Each species tends to prefer very specific conditions, and in this case, they’ve got evidence that they were not manufactured where they were found. Per the paper:
They likely were introduced as finished tools to the site since working debris of the initial production stage is absent (bark/branches), while point fragments and traces of reworking demonstrate spears and DPSs were used and repaired on-site. They can be considered curated tools of personal gear used and maintained for as long as possible.
The distance they give is the nearest location where the materials would be available, based on somebody else’s study:
The ratio of spruce plus spruce/larch to pine items decreases from 3.8 in category 1 to 1.1 in category 4 meaning that the former more often provides clear artifacts. Paleoenvironmental studies show the raw material was not available at the lakeshore but must have been transported from the nearby Elm Mountain some 3 to 5 km away or locations farther afield like the Harz Mountains (26).
Each species tends to prefer very specific conditions, and in this case, they’ve got evidence that they were not manufactured where they were found. Per the paper:
The distance they give is the nearest location where the materials would be available, based on somebody else’s study:
That study can be found here