https://www.theguardian.com/environment/2022/mar/23/swap-fence-for-hedge-rhs-climate-study

Charity to look at how hedge varieties provide benefits such as rainwater control and wildlife shelter

Gardeners and homeowners should swap their fence for a hedge, the Royal Horticultural Society is urging as it begins a study into which species are best for tackling the climate crisis and pollution.

Scientists at the charity are looking into green infrastructure, particularly in urban areas. One example of such infrastructure is using hedges to mark boundaries between properties and gardens.

A team led by the RHS's principal horticultural scientist, Dr Tijana Blanusa, will investigate the properties of different types of hedge, looking into how they provide important ecosystem services and assessing the benefits of mixed hedging.

Hedges can reduce pollution and improve air quality; slow the flow of rainwater which can help with flood management; provide shelter for wildlife; and help regulate temperature through shading and cooling.

Blanusa said: "The humble hedge is often the hero feature in any garden. Acting as a natural screen, they not only provide important environmental services but are relatively cheap, long lasting and have only a small ground footprint.

"Knowing which planting combinations to choose to get the most environmental benefit, and how to look after them effectively, could enable wider uptake as we seek to future-proof our towns and cities."

Current research suggests beech, privet and holly plants have the best all-round effects.

The charity will study how different species provide their benefits. They will be looking at factors including leaf shape, texture and branch structure, which are all thought to make them more adept at various roles.

Many areas have a monoculture of hedges, meaning that just one species is planted, perhaps for aesthetic purposes. While this is a traditional way to plant in a garden or urban area, scientists fear it can leave plants susceptible to disease and limit biodiversity.

Blanusa's two-year project will look into the best combinations of hedges for year-round benefits to urban areas. She will study plants in a laboratory setting but also in a real-life application at a school.

She will be trialling six combinations of mixed hedging, using four plants: privet, western red cedar, hawthorn and elaeagnus.