Assessing interannual variation in leaf chlorophyll dynamics using optical and destructive methods with mixed-effects...

Area of Science:

• Plant Physiology
• Ecology
• Remote Sensing

Background:

• Accurate leaf chlorophyll assessment is vital for understanding plant responses to environmental changes.
• Solvent extraction is precise but destructive; portable optical meters offer non-destructive measurements but need calibration.

Purpose of the Study:

• To evaluate the performance of the CCM-300 portable chlorophyll meter.
• To reconstruct seasonal chlorophyll dynamics in field maple (Acer campestre).
• To compare chlorophyll dynamics across two contrasting UK summers.

Main Methods:

• Paired chlorophyll fluorescence ratio (CFR) and acetone-extracted chlorophyll data were collected in 2023.
• Calibration models were developed using RF regression and a simple linear model for cross-year projection.
• CCM-300 data from 2022 were projected using the calibration to create a "virtual acetone" trajectory.

Main Results:

• Both years showed mid-season chlorophyll plateaus and late-summer declines.
• Senescence initiated earlier in the warmer, drier 2022 season.
• Temperature and wind speed positively affected CFR in 2022; mild conditions showed non-linear decline in 2023.

Conclusions:

• The CCM-300 can track seasonal chlorophyll dynamics, with earlier senescence observed in a warmer, drier year.
• Cross-year projections provide insights into relative seasonal trajectory shape and timing.
• Environmental factors significantly influence plant chlorophyll dynamics and senescence timing.