**2. Materials and Methods**

#### *2.1. Description of the Study Area*

We selected three forest stands for our experiment from Karpanmaa forests in southern Finland (Figure 1). One stand is young and had undergone its first commercial thinning. Two other stands are mature and are waiting for their second/third commercial thinning operations. The tree species compositions are pine, spruce, and birch, with a predominance of pine in the three stands. The age of stands is distributed from 34 to 72 years. The height of trees is between 5 and 29 m. The ground elevation of the forest ranges between 127 and 149 m.

**Figure 1.** The study site and field measurements in southern Finland: (**a**) the locations of base stations and study area, (**b**) selected stands in Karpanmaa site, (**c**) logging trails, measured positions using the Trimble R2 and u-blox ZED-F9P and (**d**) the patterns of the recorded positions by u-blox ZED-F9P on the logging trails within an example of the study stands.
