The Global Positioning System (GPS) is a satellite-based system that provides accurate location and timing information to people worldwide. The system transmits signals that can be used by GPS receivers to calculate position, velocity and time anywhere on earth, any time of day or night, in any kind of weather.
Accuracy is determined by your GPS unit. All units use the same basic satellite system. Therefore, you can spend tens of thousands of dollars to locate yourself to within a couple of millimeters of your actual location, or a couple hundred dollars to locate yourself to within about 30 meters.
For the average forestland owner who owns a computer, a $500 investment in a handheld GPS unit, some software, and a download cable will get you on your way to accurately mapping features on your property and adding to the wealth of information you use to manage your forestlands. We are recommending Garmin MAP76 series GPS units to most of our clients and colleagues. This series of handheld GPS receivers comes in a variety of models including a couple with color screens (for more money). We use them at Northwest Management for many of our field projects where an accuracy of 10 to 30 feet is acceptable. We can increase that accuracy to about 3 feet through some advanced data collection techniques.
We like these units because of their cost to accuracy ratio, the ability to load information from a variety of mapping software platforms into the GPS unit and then pull data collected by the units back to the mapping data. Base maps can be loaded into the unit from accompanying software to show roads, streams, contours, and other features on its built in screen.
The other factor is their ease of use. Suppose you want to traverse a planting unit, timber sale boundary, or insect infestation. By walking the perimeter of the area with your GPS unit you can instantly view the acreage of the unit without a calculator. Then when you upload your data to your computer, you can produce a map of the unit accurately showing its location. The same can be done for roads. Simply walk the route and receive distance, accurate location, even slope profiles along the route. Although I am not quite ready to throw away my compass, the Map76S series comes with not only a barometer but a magnetic compass built in.
Northwest Management, Inc., will be sponsoring a series of GPS classes for forestland owners this spring and summer. They will be offered in Moscow, Idaho, Deer Park, Washington, and Helena, Montana. Watch this newsletter for details and dates, or our web page for more information.
Dr. William E. Schlosser is a forester, natural resource economist, and regional planner with Northwest Management, Inc. located in the Moscow, Idaho, office. He is the Director of the Northwest Management Geographical Information Systems Laboratory and lead instructor of GPS and GIS training sessions.