl-sulfoxide, pigments, algae, n,n-dimethylformamide, identification, products ER - TY - GEN ID - blackburn1998 AU - Blackburn, G. A. TI - Spectral indices for estimating photosynthetic pigment concentrations: A test using senescent tree leaves UR - http://dx.doi.org/10.1080/014311698215919 DO - 10.1080/014311698215919 PR - Taylor & Francis T2 - International Journal of Remote Sensing PY - 1998 DA - 1998/01/01 SN - 0143-1161 VL - 19 IS - 4 SP - 657-675 AB - Abstract The possibility of estimating the concentration of individual photosynthetic pigments within vegetation from reflectance spectra offers great promise for the use of remote sensing to assess physiological status, species type and productivity. This study evaluates a number of spectral indices for estimating pigment concentrations at the leaf scale, using samples from deciduous trees at various stages of senescence. Two new indices (PSSR and PSND) are developed which have advantages over previous techniques. The optimal individual wavebands for pigment estimation are identified empirically as 680nm for chlorophyll a, 635nm for chlorophyll b and 470nm for the carotenoids. These wavebands are justified theoretically and are shown to improve the performance of many of the spectral indices tested. Strong predictive models are demonstrated for chlorophyll a and b, but not for the carotenoids and the paper explores the reasons for this. ER - TY - JOUR ID - blackburn2007 AU - Blackburn, George Alan TI - Hyperspectral remote sensing of plant pigments UR - http://jxb.oxfordjournals.org/content/58/4/855.abstract DO - 10.1093/jxb/erl123 T2 - Journal of Experimental Botany PY - 2007 DA - March 1, 2007 VL - 58 IS - 4 SP - 855-867 AB - The dynamics of pigment concentrations are diagnostic of a range of plant physiological properties and processes. This paper appraises the developing technologies and analytical methods for quantifying pigments non-destructively and repeatedly across a range of spatial scales using hyperspectral remote sensing. Progress in deriving predictive relationships between various characteristics and transforms of hyperspectral reflectance data are evaluated and the roles of leaf and canopy radiative transfer models are reviewed. Requirements are identified for more extensive intercomparisons of different approaches and for further work on the strategies for interpreting canopy scale data. The paper examines the prospects for extending research to the wider range of pigments in addition to chlorophyll, testing emerging methods of hyperspectral analysis and exploring the fusion of hyperspectral and LIDAR remote sensing. In spite of these opportunities for further development and the refinement of techniques, current evidence of an expanding range of applications in the ecophysiological, environmental, agricultural, and forestry sciences highlights the growing value of hyperspectral remote sensing of plant pigments. ER - TY - ABST ID - broge2000 AU - Broge, N. H. AU - Leblanc, E. TI - Comparing prediction power and stability of broadband and hyperspectral vegetation indices for estimation of green leaf area index and canopy chlorophyll density DO - 10.1016/s0034-4257(00)00197-8 T2 - Remote Sensing of Environment PY - 2000 SN - 0034-4257 VL - 76 IS - 2 SP - 156-172 AB - Hyperspectral reflectance data representing a wide range of canopies were simulated using the combined PROSPECT+SAIL model. The simulations were used to study the stability of recently proposed vegetation indices (VIs) derived from adjacent narrowband spectral reflectance data across the visible (VIS) and near infrared (NIR) region of the electromagnetic spectrum. The prediction power of these indices with respect to green leaf area index (LAI) and canopy chlorophyll density (CCD) was compared, and their sensitivity to canopy architecture, illumination geometry, soil background reflectance, and atmospheric conditions were analyzed. The second soil-adjusted vegetation index (SAVI2) proved to be the best overall choice as a greenness measure. However, it is also shown that the dynamics of the VIs are very different in terms of their sensitivity to the different external factors that affects the spectral reflectance signatures of the various modeled canopies. It is concluded that hyperspectral indices are not necessarily better at predicting LAI and CCD, but that selection of a VI should depend upon (1) which parameter that needs to be estimated (LAI or CCD), (2) the expected range of this parameter, and (3) a priori knowledge of the variation of external parameters affecting the spectral reflectance of the canopy. ER - TY - CONF ID - brunn2003 AU - Brunn, A. AU - Busch, W. AU - Dittmann, C. AU - Fischer, C. AU - Vosen, P. TI - Monitoring Mining Induced Plant Alteration and Change Detection in a German Coal Mining Area using Airborne Hyperspectral Imagery T2 - Spectral Remote Sensing of Vegetation Conference at the U.S. EPA Environmental Sciences Div. CY - Las Vegas, Nevada PY - 2003 DA - March 12-14th, 2003 ER - TY - GEN ID - buschmann1993 AU - Buschmann, C. AU - Nagel, E. TI - In vivo spectroscopy and internal optics of leaves as basis for remote sensing of vegetation DO - 10.1080/01431169308904370 PR - Taylor & Francis T2 - International Journal of Remote Sensing PY - 1993 SN - 0143-1161 VL - 14 IS - 4 SP - 711-722 AB - Abstract In vivo reflection spectra of intact bean leaves (Phaseolus vulgaris) were measured between 400 and 800  nm under remote sensing conditions (illumination with white light, detection of a narrow angle of the reflected light) using the VIRAF spectrometer. The leaves with colours from yellow to green were chosen at different times during light-induced greening. The colours of the leaves were characterized by the chromaticity coordinates according to CIE 1931 calculated from the reflection spectra. The influence of the absorption of chlorophyll?the main pigment of green leaves?on the reflection spectrum of leaves is outlined. The shape of the in vivo reflection spectra is interpreted taking into account (a)the formation of pigment-protein complexes, (b) the sieve effect and the detour effect, as well as (c) the reflection, refraction and scattering of light inside the leaf tissue. Reflection signals at several distinct wavelengths and their ratios as well as the inflection point of the reflection rise from the far red towards the near-infrared were checked for linear correlation with the chlorophyll content per leaf area. The normalized difference vegetation index (NDVI) exhibited a relatively bad correlation with the chlorophyll content. The best correlation was found for the logarithm of the ratio of the reflection signals at 800 and 550 nm. We suggest that this parameter is used, in combination with the detection of the inflection point, for remotely-detecting vegetation and for the estimation of its chlorophyll content. ER - TY - JOUR ID - buschmann1993-2 AU - Buschmann, Claus TI - Fernerkundung von Pflanzen - Ausbreitung, Gesundheitszustand und Produktivitfit T2 - Naturwissenschaften PY - 1993 VL - 80 SP - 439-453 ER - TY - JOUR ID - carter1996 AU - Carter, Gregory A. AU - Cibula, William G. AU - Miller, Richard L. TI - Narrow-band Reflectance Imagery Compared with ThermalImagery for Early Detection of Plant Stress UR - http://www.sciencedirect.com/science/article/pii/S0176161796800708 DO - 10.1016/s0176-1617(96)80070-8 T2 - Journal of Plant Physiology PY - 1996 SN - 0176-1617 VL - 148 IS - 5 SP - 515-522 AB - Summary A field experiment compared plant stress detection by narrow-band reflectance and ratio images withthermal infrared images. Stress was induced in a mixed stand of 5 year old loblolly pine (Pinus taeda L.) and slash pine {Pinus elliottii Engelm.) by a soil application of diuron (DCMU) on 22 August followed by bromacil on 19 September, 1994. Herbicide-induced stress was first indicated on 24 and 26 September by significant (p⪯0.05) decreases in photosynthesis and the ratio of variable to maximum fluorescence (Fv/Fm), respectively. Stress was first detected remotely on 5 October by 694 ± 3 nm reflectance imagery and its ratio with reflectance at 760 ± 5 nm (p⪯0.05). This reflectance increase was detected at least 16 days prior to the first visible signs of damage, as quantified by the CIE color coordinate u', that occurred between 21 and 26 October. Reflectance images at 670 + 5 nm, 700 ± 5 nm and 760 ± 5 nm first detected stress on 21 October, 12 October and 20 December, respectively. Canopy temperature as indicated by imagery in the 8 to 12 μm band never differed significantly between herbicide-treated and control plots. This resulted from the close coupling of leaf temperatures with air temperature, and the tendency of wind and environmental moisture to equalize temperatures among treatments. The high sensitivity to stress of reflectance imagery at 694 ± 3 nm supports similar conclusions of earlier work, and indicates that imagery in the 690 to 700 nm band is far superior to thermal imagery for the early and pre-visual detection of stress in pine. KW - Pinus taeda, Pinus elliottii, plant stress, diuron, bromacil, chlorosis, canopy reflectance, canopy temperature, narrow-band imagery ER - TY - GEN ID - chappelle1992 AU - Chappelle, E.W. AU - Kim, M.S. AU - McMurtrey, J.E. TI - Ratio analysis of reflectance spectra (RARS): an algorithm for the remote estimation of the concentrations of chlorophyll a, chlorophyll b, and carotenoids in soybean leaves T2 - Remote Sensing of Environment PY - 1992 VL - 39 SP - 239–247 ER - TY - JOUR ID - choubey1999 AU - Choubey, V. K. AU - Choubey, R. TI - Spectral reflectance, growth and chlorophyll relationships for rice crop in a semi-arid region of India UR - ://WOS:000083824500001 DO - 10.1023/a:1008056400348 T2 - Water Resources Management PY - 1999 DA - Apr SN - 0920-4741 VL - 13 IS - 2 SP - 73-84 N1 - ISI Document Delivery No.: 258EE Times Cited: 2 Cited Reference Count: 23 Choubey, VK Choubey, R Kluwer academic publ Dordrecht AB - Relations among spectral reflectance, chlorophyll 'a', and growth of rice plants grown on irrigated light textured soil in a semi arid region are presented here. There was a linear relation between spectral reflectance and rice plant height (r = 0.97), for band 1 (0.45-0.52 mu m) reflectance values. On the other hand, in bands 2 (0.52-0.60 mu m) and 3 (0.63-0.69 mu m), reflectance values decreased until 70 days after planting (DAP) and then increased during the reproductive phase of the crop. The near infrared band 4 (0.76-0.90 mu m) showed a maximum reflectance at 59 DAP (panicle initiation stage) and a decline in reflectance thereafter through maturity. The peak value of IR/R ratio was 16.39 at 62 DAP during the early reproductive phase; thereafter, it declines gradually with the maturity of the crop. Chlorophyll 'a' concentration was high during early growth (vegetative and early reproductive stages) and decreased during the flowering and maturity stages. The rice plant canopy show a high chlorophyll 'a' concentration at 64 and 59 DAP for sites A and B, respectively. Chlorophyll 'a' concentration is higher in site A plant canopies than it is in site B during the entire crop cycle. A good inverse correlation (r = 0.91) has been found between chlorophyll 'a' and band 1, while the IR/R ratio and the normalised difference vegetation index (NDVI) showed a relationship (r = 0.78) with the chlorophyll 'a' concentration during the crop cycle. Band 2, 3 and 4 radiance values show a biphasic linear relationship with chlorophyll 'a' concentrations, negative for early growth and positive for flowering and maturity stages. Results indicate that the period between 66 to 70 DAP is most suitable for the assessment of rice crop yield, based on chlorophyll 'a' concentration. KW - chlorophyll KW - growth KW - rice crop KW - spectral reflectance KW - red edge KW - leaf biochemistry KW - vegetation KW - prospect KW - model ER - TY - JOUR ID - clevers2002 AU - Clevers, J. G. P. W. AU - De Jong, S. M. AU - Epema, G. F. AU - Van Der Meer, F. D. AU - Bakker, W. H. AU - Skidmore, A. K. AU - Scholte, K. H. TI - Derivation of the red edge index using the MERIS standard band setting UR - http://dx.doi.org/10.1080/01431160110104647 DO - 10.1080/01431160110104647 T2 - International Journal of Remote Sensing PY - 2002 DA - 2002/01/01 SN - 0143-1161 VL - 23 IS - 16 SP - 3169-3184 AB - Within ESA's Earth Observation programme, the Medium Resolution Imaging Spectrometer (MERIS) is one of the payload components of the European polar platform ENVISAT-1. MERIS will be operated with a standard band setting of 15 bands. The objective of this paper was to study whether the vegetation red edge index can be derived from the MERIS standard band setting. This red edge provides useful information on the physiological status of the vegetation. Two different data sets are explored for simulating the red edge using MERIS spectral bands. Results show that the maximum first derivative and a three-point Lagrangian technique are not appropriate measures for the red edge index. A 'linear method', estimating the inflexion point as the reflectance midpoint between the NIR plateau and the red minimum, is a more robust method. Results also show that the MERIS bands at 665, 705, 753.75 and 775 nm can be used for applying the linear method for red edge index estimation. However, since the band at 753.75 nm is located very close to the oxygen absorption feature of the atmosphere, an atmospheric correction must be applied previous to calculating the position of the red edge using the MERIS bands. ER - TY - JOUR ID - clevers2004 AU - Clevers, J. G. P. W. AU - Kooistra, L. AU - Salas, E. A. L. TI - Study of heavy metal contamination in river floodplains using the red-edge position in spectroscopic data UR - http://dx.doi.org/10.1080/01431160310001654473 DO - 10.1080/01431160310001654473 T2 - International Journal of Remote Sensing PY - 2004 DA - 2004/10/01 SN - 0143-1161 VL - 25 IS - 19 SP - 3883-3895 AB - One of the major environmental problems resulting from the regular flooding of rivers in Europe is the heavy metal contamination of soils. Various studies have shown that soil contamination may influence plant physiology and, through changes in leaf pigment concentrations, influence reflectance spectra. The main objective of this case study was to study whether the red-edge position (REP) of vegetation spectra may provide information on soil contamination by heavy metals in river floodplains. The use of the maximum first derivative, smoothing methods (like polynomial fitting and the inverted Gaussian function) and interpolation methods based on just a few spectral bands were evaluated for a test site in the floodplain of the river Waal in the Netherlands. On selected transects, heavy metal concentrations of soil samples and reflectance spectra of the growing vegetation using a field spectroradiometer were measured. A significant negative correlation between the REP and heavy metal concentration was found using the maximum first derivative method (R 2=0.64). The first derivative spectra in this study showed the presence of more than one peak within the red-edge region, as found by other authors. This phenomenon requires further detailed research using very fine spectral measurements. ER - TY - JOUR ID - curran1989 AU - Curran, Paul J. TI - Remote sensing of foliar chemistry UR - http://www.sciencedirect.com/science/article/pii/0034425789900692 DO - 10.1016/0034-4257(89)90069-2 T2 - Remote Sensing of Environment PY - 1989 SN - 0034-4257 VL - 30 IS - 3 SP - 271-278 AB - Remotely sensed data are being used to estimate foliar chemical content as a result of our need for the information and our increasing ability to understand and measure foliar spectra. This paper reviews how stepwise multiple regression and deconvolution have been used to extract chemical information from foliar spectra, and concludes that both methods are useful, but neither is ideal. It is recommended that the focus of research be modeling in the long term and experimentation in the short term. Long-term research should increase our understanding of the interaction between radiation and foliar chemistry so that the focus of research can move from leaf model to canopy model to field experiment. Short-term research should aim to design experiments in which remotely sensed data are used to generate unambiguous and accurate estimates of foliar chemical content. ER - TY - JOUR ID - curran1995 AU - Curran, Paul J. AU - Windham, W. Robert AU - Gholz, Henry L. TI - Exploring the relationship between reflectance red edge and chlorophyll concentration in slash pine leaves UR - http://treephys.oxfordjournals.org/content/15/3/203.abstract DO - 10.1093/treephys/15.3.203 T2 - Tree Physiology PY - 1995 DA - March 1, 1995 VL - 15 IS - 3 SP - 203-206 AB - Chlorophyll concentration is related positively to the point of maximum slope in the reflectance spectra of leaves and this point is termed the red edge. The reflectance spectra of slash pine (Pinus elliottii Engelm.) needles were measured in the field and the chlorophyll concentrations of the same needles were measured in the laboratory. The measurement errors for red edge and chlorophyll concentration were determined to be 2.2 nm (3% of mean) and 0.35 mg g-1 (19% of mean), respectively. The red edge–chlorophyll concentration relationship was strong (r2 = 0.82, n = 152). A red edge–chlorophyll concentration relationship for n = 100 was used with red edge measurements to estimate chlorophyll concentration with an rms error of 0.31 mg g-1 (17% of mean, n = 52). The entire red edge–chlorophyll concentration relationship for n = 152 was also used with red edge measurements to estimate the chlorophyll concentration of samples from an earlier experiment with an rms error of 0.47 mg g-1 (30% of mean, n = 38). We conclude that measures of red edge can be used to estimate the chlorophyll concentration of detached needles in the field with an accuracy similar to that obtained by conventional laboratory measurements. ER - TY - JOUR ID - dash2004 AU - Dash, J. AU - Curran, P. J. TI - The MERIS terrestrial chlorophyll index UR - http://dx.doi.org/10.1080/0143116042000274015 DO - 10.1080/0143116042000274015 PR - Taylor & Francis T2 - International Journal of Remote Sensing PY - 2004 DA - 2004/12/01 SN - 0143-1161 VL - 25 IS - 23 SP - 5403-5413 AB - The long wavelength edge of the major chlorophyll absorption feature in the spectrum of a vegetation canopy moves to longer wavelengths with an increase in chlorophyll content. The position of this red-edge has been used successfully to estimate, by remote sensing, the chlorophyll content of vegetation canopies. Techniques used to estimate this red-edge position (REP) have been designed for use on small volumes of continuous spectral data rather than the large volumes of discontinuous spectral data recorded by contemporary satellite spectrometers. Also, each technique produces a different value of REP from the same spectral data and REP values are relatively insensitive to chlorophyll content at high values of chlorophyll content. This paper reports on the design and indirect evaluation of a surrogate REP index for use with spectral data recorded at the standard band settings of the Medium Resolution Imaging Spectrometer (MERIS). This index, termed the MERIS terrestrial chlorophyll index (MTCI), was evaluated using model spectra, field spectra and MERIS data. It was easy to calculate (and so can be automated), was correlated strongly with REP but unlike REP was sensitive to high values of chlorophyll content. As a result this index became an official MERIS level-2 product of the European Space Agency in March 2004. Further direct evaluation of the MTCI is proposed, using both greenhouse and field data. ER - TY - JOUR ID - datt1998 AU - Datt, Bisun TI - Remote Sensing of Chlorophyll a, Chlorophyll b, Chlorophyll a+b, and Total Carotenoid Content in Eucalyptus Leaves UR - http://www.sciencedirect.com/science/article/pii/S0034425798000467 DO - 10.1016/s0034-4257(98)00046-7 T2 - Remote Sensing of Environment PY - 1998 SN - 0034-4257 VL - 66 IS - 2 SP - 111-121 AB - Algorithms based on reflectance band ratios have been developed for the remote estimation of chlorophyll a, chlorophyll b, chlorophyll a+b, and total carotenoid content of Eucalyptus leaves. Reflectance spectra over the 400–2500 nm range with a spectral resolution of 2 nm and the content of chlorophylls a, b, a+b, and total carotenoids were determined for leaves from several Eucalyptus species covering a wide range of chlorophyll a content (0.0121–0.0435 mg/cm2). Maximum sensitivity of reflectance to variation in pigment content was found in the green wavelength region at 550 nm and at 708 nm in the far-red wavelengths. The reflectance in the main pigment absorption regions in the blue (400–500 nm) and red (660–690 nm) wavelengths proved to be insensitive to variation in pigment content. The ratio R672/(R550× R708) correlated best with chlorophyll a, chlorophyll a+b, and total carotenoid contents. The ratio R672/R550 correlated best with chlorophyll b content. Reflectance ratios involving near infrared bands such as R750/R550 and R750/R700 did not correlate well with pigment content. This was due to the differential scattering effects of the wide range of young and mature leaf samples. A method was developed for adjusting all spectra to the same level of scatter. The near-infrared-based reflectance ratios from the scatter adjusted spectra showed high sensitivity to pigment content. The ratio R860/(R550×R708) from the scatter adjusted spectra correlated best with chlorophyll a, chlorophyll a+b, and total carotenoid contents, while R860/R550 correlated best with chlorophyll b content. The newly developed algorithms were tested on a validation data set and allowed accurate estimates of leaf pigment content. The pigment contents estimated by the ratios from untransformed spectra, R672/(R550×R708) and R672/R550, were found to be not significantly different from the estimates obtained using the scatter-adjusted reflectance ratios, R860/(R550×R708) and R860/R550. ER - TY - JOUR ID - daughtry2000 AU - Daughtry, C. S. T. AU - Walthall, C. L. AU - Kim, M. S. AU - de Colstoun, E. Brown AU - McMurtrey Iii, J. E. TI - Estimating Corn Leaf Chlorophyll Concentration from Leaf and Canopy Reflectance UR - http://www.sciencedirect.com/science/article/pii/S0034425700001139 DO - 10.1016/s0034-4257(00)00113-9 T2 - Remote Sensing of Environment PY - 2000 SN - 0034-4257 VL - 74 IS - 2 SP - 229-239 AB - Farmers must balance the competing goals of supplying adequate N for their crops while minimizing N losses to the environment. To characterize the spatial variability of N over large fields, traditional methods (soil testing, plant tissue analysis, and chlorophyll meters) require many point samples. Because of the close link between leaf chlorophyll and leaf N concentration, remote sensing techniques have the potential to evaluate the N variability over large fields quickly. Our objectives were to (1) select wavelengths sensitive to leaf chlorophyll concentration, (2) simulate canopy reflectance using a radiative transfer model, and (3) propose a strategy for detecting leaf chlorophyll status of plants using remotely sensed data. A wide range of leaf chlorophyll levels was established in field-grown corn (Zea mays L.) with the application of 8 N levels: 0%, 12.5%, 25%, 50%, 75%, 100%, 125%, and 150% of the recommended rate. Reflectance and transmittance spectra of fully expanded upper leaves were acquired over the 400-nm to 1,000-nm wavelength range shortly after anthesis with a spectroradiometer and integrating sphere. Broad-band differences in leaf spectra were observed near 550 nm, 715 nm, and >750 nm. Crop canopy reflectance was simulated using the SAIL (Scattering by Arbitrarily Inclined Leaves) canopy reflectance model for a wide range of background reflectances, leaf area indices (LAI), and leaf chlorophyll concentrations. Variations in background reflectance and LAI confounded the detection of the relatively subtle differences in canopy reflectance due to changes in leaf chlorophyll concentration. Spectral vegetation indices that combined near-infrared reflectance and red reflectance (e.g., OSAVI and NIR/Red) minimized contributions of background reflectance, while spectral vegetation indices that combined reflectances of near-infrared and other visible bands (MCARI and NIR/Green) were responsive to both leaf chlorophyll concentrations and background reflectance. Pairs of these spectral vegetation indices plotted together produced isolines of leaf chlorophyll concentrations. The slopes of these isolines were linearly related to leaf chlorophyll concentration. A limited test with measured canopy reflectance and leaf chlorophyll data confirmed these results. The characterization of leaf chlorophyll concentrations at the field scale without the confounding problem of background reflectance and LAI variability holds promise as a valuable aid for decision making in managing N applications. ER - TY - JOUR ID - dorigo2007 AU - Dorigo, W. A. AU - Zurita-Milla, R. AU - de Wit, A. J. W. AU - Brazile, J. AU - Singh, R. AU - Schaepman, M. E. TI - A review on reflective remote sensing and data assimilation techniques for enhanced agroecosystem modeling UR - ://WOS:000246320700008 DO - 10.1016/j.jag.2006.05.003 T2 - International Journal of Applied Earth Observation and Geoinformation PY - 2007 DA - May SN - 0303-2434 VL - 9 IS - 2 SP - 165-193 N1 - ISI Document Delivery No.: 165QP Times Cited: 39 Cited Reference Count: 181 Dorigo, W. A. Zurita-Milla, R. de Wit, A. J. W. Brazile, J. Singh, R. Schaepman, M. E. Conference on Advances in Airborne Electromagnetics and Remote Sensing of Agro-Ecosystems 2004 Wageningen, NETHERLANDS Elsevier science bv Amsterdam AB - During the last 50 years, the management of agroecosystems has been undergoing major changes to meet the growing demand for food, timber, fibre and fuel. As a result of this intensified use, the ecological status of many agroecosystems has been severely deteriorated. Modeling the behavior of agroecosystems is, therefore, of great help since it allows the definition of management strategies that maximize (crop) production while minimizing the environmental impacts. Remote sensing can support such modeling by offering information on the spatial and temporal variation of important canopy state variables which would be very difficult to obtain otherwise. In this paper, we present an overview of different methods that can be used to derive biophysical and biochemical canopy state variables from optical remote sensing data in the VNIR-SWIR regions. The overview is based on an extensive literature review where both statistical-empirical and physically based methods are discussed. Subsequently, the prevailing techniques of assimilating remote sensing data into agroecosystem models are outlined. The increasing complexity of data assimilation methods and of models describing agroecosystem functioning has significantly increased computational demands. For this reason, we include a short section on the potential of parallel processing to deal with the complex and computationally intensive algorithms described in the preceding sections. The studied literature reveals that many valuable techniques have been developed both for the retrieval of canopy state variables from reflective remote sensing data as for assimilating the retrieved variables in agroecosystem models. However, for agroecosystem modeling and remote sensing data assimilation to be commonly employed on a global operational basis, emphasis will have to be put on bridging the mismatch between data availability and accuracy on one hand, and model and user requirements on the other. This could be achieved by integrating imagery with different spatial, temporal, spectral, and angular resolutions, and the fusion of optical data with data of different origin, such as LIDAR and radar/microwave. (c) 2006 Elsevier B.V. All rights reserved. KW - data assimilation KW - agroecosystem modeling KW - vegetation indices KW - canopy KW - reflectance modeling KW - biophysical variables KW - biochemical variables KW - parallel processing KW - radiative-transfer models KW - leaf-area index KW - hyperspectral vegetation KW - indexes KW - hydrologic data assimilation KW - multiple linear-regression KW - canopy chlorophyll density KW - ensemble kalman filter KW - bidirectional KW - reflectance KW - soil-moisture KW - crop models ER - TY - CONF ID - dorigo2007-2 AU - Dorigo, Wouter AU - Gerighausen, Heike TI - Automatic retrieval of crop characteristics: an example for hyperspectral AHS data from the AgriSAR campaign T2 - Proc. on AGRISAR and EAGLE Campaigns Final Workshop CY - Noordwijk, The Netherlands PY - 2007 DA - 2007-10-15 - 2007-10-16 KW - hyperspectral, AHS, imaging spectroscopy, radiative transfer model inversion, CRASh, PROSPECT, SAILh, LAI, chlorophyll, winter wheat, winter barley, winter rape, maize, sugar beet ER - TY - JOUR ID - eitel2007 AU - Eitel, J. U. H. AU - Long, D. S. AU - Gessler, P. E. AU - Smith, A. M. S. TI - Using insitu measurements to evaluate the new RapidEye™ satellite series for prediction of wheat nitrogen status UR - http://dx.doi.org/10.1080/01431160701422213 DO - 10.1080/01431160701422213 T2 - International Journal of Remote Sensing PY - 2007 DA - 2007/09/20 SN - 0143-1161 VL - 28 IS - 18 SP - 4183-4190 AB - This study assessed whether vegetation indices derived from broadband RapidEye? data containing the red edge region (690?730 nm) equal those computed from narrow band data in predicting nitrogen (N) status of spring wheat (Triticum aestivum L.). Various single and combined indices were computed from in?situ spectroradiometer data and simulated RapidEye? data. A new, combined index derived from the Modified Chlorophyll Absorption Ratio Index (MCARI) and the second Modified Triangular Vegetation Index (MTVI2) in ratio obtained the best regression relationships with chlorophyll meter values (Minolta Soil Plant Analysis Development (SPAD) 502 chlorophyll meter) and flag leaf N. For SPAD, r 2 values ranged from 0.45 to 0.69 (p<0.01) for narrow bands and from 0.35 and 0.77 (p<0.01) for broad bands. For leaf N, r 2 values ranged from 0.41 to 0.68 (p<0.01) for narrow bands and 0.37 to 0.56 (p<0.01) for broad bands. These results are sufficiently promising to suggest that MCARI/MTVI2 employing broadband RapidEye? data is useful for predicting wheat N status. ER - TY - JOUR ID - el-shikha2008 AU - El-Shikha, D. M. AU - Barnes, E. M. AU - Clarke, T. R. AU - Hunsaker, D. J. AU - Haberland, J. A. AU - Pinter, P. J. AU - Waller, P. M. AU - Thompson, T. L. TI - Remote sensing of cotton nitrogen status using the Canopy Chlorophyll Content Index (CCCI) UR - ://WOS:000255421800007 T2 - Transactions of the Asabe PY - 2008 DA - Jan-Feb SN - 0001-2351 VL - 51 IS - 1 SP - 73-82 N1 - ISI Document Delivery No.: 294QY Times Cited: 6 Cited Reference Count: 37 El-Shikha, D. M. Barnes, E. M. Clarke, T. R. Hunsaker, D. J. Haberland, J. A. Pinter, P. J., Jr. Waller, P. M. Thompson, T. L. Amer soc agricultural & biological engineers St joseph AB - Various remote sensing indices have been used to infer crop nitrogen (N) status for field-scale nutrient management. However, such indices may indicate erroneous N status if there is a decrease in crop canopy density influenced by other factors, such as water stress. The Canopy Chlorophyll Content Index (CCCI) is a two-dimensional remote sensing index that has been proposed for inferring cotton N status. The CCCI uses reflectances in the near-infrared (NIR) and red spectral regions to account for seasonal changes in canopy density, while reflectances in the NIR and far-red regions are used to detect relative changes in canopy chlorophyll, a surrogate for N content. The primary objective of this study was to evaluate the CCCI and several other remote sensing indices for detecting the N status for cotton during the growing season. A secondary objective was to evaluate the ability of the indices to appropriately detect N in the presence of variable water status. Remote sensing data were collected during the 1998 (day of year [DOY] 114 to 310) and 1999 (DOY 106 to 316) cotton seasons in Arizona, in which treatments of optimal and low levels of N and water were imposed. In the 1998 season, water treatments were not imposed until late in the season (DOY 261), well after full cover Following an early season N application in 1998 for the optimal (DOY 154) but not the low N treatment, the CCCI detected significant differences in crop N status between the N treatments starting on DOY 173, when canopy cover was about 30%. A common vegetation index, the ratio of NIR to red (RVI), also detected significant separation between N treatments, but RVI detection occurred 16 days after the CCCI response. After an equal amount of N was applied to both optimal and low N treatments on DOY 190 in 1998, the CCCI indicated comparable N status for the N treatments on DOY 198, a trend not detected by RVI. In the 1999 season, both N and water treatments were imposed early and frequently during the season. The N status was poorly described by both the CCCI and RVI under partial canopy conditions when water status differed among treatments. However, once full canopy was obtained in 1999, the CCCI provided reliable N status information regardless of water status. At full cotton cover, the CCCI was significantly correlated with measured parameters of N status, including petiole NO3-N (r = 0.74), SPAD chlorophyll (r = 0.65), and total leaf N contents (r = 0.86). For well-watered cotton, the CCCI shows promise as a useful indicator of cotton N status after the canopy reaches about 30% cover However, further study is needed to develop the CCCI as a robust N detection tool independent of water stress. KW - canopy reflectance KW - fertility detection KW - radiometers KW - spectral analysis KW - water stress KW - reflectance indexes KW - spectral radiance KW - winter-wheat KW - corn leaves KW - grain-yield KW - water KW - stress KW - plants KW - light KW - field ER - TY - JOUR ID - gamon1999 AU - Gamon, J. A. AU - Surfus, J. S. TI - Assessing leaf pigment content and activity with a reflectometer UR - http://dx.doi.org/10.1046/j.1469-8137.1999.00424.x DO - 10.1046/j.1469-8137.1999.00424.x PR - Cambridge University Press T2 - New Phytologist PY - 1999 SN - 1469-8137 VL - 143 IS - 1 SP - 105–117 AB - This study explored reflectance indices sampled with a ‘leaf reflectometer’ as measures of pigment content for leaves of contrasting light history, developmental stage and functional type (herbaceous annual versus sclerophyllous evergreen). We employed three reflectance indices: a modified normalized difference vegetation index (NDVI), an index of chlorophyll content; the red/green reflectance ratio (RRED∶RGREEN), an index of anthocyanin content; and the change in photochemical reflectance index upon dark–light conversions (ΔPRI), an index of xanthophyll cycle pigment activity. In Helianthus annuus (sunflower), xanthophyll cycle pigment amounts were linearly related to growth light environment; leaves in full sun contained approximately twice the amount of xanthophyll cycle pigments as leaves in deep shade, and at midday a larger proportion of these pigments were in the photoprotective, de-epoxidized forms relative to shade leaves. Reflectance indices also revealed contrasting patterns of pigment development in leaves of contrasting structural types (annual versus evergreen). In H. annuus sun leaves, there was a remarkably rapid increase in amounts of both chlorophyll and xanthophyll cycle pigments along a leaf developmental sequence. This pattern contrasted with that of Quercus agrifolia (coast live oak, a sclerophyllous evergreen), which exhibited a gradual development of both chlorophyll and xanthophyll cycle pigments along with a pronounced peak of anthocyanin pigment content in newly expanding leaves. These temporal patterns of pigment development in Q. agrifolia leaves suggest that anthocyanins and xanthophyll cycle pigments serve complementary photoprotective roles during early leaf development. The results illustrate the use of reflectance indices for distinguishing divergent patterns of pigment activity in leaves of contrasting light history and functional type. KW - leaf development, leaf pigments, anthocyanins, chlorophyll, xanthophyll cycle, leaf reflectometer, reflectance indices, photoprotection ER - TY - JOUR ID - gitelson1997 AU - Gitelson, A. A. AU - Merzlyak, M. N. TI - Remote estimation of chlorophyll content in higher plant leaves UR - http://dx.doi.org/10.1080/014311697217558 DO - 10.1080/014311697217558 PR - Taylor & Francis T2 - International Journal of Remote Sensing PY - 1997 SN - 0143-1161 VL - 18 IS - 12 SP - 2691-2697 AB - Abstract Indices for the non-destructive estimation of chlorophyll content were formulated using various instruments to measure reflectance and absorption spectra in visible and near-infrared ranges, as well as chlorophyll contents from several non-related species from different climatic regions. The proposed new algorithms are simple ratios between percentage reflectance at spectral regions that are highly sensitive (540 to 630nm and around 700nm) and insensitive (nearinfrared) to variations in chlorophyll content: R NIR / R 700 and R NIR / R 550. The developed algorithms predicting leaf chemistry from the leaf optics were validated for nine plant species in the range of chlorophyll content from 0.27 to 62.9mug cm -2. An error of less than 4.2 mugcm -2 in chlorophyll prediction was achieved. The use of green and red (near 700nm) channels increases the sensitivity of NDVI to chlorophyll content by about five-fold. ER - TY - JOUR ID - gitelson1999 AU - Gitelson, Anatoly A. AU - Buschmann, Claus AU - Lichtenthaler, Hartmut K. TI - The Chlorophyll Fluorescence Ratio F735/F700 as an Accurate Measure of the Chlorophyll Content in Plants UR - http://www.sciencedirect.com/science/article/pii/S0034425799000231 DO - 10.1016/s0034-4257(99)00023-1 T2 - Remote Sensing of Environment PY - 1999 SN - 0034-4257 VL - 69 IS - 3 SP - 296-302 AB - A remote sensing technique is presented to estimate the chlorophyll content in higher plants. The ratio between chlorophyll fluorescence at 735 nm and in the range 700–710 nm, F735/F700 was found to be linearly proportional to the chlorophyll content (with determination coefficient, r2, more than 0.95), and, thus, this ratio can be used as a precise indicator of chlorophyll content in plant leaves. This new chlorophyll fluorescence ratio indicates chlorophyll levels with high precision- the error in chlorophyll prediction over a wide range of chlorophyll content (from 41 to 675 mg m−2) was less than 40 mg m−2. The technique was tested and validated in three plant species: beech (Fagus sylvatica L.), elm (Ulmus minor Miller), and wild vine (Parthenocissus tricuspidata L.). ER - TY - JOUR ID - gitelson1996 AU - Gitelson, Anatoly A. AU - Kaufman, Yoram J. AU - Merzlyak, Mark N. TI - Use of a green channel in remote sensing of global vegetation from EOS-MODIS DO - 10.1016/s0034-4257(96)00072-7 T2 - Remote Sensing of Environment PY - 1996 SN - 0034-4257 VL - 58 IS - 3 SP - 289-298 AB - Most animals use a “green” spectral range to remotely sense the presence and vitality of vegetation. While humans possess the same ability in their eyes, man-made space-borne sensors that sense evolution of global vegetation, have so far used a combination of the red and near infrared channels instead. In this article we challenge this approach, using measurements of reflectance spectra from 400 nm to 750 nm with spectral resolution of 2 nm, with simultaneous determination of pigment concentrations of mature and autumn senescing leaves. We show that, for a wide range of leaf greenness, the maximum sensitivity of reflectance coincides with the red absorption maximum of chlorophyll-a (Chl-a) at 670 nm. However, for yellow-green to green leaves (with Chl-a more than 3–5 μg/cm2), the reflectance near 670 nm is not sensitive to chlorophyll concentration because of saturation of the relationship of absorptions versus chlorophyll concentration. Maximum sensitivity of Chl-a concentration for a wide range of its variation (0.3–45 μg/cm2) was found, not surprisingly so, around the green band from 520 nm to 630 nm and also near 700 nm. We found that the inverse of the reflectance in the green band was proportional to Chl-a concentration with correlation r2 > 0.95. This band will be present on several future satellite sensors with a global view of vegetation (SeaWiFS to be launched in 1996, Polder on ADEOS-1 also in 1996, and MODIS on EOS in 1998 and 2000). New indexes that use the green channel and are resistant to atmospheric effects are developed. A green NDVI = (ϱnir − ϱgreen(ϱnir + ϱgreen) was tested for a range of Chl-a from 0.3 μg/cm2 to 45 μg/cm2, and found to have an error in the chlorophyll a derivation at leaf level of less than 3 μg/cm2. The new index has wider dynamic range than the NDVI and is, on average, at least five times more sensitive to Chl-a concentration. A green atmospherically resistant vegetation index (GARI), tailored on the concept of ARVI (Kaufman and Tanré, 1992), is developed and is expected to be as resistant to atmospheric effects as ARVI but more sensitive to a wide range of Chl-a concentrations. While NDVI and ARVI are sensitive to vegetation fraction and to rate of absorption of photosynthetic solar radiation, a green vegetation index like GARI should be added to sense the concentration of chlorophyll, to measure the rate of photosynthesis and to monitor plant stress. ER - TY - JOUR ID - gitelson1996-2 AU - Gitelson, Anatoly A. AU - Merzlyak, Mark N. AU - Lichtenthaler, Hartmut K. TI - Detection of Red Edge Position and Chlorophyll Content by Reflectance Measurements Near 700 nm UR - http://www.sciencedirect.com/science/article/pii/S0176161796802859 DO - 10.1016/s0176-1617(96)80285-9 T2 - Journal of Plant Physiology PY - 1996 SN - 0176-1617 VL - 148 IS - 3–4 SP - 501-508 AB - Summary Pigment contents was determined in and high spectral resolution reflectance measurements were acquired for spring, summer and autumn maple and horse chestnut leaves covering a wide range of chlorophyll content. Consistent and diagnostic differences in the red edge range (680-750 nm) of the reflectance spectrum were obtained for the various leaf samples of both species studied. This included the differences in the wavelength position of the red edge and in the reflectance values in the range of 690 to 710 nm. Both characteristics were found to be dependent on leaf chlorophyll concentration. The first derivative of reflectance spectra showed four peaks at 685-706, 710, 725 and 740 nm that were dependent in different degree on leaf age and pigment concentration in the leaves. The position and the magnitude of the first peak showed a high correlation with the leaf chlorophyll concentration. Reflectance at 700 nm was linearly dependent on the wavelength of the first peak. Variation of inflection point position with change in chlorophyll content was found small for yellow-green to dark green leaves (total chlorophyll in the range above 10 nmol/cm2). Reflectance near 700 nm was found to be a very sensitive indicator of the red edge position as well as of chlorophyll concentration. The ratio of reflectances at 750 nm to that near 700 nm (R750/R700) was directly proportional (correlation r2 > 0.95) to chlorophyll concentration. The ratio R750/R700 as a newly established index for non-invasive in-vivo chlorophyll determination was tested by independent data sets in the range of Chl contents from 0.6 to more than 60nmol/cm2 of maple and chestnut leaves with an estimation error of Chl of less than 3.7 nmol/cm2. KW - chlorophyll content KW - reflectance spectra of leaves KW - red edge position KW - vegetation indices ER - TY - CONF ID - gitelson2001 AU - Gitelson, Anatoly A. AU - Merzlyak, Mark N. AU - Zur, Y. AU - Stark, R. AU - Gritz, U. TI - Non-destructive and remote sensing techniques for estimation of vegetation status T2 - Third European Conference on Precision Agriculture CY - Montpellier, France PY - 2001 VL - 1 SP - 301-306 ER - TY - JOUR ID - gitelson2003 AU - Gitelson, Anatoly A. AU - Viña, Andrés AU - Arkebauer, Timothy J. AU - Rundquist, Donald C. AU - Keydan, Galina: Leavitt, Bryan TI - Remote estimation of leaf area index and green leaf biomass in maize canopies DO - 10.1029/2002gl016450 PR - AGU T2 - Geophys. Res. Lett. PY - 2003 SN - 0094-8276 VL - 30 IS - 5 SP - 1248 AB - Leaf area index (LAI) is an important variable for climate modeling, estimates of primary production, agricultural yield forecasting, and many other diverse studies. Remote sensing provides a considerable potential for estimating LAI at local to regional and global scales. Several spectral vegetation indices have been proposed, but their capacity to estimate LAI is highly reduced at moderate-to-high LAI. In this paper, we propose a technique to estimate LAI and green leaf biomass remotely using reflectances in two spectral channels either in the green around 550 nm, or at the red edge near 700 nm, and in the NIR (beyond 750 nm). The technique was tested in agricultural fields under a maize canopy, and proved suitable for accurate estimation of LAI ranging from 0 to more than 6. KW - Remote sensing, Instruments and techniques. General or miscellaneous ER - TY - JOUR ID - gitelson1994 AU - Gitelson, Anatoly AU - Merzlyak, Mark N. TI - Quantitative estimation of chlorophyll-a using reflectance spectra: Experiments with autumn chestnut and maple leaves DO - 10.1016/1011-1344(93)06963-4 T2 - Journal of Photochemistry and Photobiology B: Biology PY - 1994 SN - 1011-1344 VL - 22 IS - 3 SP - 247-252 AB - The signature analysis of reflectance spectra of autumn Aesculus hippocastanum L. and Acer platanoides L. leaves revealed spectral bands maximally (near 550 and 705 nm) and minimally (at more than 750 nm) sensitive to variation in chlorophyll content, which can serve as sensitive indicators of early stages of leaf senescence. Several functions of reflectance directly proportional to chlorophyll-a have been found. These make it possible to determine chlorophyll accurately with a background of high pigment concentration. KW - Chlorophyll-a, Leaf, Reflectance spectrum ER - TY - JOUR ID - glenn2010 AU - Glenn, E. P. AU - Nagler, P. L. AU - Huete, A. R. TI - Vegetation Index Methods for Estimating Evapotranspiration by Remote Sensing UR - ://WOS:000284318100001 DO - 10.1007/s10712-010-9102-2 T2 - Surveys in Geophysics PY - 2010 DA - Dec SN - 0169-3298 VL - 31 IS - 6 SP - 531-555 N1 - ISI Document Delivery No.: 681LY Times Cited: 7 Cited Reference Count: 112 Glenn, Edward P. Nagler, Pamela L. Huete, Alfredo R. Springer Dordrecht AB - Evapotranspiration (ET) is the largest term after precipitation in terrestrial water budgets. Accurate estimates of ET are needed for numerous agricultural and natural resource management tasks and to project changes in hydrological cycles due to potential climate change. We explore recent methods that combine vegetation indices (VI) from satellites with ground measurements of actual ET (ET(a)) and meteorological data to project ET(a) over a wide range of biome types and scales of measurement, from local to global estimates. The majority of these use time-series imagery from the Moderate Resolution Imaging Spectrometer on the Terra satellite to project ET over seasons and years. The review explores the theoretical basis for the methods, the types of ancillary data needed, and their accuracy and limitations. Coefficients of determination between modeled ET(a) and measured ET(a) are in the range of 0.45-0.95, and root mean square errors are in the range of 10-30% of mean ET(a) values across biomes, similar to methods that use thermal infrared bands to estimate ET(a) and within the range of accuracy of the ground measurements by which they are calibrated or validated. The advent of frequent-return satellites such as Terra and planed replacement platforms, and the increasing number of moisture and carbon flux tower sites over the globe, have made these methods feasible. Examples of operational algorithms for ET in agricultural and natural ecosystems are presented. The goal of the review is to enable potential end-users from different disciplines to adapt these methods to new applications that require spatially-distributed ET estimates. KW - NDVI KW - Enhanced Vegetation Index KW - Fluxnet KW - MODIS KW - Remote sensing KW - land-surface evaporation KW - basal crop coefficients KW - colorado river delta KW - modis satellite data KW - canopy reflectance KW - potential evapotranspiration KW - riparian evapotranspiration KW - meteorological data KW - eddy covariance KW - energy-balance ER - TY - GEN ID - gobron2000 AU - Gobron, N. AU - Pinty, B. AU - Verstraete, M. M. AU - Widlowski, J. L. TI - Advanced vegetation indices optimized for up-coming sensors: Design, performance, and applications DO - 10.1109/36.885197 T2 - Geoscience and Remote Sensing, IEEE Transactions on PY - 2000 SN - 0196-2892 VL - 38 IS - 6 SP - 2489-2505 AB - This paper describes the implementation of a physical and mathematical approach to designing advanced vegetation indices optimized for future sensors operating in the solar domain such as the medium resolution imaging spectrometer (MERIS), the global imager (GLI), and the VEGETATION instrument, and proposes an initial evaluation of such indices. These optimized indices address sensor-specific issues such as dependencies with respect to the actual spectral response of the sensor as well as the natural sensitivity of remote sensing measurements to illumination and observing geometry, to atmospheric absorption and scattering effects, and to soil color or brightness changes. The derivation of vegetation index formulae optimized to estimate the same vegetation property fraction of absorbed photosynthetically active radiation (FAPAR) from data generated by different sensors allows the comparison of their relative performances compared with existing vegetation indices, both from a theoretical and experimental point of view and permits the creation of global products, as well as the constitution of long time series from multiple sensors. KW - geophysical techniques, remote sensing, vegetation mapping, FAPAR, GLI, IR, MERIS, SPOT, VEGETATION, advanced vegetation indices, formula, fraction of absorbed photosynthetically active radiation, geophysical measurement technique, global imager, infrared, mathematical approach, medium resolution imaging spectrometer, optical method, vegetation index, visible ER - TY - JOUR ID - gonz_lez-sanpedro2008 AU - González-Sanpedro, MC AU - Le Toan, T AU - Moreno, J AU - Kergoat, L AU - Rubio, E TI - Seasonal variations of leaf area index of agricultural fields retrieved from Landsat data T2 - Remote Sensing of Environment PY - 2008 VL - 112 SP - 810-824 ER - TY - CONF ID - guyot1988 AU - Guyot, G. AU - Baret, F. AU - Major, D. J. TI - High spectral resolution: Determination of specral shifts between the red and the near infrared T2 - International Archives of Photogrammetry and Remote Sensing CY - XVIth ISPRS Congress, Technical Commission VII: Interpretation of Photographic and Remote Sensing Data , July 1-10, 1988, Kyoto, Japan PY - 1988 VL - 11 SP - 750−760 ER - TY - JOUR ID - haboudane2004 AU - Haboudane, Driss AU - Miller, John R. AU - Pattey, Elizabeth AU - Zarco-Tejada, Pablo J. AU - Strachan, Ian B. TI - Hyperspectral vegetation indices and novel algorithms for predicting green LAI of crop canopies: Modeling and validation in the context of precision agriculture UR - http://www.sciencedirect.com/science/article/pii/S0034425704000264 DO - 10.1016/j.rse.2003.12.013 T2 - Remote Sensing of Environment PY - 2004 SN - 0034-4257 VL - 90 IS - 3 SP - 337-352 AB - A growing number of studies have focused on evaluating spectral indices in terms of their sensitivity to vegetation biophysical parameters, as well as to external factors affecting canopy reflectance. In this context, leaf and canopy radiative transfer models are valuable for modeling and understanding the behavior of such indices. In the present work, PROSPECT and SAILH models have been used to simulate a wide range of crop canopy reflectances in an attempt to study the sensitivity of a set of vegetation indices to green leaf area index (LAI), and to modify some of them in order to enhance their responsivity to LAI variations. The aim of the paper was to present a method for minimizing the effect of leaf chlorophyll content on the prediction of green LAI, and to develop new algorithms that adequately predict the LAI of crop canopies. Analyses based on both simulated and real hyperspectral data were carried out to compare performances of existing vegetation indices (Normalized Difference Vegetation Index [NDVI], Renormalized Difference Vegetation Index [RDVI], Modified Simple Ratio [MSR], Soil-Adjusted Vegetation Index [SAVI], Soil and Atmospherically Resistant Vegetation Index [SARVI], MSAVI, Triangular Vegetation Index [TVI], and Modified Chlorophyll Absorption Ratio Index [MCARI]) and to design new ones (MTVI1, MCARI1, MTVI2, and MCARI2) that are both less sensitive to chlorophyll content variations and linearly related to green LAI. Thorough analyses showed that the above existing vegetation indices were either sensitive to chlorophyll concentration changes or affected by saturation at high LAI levels. Conversely, two of the spectral indices developed as a part of this study, a modified triangular vegetation index (MTVI2) and a modified chlorophyll absorption ratio index (MCARI2), proved to be the best predictors of green LAI. Related predictive algorithms were tested on CASI (Compact Airborne Spectrographic Imager) hyperspectral images and, then, validated using ground truth measurements. The latter were collected simultaneously with image acquisition for different crop types (soybean, corn, and wheat), at different growth stages, and under various fertilization treatments. Prediction power analysis of proposed algorithms based on MCARI2 and MTVI2 resulted in agreements between modeled and ground measurement of non-destructive LAI, with coefficients of determination (r2) being 0.98 for soybean, 0.89 for corn, and 0.74 for wheat. The corresponding RMSE for LAI were estimated at 0.28, 0.46, and 0.85, respectively. KW - Hyperspectral KW - Spectral indices KW - Green LAI KW - Prediction algorithms KW - Chlorophyll content KW - Precision agriculture ER - TY - JOUR ID - haboudane2002 AU - Haboudane, Driss AU - Miller, John R. AU - Tremblay, Nicolas AU - Zarco-Tejada, Pablo J. AU - Dextraze, Louise TI - Integrated narrow-band vegetation indices for prediction of crop chlorophyll content for application to precision agriculture UR - http://www.sciencedirect.com/science/article/pii/S0034425702000184 DO - 10.1016/s0034-4257(02)00018-4 T2 - Remote Sensing of Environment PY - 2002 SN - 0034-4257 VL - 81 IS - 2–3 SP - 416-426 AB - Recent studies have demonstrated the usefulness of optical indices from hyperspectral remote sensing in the assessment of vegetation biophysical variables both in forestry and agriculture. Those indices are, however, the combined response to variations of several vegetation and environmental properties, such as Leaf Area Index (LAI), leaf chlorophyll content, canopy shadows, and background soil reflectance. Of particular significance to precision agriculture is chlorophyll content, an indicator of photosynthesis activity, which is related to the nitrogen concentration in green vegetation and serves as a measure of the crop response to nitrogen application. This paper presents a combined modeling and indices-based approach to predicting the crop chlorophyll content from remote sensing data while minimizing LAI (vegetation parameter) influence and underlying soil (background) effects. This combined method has been developed first using simulated data and followed by evaluation in terms of quantitative predictive capability using real hyperspectral airborne data. Simulations consisted of leaf and canopy reflectance modeling with PROSPECT and SAILH radiative transfer models. In this modeling study, we developed an index that integrates advantages of indices minimizing soil background effects and indices that are sensitive to chlorophyll concentration. Simulated data have shown that the proposed index Transformed Chlorophyll Absorption in Reflectance Index/Optimized Soil-Adjusted Vegetation Index (TCARI/OSAVI) is both very sensitive to chlorophyll content variations and very resistant to the variations of LAI and solar zenith angle. It was therefore possible to generate a predictive equation to estimate leaf chlorophyll content from the combined optical index derived from above-canopy reflectance. This relationship was evaluated by application to hyperspectral CASI imagery collected over corn crops in three experimental farms from Ontario and Quebec, Canada. The results presented here are from the L'Acadie, Quebec, Agriculture and Agri-Food Canada research site. Images of predicted leaf chlorophyll content were generated. Evaluation showed chlorophyll variability over crop plots with various levels of nitrogen, and revealed an excellent agreement with ground truth, with a correlation of r2=.81 between estimated and field measured chlorophyll content data. ER - TY - JOUR ID - hancock2007 AU - Hancock, D. W. AU - Dougherty, C. T. TI - Relationships between blue- and red-based vegetation indices and leaf area and yield of alfalfa UR - ://WOS:000251409000038 DO - 10.2135/cropsci2007.01.0031 T2 - Crop Science PY - 2007 DA - Nov-Dec SN - 0011-183X VL - 47 IS - 6 SP - 2547-2556 N1 - ISI Document Delivery No.: 237XF Times Cited: 1 Cited Reference Count: 30 Hancock, Dennis W. Dougherty, Charles T. Crop science soc amer Madison AB - The need for site-specific yield assessments of alfalfa (Medicago sativa L.) has spurred interest in developing methods to remotely sense biomass at harvest, Relationships between reflectance-based vegetation indices (Vis) and yield and yield-components of alfalfa have not been fully characterized. The objectives of this study were to evaluate the relationships between blue- and red-reflectance based Vis and canopy variables such as leaf area index (LAI), mass shoot(-1), shoot length, and alfalfa yield. Canopy reflectance was obtained with two reflectance spectrometers 1 d before each of five harvests in 2005 within rainfed and subsurface drip-irrigated alfalfa. Blue- and red-based normalized difference vegetation indices (NDVIs) and wide dynamic range vegetation indices (WDRVIs) at three levels of a near-infrared (NIR) reflectance-scalar ('alpha' = 0.1, 0.05, and 0.01) were calculated and regressed on alfalfa canopy variables. A quadratic-plateau model was used to determine when VIs no longer detected yield increments. Both blue- and red-based NDVIs and WDRVIs exhibited significant (P < 0.0001) saturative responses to LAI, yield components, and dry matter (DM) yield. Decreasing a widened the estimable yield range (0-1.82 vs. 0-2.76 Mg ha(-1) and 0-2.60 vs. 0-3.74 Mg ha-1, respectively) of both blue- and red-based WDRVIs. Significant (P < 0.0001) yield regression models within the effective range of the VIs (://WOS:000221193400006 T2 - Photogrammetric Engineering and Remote Sensing PY - 2003 DA - Jun SN - 0099-1112 VL - 69 IS - 6 SP - 647-664 N1 - ISI Document Delivery No.: 817RA Times Cited: 88 Cited Reference Count: 256 Pinter, PJ Hatfield, JL Schepers, JS Barnes, EM Moran, MS Daughtry, CST Upchurch, DR Amer soc photogrammetry Bethesda AB - Scientists with the Agricultural Research Service (ARS) and various government agencies and private institutions have provided a great deal of fundamental information relating spectral reflectance and thermal emittance properties of soils and crops to their agronomic and biophysical characteristics. This knowledge has facilitated the development and use of various remote sensing methods for non-destructive monitoring of plant growth and development and for the detection of many environmental stresses which limit plant productivity. Coupled with rapid advances in computing and position-locating technologies, remote sensing from ground-, air-, and space-based platforms is now capable of providing detailed spatial and temporal information on plant response to their local environment that is needed for site specific agricultural management approaches. This manuscript, which emphasizes contributions by ARS researchers, reviews the biophysical basis of remote sensing; examines approaches that have been developed, refined, and tested for management of water, nutrients, and pests in agricultural crops; and assesses the role of remote sensing in yield prediction. It concludes with a discussion of challenges facing remote sensing in the future. KW - water-stress index KW - spectral-biophysical data KW - soil heat-flux KW - infrared KW - aerial photography KW - laser-induced fluorescence KW - constant leaf KW - temperature KW - adjusted vegetation index KW - surface-energy balance KW - clover-seed production KW - gossypium-hirsutum l ER - TY - JOUR ID - richardson2002 AU - Richardson, Andrew D. AU - Duigan, Shane P. AU - Berlyn, Graeme P. TI - An evaluation of noninvasive methods to estimate foliar chlorophyll content UR - http://dx.doi.org/10.1046/j.0028-646X.2001.00289.x DO - 10.1046/j.0028-646X.2001.00289.x PR - Blackwell Science Ltd T2 - New Phytologist PY - 2002 SN - 1469-8137 VL - 153 IS - 1 SP - 185-194 AB - Over the last decade, technological developments have made it possible to quickly and nondestructively assess, in situ, the chlorophyll (Chl) status of plants. We evaluated the performance of these optical methods, which are based on the absorbance or reflectance of certain wavelengths of light by intact leaves. * •As our benchmark, we used standard extraction techniques to measure Chla, Chlb, and total Chl content of paper birch (Betula papyrifera) leaves. These values were compared with the nominal Chl index values obtained with two hand-held Chl absorbance meters and several reflectance indices correlated with foliar Chl. * •The noninvasive optical methods all provided reliable estimates of relative leaf Chl. However, across the range of Chl contents studied (0.0004–0.0455 mg cm−2), some reflectance indices consistently out-performed the hand-held meters. Most importantly, the reflectance indices that performed best were not those most commonly used in the literature. * •We report equations to convert from index values to actual Chl content, but caution that differences in leaf structure may necessitate species-specific calibration equations. KW - absorbance KW - chlorophyll KW - Chla : Chlb leaf optical properties KW - pigment KW - red edge KW - reflectance KW - spectral index ER - TY - JOUR ID - serrano2000 AU - Serrano, Lydia AU - Filella, Iolanda AU - Peñuelas, Josep TI - Remote Sensing of Biomass and Yield of Winter Wheat under Different Nitrogen Supplies UR - https://www.crops.org/publications/cs/abstracts/40/3/723 DO - 10.2135/cropsci2000.403723x T2 - Crop Science PY - 2000 DA - 2000/5 VL - 40 IS - 3 SP - 723-731 AB - Vegetation indices derived from reflectance data are related to canopy variables such as aboveground biomass, leaf area index (LAI), and the fraction of intercepted photosynthetically active radiation (fIPAR). However, under N stress the relationships between vegetation indices (VI) and these canopy variables might be confounded due to plant chlorosis. We studied the relationships between reflectance-based VI and canopy variables (aboveground biomass, LAI canopy chlorophyll A content [LAI × Chl A], and fIPAR) for a wheat (Triticum aestivum L.) crop growing under different N supplies. Nitrogen fertilization promoted significant increases in radiation interception (plant growth) and, to a lesser extent, in radiation use efficiency (RUE). The VI vs. LAI relationships varied significantly among treatments, rendering the VI-based equations unreliable to estimate LAI under contrasting N conditions. However, a single relationship emerged when LAI × Chl A was considered. Moreover, VI were robust indicators of fIPAR by green canopy components independently of N treatment and phenology. Aboveground biomass was poorly correlated with grain yield, whereas cumulative VI simple ratio (SR) was a good predictor of grain yield, probably because cumulative SR closely tracked the duration and intensity of the canopy photosynthetic capacity. ER - TY - JOUR ID - sims2002 AU - Sims, Daniel A. AU - Gamon, John A. TI - Relationships between leaf pigment content and spectral reflectance across a wide range of species, leaf structures and developmental stages UR - http://www.sciencedirect.com/science/article/pii/S003442570200010X DO - 10.1016/s0034-4257(02)00010-x T2 - Remote Sensing of Environment PY - 2002 SN - 0034-4257 VL - 81 IS - 2–3 SP - 337-354 AB - Leaf pigment content can provide valuable insight into the physiological performance of leaves. Measurement of spectral reflectance provides a fast, nondestructive method for pigment estimation. A large number of spectral indices have been developed for estimation of leaf pigment content. However, in most cases these indices have been tested for only one or at most a few related species and thus it is not clear whether they can be applied across species with varying leaf structural characteristics. Our objective in this study was to develop spectral indices for prediction of leaf pigment content that are relatively insensitive to species and leaf structure variation and thus could be applied in larger scale remote-sensing studies without extensive calibration. We also quantified the degree of spectral interference between pigments when multiple pigments occur within the same leaf tissue. We found that previously published spectral indices provided relatively poor correlations with leaf chlorophyll content when applied across a wide range of species and plant functional types. Leaf surface reflectance appeared to be the most important factor in this variation. By developing a new spectral index that reduces the effect of differences in leaf surface reflectance, we were able to significantly improve the correlations with chlorophyll content. We also found that an index based on the first derivative of reflectance in the red edge region was insensitive to leaf structural variation. The presence of other pigments did not significantly affect estimation of chlorophyll from spectral reflectance. Previously published carotenoid and anthocyanin indices performed poorly across the whole data set. However, we found that the photochemical reflectance index (PRI, originally developed for estimation of xanthophyll cycle pigment changes) was related to carotenoid/chlorophyll ratios in green leaves. This result has important implications for the interpretation of PRI measured at both large and small scales. Our results demonstrate that spectral indices can be applied across species with widely varying leaf structure without the necessity for extensive calibration for each species. This opens up new possibilities for assessment of vegetation health in heterogeneous natural environments. ER - TY - JOUR ID - strachan2002 AU - Strachan, Ian B. AU - Pattey, Elizabeth AU - Boisvert, Johanne B. TI - Impact of nitrogen and environmental conditions on corn as detected by hyperspectral reflectance DO - 10.1016/s0034-4257(01)00299-1 T2 - Remote Sensing of Environment PY - 2002 SN - 0034-4257 VL - 80 IS - 2 SP - 213-224 AB - Indices derived from hyperspectral reflectance spectra have the potential to be used as indicators of environmental stress in crops. This study uses canopy-scale, ground-based measurements of hyperspectral reflectance to demonstrate the temporal patterns in corn development under imposed fertility (N rate) and environmental (water availability) stresses. In 1998, two large areas in a 30-ha corn (Zea mays, L.) field near Ottawa, Canada (45°18′N, 75°44′W) were supplied with 99 and 17 kg N ha−1, while the balance of the field received the recommended rate of 155 kg N ha−1. Reflectance measurements were taken nine times using a portable spectroradiometer at georeferenced locations within these areas. Individual reflectance-based indices demonstrated the relative differences between application rates and identified both nitrogen and water stresses at various times in the growing season. No single index was able to describe the status of the corn crop throughout the season. Canonical discriminant analysis provided accurate classification of samples by N rate during early, mid, and late season conditions with overall success rates of 70%, 88%, and 93%, respectively. A shift in importance from green-based derivatives to red-based derivatives was noted from mid to late season and attributed to the natural reduction in green pigments as the crop entered senescence. Canopy-scale photochemical reflectance index (PRI) was shown to be correlated with canopy radiation use efficiency (RUE). Mid-season water stress affected the relationship. Multiple years of data are required to demonstrate robust relationships between hyperspectral indices and corn ecophysiological status because of the interaction between environmental and nutrient stresses. Identifying areas of fields sensitive to weather-induced stresses will allow better management of N application. Timing the collection of hyperspectral image data at early and late vegetative phase could enhance precision agriculture by allowing supplemental nutrient application, identifying stress patterns and aid in yield forecasting. KW - Hyperspectral reflectance KW - Precision agriculture KW - Stress detection KW - Corn field KW - Radiation use efficiency KW - Chlorophyll KW - Leaf area index KW - Crop water content ER - TY - JOUR ID - wu2008 AU - Wu, Chaoyang AU - Niu, Zheng AU - Tang, Quan AU - Huang, Wenjiang TI - Estimating chlorophyll content from hyperspectral vegetation indices: Modeling and validation UR - http://www.sciencedirect.com/science/article/pii/S0168192308000920 DO - 10.1016/j.agrformet.2008.03.005 T2 - Agricultural and Forest Meteorology PY - 2008 SN - 0168-1923 VL - 148 IS - 8–9 SP - 1230-1241 AB - Leaf chlorophyll content, a good indicator of photosynthesis activity, mutations, stress and nutritional state, is of special significance to precision agriculture. Recent studies have demonstrated the feasibility of retrieval of chlorophyll content from hyperspectral vegetation indices composed by the reflectance of specific bands. In this paper, a set of vegetation indices belonged to three classes (normalized difference vegetation index (NDVI), modified simple ratio (MSR) index and the modified chlorophyll absorption ratio index (MCARI, TCARI) and the integrated forms (MCARI/OSAVI and TCARI/OSAVI)) were tested using the PROSPECT and SAIL models to explore their potentials in chlorophyll content estimation. Different bands combinations were also used to derive the modified vegetation indices. In the sensitivity study, four new formed indices (MSR[705,750], MCARI[705,750], TCARI/OSAVI[705,750] and MCARI/OSAVI[705,750]) were proved to have better linearity with chlorophyll content and resistant to leaf area index (LAI) variations by taking into account the effect of quick saturation at 670 nm with relatively low chlorophyll content. Validation study was also conducted at canopy scale using the ground truth data in the growth duration of winter wheat (chlorophyll content and reflectance data). The results showed that the integrated indices TCARI/OSAVI[705,750] and MCARI/OSAVI[705,750] are most appropriate for chlorophyll estimation with high correlation coefficients R2 of 0.8808 and 0.9406, respectively, because more disturbances such as shadow, soil reflectance and nonphotosynthetic materials are taken into account. The high correlation between the vegetation indices obtained in the developmental stages of wheat and Hyperion data (R2 of 0.6798 and 0.7618 for TCARI/OSAVI[705,750] and MCARI/OSAVI[705,750], respectively) indicated that these two integrated index can be used in practice to estimate the chlorophylls of different types of corns. KW - Vegetation indices KW - Sensitivity KW - Chlorophyll content KW - LAI KW - Validation ER - TY - JOUR ID - wu2009 AU - Wu, Chaoyang AU - Niu, Zheng AU - Tang, Quan AU - Huang, Wenjiang AU - Rivard, Benoit AU - Feng, Jilu TI - Remote estimation of gross primary production in wheat using chlorophyll-related vegetation indices UR - http://www.sciencedirect.com/science/article/pii/S0168192308003560 DO - 10.1016/j.agrformet.2008.12.007 T2 - Agricultural and Forest Meteorology PY - 2009 SN - 0168-1923 VL - 149 IS - 6–7 SP - 1015-1021 AB - A number of recent studies have focused on estimating gross primary production (GPP) using vegetation indices (VIs). In this paper, GPP is retrieved as a product of incident light use efficiency (LUE), defined as GPP/PAR, and the photosynthetically active radiation (PAR). As a good correlation is found between canopy chlorophyll content and incident LUE for six types of wheat canopy (R2 = 0.87, n = 24), indices aimed for chlorophyll assessment can be used as an indicator of incident LUE and the product of chlorophyll indices and PAR will be a proxy of GPP. In a field experiment, we investigated four canopy chlorophyll content related indices (Red edge Normalized Difference Vegetation Index [Red Edge NDVI], modified Chlorophyll Absorption Ratio Index [MCARI710], Red Edge Chlorophyll Index [CIred edge] and the MERIS Terrestrial Chlorophyll Index [MTCI]) for GPP estimation during the growth cycle of wheat. These indices are validated for leaf and canopy chlorophyll estimation with ground truth data of canopy chlorophyll content. With ground truth data, a strong correlation is observed for canopy chlorophyll estimation with correlation coefficients R2 of 0.79, 0.84, 0.85 and 0.87 for Red Edge NDVI, MCARI710, CIred edge and MTCI, respectively (n = 24). As evidence of the existence of a relationship between canopy chlorophyll and GPP/PAR, these indices are shown to be a good proxy of GPP/PAR with R2 ranging from 0.70 for Red Edge NDVI and 0.75 for MTCI (n = 240). Remote estimation of GPP from canopy chlorophyll content Ã— PAR is proved to be relatively successful (R2 of 0.47, 0.53, 0.65 and 0.66 for Red edge NDVI, MCARI710, CIred edge and MTCI respectively, n = 240). These results open up a new possibility to estimate GPP and should inspire new models for remote sensing of GPP. KW - GPP KW - LUE KW - Vegetation indices KW - Canopy chlorophyll content KW - Sensitivity KW - Validation ER - TY - JOUR ID - zarco-tejada_p_j_sepulcre-cant_2007 AU - Zarco-Tejada P.J. AU - Sepulcre-Cantó, G. TI - REMOTE SENSING OF VEGETATION BIOPHYSICAL PARAMETERS FOR DETECTING STRESS CONDITION AND LAND COVER CHANGES T2 - Estudios de la Zona No Saturada del Suelo PY - 2007 VL - 8 ER - TY - JOUR ID - zarco-tejada2001 AU - Zarco-Tejada, P. J. AU - Miller, J. R. AU - Noland, T. L. AU - Mohammed, G. H. AU - Sampson, P. H. TI - Scaling-up and model inversion methods with narrow-band optical indices for chlorophyll content estimation in closed forest canopies with hyperspectral data T2 - IEEE Transactions on Geoscience and Remote Sensing PY - 2001 VL - 39 SP - 1491−1507 ER - TY - ELEC ID - idb AU - Henrich, V. AU - Krauss, G. AU - Götze, C. AU - Sandow, C. TI - The IndexDatabase UR - https://www.indexdatabase.de/ CY - Bonn PY - 2011 DA - 2011 ER -