Tree Guards Part 2: Natural Materials

There is still work to be done...

Cardboard guards in use at a Tree Council planting site in Petersfield, Hampshire

Right from the start, let’s remember that the most sustainable tree guard is always going to be no tree guard at all. However, guards are used because they perform an important purpose – to protect a newly planted tree from predation, usually from deer and rabbits.  

When plastic tree guards were first introduced around 40 years ago, the sector saw a minimum 25% reduction in planting losses. They are still widely used across large planting projects and have become so ubiquitous that they are an easily identifiable sign of new tree planting schemes. However, the continuing presence of guards made from damaging chemical and oil-based materials in the environment remains a serious problem.

This needs to change! The Tree Council has wanted to remove all plastic from tree protection for many years. However, whilst possible in theory, as deer numbers continue to rise, in practice it could lead to a large increase in tree losses unless effective non-plastic guards, or alternatives like fencing, are available.

The next generation…

Although in their relative infancy, the next generation of biodegradable tree guards show the potential to move away from dependence on petrochemical plastic-based products and their micro plastic pollution.

Whilst there are currently no natural fibre ‘spiral guards’, there are cardboard tubes and wraps. These appear to provide the same protection as the plastic guards currently available and can maintain the same levels of tree establishment. Crucially, they have the added value of not needing to be removed manually as they decompose.

As these new products are being brought to market, we are now able to observe how the first generation of these natural guards endure, biodegrade or fail. The rate of degradation is a hot topic, given that too swift a process could lead to trees being prematurely exposed to browsing by animals.

The Tree Council and volunteers planting with cardboard guards at the Petersfield site

Talking of hot topics, there does seem to be some evidence (although currently anecdotal) around wood fibre and cardboard guards’ ability to provide protection from hot and dry summers, mostly by keeping young trees shaded from direct sunlight. These ‘new generation’ guards also avoid the unhealthy greenhouse environment often experienced within plastic guards.

New types of tree guards are currently being made from wood fibre/cardboard and wool, but future alternative natural materials could include; waste fibres, such as sugar cane; jute; coir; bamboo; or a UK grown coppice material. It will be vital to look at the overall sustainability of all of these, factoring in where original materials are grown and manufactured and how many miles they have travelled to reach our shores.

Managing change…

Managing change is difficult. It can add costs and extra time to adapt to new methods.

A big challenge with any planting is estimating the number of trees required to allow for losses. As well as considering tree protection, there must be greater emphasis on aftercare, as we are losing far too many trees due to poor aftercare practice. This is a large and very visible weakness in the tree planting industry.

From policy and procurement, to delivery, there needs to be a shift in understanding of the whole life cost and benefits of tree protection. Although purchase cost per unit of biodegradable guards is often higher, no time-consuming removal or expensive disposal is required.

Plastic tree guards are often left to litter the environment (left) and cause damage to a trees (right) if not removed properly

As my colleague, Jackie Shallcross pointed out in Tree Guards Part 1: Plastic, in many cases plastic tree guards are left in place due to poor management and financial costs. This can damage the trees through restricted stem growth, stilted hedges (spiral guards), weakened stems in forestry trees (square plastic guards), and worse, many guards simply remain stuck on and in trees.

Let’s talk about deer…

UK landowners face increased pressure from wild browsing animals, mostly due to a significant increase in the deer population.

Unfortunately, tree protection is needed for many years to avoid trees being damaged by heavy browsing or bark stripping. This pushes up the cost per tree, and is likely to move our focus away from individual tree protection to ‘tree community’ protection. This could involve well-designed fencing which includes ensuring the right heights of posts, density of mesh and barbed or other wire. This can work out at around £15-20 per metre, making it only feasible for larger groups of trees, copses and woodlands.

Spiral guards can be vulnerable to determined browsers

With a high deer population, planting linear features such as hedges may also require a fence either side of the hedge to prevent the loss of trees to browsing.

Vulnerability to browsing is determined by the guard type - taller tree shelters will prevent deer browsing, whereas shorter guards will prevent damage from smaller rodents and rabbits. However, we know that deer are not deterred by plastic spiral guards (see above). Positively however we are hearing anecdotal evidence that guards made from natural materials are more successful at protecting a young whip’s crown.

Solutions?

The Tree Council is trialling alternative methods of tree protection, to determine what works well and what doesn’t. For me, good quality tree protection should meet the following expectations:

·        Suitable for the tree type

·        Natural

·        Strong enough

·        Plant friendly

·        Quick to install

·        Low cost (over the lifetime)

·        Protects tree from more than just browsing

·        Durable (lasts as long as it’s needed)

·        Sustainable – fibre or material source

·        Biodegradable

Reducing the use of ‘traditional’ guards is a big step towards removing harmful plastics and their toxic legacy, but there are still some limitations to each of the natural alternatives available. Therefore our collective focus must be on innovation and creativity, to develop and refine flexible, effective, sustainable tree protection that can be replicated with ease. This is vital to ensure our tree planting aspirations deliver healthy treescapes of the future, and I look forward to being part of the journey!      

Ian Turner is The Tree Council’s Head of Major Planting & Ecology Projects - Southern Region. To find out more about The Tree Council, please visit treecouncil.org.uk

Read Tree Guards Part 1: Plastic

Useful links:

Manufacturers of guards made from natural materials: Ezeetree and NexGen

Further reading:

The Guardian: Trees should be planted without plastic guards, says UK study