At 50, the barcode isn’t ready to retire

The Carbon Community uses barcodes as a critical component of our scientific field trial to identify and track individual trees.

The story of how barcodes came about is fascinating, because they almost looked like the concentric circles of tree rings. In this article, we celebrate the barcode from its humble beginnings through to its use in tracking trees today.

Did you know the humble barcode just turned 50 years old on June 26th? What’s amazing is that the rectangular barcode we all know so well very nearly didn’t happen.

The original barcode design looked very different: in 1949, Joseph Woodland and Bernard Silver submitted a patent for the first barcode which used concentric circles, ironically looking very much like tree rings. The idea didn’t take off until 1960, when physicist Theodore H. Maiman built the first working laser, which made it possible to quickly decode a barcode’s line patterning. Then in 1971 the US grocery industry formed a standard called the Universal Product Code, and formed a committee to chose a standard barcode design.

The seven barcode design finalists. Image: From US Symbol Standards Subcommittee

The leading candidate was the concentric circles design, but a late entry into the competition by IBM changed everything, and the rectangular barcode we all know today was born, only to go on and be used in a huge number of applications beyond grocery.

The Carbon Community uses barcodes extensively

Across its landmark field trial, The Carbon Community individually tracks 6,400 trees using aluminium barcodes. This is a critical component of our scientific field trial because through wind, rain and shine, we have to be able to identify each tree, every year, even though it may be unrecognizable from the prior year. Every October, hundreds of volunteers use barcode scanners to measure these trees, collecting critical data which is then used by scientific teams to access how well the trees are growing.

It’s made complex, of course, because our field trial is on such a scale – 72 test cells over a 25 acre area comprising 25,600 trees in total, of which 6,400 are individually tracked.  

How and why we chose barcodes

When our scientific team designed this field trial, implicit in the design was that the 100 centre-most trees in every plot would be individually tracked. This has enormous implications for running a large-scale field trial, and we simply could not measure these trees individually without the massive help we receive every year from our volunteers.

Identifying individual trees enables tree species level data to be analysed across the 72 plots, giving a much richer picture of how individual species react to the different treatments being tested.  For example, to compare the tree mortality and growth of oak vs alder when treated with crushed basalt requires individual tree level data.  

While there are higher tech solutions to identifying individual assets, such as RFID and NFC, high-tech in this case might not be the best route. What we were looking for was a way of identifying individual trees that would last for 40 years or more, irrespective of 40 years of rain, sun bleaching and frost. The humble barcode needs no batteries, is maintenance free and also had the advantage that it could be read by a smart phone.

We considered many different ways of printing barcodes, but few can survive the harsh conditions of upland Wales for 40 years. Then we discovered laser-etched barcodes, typically used in harsh environments like the North Sea for asset tracking, and we developed a custom barcode following this pattern:


27 is the plot number which identifies the type of planting (mixed broadleaf or monoculture conifer) and the specific treatment being tested.

The first 0 is a spacing character and the 006 is the individual tree number, typically numbered 1-100 in each plot. Combined together as 270006 this uniquely identifies each tree in its plot.

This simple formula means that the tree number can be easily read off the barcode by eye as well.

Scanning with phones, then scanners

In our first two years of measurement, we used the cameras on mobile phones together with an Airtable app we developed to scan the barcodes on the tree stakes and capture the data. In the second year we used only rented iPhones having learned that the barcode scanning of Apple devices is far superior to most Android devices.

But still problems with false readings persisted, and in 2023 with the help of a Forestry Commission grant, we were able to purchase Nautiz x41 Handheld scanners which use a laser scanner, much like you use in a supermarket self-checkout.

These are much more reliable in the field at reading barcodes accurately, and critically, faster too. Speed and accuracy are all important when you have 6,400 trees to measure in an eight-day period!

The weak point in this measurement system is the humble softwood tree stake onto which the barcodes are attached. In only the 4th year after planting we are already needing to replace a few tree stakes, and with the benefit of hindsight next time maybe hardwood stakes would be a better option. In time the plan is that as the trees reach maturity we will be able to transfer the barcodes to be attached to a low hanging branch, eliminating the need for a tree stake.

The other challenge with tree stakes is that as the plots are maintained, they can get lost. In 2023 we geo-positioned every tree so that we now know exactly where every tree is matched to its barcode, reducing the reliance on an individual aluminium tag still being there in 40 years time and providing a great back up.

But the humble barcode will continue to be our primary method of identifying and tracking trees for many years to come. Happy birthday, Barcodes everywhere!!

You can read more about our individual tree geo-positioning here.