Natural history collections were initially motivated by aesthetics and human curiosity but have since developed into invaluable scientific resources. In particular, herbaria were historically established and maintained primarily for taxonomic study, species identification, biodiversity documentation, education, and to serve as repositories for scientific vouchers. While these conventional, anticipated functions remain relevant in modern research, herbarium data are increasingly used in unanticipated ways. As such, herbarium specimens now serve in novel research capacities, especially in ecological and evolutionary fields. Bolstered by ongoing widespread digitization efforts, these reportedly diverse uses have reinvigorated the perception of herbaria as valuable scientific resources. However, the published uses of herbarium data have not yet been comprehensively reviewed. In order to quantify the dynamic roles of herbaria, we used a topic model, or automated content analysis, to perform a systematic review of more than 13,000 studies published over the last century that used herbarium data.
Results/Conclusions
The frequency of herbarium-based studies steadily increased through time, at similar rates to the plant sciences literature overall. Although herbarium specimen-related research still maintains its centuries-long taxonomic focus, the uses of herbaria have drastically expanded to include many other basic and applied disciplines. The literature has functionally diversified from few topics that dominated herbarium-based research a century ago to many distinct topics with no single topic clearly prevailing. Recent and ongoing technological advances in molecular biology have magnified the role of specimens as an enormous archive for genetic material. Herbaria are increasingly appreciated as temporally and spatially extensive sources of genotypic, phenotypic and biogeographic data. Particularly over the past decade, studies leverage historic and recent collections to quantify the effects of human-induced environmental change. We provide evidence beyond anecdotes to document and promote the diversification of collections-based studies in the current era of rapid environmental change, highlight the need for long-term support for herbaria as critical biological infrastructure, and to stimulate a broader discussion on new curatorial needs and perspectives as these novel functions of herbaria become more prevalent. As we enter the Anthropocene, herbaria have likewise entered a new era with renewed scientific, educational, and societal relevance.