Global Positioning System (GPS) has been applied successfully in many areas of forest industry. Typically applications include fire prevention and control, harvesting operations, insect infestation, boundary determination, and aerial spraying. The past scientific literature found that the equivalent accuracies could be obtained under a canopy compared with the open field. These results are not supported by recent studies. While the topic seems to be somewhat avoided in the relevant scientific literature (GPS first place), it is still recurrent in many discussion lists on the web. Decker and Bolstadt (1996) studied the effects of terrain, forest canopy, number of consecutive position fixes and Position Dilution of Precision (PDOP) on GPS accuracy. They found that the positional accuracy was higher for deciduous sites versus coniferous. Sigrist et al. (1999) discussed the impact of the forest canopy on quality and accuracy assessment of GPS measurements. Hasegawa and Yoshimura (2003) studied the performance of dual-frequency GPS receivers for static surveying under tree canopies.

  Forest and natural resource applications can be achieved efficiently employing GPS data collection technologies. However, there are limiting factors in environments, such as forest canopy, that cause adverse effects on the reception of GPS signal. Steep terrain and heavy forest cover make GPS data capture slow due to reception of acceptable satellite coverage. So, position accuracy is often degraded in difficult terrain conditions, and in some cases it may not meet accuracy standards and requires resurveying. In the forests, canopy cover may interfere with satellite signal reception and make it difficult to make reliable measurements. The GPS signals are affected by the surrounding trees and earth and that affects adversely both accuracy (how close the lines and points are to their true location) and productivity (how much of the time the receiver is tracking enough satellites). The users are limited by the view of the sky in a tree canopy environment resulting in the GPS receiver to be locked to only to only high elevation satellites. Satellite constellation has a large effect on the quality of the data collected in forested environments such as data bias. Constantly changing constellations result in inconsistent and poor relative data accuracy.