This dataset could be used to test whether the commonly observed positive range size–niche breadth relationship, as posited by the “niche breadth hypothesis”, exists for Fagus, one of the most dominant and widespread broad‐leaved deciduous tree genera in temperate forests of the Northern Hemisphere.

There are many ways to estimate niche breadth. Here, we estimated biotic and climatic niche breadths per species using plot‐based co‐occurrence data and climate data, respectively. The range sizes of the Fagus species were estimated with the raw data from the Chorology Database Halle. We examined the relationships of these estimates, and found that neither biotic niche breadth nor climatic niche breadth was correlated with range size, and the two niche breadths were incongruent as well.

Our findings proved that the “niche breadth hypothesis” did not apply to the genus Fagus, and thus more attention should be paid to other factors (e.g., high among‐region variation in available niche space, landscape heterogeneity and Quaternary history) when explaining the geographic distribution patterns of Fagus. In addition, the climate data provided here could be used for climate-related studies on Fagus species worldwide.

The raw plot data for the estimation of biotic niche breadth can be applied from the sPlot vegetation database (Bruelheide et al., 2019), and the estimation method was described in Fridley et al. (2007) and Manthey & Fridley (2009). The climate data used for climatic niche breadth estimation were extracted from the CHELSA database (https://chelsa-climate.org/; Karger et al., 2017) based on the plot coordinates. The raw data for range size estimation were collected from sPlot as describe above and  Chorology Database Halle (CDH; http://chorologie.biologie.uni‐halle.de//areale/). For each Fagus species, the range size was calculated as the geographical area (km²) of the range polygons in an equal-area cartographic projection, and isolated point clusters were converted to minimum convex polygons.

See README file.