DOI: 10.5061/dryad.0cfxpnw9f
title: Data from: Trees have overlapping potential niches that extend beyond their realized niches

description: Tree species appear to prefer distinct climatic conditions, but the true
 nature of these preferences is obscured by species interactions and
 dispersal, which limit species’ ranges. We quantified realized and
 potential thermal niches of 188 North American tree species to conduct the
 first continental-scale test of the architecture of niches. We found
 strong and consistent evidence that species occurring at thermal extremes
 occupy less than three-quarters of their potential niches and species’
 thermal niches overlap at a mean annual temperature of approximately 12
 °C. These results clarify the breadth of thermal tolerances of temperate
 tree species and support the centrifugal organization of thermal niches.
 Accounting for the non-realized components of ecological niches will
 advance theory and prediction in global change ecology.
description: We compiled occurrence data for 188 North American tree species.
 We submitted a data request to Botanic Gardens Conservation International
 (BGCI) for lists of arboreta in which 298 North American trees were
 growing and surviving. We received information from 447 arboreta around
 the world. After taxonomic matching, we analyzed the 188 species that had
 a minimum of 20 occurrences in arboreta and for which natural occurrence
 data was available. Realized niches for each species
 were quantified as the range of climate conditions across their native
 ranges in North America. We downloaded native occurrence data for these
 species from the Botanical Information and Ecology Network (BIEN 4.1). We
 removed cultivated records from the BIEN data to ensure these were native
 occurrence records and limited all occurrences to within North America. We
 supplemented occurrence records in BIEN with point samples from Little’s
 range maps to ensure full sampling of species ranges into Canada and
 Mexico. We used CHELSA V2.1 climate normals (1980-2010) to quantify mean
 annual temperature, maximum temperature of the warmest month, and minimum
 temperature of the coldest month for each occurrence record.
 Potential niches for each species were quantified as the range of
 climate conditions across their native ranges in North America in addition
 to the range of climate conditions across the globally-distributed
 arboretums (i.e., native occurrences plus arboreta occurrences), because
 realized niches are subsets of potential niches. We use the term
 ‘potential niche’ to represent the conditions that permit survival but not
 necessarily reproduction. Given that natural occurrences outnumbered the
 arboretum occurrences by several orders of magnitude and would overwhelm
 the estimates of niche ranges, we randomly sampled occurrences from BIEN
 and Little’s range maps at 10 times the number of occurrences in the
 arboretums for a total of 165,315 occurrences.
description: # Data from: Trees have overlapping potential niches that extend beyond
 their realized niches
 [https://doi.org/10.5061/dryad.0cfxpnw9f](https://doi.org/10.5061/dryad.0cfxpnw9f) This dataset includes records of tree occurrences for 188 temperate tree species of North America and associated climate data and geographical coordinates (latitude/longitude). It also includes records of tree occurrences in arboreta around the world obtained from Botanic Gardens Conservation International (BGCI). The terms of conditions to use this data prevent us from publishing the geographical coordinates of the occurrences so these are scrubbed from the data set, although the climate data are included so that the results can be reproduced. **Data file structure** The occurrences.csv file includes records of species occurrences and climate data. Fields include: species – Latin binomial bio1 – mean annual temperature, degrees C bio5 – maximum temperature of the warmest month, degrees C bio6 – minimum temperature of the coldest month, degrees C longitude – decimal degrees latitude – decimal degrees source – character vector, either “arb” or “bien”             arb = occurrence from arboretum. If so, then location information is not included.             bien = occurrence record from BIEN or Little’s range maps **Sources of data** B. S. Maitner* et al.*, The BIEN R package: A tool to access the Botanical Information and Ecology Network (BIEN) database. *Methods in Ecology and Evolution* **9**, 373-379 (2018). E. L. Little, *Atlas of United States Trees, volume 1, conifers and important hardwoods*.  (US Department of Agriculture Miscellaneous Publication 1146, 1971). BGCI. (Richmond, U.K. Available at [https://plantsearch.bgci.org](https://plantsearch.bgci.org). Accessed on 06/03/2014, 2014). **Code** The R script analysis.R is included to reproduce data analyses using the occurrences.csv file.