Jake Hendee, Consulting Forester
GIS is a simple program. It makes maps from simple layers - layers that are easy to access or create. For the needs of most foresters and all landowners, we need a program that costs less than $1500. This page cuts through the jargon to detail how any average computer user and/or landowner or forester can utilize the Quantum GIS open source freeware to do professional analyses of their land or their clients' land for free.
With Quantum GIS software, any landowner or forester can do the following in just a few minutes...
Map and save property boundaries
Measure acreage and save acreage measurements
Mark roads or fire breaks
Keep yearly records of management activities for forest stand compartments
Create random points for a timber inventory (GPS and Minnesota DNR Garmin Tool required)
Map soils for your property
Map soil site indices for your property
Calculate how much timber stand improvement, invasive species removal, tree planting, or other management you have done using a your GPS track function (GPS unit and Minnesota DNR Garmin tool required)
Explaining each step of creating the maps above would be tedious and beyond the scope of this blog post. However, with a few simple guidelines, anyone can get started making these maps. First, install Quantum GIS from www.qgis.org
Two types of files exist in GIS: Vectors and Rasters. Vectors are points (examples: inventory point, marker for endangered plant, an exact location), lines (examples: road, fire break), or polygons (examples: a forest stand, a soil unit, a property). Rasters are images like aerial photos and topographic maps. These are all the file types you will need. Scientists have already created most of these data layers you will need. You just have to download them from the the NRCS Geospatial Data Gateway. Sometimes you will need to create a vector layer to designate a forest stand, your property, or a timber stand improvement unit.
Point, line, and polygon vector data (the raster data is the background aerial photo)
Adding existing layers
1) Go to the NRCS Geospatial Data Gateway and select layers you want to add for your map. The choices will include color aerial photos (raster), black and white aerial photos (raster), topographic maps (raster), soils (polygon vector), and geographic names of populated and non-populated places (point vector).
2) Download layers and extract them from compressed folders to a location you will remember.
3) Add to map using "Add Vector Layer" or "Add Raster Layer" options in the "Layer" menu on the top menu toolbar.
4) You will see the layers appear in the Layers box on the left side of the screen. Drag the layers that you would like visible to the top and the layers you would like less visible to the bottom.
Creating new vector layers
1) Go to Layer option on top menu bar. Select Layer -> New -> New Shapfile Layer.
2) Fill in options (points, line, or polygon?) and create attributes (Examples: acres of each polygon, stand numbers, point identification numbers, road line number).
3) See layer appear in Layers box on left. Make sure it is highlighted.
4) Click "Toggle Editing" under "Layer" option on top menu toolbar.
5) Click "Capture Polgyon" or "Capture Point" or "Capture Line" under "Edit" on the top menu bar.
6) Left-click to create polygon, point, or line and right-click to finish each shape.
7) Fill in any attributes and check our your new vector feature!
You know how to use GIS!
You have officially created a GIS map. Play around and continue to see what more you can do. The functions that GIS can complete are endless. A Google search will usually easily resolve issues.
Note on projections or the Coordinate Reference System: Mapping relies on a number of different projections for different parts of the world--for changing a 3-D world into a 2-D map. For best results, download and create shapefiles and raster files with the same coordinate reference system. If two layers that should overlap appear on different parts of the map, they are probably projected in two different systems. This can be difficult to fix and should be avoided if possible.
Using a GPS unit with QGIS
A number of the maps above used line or point data created with a cost-effective GPS unit. For example, by attaching a GPS unit to my belt during timber stand improvement, I can later measure (in QGIS!) how many acres I completed in a day. I can also mark a "waypoint" at each tree in a high-value hardwood sale to provide information to timber buyers to improve removal and cruise efficiency and also increase the timber buyers' accountability to only remove marked timber. With a Garmin GPS unit and the Minnesota DNR Garmin Tool, you can easily integrate GPS and GIS. While the DNR Garmin tool is created for ArcView, it will still save GPS unit data to a vector point or vector line file that you can later load into QGIS.
EDIT: The new version of QGIS 1.8 does a good job of importing and exporting GPS waypoints and tracks. Just go to the Vector Menu -> GPS -> GPS Tools to check this feature out.
A consortium of dedicated open source programmers have made QGIS an alternative to an otherwise financially inaccessible technology for private consultants, cash-strapped state agencies, and private landowners. QGIS (with the guidance of a semi-skilled user) greatly improves accuracy and efficiency for assessment and monitoring of natural resources. In the case of forestry, QGIS is substantially more user-friendly than its $1500 counterpart. After orientation to the technical features of the program, the possibilities are endless! Enjoy, and as always, I am happy to provide some assistance.