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

Abstract

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.

Code and data availability

This paper is a community protocol/standard (IHerbSpec) for herbarium spectral digitization, not an empirical phenotyping study. It reports no plant-phenotyping measurements, no spectral datasets of its own, and no analysis code, models, or checkpoints. The public resources mentioned (protocol website, GitHub repo ofQu

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