Key message The soil plant analysis development (SPAD) meter proved effective at estimating leaf Chl content of native and non-native temperate deciduous shrubs. However, due to the change in the relationship between SPAD values and Chl content during the course of autumn senescence, it may be necessary to establish separate calibration equations to cover a range of leaf Chl concentrations.
Context Non-destructive estimates of leaf chlorophyll (Chl) content by hand-held chlorophyll meters such as the Minolta SPAD-502 provide an effective time-efficient method of collecting field data on senescence.
Aims To establish useable species-specific calibration equations of relationships between chlorophyll meter readings and leaf Chl content.
Methods During autumn, we collected SPAD values and quantum yield of photosystem-II (ΦPSII) over a 10-week period from 1044 leaf samples representing native and non-native temperate deciduous shrub species growing in the wild. Subsequently, Chl was extracted from leaf discs (1 cm diameter), incubated at 65 °C for 2 h in dimethyl sulfoxide, and quantified by spectroscopy. Relationships between extracted Chl and SPAD values were established using linear, quadratic, and exponential equations.
Results Quadratic functions proved the most reliable fit for the data. Interestingly, non-native species tended to have higher leaf Chl content and SPAD values but also exhibited higher variability than native species. The strength (r2) of the SPAD-Chl relationships was weaker than those reported for agricultural or greenhouse-grown plants, but strengthened over time as Chl, ΦPSII, and SPAD values declined.
Conclusion The SPAD meter proved effective at estimating leaf Chl content of native and non-native temperate deciduous shrubs. These estimates may be used in future to validate remote sensing (satellite and near-surface) vegetation indices in late autumn when trees are leafless.
Temperate deciduous shrubs, Native and non-native, SPAD-502 meter, Quantum yield of photosystem II, Leaf chlorophyll content, Autumn senescence
Donnelly, A., Yu, R., Rehberg, C. et al. Leaf chlorophyll estimates of temperate deciduous shrubs during autumn senescence using a SPAD-502 meter and calibration with extracted chlorophyll. Annals of Forest Science 77, 30 (2020). https://doi.org/10.1007/s13595-020-00940-6
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The datasets generated and/or analyzed during the current study are available in the PANGEA repository, https://doi.pangaea.de/10.1594/PANGAEA.907932