UV-Vis-NIR Spectroscopy based Herbarium Digitization for Plant Trait and Biodiversity Research
An herbarium is a systematically arranged collection of dried plants. Herbaria worldwide house more than 400 million preserved plant specimens that document global plant diversity and physiology. Traditionally, herbarium in the modern age have focused on high-resolution imaging to capture morphology for digitization. Reflectance spectroscopy beyond the visible range enables a targeted and innovative approach by extracting information on plant chemistry, structure, and physiology. Recent advances in hyperspectral analysis demonstrate that herbarium-based spectroscopy can support functional traits, taxonomic discrimination, evolutionary changes, and integration with modern remote sensing observations.
Reflectance spectra characterize how plant tissues interact with light across the UV-VIS-NIR range (350-2500nm). Studies have shown that spectra collected from older pressed samples can still accurately predict traits such as carbon, calcium, carotenoids, cellulose, chlorophyll, and nitrogen using partial least squares regression (PLSR) models. In addition, machine learning models trained on herbarium spectra can successfully classify specimens to genus and species, even when diagnostic morphological features are absent or degraded.
Spectral digitization of herbarium specimens is a common application for Spectral Evolutions full-range UV-VIS-NIR Naturaspec™ spectroradiometers. The Naturaspec combined with accessory probes like the surface probe, leaf clip, and pine needle adapter allow non-destructive and repeatable measurements of leaves and pine needles. These accessories standardize illumination geometry for high quality data repeatability. Due to their rapid and non-destructive nature, spectral acquisition digitizes large datasets efficiently without compromising specimen integrity.
When paired with Spectral Evolution’s metadata tools, spectral measurements become a powerful tool within herbarium databases. Herbarium spectra also serve as critical reference data for linking leaf-level chemistry to airborne and satellite hyperspectral observations, thereby connecting historical specimens to modern ecosystem and biosphere models.
Reflectance spectroscopy transforms herbarium specimens from a cataloged record into dynamic quantitative resources for biodiversity science. By enabling reproducible, scalable, and non-destructive measurement of plant traits from dried material, spectrometer-based measurements expand the scientific value of herbaria and support research across ecology, evolution, and Earth system sciences. As community standards for spectral digitization continue to develop, spectroscopy will play a central role in building a global spectral archive of the world’s plant collections.