|SREL Reprint #1829|
Accuracy of tree growth measurements using dendrometer
Dendrometer bands are commonly used to make repeated measurements of tree
circumference despite their tendency to underestimate first-year growth.
Underestimates of growth are generally attributed to slack remaining in the bands
after installation. To test for first-year measurement errors, 60 trees were fitted
with a second dendrometer band 2 years after installation of the first band. The
new bands consistently showed significantly less growth than the old bands
(old-band measurements were assumed to represent true growth). Regression
equations were developed to relate new-band estimates to true growth. There
were no significant differences in regression intercepts for the three tree species
tested, but significant differences in regression slopes were detected.
Comparisons between canopy and subcanopy trees and between angiosperm
species (Nyssa aquatica L. and Nyssa sylvatica var. biflora (Walter) Sargent)
and a gymnosperm (Taxodium distichum (L.) Rich.) explained 95.7% of the
variance in regression slopes for the individual species. It appears that in addition
to band slack, part of the first-year error in dendrometer band data may result
from species differences that are related to bark and stem characteristics.
SREL Reprint #1829
Keeland, B.D. and R.R. Sharitz. 1993. Accuracy of tree growth measurements using dendrometer bands. Canadian Journal of Forest Research 23:2454-2457.