Plastic Guards Should Not Be Used When Planting Trees

They're carbon-intensive to produce, and they pollute soil with microplastics.

plastic tree guard

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A recent UK study has found that plastic guards used when planting trees add significantly to carbon emissions and environmental harm. Planting trees without protective guards is the best option. Research has found that it's preferable to lose a certain percentage of saplings than to use plastic guards to protect them. 

The Problem With Plastic Tree Guards

This comprehensive life cycle assessment compares the environmental performance of shelter-aided seedling planting to a base case where protective guards were not employed. While this study focuses on the United Kingdom, the conclusions are also valid for other temperate climates.

There are emissions associated with the production of plastics. What is more, since plastic guards are rarely reclaimed and recycled after use, they break down into microplastics, polluting the natural environment and causing harm to wildlife.

While polypropylene (PP) tree guards are technically recyclable (at least once), the problem is that most tree guards become brittle in UV light. By the time they are ready for removal, they are often tangled and easily broken. So they are typically left to pollute the surrounding ecosystem—which, of course, is not exactly compatible with what tree planters usually want to achieve.

Tree Guards or No Tree Guards?

This research confirms that plastic guards should not be used when planting trees. Though this has been the norm in tree planting since the 1970s, things are beginning to change, and there is a growing interest in more sustainable solutions. 

While all scenarios investigated in the study resulted in a tiny fraction of emissions when compared to the carbon sequestered by the trees planted over a 25-year period, it is clear that we should find alternatives for plastic guards to implement best practice in reforestation and afforestation schemes. 

Scientists found that when guards were used, 85% of trees survive, whereas only 50% survive if no guards are used. But rather than using tree guards to obtain a higher rate of survival, those involved in the study concluded that it was better for the environment to go plastic-free. Amongst other issues, the carbon footprint of using a plastic guard is at least double the carbon footprint of planting plastic-free. 

Sustainable Tree Guard Alternatives

The Woodland Trust, a charity which plans to plant 10 million trees each year until 2025, has announced its aim to stop using plastic tree guards by the end of this year. It is trialing plastic-free options at its Avoncliff site in Wiltshire, including cardboard and British wool. 

The National Trust, among the biggest landowners in the UK, aims to plant 20 million trees by 2030 and it too is experimenting with sustainable alternatives, such as using fences or crates built from local diseased trees, cardboard, or wool tubes, and—most interestingly, perhaps—using shrubs such as gorse and hawthorn to create natural protective barriers.

Utilizing other plants to improve the resilience of a fledgling woodland or forest ecosystem could potentially be more effective than using guards in the short term. Trees placed within a resilient, diverse, symbiotic system are far more likely to survive and thrive long term.

What this recent study shows is how important it is to look for "hidden" sources of emissions, and how important it is to take an evidence-based approach to tree planting. Of course, the strategies required will vary depending on the local incidence of pests like deer and rabbits, and the details of a specific site; but finding sustainable alternatives to plastic tree guards will help make sure that doing the right thing does not come at an environmental cost.

Rewilding Strategies: Letting Trees Plant Themselves

While not covered in this study, another interesting thing to consider is that human intervention in terms of direct tree planting may not be the only way to go. 

Rewilding strategies can lead to a great many trees simply seeding themselves on appropriate sites. So intervention strategies other than actually planting trees may sometimes be the best solution to achieve the increase in tree cover required in combating our climate crisis. 

We need a lot of trees to grow. But whether we decide to plant them ourselves, or rewild and let nature do the job for us, plastic tree guards should not be, and do not need to be, part of the solution.

View Article Sources
  1. Chau, Charnett, et al. "The Environmental Performance of Protecting Seedlings with Plastic Tree Shelters for Afforestation in Temperate Oceanic Regions: A UK Case Study." Science of the Total Environment, vol. 791, 2021, p. 148239., doi:10.1016/j.scitotenv.2021.148239