New Automatic Band and Point Dendrometers for Measuring Stem Diameter Growth [ PDF ]

J. Wang, T. W. Sammis

Applied Engineering in Agriculture Vol. 24(6): 731-742

ABSTRACT: A fast-responding dendrometer is needed for measuring tree growth responses (daily or hourly) to drought, fertilization stress, and other stresses. This study reports on operational comparisons between new inexpensive automatic point and band contact dendrometers. For this study, 18 point and 5 band dendrometers were installed on pecan tree trunks and branches during the 2005 growing season. Their performance and measurements were compared by analyzing data downloaded weekly. The annual radial growth measured by these dendrometers was compared with the data manually measured by core samples of annual rings. Point dendrometers’ measurements were statistically the same as the manual measurements (F<0.25, P>0.05). However, band dendrometers underestimated the radial growth by 42% compared to the manual measurements (F=10.6, P<0.05) and may not be able to measure the hourly diameter change of small-diameter branches (e.g., < 10.1 cm) over several days. Point dendrometers were found to be suitable for large-scale tree growth measurements and water and fertilizer stress monitoring due to their fast response (hourly or faster), ease of construction and installation, and low expense (<$40 each). However, multiple point dendrometers (two or more) are recommended for growth measurements of each branch/trunk, because the radial change of each point on the branch/trunk girth is different. The possible underestimation of trunk/branch growth by band dendrometers may be caused by the slack between the band and the trunk/branch surface. For this reason, researchers should be careful using growth data from the literature when measurements were made by automated contact band dendrometers.

(click image for larger version)