The United States is home to 686 active herbaria containing more than 78 million specimens that represent a crucial resource for research in such varied fields as taxonomy, biogeography, climate science, and pollution trends, among others. Of the total specimen count, roughly one third (23 million specimens) is held in smaller herbaria, many of which have fewer than 100,000 specimens. These herbaria are often regional in their focus, and often have an additional taxonomic or ecological specialty. Though small herbaria individually receive three to six times fewer visits than large herbaria, as a class size (small vs. large), they receive an equal proportion of visits, hinting at their importance. However, the unique contributions to research of small herbaria has not been well-studied.
In a new article in the American Journal of Botany, lead author Travis D. Marsico and colleagues attempted to quantify the contribution of small herbaria in terms of biogeographic knowledge at the geographic and temporal scales. The researchers sampled specimens of 40 plant taxa from eight American states, categorizing them as extremely rare, very rare, common native, or introduced, and gathering geographic information. Considering small (<100,000 specimens) and large (≥100,000 specimens) herbaria, the unique information provided by specimens from each was assessed.
The authors found that herbaria in general contain specimens that are largely unduplicated within their state, and represent unique contributions on county, locality, and temporal scales. This implies that researchers needing a complete picture of specimen occurrence at these scales must include both large and small herbaria in their surveys. A staggering 97.4% of the small herbarium specimens sampled for the study were either unduplicated elsewhere, or duplicated only within another small herbarium.
Small herbaria are particularly valuable in research focussing on regionally-occurring taxa, not only because of specimen holdings, but also due to personnel having greater familiarity with local geography and place names. Though touring many small herbaria in person is arduous, digitization efforts have made their inclusion in projects much more manageable. Recent efforts to digitize smaller collections, funded through the National Science Foundation’s Advancing Digitization of Biodiversity Collections (ADBC) programme, have gone well beyond what individual facilities might have been able to do otherwise.
“Digitization, continued collecting, and maintaining and enhancing regional biogeographical knowledge require the recognition of herbaria as critical research infrastructure and the understanding that in the USA this infrastructure comprises 686 individual herbaria, 85% of which are small collections with fewer than 100,000 specimens,” write the authors.