Accounting for Changes in Radiation Improves the Ability of SIF to Track Water Stress‐Induced Losses in Summer GPP in a Temperate Deciduous Forest

Butterfield, Zachary; Magney, Troy S.; Großmann, Katja; Bohrer, Gil; Vogel, Christoph; Barr, Stephen M.; Keppel‐Aleks, G.

doi:10.1029/2022jg007352

Cited by 4 publications

(2 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2017Paul-Limoges et al 2018 ; ; 2018Zhang et al 2018 ). While in others, a decrease in SIF during the drought has been observed ( Zarco-Tejada et al 2016 ; Wieneke et al. 2018Butterfield et al 2023 ; ).…”

Section: Introductionmentioning

confidence: 91%

Tracking canopy chlorophyll fluorescence with a low-cost light emitting diode platform

Brissette,

Wong,

McHugh

et al. 2023

AoB PLANTS

View full text Add to dashboard Cite

Chlorophyll fluorescence measured at the leaf scale through pulse-amplitude modulation (PAM) has provided valuable insight into photosynthesis. At the canopy- and satellite-scale, solar-induced fluorescence (SIF) provides a method to estimate the photosynthetic activity of plants across spatiotemporal scales. However, retrieving SIF signal remotely requires instruments with high spectral resolution, making it difficult and often expensive to measure canopy-level steady-state chlorophyll fluorescence under natural sunlight. Considering this, we built a novel low-cost photodiode system that retrieves far-red chlorophyll fluorescence emission induced by a blue light emitting diode (LED) light-source, for two hours at night, above the canopy. Our objective was to determine if an active remote sensing based nighttime photodiode method could track changes in canopy-scale LED-induced chlorophyll fluorescence (LEDIF) during an imposed drought on a broadleaf evergreen shrub, Polygala myrtifolia. Far-red LEDIF (720 - 740 nm) was retrieved using low-cost photodiodes (LEDIFphotodiode) and validated against measurements from a hyperspectral spectroradiometer (LEDIFhyperspectral). To link the LEDIF signal with physiological drought response, we tracked stomatal conductance (gsw) using a porometer, two leaf-level vegetation indices — photochemical reflectance index, PRI; normalized difference vegetation index, NDVI— to represent xanthophyll and chlorophyll pigment dynamics, respectively, and a PAM fluorimeter to measure photochemical and non-photochemical dynamics. Our results demonstrate a similar performance between the photodiode and hyperspectral retrievals of LEDIF (R2=0.77). Furthermore, LEDIFphotodiode closely tracked drought responses associate with a decrease in photochemical quenching (R2=0.69), Fv/Fm (R2=0.59), and leaf-level PRI (R2= 0.59). Therefore, the low-cost LEDIFphotodiode approach has the potential to be a meaningful indicator of photosynthetic activity at spatial scales greater than an individual leaf and over time.

show abstract

Section: Introductionmentioning

confidence: 91%

Tracking canopy chlorophyll fluorescence with a low-cost light emitting diode platform

Brissette,

Wong,

McHugh

et al. 2023

AoB PLANTS

View full text Add to dashboard Cite

show abstract

“…Variations in SIF are closely linked to irradiance and f esc . To account for irradiance and canopy structure effects, we also calculate relative SIF (unitless) using total reflected radiance surrounding the absorption feature (RAD 757−762 ) (Butterfield et al., 2023; Pierrat et al., 2021, 2022):

relative\ SIF=\frac{SI{F}_{760}}{RA{D}_{\mathit{757\mbox{-}762}}}

…”

Section: Field Methodsmentioning

confidence: 99%

Quantifying Seasonal and Diurnal Cycles of Solar‐Induced Fluorescence With a Novel Hyperspectral Imager

Ruehr,

Gerlein‐Safdi,

Falco

et al. 2024

Geophysical Research Letters

View full text Add to dashboard Cite

Solar‐induced fluorescence (SIF) is a proxy of ecosystem photosynthesis that often scales linearly with gross primary productivity (GPP) at the canopy scale. However, the mechanistic relationship between GPP and SIF is still uncertain, especially at smaller temporal and spatial scales. We deployed a ultra‐hyperspectral imager over two grassland sites in California throughout a soil moisture dry down. The imager has high spatial resolution that limits mixed pixels, enabling differentiation between plants and leaves within one scene. We find that imager SIF correlates well with diurnal changes in leaf‐level physiology and gross primary productivity under well‐watered conditions. These relationships deteriorate throughout the dry down event. Our results demonstrate an advancement in SIF imaging with new possibilities in remotely sensing plant canopies from the leaf to the ecosystem. These data can be used to resolve outstanding questions regarding SIF's meaning and usefulness in terrestrial ecosystem monitoring.

show abstract

Seasonal timing of fluorescence and photosynthetic yields at needle and canopy scales in evergreen needleleaf forests

Pierrat,

Magney,

Maguire

et al. 2024

Ecology

View full text Add to dashboard Cite

The seasonal timing and magnitude of photosynthesis in evergreen needleleaf forests (ENFs) has major implications for the carbon cycle and is increasingly sensitive to changing climate. Earlier spring photosynthesis can increase carbon uptake over the growing season or cause early water reserve depletion that leads to premature cessation and increased carbon loss. Determining the start and the end of the growing season in ENFs is challenging due to a lack of field measurements and difficulty in interpreting satellite data, which are impacted by snow and cloud cover, and the pervasive “greenness” of these systems. We combine continuous needle‐scale chlorophyll fluorescence measurements with tower‐based remote sensing and gross primary productivity (GPP) estimates at three ENF sites across a latitudinal gradient (Colorado, Saskatchewan, Alaska) to link physiological changes with remote sensing signals during transition seasons. We derive a theoretical framework for observations of solar‐induced chlorophyll fluorescence (SIF) and solar intensity‐normalized SIF (SIFrelative) under snow‐covered conditions, and show decreased sensitivity compared with reflectance data (~20% reduction in measured SIF vs. ~60% reduction in near‐infrared vegetation index [NIRv] under 50% snow cover). Needle‐scale fluorescence and photochemistry strongly correlated (r2 = 0.74 in Colorado, 0.70 in Alaska) and showed good agreement on the timing and magnitude of seasonal transitions. We demonstrate that this can be scaled to the site level with tower‐based estimates of LUEP and SIFrelative which were well correlated across all sites (r2 = 0.70 in Colorado, 0.53 in Saskatchewan, 0.49 in Alaska). These independent, temporally continuous datasets confirm an increase in physiological activity prior to snowmelt across all three evergreen forests. This suggests that data‐driven and process‐based carbon cycle models which assume negligible physiological activity prior to snowmelt are inherently flawed, and underscores the utility of SIF data for tracking phenological events. Our research probes the spectral biology of evergreen forests and highlights spectral methods that can be applied in other ecosystems.

show abstract

Accounting for Changes in Radiation Improves the Ability of SIF to Track Water Stress‐Induced Losses in Summer GPP in a Temperate Deciduous Forest

Cited by 4 publications

References 62 publications

Tracking canopy chlorophyll fluorescence with a low-cost light emitting diode platform

Tracking canopy chlorophyll fluorescence with a low-cost light emitting diode platform

Quantifying Seasonal and Diurnal Cycles of Solar‐Induced Fluorescence With a Novel Hyperspectral Imager

Seasonal timing of fluorescence and photosynthetic yields at needle and canopy scales in evergreen needleleaf forests

Contact Info

Product

Resources

About