Tree Tubes – a discussion

Plastic Free Forests – by Nicky Hume

According to legend, Sir Ewan of Lochiel shot the last wolf in Scotland in 1680. At the time it was considered a heroic act, saving livestock and people from these ferocious beasts. There are many foresters today, however, who wish that Sir Ewan, along with countless others, had missed…

A long history of predator persecution and habitat destruction has resulted in big gaps in our food chains and huge ecosystem imbalances in the UK. We now have unsustainable numbers of wild herbivores, especially deer, since their populations go largely unchecked. All those hungry, tree-eating mouths prevent our last remaining woodlands from regenerating and make it very difficult to establish new ones.

And so, along came the wonder solution, or so we though: the tree tube, invented in 1979 by Scotsman Graham Tuley. It seemed like the perfect answer: an individual guard for each new tree, protecting them from herbivores and sheltering them from the harshest Scottish conditions. Since then, millions of tree tubes have been used (particularly for broadleaf trees which are more palatable than conifers) to help create new woodlands across the country. Tree tubes work, they keep the deer, rabbits, hares and voles away from tasty young saplings, allowing the trees to grow to a size where herbivores are no longer a risk. Without tree tubes, we would not have some of the fantastic new woodlands that we enjoy today and for that, we must thank Mr Tuley.

Left: Tree tubes helping young, native woodland to establish. Right: the damage that voles can cause when tree tubes are not used.

We have known for some time however that tree tubes aren’t perfect. Here are a few of the problems they can cause:

  • Tree tubes act like mini greenhouses, causing trees to grow rapidly within them. Often, once the tree emerges from the top, it is thin and fragile and not prepared for the harsh wind and frost that greets it. Trees can snap or die of shock at this point.

  • Tubes shelter young trees from the wind meaning that they do not develop the strong root plates they need to withstand the wind. This can result in trees leaning over or falling completely once they grow beyond the tube.

  • Tubes often do not break open and, unless the forest has a very attentive manager with an excellent memory (or management plan) and plenty of time and money, tubes are often forgotten about and left on the trees for too long, strangling them.

  • Tubes are warm and damp inside, which some species such as beech and pine hate. The moisture can also causes moss and other plants to grow around the trunk of the tree and this can lead to rot.

  • Some tree species are poorly suited to growing in narrow tubes: shrubs like hazel or juniper for example – naturally they would grow with bushy forms but the tubes prevent this and can cause strangely shaped or unstable plants.

  •  Tubes only protect individual trees. They don’t solve wider problem of overgrazing or allow natural regeneration, which is generally preferable to planting where possible.

  • Tree tubes are expensive: saplings cost around 50p each whereas a 1.2m tube will set you back around £1.30. It’s an incredibly cost inefficient way to protect trees.

Top left: tube constricting tree. Top right: Damp moss and rot caused by tree tube. Bottom left: Moss growing within tube. A tube forcing a juniper to grow with a n unstable, top-heavy form.

Tree tubes are difficult to recycle since they are usually covered in moss and mud which recycling facilities can’t handle. In addition to this, many are made of more than one plastic which makes them difficult to break down into useful raw materials.

Until recently, we have been able to justify the use of tree tubes by saying that the less than ideal growing conditions are worth it, since without the tubes, the trees wouldn’t grow at all. Or, we’ve overcome some of the problems with changes to the design such as the addition of pre-perforated split-lines to help the tubes break open, mesh tubes that allow greater air flow and prevent the greenhouse effect or shrub shelters which are slightly wider and allow shrubs to spread out a little. In the last decade, however, we’ve become aware of a new problem and this time, it’s not so easy to justify or fix.

Plastic pollution: we’ve always know it wasn’t great but in the last few years we’ve all been forced to face the facts about the scale and impact of the problems created by our favourite material. Whether it was brought to your attention by Blue Planet 2 or a personal encounter of a plastic strewn beaches or riverbanks, it’s an unavoidable, ever increasing problem that we all have a responsibility to do something about, including foresters.

Borders Forest Trust, are lucky to have a fantastic team of volunteers who help us to remove tree tubes and vole guards from our sites but most forests don’t have that luxury. Tubes and guards are bulky, awkward and expensive to collect and so in other places they are frequently left in place. They do not biodegrade. Several models were on the market a few years ago that claimed to be ‘degradable’. This is not the same as biodegradable, it simply means that they gradually break down in to smaller pieces of plastic. Fragments of plastics like this end up in waterways and eventually the ocean where they are ingested by marine mammals, fish and sea birds. They can even enter our food chain.

The scale of the problem here in the Borders was highlighted during the Great Borders River Clean in February 2020 when plastic tree tubes were found at alomost all of the 30 clean up points along the Tweed. St. Mary’s Schoolteacher and organiser of the Great Borders River Clean Tom Rawson said: “Plastic tree tubes are a regular find on riverside litterpicks. As large and high-floating items they readily snag in bankside vegetation and are therefore simple to identify and collect. It is ironic that an item serving such a laudable purpose should become such a visible pollutant at the end of its service.”

Tree tubes were amongst the rubbish collected by volunteers during the Great Borders River Clean. Image credit: Lauder in Bloom

In the midst of a climate and biodiversity crisis, we need more trees now than ever before. But we have to plant them in a way that doesn’t inadvertently cause further harm to the environment.  So what are our options?

Biodegradable tree tubes

Some companies are trying to develop biodegradable alternatives that can be left on trees, eventually breaking down into organic matter. Borders Forest Trust have been testing some of them out over the last year. Here are our findings:

Ezee Tree  – Tree Guard

These guards are made from moulded card fiber and are completely biodegradable. According to the producers, they also have “a special biodegradable additive in them which makes them waterproof”. They are supplied with a “sustainable eucalyptus” cane that is used to hold the tube together and secure it in to the ground. No cable ties or other fixings are required thanks to the clever design that includes slots for the cane. The guards are 0.6m tall but two can be stacked to make a 1.2m tube.

Pros:

  • Clever, robust design that requires no cable ties and is easy to install.
  • Card fibre can be made from recycled materials and sourced in the UK. It is a timber product and so using it to protect new trees creates a self-sustaining supply chain.
  • The come flat packed so aren’t too bulky for transporting to planting sites.
  • Fairly lightweight.
  • Invented by a UK, family owned businesses that supply a range of ‘eco’ products and strive to reduce waste. They supply their products without plastic packaging.

Cons:

  • Borders Forest Trust and one of our supporters put over 100 of these to the test and the results were mixed. After 10 months, some were still in-tact but many had started to disintegrate already, offering no protection.
  • It is dark inside the tubes, which will be a problem for light demanding species. Most trees did survive in the 0.6m tubes that we trialled but growth was slow. Stacking two together for a 1.2m tube would create a very dark environment.
  • Some canes started to snap after less than a year. They appear to be untreated and do not have pointed ends making them difficult to drive in to the ground.

Tubes and stakes degrading quickly after only 10 months outside. Image Credit: Edward Hurst.

Summary: An innovate design that shows a lot of promise and is certainly a step in the right direction but unfortunately these tubes biodegrade too quickly in a wet Scottish winter and leave the trees exposed to herbivores. These may be a good solution in drier areas and for small-scale applications such as gardens and parklands where deer numbers are not high.

Ezee Tree – Hedge Guard

Ezee Tree also produce a simple, fold flat, hedge guard made from recycled card.  Standard plastic spiral guards widely used for hedging are one of the worst plastic polluters; they shatter into fragments making them difficult to collect, so these card alternatives are a welcome invention.

Pros:

  • Made from recycled card.
  • Come flat packed and so are easy to transport to planting site.
  • Lightweight.
  • Clever design with slots for a bamboo cane.

Cons:

  • These broke down in less than 6 months, providing very little protection.

No longer serving a purpose after only one winter winter.

Summary: A nice concept but not a useful solution yet.

Treebio – Biodegradable Spiral Guard

These spiral guards are made from Poly Lactic Acid (PLA) which is a ‘bioplasic’ made form fermented starch from plants such as corn, sugar cane or potatoes. It looks and feels like plastic. They are sold in 60cm or 20cm models for protection from rabbits or voles.

BFT had concerns about whether these were truly biodegradable and so consulted with polymer scientists at the University of Wolverhampton. They confirmed that PLA is biodegradable and is one of the better options currently available. They did say, however that most tests are carried out in industrial scale compost heaps which reach high temperatures. Little is therefore known about how long these tubes will take to fully biodegrade on cold Scottish hillsides with only one small area in contact with the soil. It could take decades. If, however, an animal of fish were to ingest a piece of PLA before it had fully degraded, it would, in theory, be able to break it down, as the body does naturally with lactic acid.

The manufacturer, Rainbow Professional, explain the biodegradation process: “First the moisture and heat present in a compost pile and to a lesser degree in soil attacks the polymer chains and splits them into much smaller parts of polymer and eventually pure lactic acid. Finally, Microorganisms found in compost and soil will consume the lactic acids as nutrients as a food source for them. The result is Carbon Dioxide, Water and Humus which is a soil nutrient.”

Pros:

  • Translucent material allows some light to reach saplings.
  • The 4 samples on trial were still in tact after 10 months but were showing hairline cracks.
  • Light weight.
  • Simple, familiar design.

Cons:

  • The spiral design is not ideal: it is difficult to push in to the ground as the tube compresses, this leaves the sapling at risk from voles.
  • At 0.6m it is only useful against voles and rabbits.
  • Lack of evidence about how long PLA takes to fully biodegrade when not in a commercial compost heap.
  • Uncertainty about sustainability of the material – is land used to grow corn or potatoes specifically for this material or are waste products from food production used? No information about where materials are sourced. However, it is likely to be better than oil based plastic.

Still in-tact after 10 months outside but with some hairline cracks starting to show.

Summary: A very promising material that would benefit from some more field trials and improved product design.

BioCycle – BioTube tree shelter

The Biotube is made of made from flax and a cashew nut oil resin. The manufacturers claim it will fully biodegrade within 8 years. They are made by a small UK start-up inspired by the high cost of removing and disposing of plastic tubes.  The tubes are 0.6m tall and like the Ezee Tree Guard, can be stacked to make taller tubes.

Pros:

  • Very robust design, still in tact after 10 months outside.
  • Natural string ties are supplied instead of plastic cable ties.
  • Comes in two halves for easy stacking and to allow it open around a growing tree.

Cons:

  • Very heavy and bulky: only practical for small scale planting projects or sites than can be accessed by vehicle.
  • Very dark inside: This may not be a major issue for the 0.6m tubes since the trees will quickly grow to the light but is likely to cause problems when two tubes are stacked to make a 1.2m tube.
  • Concerns about the sustainability of the materials: Cashews do not grow in the UK so emmisions from transport must be considered. The nuts are not always farmed sustainably so we would need to see evidence that these are sourced from sustainably managed forests before we could endorse this product.

Summary: Not currently a suitable replacement for plastic tubes in remote or inaccessible sites, but may be useful for more accessible locations. BioCycle have a new product under development that they say will address some of these issues so we look forward to testing it out soon.

Conclusion:

Although some shortcomings have been identified with the tubes that we tested, it should be emphasised that these reviews are not intended to criticise the product developers. They deserve recognition for trying to tackle a complex problem that we all want to find a solution to and it will take continued innovation, like theirs, to get there. Many of these tubes may preform better in slightly drier conditions such as in the South of England where some of them were developed.

None of the tubes tested could compete with plastic tubes yet, but if feels like we’re getting close. Humans are smart and the technology and materials are already out there, it just requires a bit more funding and pressure from the forestry industry. Let’s send a strong, united message to tube manufacturers, sellers, designers and scientists that we need change.

Another important step to reducing plastics in our forests would be to adjust the grant system to disincentivize the use of tubes in favour of fencing, deer stalking or simply over stocking to allow for some losses. Final maintenance payments could be withheld until tubes are removed or fines could be issued when industrial plastic litter is left in forests beyond its useful life.

But in the end, it comes down to the same old elephant in the room: until we either control herbivore numbers more effectively ourselves or bring back apex predators to Scotland, we’ll be stuck building barriers against nature rather than letting it take care of its self.


Information:
This article is available as a PDF to download. This article was produced in August 2020 by The Borders Forest Trust. It may be distributed and shared, but please credit the article and photos appropriately. This article is not intended to be a definite guide to tree tubes, rather a discussion about the current situation. We may update this article periodically, so please check our website www.bordersforesttrust.org for more information or to make a donation to our work.