Calibration and characterisation of four chlorophyll meters and transmittance spectroscopy for non-destructive estimation of forest leaf chlorophyll concentration

Chlorophyll meters enable efficient and non-destructive estimation of leaf chlorophyll concentration (LCC), but require calibration against destructively-determined values to provide an absolute quantity that is comparable between different studies species. Well-established instruments can accurate LCC estimates, the performance recent low-cost devices less clear. Questions also remain over choice generic or species-specific functions. Additionally, little attention has been paid transmittance spectroscopy, which offers substantially increased spectral sampling, as a potential alternative. We investigated well-established Konica Minolta SPAD-502+ Opti-Sciences CCM-200 atLEAF CHL PLUS PhotosynQ MultispeQ V1.0 for forest LCC. calibrated each meter eight temperate deciduous broadleaf species, characterised relationships instruments. assessed whether spectroscopy could improved accuracy. All demonstrated similarly strong with LCC, indicating once calibrated, even represent suitable estimation. With exception oak, – were consistent these function may be depending on required Specifically, provided by functions fell within prediction uncertainties most considered The explained 2% 16% variation in than functions, resulting mean increase RMSE (NRMSE) just 0.01 g m−2 0.02 (2% 5%). Transmittance was able meters, they miss some relevant information at blue green wavelengths. However, this comes expense reduced practicality field.