ElevDistr - Calculate the Distance to the Nearest Local Treeline

A method to calculate the distance to the climatic tree line for large data sets of coordinates (World Geodetic System 1984) with geographical uncertainty. The default thresholds and the treeline definition is based on Paulsen and Körner (2014) <doi:10.1007/s00035-014-0124-0>, users are free to decide what climate layers they would like to use.