The climatic niche of a species is determined by variety of parameters including tolerance to variables such as temperature and precipitation. The USDA Plants database offers climatic tolerance estimates based on expert knowledge for a wide range of plant species, and this study aimed to investigate how such estimates relate to tolerance inferred from plant distributions based on GBIF-mediated occurrences and WorldClim climate data.
By comparing tolerance values for 1800 species, the researchers find that climatic niches based on occurrence data are much broader than expert estimates. On average, plants tolerate lower minimum and higher maximum precipitation values as well as lower minimum temperatures. More than 70 per cent of the investigated species had lower minimum values for occurrence data compared to expert estimates. The observed difference increased with species range size.
The combined results suggest that expert-based estimates tend to underrepresent species’ fundamental niches, and that distributions based on occurrence data produce better approximations of climatic tolerance.