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

叶绿素计能够有效且无损地估计叶片叶绿素浓度 (LCC)，但需要针对破坏性确定的值进行校准，以提供在不同研究和物种之间具有可比性的绝对量。成熟的仪器可以提供准确的 LCC 估计，但最近的低成本设备的性能不太清楚。关于通用或特定物种校准函数的选择也存在问题。此外，很少有人关注透射光谱，它提供了显着增加的光谱采样，作为一种潜在的替代方案。我们研究了成熟的 Konica Minolta SPAD-502+ 和 Opti-Sciences CCM-200 仪器以及低成本的 atLEAF CHL PLUS 和 PhotosynQ MultispeQ V1.0 设备，用于森林 LCC 的无损估计。我们根据破坏性确定的八种温带落叶阔叶林物种的 LCC 值校准了每个叶绿素计，并描述了不同仪器之间的关系。我们还评估了透射光谱是否可以提供更高的准确性。所有研究的叶绿素计都表现出与破坏性确定的 LCC 相似的强关系，这表明一旦校准，即使是低成本设备也代表了非破坏性森林 LCC 估计的合适选择。除橡木外，叶绿素计 - LCC 关系在物种之间是一致的，这表明对于这些物种，通用校准功能可能是合适的，具体取决于所需的精度。具体来说，通用校准函数提供的 LCC 值属于大多数考虑物种的物种特定校准函数的预测不确定性。与特定物种的校准函数相比，通用校准函数解释的 LCC 变化小 2% 至 16%，导致 RMSE (NRMSE) 的平均增加仅为 0.01 g m^-2至 0.02 g m ^-2 (2% 至 5%)。透射光谱能够提供比叶绿素计更好的性能，这表明它们可能会错过蓝色和绿色波长的一些相关光谱信息。然而，这种改进的性能是以降低该领域的实用性为代价的。