Abstract
Solar-induced chlorophyll fluorescence (SIF) is a powerful tool for the estimation of gross primary productivity (GPP), but the relationship between SIF and GPP under drought stress remains incompletely understood. Elucidating the response of the relationship between SIF and GPP to drought stress is essential in order to enhance the precision of GPP estimation in forests. In this study, we obtained SIF in the red (SIF687) and far-red (SIF760) bands and GPP data from tower flux observations in a Chinese cork oak plantation to explore the response of the diurnal GPP-SIF relationship to drought stress. The plant water stress index (PWSI) was used to quantify drought stress. The results show that drought reduced SIF and GPP, but GPP was more sensitive to drought stress than SIF. The diurnal non-linear relationship of GPP-SIF (R2) decreased with the increase in drought stress, but a significant non-linear correlation remained for GPP-SIF (R2_GPP-SIF760 = 0.30, R2_GPP-SIF687 = 0.23) under severe drought stress (PWSIbin: 0.8–0.9). Physiological coupling strengthened the GPP-SIF relationship under drought, while canopy structure effects were negligible. Random forest and path analyses revealed that VPD was the key factor reducing the GPP-SIF correlation during drought. Incorporating VPD into the GPP-SIF relationship improved the GPP estimation accuracy by over 48% under severe drought stress. The red SIF allowed for more accurate GPP estimations than the far-red SIF under drought conditions. Our results offer important perspectives on the GPP-SIF relationship under drought conditions, potentially helping to improve GPP model predictions in the face of climate change.
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Claims 10
Claim · model-written summary
Drought reduced both SIF and GPP in the cork oak plantation.
- Taxon
- cork oak
Quercus subere0 - Treatment
- droughte1
- Outcome
- SIF and GPPe1
- Direction
- reducede1
- Setting
- Chinese cork oak plantatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“drought reduced SIF and GPP”
Claim · model-written summary
GPP was more sensitive to drought stress than SIF in the cork oak plantation.
- Taxon
- cork oakQuercus subere0
- Treatment
- drought stresse1
- Outcome
- GPP was more sensitivee1
- Direction
- more sensitivee1
- Comparator
- SIFe1
- Setting
- Chinese cork oak plantatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“but GPP was more sensitive to drought stress than SIF”
Claim · model-written summary
The diurnal non-linear GPP-SIF relationship (R2) decreased as drought stress increased.
- Taxon
- cork oakQuercus subere0
- Treatment
- increase in drought stresse1
- Outcome
- diurnal non-linear relationship of GPP-SIF (R2)e1
- Setting
- Chinese cork oak plantatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“The diurnal non-linear relationship of GPP-SIF (R2) decreased with the increase in drought stress”
Claim · model-written summary
Under severe drought stress (PWSIbin 0.8-0.9) a significant non-linear GPP-SIF760 correlation remained (R2 = 0.30).
- Taxon
- cork oakQuercus subere0
- Outcome
- significant non-linear correlation remained for GPP-SIFe1
- Value
- 0.30e1
- Qualifier
- severe drought stress (PWSIbin: 0.8–0.9)e1
- Setting
- Chinese cork oak plantatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“a significant non-linear correlation remained for GPP-SIF (R2_GPP-SIF760 = 0.30, R2_GPP-SIF687 = 0.23) under severe drought stress (PWSIbin: 0.8–0.9)”
Claim · model-written summary
Under severe drought stress (PWSIbin 0.8-0.9) a significant non-linear GPP-SIF687 correlation remained (R2 = 0.23).
- Taxon
- cork oakQuercus subere0
- Outcome
- significant non-linear correlation remained for GPP-SIFe1
- Value
- 0.23e1
- Qualifier
- severe drought stress (PWSIbin: 0.8–0.9)e1
- Setting
- Chinese cork oak plantatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“a significant non-linear correlation remained for GPP-SIF (R2_GPP-SIF760 = 0.30, R2_GPP-SIF687 = 0.23) under severe drought stress (PWSIbin: 0.8–0.9)”
Claim · model-written summary
Physiological coupling strengthened the GPP-SIF relationship under drought.
- Taxon
- cork oakQuercus subere0
- Outcome
- GPP-SIF relationshipe1
- Direction
- strengthenede1
- Qualifier
- Physiological couplinge1
- Setting
- Chinese cork oak plantatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“Physiological coupling strengthened the GPP-SIF relationship under drought”
Claim · model-written summary
Canopy structure effects on the GPP-SIF relationship under drought were negligible.
- Taxon
- cork oakQuercus subere0
- Outcome
- canopy structure effects were negligiblee1
- Qualifier
- canopy structure effectse1
- Setting
- Chinese cork oak plantatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“canopy structure effects were negligible”
Claim · model-written summary
Random forest and path analyses identified VPD as the key factor reducing the GPP-SIF correlation during drought.
- Taxon
- cork oakQuercus subere0
- Outcome
- GPP-SIF correlatione1
- Direction
- reducinge1
- Qualifier
- VPD was the key factore1
- Setting
- Chinese cork oak plantatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“Random forest and path analyses revealed that VPD was the key factor reducing the GPP-SIF correlation during drought”
Claim · model-written summary
Incorporating VPD into the GPP-SIF relationship improved GPP estimation accuracy by over 48% under severe drought stress.
- Taxon
- cork oakQuercus subere0
- Outcome
- GPP estimation accuracye1
- Direction
- improvede1
- Value
- over 48%e1
- Qualifier
- under severe drought stresse1
- Setting
- Chinese cork oak plantatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“Incorporating VPD into the GPP-SIF relationship improved the GPP estimation accuracy by over 48% under severe drought stress”
Claim · model-written summary
Red SIF allowed more accurate GPP estimation than far-red SIF under drought conditions.
- Taxon
- cork oakQuercus subere0
- Outcome
- GPP estimationse1
- Direction
- more accuratee1
- Comparator
- far-red SIFe1
- Setting
- Chinese cork oak plantatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chinese cork oak plantation”
e1“The red SIF allowed for more accurate GPP estimations than the far-red SIF under drought conditions”
The same questions in other papers
drought · physiology: photosynthesis · Quercus suber (cork oak)Results agree
5 papers in the same direction as this paper
- negative
- negative
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2 papers more in this group
See all 6 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.