Effects of forest thinning on static horizontal positions collected with a mapping-grade GNSS receiver

The static horizontal position accuracy of a mapping-grade GPS receiver was tested in two different pine forest conditions (pre-thinning and post-thinning). The main objective of this study was to describe the horizontal position error that might be observed shortly before and shortly after the thinning operation. In general, by using the Trimble Juno T41 series receiver, we found the static horizontal position error prior to the thinning operation averaged 4.14 m when each individual point was assumed to be as a sample. If the northing and easting values of each epoch were averaged, the error would be 1.57 m. According to the most immediate post-thinning measurements, the horizontal position error averaged 2.32 m for individual samples, and 1.02 m when the northing and easting values were averaged. Subsequent post-thinning measurements showed further improvements in static horizontal position accuracy. The findings suggested that the magnitude of horizontal position error decreased after the thinning operation. Therefore, the quality of the data and the density of the trees around the data collection area are dependent.