Multiple drivers of seasonal change in PRI: Implications for photosynthesis 2. Stand level

Gitelson, Anatoly A.; Gamon, John A.; Solovchenko, Alexei

doi:10.1016/j.rse.2016.12.015

Cited by 89 publications

(52 citation statements)

References 44 publications

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“…1S). The temporal changes may be driven by whole-plant growth during the early season, and by drought response for the mid-season decline, consistent with the findings of Gitelson et al (2017b) in annual crops.…”

Section: Discussionsupporting

confidence: 84%

“…At low levels of canopy closure or projected leaf area index -defned as one-sided leaf area per unit ground area -the signature of the soil background has a strong effect on remotely sensed spectra. Low plant cover and canopy architectures that make soil more visible from above can make remotely sensed PRI more dependent on the soil background (Barton and North 2001), weakening or erasing its relationship with leaf-level pigment concentrations and LUE (Soudani et al 2014, Gitelson and Gamon 2015, Gitelson et al 2017b. Abiotic drivers like drought can influence the structure of the canopy by causing mortality, altering phenology, and causing plants to modify their leaf display -for example, by leaf rolling (Kadioglu and Terzi 2007) or assuming more vertical leaf inclinations (Comstock and Mahall 1985, Gamon and Pearcy 1989, Joel et al 1997, which under stressful conditions can help protect the photosynthetic function of the plant (Turgut and Kadioglu 1998, Pearcy et al 2005, Nar et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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Community-wide consequences of variation in photoprotective physiology among prairie plants

Kothari¹,

Cavender‐Bares²,

Bitan³

et al. 2018

Photosynt.

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Photoprotective pigments, like those involved in the xanthophyll cycle, help plants avoid oxidative damage caused by excess radiation. This study aims to characterize a spectrum of strategies used to cope with light stress by a diverse group of prairie plants at Cedar Creek Ecosystem Science Reserve (East Bethel, MN). We find that concentrations of photosynthetic and photoprotective pigments are highly correlated with one another and with other physiological traits across species and over time, and tend to be phylogenetically conserved. During a period of water limitation, plots dominated by species with constitutively low pigment concentrations showed a greater decline in mean reflectance and photochemical reflectance index, a reflectance-based indicator of photoprotective physiology, possibly due to alterations in canopy structure. Our findings suggest two contrasting strategies for withstanding light stress: (1) Using photoprotective pigments to dissipate excess energy, and (2) altering canopy structure to minimize absorbance of excess radiation.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Community-wide consequences of variation in photoprotective physiology among prairie plants

Kothari¹,

Cavender‐Bares²,

Bitan³

et al. 2018

Photosynt.

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“…The need to take into account the daily cycle of forest PRI for an improved remote estimate of LUE was recently demonstrated using the two satellites with the MODIS sensor on Aqua and Terra, with different overpass times [9]. The remotely-sensed PRI values corresponding to a specific vegetation type is strongly affected by vegetation structure, observation geometry and the spectral composition of diffuse sky radiation [9,[20][21][22][23][24][25] and, hence, not direct measures of leaf PRI. In a boreal forest, canopy structure does not change on a daily time scale, but illumination geometry and the spectral composition of incident radiation (caused by the varying fraction of diffuse sky radiation dominated by shorter wavelengths) does vary with the solar angle continuously on a clear day.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Diurnal Variation in Needle PRI and Shoot Photosynthesis in a Boreal Forest

et al. 2018

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Abstract:The photochemical reflectance index (PRI) is calculated from vegetation narrowband reflectance in two bands in the visible part of the spectrum. Variations in PRI are associated with changes in the xanthophyll cycle pigments which regulate the light use efficiency of vegetation. Correlations have been found between remotely-sensed PRI and various photosynthetic productivity parameters at the scales from leaves to landscapes. Environmental satellites can provide only an instantaneous value of this index at the time of overpass. The diurnal course of needle (leaf) PRI needs to be known in order to link the instantaneous values robustly with photosynthetic parameters at time scales exceeding one day. This information is not currently available in the scientific literature. Here we present the daily cycle of Scots pine needle and canopy PRI in a southern boreal forest zone in the presence of direct solar radiation during the peak growing season of two consecutive years. We found the PRI of the needles which are exposed to direct radiation to have a distinct diurnal cycle with constant or slightly increasing values before noon and a daily minimum in the afternoon. The cycle in needle PRI was not correlated with that in the incident photosynthetic photon flux density (PPFD). However, when PPFD was above 1000 µmol m −2 s −1 , approximately between 8 a.m. and 5 p.m., needle PRI was correlated with the light use efficiency (LUE), measured with shoot chambers. The timing of the minimum needle PRI coincided with the minimum canopy value, as measured by an independent sensor above the canopy, but the correlation between the two variables was not significant. Our field results corroborate the applicability of needle PRI in monitoring the daily variation in LUE. However, to apply this to remote sensing of seasonal photosynthetic productivity, the daily cycle of leaf PRI needs to be known for the specific vegetation type.

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“…R 2 of the relationship PRI versus F v ∕F m increased significantly in stressed leaves (0.32 versus 0.68). Many studies showed that in ecosystems when chlorophyll content changed over a wide range, PRI was highly correlated to chlorophyll variations at both leaf and canopy level, 65,66 and it may be not effective for detecting vegetation photosynthetic efficiency. But PRI acted as a useful index of photosynthetic efficiency in evergreen species when chlorophyll content changed slightly and its variation was quite independent to chlorophyll.…”

Section: Remote Estimation Of Chlorophyll Fluorescence In Stressed Lementioning

confidence: 99%

Using remotely sensed spectral reflectance to indicate leaf photosynthetic efficiency derived from active fluorescence measurements

Zeng

Zhu

et al. 2017

J. Appl. Remote Sens

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, "Using remotely sensed spectral reflectance to indicate leaf photosynthetic efficiency derived from active fluorescence measurements," J. Appl. Remote Sens. 11(2), 026034 (2017), doi: 10.1117/1.JRS.11.026034. Abstract. Chlorophyll fluorescence (ChlF) is an important signature of photosynthesis to evaluate plant response to the environment. We explored an approach to estimate an important leaf ChlF-derived parameter, the intrinsic efficiency of photosystem II photochemistry (F v ∕F m ), using spectral indices calculated from leaf reflectance measured by a hyperspectral radiometer. It is observed that leaf chlorophyll content closely related to F v ∕F m in nonstressed leaves, thus the indices developed for chlorophyll estimation were successfully used to estimate F v ∕F m . For leaves under short-term stress, F v ∕F m dropped dramatically while leaf chlorophyll content remained almost the same. Compared to leaf chlorophyll content, reflectance was more sensitive to F v ∕F m variations. As F v ∕F m decreased, the slope of reflectance in the spectrum range of 700 to 900 nm obviously increased, and the first derivative reflectance in the red edge and infrared (NIR) regions was highly correlated with F v ∕F m . The indices using longwave red edge and NIR reflectance (NDRE 740 and CI 740 ) worked well for F v ∕F m retrieval in both stressed and nonstressed leaves with the coefficients of determination (R 2 ) above 0.72 and normalized root-meansquare errors below 0.16. Note that the relationships NDRE 740 and CI 740 versus F v ∕F m were significantly different between nonstressed and stressed leaves, which may give a good implication to detect short-term stress occurrence.

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Multiple drivers of seasonal change in PRI: Implications for photosynthesis 2. Stand level

Cited by 89 publications

References 44 publications

Community-wide consequences of variation in photoprotective physiology among prairie plants

Community-wide consequences of variation in photoprotective physiology among prairie plants

Measurement of Diurnal Variation in Needle PRI and Shoot Photosynthesis in a Boreal Forest

Using remotely sensed spectral reflectance to indicate leaf photosynthetic efficiency derived from active fluorescence measurements

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