A Protocol for Standardizing Measurements and Enabling Global Harmonization of Herbarium Leaf Reflectance Spectra

Dawson M White , Flávia M Durgante, Matthew Austin, J. Antonio Guzmán Q., Jonathan A Kennedy, Cornelius Onyedikachi Nichodemus, Natalie Iwanycki Ahlstrand, Chris Baraloto, Billur Bektaş, Khalil Boughalmi, Warren Cardinal-McTeague, Thomas L.P. Couvreur, Riley P Fortier, Ryan S Fuller, Olwen M. Grace, Rykkar Jackson, Kevin Karbstein, Shan Kothari, Aaron Lee, Jéssica Lira Viana, Elizabeth Martinez-Victoria, Jose Eduardo Meireles, Thomas H Murphy, Carlos Rodriguez Vaz, Daniel Spalink, Hanna Tuomisto, Caroline C. Vasconcelos , Jeannine Cavender-Bares 

Reflectance spectroscopy offers a powerful approach to integrate high-throughput phenotypic data from herbarium specimens into the digital landscapes of ecology, evolution, and systematics. Because inconsistencies in instrumentation and measurement practices can increase noise and limit dataset compatibility, the International Herbarium Spectral Digitization Working Group (IHerbSpec) has published the Protocol for Spectral Digitization of Herbarium Specimens, currently in version 1.2.1, as an open resource that will continue to evolve through community use and collaboration (https://iherbspec.github.io/protocol). The protocol defines a stepwise measurement workflow, standardized filename conventions, structured metadata tables with controlled vocabularies, and guidance on tissue selection, materials, and instrumentation quality control to ensure that newly generated spectral datasets are robust and comparable. By embedding standardized practices at the point of data collection, it provides a scalable foundation for data synthesis and new quantitative insights into plant diversity across taxonomic, geographic, and temporal scales.