  Taper equations are indispensable tools for characterizing the stem profile
of trees, providing valuable insights for forest management, timber inventory,
and optimal assortments allocation. The recent progress in Terrestrial Laser
Scanning (TLS) has revolutionized forest inventory practices by enabling
non-destructive data collection. In this study, four taper models from three
different model categories were established based on point cloud data of 219
Pinus nigra trees. The taper equations fitted with TLS data were used to
predict the diameter at specific stem heights and the total stem volume. The
results show that among fitted models, the Max and Burkhart segmented model
calibrated by the means of a mixed-effects approach provided the best estimate
of the diameter at different heights and the total stem volume evaluated for
different diameter at breast height (DBH) classes. In numerical terms, this
model estimated the diameter and the volume with a respective overall error of
0.781 cm and 0.021 m3. The predicted profile also shows that above a relative
height of 0.7, the diameter error tends to increase due to the low reliability
of data collected beyond the base of the crown primarily caused by interference
from branches and leaves. Nevertheless, this study shows that TLS technology
presents a compelling opportunity and a promising non-destructive alternative
for generating taper profiles and estimating tree volume.
