Estimating maize GPP using near-infrared radiance of vegetation

Liu, Liangyun; Liu, Xinjie; Chen, Jidai; Du, Shanshan; Ma, Yan; Qian, Xiaojin; Chen, Siyuan; Peng, Dailiang

doi:10.1016/j.srs.2020.100009

Cited by 24 publications

(20 citation statements)

References 59 publications

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“…S8b) cannot be easily explained by invoking SIF retrieval noise and therefore other potential reasons for these differences should be investigated. Our results on the direct comparison of SIF and NIRVP for GPP estimation confirm and considerably extend previous findings from site-level studies 22,40,41 . Among other things, we confirmed that previous site-level results showing better GPP estimation performance of NIRVP compared to SIF in crops 22,40 also held in a Mediterranean grassland site which experiences drought (Fig.…”

Section: Discussionsupporting

confidence: 89%

“…NIRVP was estimated from FLUO at-sensor radiance data to ensure minimal differences compared to SIF retrievals in terms of sensor and processing aspects. The approach of using NIR radiance as proxy for the product of NIR reflectance times PAR was previously introduced as NIRVR 22 and was found to show good performance in terms of correlation to SIF and GPP at the site level 22,40,41 . Those results included observations in cloudy conditions where the largest differences between PAR and NIR radiance are expected, the discrepancies between the two variables should be even smaller in the clear sky conditions under which the airborne campaign was conducted.…”

Section: Data Sets and Processingmentioning

confidence: 99%

“…However, direct comparisons of SIF and NIRVP for GPP estimation using observations from the same sensors (or at least from the same viewing geometries) have been limited to a small set of crop sites 22,40,41 .…”

mentioning

confidence: 99%

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NIRvP: a robust structural proxy for sun-induced chlorophyll fluorescence and photosynthesis across scales

Dechant¹,

Ryu²,

Badgley³

et al. 2022

Preprint

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Sun-induced chlorophyll fluorescence (SIF) is a promising new tool for remotely estimating photosynthesis. However, the degree to which incoming sunlight and the structure of the canopy rather than leaf physiology contribute to SIF variations is still not well characterized. Here we demonstrate that the canopy structure-related near-infrared reflectance of vegetation multiplied by incoming sunlight (NIRvP) is a robust proxy of far-red SIF across a wide range of spatial and temporal scales. Our findings indicate that contributions from leaf physiology to SIF variability are small compared to its structure and radiation components. NIRvP captured spatio-temporal patterns of photosynthesis better than SIF, which seems to be mostly due to the retrieval noise of SIF. Our results highlight the promise of using widely available NIRvP data for vegetation monitoring and also indicate the potential of using SIF and NIRvP in combination to extract physiological information from SIF.

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Section: Discussionsupporting

confidence: 89%

Section: Data Sets and Processingmentioning

confidence: 99%

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NIRvP: a robust structural proxy for sun-induced chlorophyll fluorescence and photosynthesis across scales

Dechant¹,

Ryu²,

Badgley³

et al. 2022

Preprint

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“…PAR and

, to eventually obtain

(often referred to as SIF yield) is considered important to estimate the photosynthetic light use efficiency (LUE) ( Mohammed et al, 2019 , Wieneke et al, 2018 ). Although recent studies have reported moderate to high correlations in the seasonal dynamics of f esc and LUE ( Dechant et al, 2020 ; Liu et al, 2020 ) and that f esc partially captures the response of LUE to diffuse light and therefore both parameters have a temporal correlation ( Kim et al, 2021 ), normalizing

with PAR or

is a well-accepted approach to relate larger scale SIF measurements to the mechanistic regulation of photosynthesis, which is normally parameterized on the leaf level. The now accessible relationship between available light energy and the emission efficiency shows a diurnal dynamic dependent on other photon pathways, including NPQ and photosynthetic activity ( Pinto et al, 2016 ; Porcar-Castell et al, 2014 ; van der Tol et al, 2009 ).…”

Section: Discussionmentioning

confidence: 99%

Downscaling of far-red solar-induced chlorophyll fluorescence of different crops from canopy to leaf level using a diurnal data set acquired by the airborne imaging spectrometer HyPlant

Siegmann

Cendrero-Mateo

Cogliati

et al. 2021

Remote Sensing of Environment

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Remote sensing-based measurements of solar-induced chlorophyll fluorescence (SIF) are useful for assessing plant functioning at different spatial and temporal scales. SIF is the most direct measure of photosynthesis and is therefore considered important to advance capacity for the monitoring of gross primary production (GPP) while it has also been suggested that its yield facilitates the early detection of vegetation stress. However, due to the influence of different confounding effects, the apparent SIF signal measured at canopy level differs from the fluorescence emitted at leaf level, which makes its physiological interpretation challenging. One of these effects is the scattering of SIF emitted from leaves on its way through the canopy. The escape fraction ( ) describes the scattering of SIF within the canopy and corresponds to the ratio of apparent SIF at canopy level to SIF at leaf level. In the present study, the fluorescence correction vegetation index (FCVI) was used to determine of far-red SIF for three structurally different crops (sugar beet, winter wheat, and fruit trees) from a diurnal data set recorded by the airborne imaging spectrometer HyPlant. This unique data set, for the first time, allowed a joint analysis of spatial and temporal dynamics of structural effects and thus the downscaling of far-red SIF from canopy ( ) to leaf level ( ). For a homogeneous crop such as winter wheat, it seems to be sufficient to determine once a day to reliably scale SIF 760 from canopy to leaf level. In contrast, for more complex canopies such as fruit trees, calculating for each observation time throughout the day is strongly recommended. The compensation for structural effects, in combination with normalizing SIF 760 to remove the effect of incoming radiation, further allowed the estimation of SIF emission efficiency ( ) at leaf level, a parameter directly related to the diurnal variations of plant photosynthetic efficiency.

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“…Some studies reported a high correlation between LUE and SIF yield using daily instantaneous measurement data, but whether a stress factor influenced this relationship and the extent of such an influence were unknown, and much of the correlation was likely due to phenology and leaf aging (Campbell et al, 2019; Li et al, 2018; Verma et al, 2017). Furthermore, the power of using SIF to estimate GPP seems not the most outstanding in all cases as near‐infrared (NIR) radiance of vegetation (NIRv, rad), defined as the product of incident NIR radiance, NIR reflectance, and Normalized Difference Vegetation Index (NDVI), provided a better GPP estimate than SIF (Badgley et al, 2017; Liu et al, 2020; Wu et al, 2019). The aforementioned findings cast questions on the quantity and quality of unique information of SIF in quantifying GPP and plant physiological stress beyond canopy structural variability.…”

Section: Introductionmentioning

confidence: 99%

Quantifying high‐temperature stress on soybean canopy photosynthesis: The unique role of sun‐induced chlorophyll fluorescence

Kimm

Guan

Burroughs

et al. 2021

Global Change Biology

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High temperature and accompanying high vapor pressure deficit often stress plants without causing distinctive changes in plant canopy structure and consequential spectral signatures. Sun‐induced chlorophyll fluorescence (SIF), because of its mechanistic link with photosynthesis, may better detect such stress than remote sensing techniques relying on spectral reflectance signatures of canopy structural changes. However, our understanding about physiological mechanisms of SIF and its unique potential for physiological stress detection remains less clear. In this study, we measured SIF at a high‐temperature experiment, Temperature Free‐Air Controlled Enhancement, to explore the potential of SIF for physiological investigations. The experiment provided a gradient of soybean canopy temperature with 1.5, 3.0, 4.5, and 6.0°C above the ambient canopy temperature in the open field environments. SIF yield, which is normalized by incident radiation and the fraction of absorbed photosynthetically active radiation, showed a high correlation with photosynthetic light use efficiency (r = 0.89) and captured dynamic plant responses to high‐temperature conditions. SIF yield was affected by canopy structural and plant physiological changes associated with high‐temperature stress (partial correlation r = 0.60 and −0.23). Near‐infrared reflectance of vegetation, only affected by canopy structural changes, was used to minimize the canopy structural impact on SIF yield and to retrieve physiological SIF yield (ΦF) signals. ΦF further excludes the canopy structural impact than SIF yield and indicates plant physiological variability, and we found that ΦF outperformed SIF yield in responding to physiological stress (r = −0.37). Our findings highlight that ΦF sensitively responded to the physiological downregulation of soybean gross primary productivity under high temperature. ΦF, if reliably derived from satellite SIF, can support monitoring regional crop growth and different ecosystems' vegetation productivity under environmental stress and climate change.

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Estimating maize GPP using near-infrared radiance of vegetation

Cited by 24 publications

References 59 publications

NIRvP: a robust structural proxy for sun-induced chlorophyll fluorescence and photosynthesis across scales

NIRvP: a robust structural proxy for sun-induced chlorophyll fluorescence and photosynthesis across scales

Downscaling of far-red solar-induced chlorophyll fluorescence of different crops from canopy to leaf level using a diurnal data set acquired by the airborne imaging spectrometer HyPlant

Quantifying high‐temperature stress on soybean canopy photosynthesis: The unique role of sun‐induced chlorophyll fluorescence

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