Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School


First Advisor

Darrell Napton


balsam fir Lidar, Superior National Forest, understory fuels, wildland fire


Fire is a natural part of the ecosystems in the Great Lakes region. Several factors including harvesting, insect outbreaks, and fire suppression have had an impact on these ecosystems. Of particular concern is the rise in the proportion of shade tolerant species, such as balsam fir. Because of its resinous bark and easily ignited needles, balsam fir is flammable. Additionally, balsam fir is vulnerable to spruce budworm infestation, which leads to additional fuel loading from needle cast. Detecting increases in fire risk is important to fire managers in Superior National Forest for many reasons. Determining the amount and extent of understory fuels, however, is difficult, because of the area’s remoteness and to the cost of collecting field data. To quantify and map the extent of understory fuels, lidar data were used in combination with field data collected using the cover line intercept method at 46 plots. Multiple lidar metrics were calculated from the original point cloud, to be used as predictor variables. Preliminary results indicated that there was a relationship (R2 ≈ 0.65) between the amount of understory canopy measured and the following lidar metrics: the height at which 50 percent of lidar pulses are returned, relative point density between the heights of 8 and 10 meters, and the total cover. The results were used to produce a preliminary understory cover model. Comparison of the model results with ancillary data increased confidence in the model. Cover line intercept data were collected at an additional 24 validation plots. The validation data were compared to the model’s predicted understory cover. The results produced an R2 ≈ 0.47, a mean difference ≈ 14.3%, and a mean absolute difference ≈ 47.0%. The understory cover model was combined with data mapping the amount of balsam fir basal area to produce a preliminary balsam fir understory cover map. This research indicates that it may be possible to map understory fuels with airborne lidar and that with proper data, individual understory components may be extracted.

Library of Congress Subject Headings

Fire management -- Environmental aspects -- Minnesota -- Superior National Forest.
Vegetation mapping -- Minnesota -- Superior National Forest.
Understory plants -- Minnesota -- Superior National Forest.
Forest ecology -- Minnesota -- Superior National Forest.
Balsam fir -- Minnesota -- Superior National Forest.
Optical radar.


Includes bibliographical references (pages 143-149)



Number of Pages



South Dakota State University



Rights Statement

In Copyright