TITLE:
Estimating Individual Tree Diameter and Stem Volume Using Airborne LiDAR in Saga Prefecture, Japan
AUTHORS:
Katsumasa Oono, Satoshi Tsuyuki
KEYWORDS:
Airborne LiDAR, Diameter at Breast Height, Individual Treevolume, Forest Resource, Individual-Tree-Based Approach
JOURNAL NAME:
Open Journal of Forestry,
Vol.8 No.2,
April
20,
2018
ABSTRACT: Advancements in airborne
LiDAR analysis technology have made it possible to quantify forest resource
volumes based on individual
trees, and such technology may soon replace field surveys. Unlike individual tree
detection or tree height measurements, diameter at breast height (DBH) is difficult to
determine directly from measured data and is instead estimated indirectly using
the correlation between crown size and DBH. Indicators that represent crown size
include crown area, surface area, length, and length ratio, and were utilized with tree
height as explanatory variables in ten combinations to determine a regression
formula. DBH and tree height calculated from the regression formula were
applied to an equation to calculate stem volumes of individual trees. Airborne
LiDAR measurements were taken using ALS50-II and ALS60 (Leica) at a density of 4
points/m2. An evaluation of the relationship between the regression
formulae and DBH estimates indicated that a combination of crown area, tree height, and
crown ratio for Japanese cedar, and a combination of crown area and tree height
for Japanese cypress, yielded the highest coefficients of determination. The
average error and RMSE were 6.9% and 2.38 cm respectively for Japanese cedar,
while the corresponding values for Japanese cypress were 8.35% and 2.51 cm.
Once the relationship was extended to the stem volumes of individual trees, the
average error was 14.4% and RMSE was 0.10 m3 for Japanese cedar. The
corresponding values for Japanese cypress were 18.9% and 0.10 m3.
These results demonstrate the potential use of airborne LiDAR as a substitute
for field surveys.