Potential alpine habitat in the western USA based on treeline elevation

Purpose: create a map of potential alpine habitat in the western USA as a basis for future studies in ecology and biogeography.
Location: all mountains in the continental USA west of 104° longitude.
Procedure: manually identify treeline elevations; interpolate a surface of these elevations; intersect the surface with a 90-m resolution DEM; record all areas above these elevations as projected alpine habitat; for display, map the area recorded as alpine at 90-m resolution.
Products: a map for display; a dataset of elevations of treeline at 268 points on 66 mountain ranges in the western USA (61) and Canada (5); a dataset of points recorded as above treeline at 90-m resolution., All mountain ranges in the western USA and southern Canada were examined. The relatively continuous Rocky Mountains were subdivided according to named ranges or previously identified regions. These totaled 61 in the USA and 5 in Canada. The Canadian ranges were included to improve the interpolation at the northern end.
At each range at least four treeline ecotone points were selected, one each on the north, east, south, and western edges of the range. Additional points were recorded on larger ranges such as the Sierra Nevada. The points were selected on Google Earth imagery by Malanson, who is experienced in treeline research (e.g., Alftine and Malanson 2004, Malanson and Butler 1994, Malanson et al. 2001, 2007, 2009, 2012, 2019, 2023, Smith-McKenna et al. 2014, Grafius and Malanson 2015, Weiss et al. 2015). The uppermost continuous forest cover was identified for the point. If an extensive zone of krummholz was observed, its elevational midpoint was identified. The elevation, latitude,..., , # Potential alpine habitat in the western USA based on treeline elevation

An elevation surface was interpolated from points in the western USA and Canada identified as treelines on Google Earth imagery. The surface was intersected with a USGS 90 m digital elevation model (, and all cells higher than the interpolated surface were recorded and mapped. Three products are included.

## Description of the data and file structure

The first dataset, Final268Points, is a csv file of the 268 points identified as alpine treelines (Treeline Elevations). The data, in columns, include their latitude, longitude, and elevation as derived from Google Earth. The elevations of the points on the elevation surface generated by inverse distance weighting (IDW) and kriging (krig) are also listed. The second dataset, All90mPoints, is a compressed (zip) csv file of the c. 1.5 x 10^9 cells that were identified as having elevations greater than the surface generated by inverse distance weighting (All90mPoint...