Automatic device for extracting increment cores from large trees for dendrochronological purposes

Smart increment borer: a portable device for automated sampling of tree-ring cores

Akira Kagawa (a), Takeshi Fujiwara (a)

 (a) Department of Wood Properties and Processing, FFPRI, Tsukuba, Ibaraki, Japan.

Journal of Wood Science, 64(1):52-58, October 2017, DOI: 10.1007/s10086-017-1668-6( External link )

To determine the age and growth of trees, it is necessary to extract cylindrical core samples from tree trunks and measure the number and width of growth rings. To that end, increment borers are commonly used tools because they enable investigators to extract samples of growth ring cores (increment cores) while causing relatively little damage to trees. Conventionally, increment cores are manually extracted. However, challenges remain as the process requires a considerably large force, making it impossible to collect many samples at once or extract long and thick cores. To address these challenges, attempts have been made to develop automatic devices for extracting increment cores. However, almost all of those devices developed have turned out to be heavy, cumbersome, and time-consuming in terms of installation, thus rendering them even less efficient than manual extraction.

In the present study, we developed the following two relatively lightweight devices powered by electric wrenches: (1) one with a total weight of 6.5 kg for extracting φ5-mm increment cores and (2) the other with a total weight of 9.5 kg for extracting φ12-mm increment cores. Despite such relative lightness, the use of reduction gears has enabled these devices to convert the high-revolution/low-torque force of electric wrenches into a low-revolution/high-torque force. This design has allowed devices to swiftly extract increment cores that are ≥80 cm long from rigid trunks of large trees, such as oaks and teaks. This process would otherwise have required onerous effort if performed manually. Currently, even lighter versions of these devices are under development with the view of further facilitating transportation during fieldwork. The use of these devices will greatly improve the efficiency of extracting increment cores used for forestry and dendrochronological research.

Note: Devices for extracting cylindrical wooden samples are called increment borers. They can extract cores of 4.3–12 mm thick and 100 cm long or shorter and cause relatively little damage to trees.

Photo. Core extraction process.
A 12-mm-thick core was extracted from a Japanese cedar trunk.

Figure. Automatic extraction device for sampling increment cores.

a. electric wrench, b. torque amplification gear, c. bars for supporting the reaction force, d. socket connecting to an increment borer.