Forest Monitoring with NASA Airborne LIDAR

Using results from two recent field studies, researchers hope to gain new insight into the use of NASA airborne laser data to monitor land cover changes in forests.

In the first study, scientists conducted research flights with a NASA airborne laser profiler during the summer of 2006 to determine its effectiveness in estimating regional forest resources. The research area was Hedmark County, Norway, a 27,000 square-kilometer (16,800 square-mile) region on the Swedish border that becomes progressively more mountainous in the north. To examine the profiler's accuracy, all data gathered will be compared against ground-based data compiled by the Norwegian Forest Inventory. Data from profilers are much cheaper to acquire than that from laser scanners, but before scientists can use profilers in a variety of research applications they must first complete such field missions to verify their accuracy.

In a second, related study, started in the summer of 2006, researchers took measurements at tree line in southern Norway in an area northwest of Oslo. The goal is to determine how well high-density scanning lidar can be used to identify small trees. This question is of particular interest because as the climate warms researchers expect forests to move upslope and populate new areas at higher elevations. Knowing the lower limit of tree sizes that can be reliably measured by airborne lasers will better identify the use and reliability of lidar in studying forest migration. To complete their research, scientists collected differential, ground-based GPS data to locate the positions of trees within a few centimeters in a commercial scanning lidar data set. Next, they will look at the tree locations in the lidar data to see how well these measurements of tree heights and crown widths compare with ground-based measures.

In recent years, lidar has become a more commonly accepted and available research tool. Airborne lidars directly measure a forest’s upper canopy, the layer formed by the leaves and branches of the forest’s tallest trees. These remotely sensed height measurements, in turn, can be used to estimate biomass, the amount of living material in a given area. All of this provides a three-dimensional look at forests and represents a significant improvement over earlier radar data sets and other technology that were not able to penetrate thick forest cover very well.

Contact:

Ross Nelson
NASA Goddard Space Flight Center
Ross.F.Nelson@nasa.gov

Science Objectives:

• Determine the accuracy and reliability of NASA airborne lidar in forest monitoring
• Map and compare results from lidar profilers to other data, including that from laser scanners
• Further develop lidar-based sampling procedures for large-area monitoring
• Document regional forest changes across parts of Norway

Partners:

Researchers from NASA, the Norwegian Institute of Land Inventory, Norwegian Research Council, and Norwegian University of Life Sciences participated in the field campaign.

When:

Summer 2006

Where:

Southern and eastern Norway

Links:

For a tutorial on lidar:
http://www.ghcc.msfc.nasa.gov/sparcle/sparcle_tutorial.html

For more information about the Norwegian Institute of Land Inventory:
http://www.nijos.no/index.asp?strurl=1002146i&context=15&menuid=1000477&topExpand=1000187

For more information about the Norwegian Research Council:
http://www.forskningsradet.no/servlet/Satellite?c=Page&cid=1138785830860&pagename=ForskningsradetEngelsk%2FPage%2FStandardSidemal

For more information about the Norwegian University of Life Sciences:
http://www.umb.no/?avd=30