Sizing up trees

A safer, cheaper device to measure tree circumference

By Shruti Chowdhari
Published: Tuesday 15 October 2013

A dendrometer band being installedEVELYN Anemaet, a biologist from the National Wetlands Research Center, Louisiana, US, and her colleague, have devised a cheap method for constructing and installing dendrometer bands. Dendrometer bands are instruments used for measuring tree circumference.

Construction of a conventional dendrometer band is expensive, time-taking and difficult. The band has to be made by hand from a bent and folded metal strip which has sharp edges. To avoid any injury, the worker has to wear thick gloves. An improperly constructed band could also damage the tree. As several dendrometer bands are required to studyÔÇêa large area, it is expensive.

Anemaet and her colleague have prepared dendrometers using smooth-edged stainless steel bands, fixed with pre-fabricated cable-tie that keeps both the tree and the worker from getting injured. A spring is used to attach the two ends of the band. The spring has sufficient tension to keep the band snug to the tree and at the same time allows the tree to grow.

As part of the study, they installed both conventional as well as modified dendrometer bands on 12 trees in the artificial wetlands of the research centre.ÔÇêThey found that the time taken to install dendrometers using the modified cable-tie method was approximately two minutes faster than the traditional method under ideal (non-´¼üeld) conditions. Under ´¼üeld conditions, traditional band construction took 30 minutes or more while the cable-tie method did not take more than 10 minutes. The study was published in the Journal of Plant Applications, on August 22.

Tree trunks, typically, shrink during winter and expand in autumn. Tolerance to freezing temperatures is often a selection criterion in breeding programmes. Monitoring tree trunk diameter is an important component of ecological studies and forestry management.

Douglas Sheil from the Institute of Tropical Forest Conservation, Uganda, and Center for International Forestry Research, Indonesia, says, “The method seems reasonable as its manufacture is easy and economical. But somehow these dendrometers are prone to large errors when displaced on the tree, as they may be knocked down by a falling branch or an animal, or tampered by children or monkeys.”

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