Measuring Douglas-fir crown growth with multi-temporal LiDAR
Frew, M. S., Evans, D. L., Londo, A., Cooke, W. H., & Irby, D. (2016). Measuring Douglas-fir crown growth with multi-temporal LiDAR. Forest Science. Society of American Foresters. 62(2), 200-212. DOI:http://dx.doi.org/10.5829/forsci. 14-062.
Crown volume, the geometric space occupied by the crown, along with the change (growth) of crown volume over time can be an important part of multitemporal forest analyses but is expensive and time-consuming to obtain through conventional forest survey methods for large or remote areas. Field- and light detection and ranging (LiDAR)-derived tree height and height to live crown measurements were compared to establish the relationships of these variables with respect to use in crown volume modeling. LiDAR-derived crown volume growth was compared with expected crown volume growth based on field data collected on 220 Douglas-fir trees in the Panther Creek, Oregon, watershed. Regression analysis of expected crown volume to LiDAR-derived crown volume in 2008 and 2012 resulted in R2 values of 0.45 and 0.53, respectively. A paired t-test between the expected crown volume growth and the LiDAR-derived crown volume growth resulted in a P value of 0.85, indicating that LiDAR-measured change in crown volume over time was not significantly different from the expected amount of change. With further research, multitemporal LiDAR could become a viable tool for forest change analyses.