Hedging our bets: greening the grey in towns and cities

By David Adshead

The humble hedge has traditionally been sacrificed to the paved front garden but maybe now is the right time for a hedge revival

A bidding war during last December’s General Election in the UK saw each of the main political parties pledge to plant very large numbers of trees. 1 Sceptics queried how these ambitions could be realised, particularly given the reduction in government spending on tree planting over the last decade.

The track record of independent, charitable organisations is better: The Woodland Trust has planted more than 47m trees since 1972, while The National Forest is close to reaching its target of 9m. Earlier this year The National Trust declared its intention to plant 20m trees in the next ten years; a credible ambition for it owns the land on which this might be done. But other events have since diverted the country’s attention and even the United Nations Climate Change Conference, COP26, to have been hosted in Glasgow in what was heralded as ‘2020 Year of Climate Action’, has been postponed thanks to the COVID-19 pandemic. The planting of trees is a long-established stratagem to counter climate change and an important component in the race to achieve the government’s legally binding target of a net zero carbon economy by 2050. Given the stark statistic that global deforestation currently outstrips afforestation, it is imperative that the UK, one of the least forested countries in Europe, sharpens its spade; the world needs to plant simply to stand still.

But what else might be done? The recent news that underwater seagrass meadows can capture carbon dioxide (CO2) at a rate 35 times faster than that of rainforest trees highlights the need to think laterally and to counter the climate emergency on multiple fronts. So how can towns and cities contribute? While many of them benefit from the amenity of green squares, parks and avenue trees, mostly laid out and planted in the 18th and 19th centuries, competition for space severely limits the number and size of trees, particularly forest trees, that can be grown within their bounds. Indeed, health and safety concerns and pressure from the insurance industry, nervous of falling boughs and heaving root systems, have in the last few decades led to the removal of many large trees, ironically just at the point in their life cycle where they were most effectively sequestering carbon. With their loss and the benefits that attend them – biodiversity, shading, cooling through transpiration, reduction in flooding, prevention of soil erosion and amelioration of air pollution – we have pushed nature further out of town. The practice of planting smaller ornamental species in their stead – and replanting on a wasteful cycle every fifteen years or so – has further diminished the efficacy and amenity of our urban green infrastructure.

Hedges at John Wesley’s house in City Road, London.

© Paul Lincoln

Imagine a future in which thousands of miles of hedges snake along our roads, separating pedestrians and vehicles...

What else might bolster our bio armoury in towns and cities? Enter the humble hedge. Conceived some 6,000 years ago in the service of agriculture, the hedge, made up of closely planted shrubs, offers many of the same benefits as the more majestic tree. We tend to notice great trees but pass by lines of hedges without giving them a second thought; by analogy, when asked to name the largest organ in the body many of us will too hastily answer ‘the brain’, but in size it is trumped by the skin. If planted at scale, urban hedges could make a very significant contribution. Imagine a future in which thousands of miles of hedges snake along our roads, separating pedestrians and vehicles, greening the grey and bringing a host of health benefits both to us and to the embattled systems that drive the natural world.

This is not a new thought, so why has more not been achieved? What would encourage local authorities and local community groups to do more and what might central government and other bodies do to remove barriers to action? There are already excellent resources online, ranging from the strategic to the practical, that help to point the way.

There are the admirably clear documents published by ‘100 Resilient Cities’, a Rockefeller Foundation initiative designed to support the United Nations’ sustainable development goal (11) of making cities inclusive, safe, resilient and sustainable. The report ‘Building Resilience with Nature: A Practitioner’s Guide to Action’, published in November 2018 is particularly valuable, not only in its encouragement of the development of green infrastructure and the proper valuing of ecosystem services, but also in showing how awareness can be built, collaboration achieved and ‘pushback’ from officialdom countered.

Academia has played its part too, publishing research reports that clearly demonstrate the ability of different shrub and tree species, when planted along the sides of roads, to trap ultrafine particulates and to remove carbon dioxide and nitrogen oxide from the air.

Hedgelink, a partnership organisation that recognises the wildlife, landscape, and cultural value of hedges, provides practical guidance on planting and management for farmers, landowners and their agents. Its work is part of the movement to reverse the wholesale removal of hedges (largely halted by the Hedgerows Regulations 1997) occasioned by the intensification of farming in the 20th century.

But there is a gap. If change is to be effected at a societal level, a radically different approach needs to be taken in devising policies and standards and translating them into practice. In this the landscape profession can play an important part, challenging longstanding norms and helping bodies such as the Department for Transport and local authority planning teams to reappraise what might be possible. Why, for example, can we not plant hedges along the pavement edge on all Red Routes (marked with double red lines), which in London at least represent 5% of the road system but carry up to 30% of its traffic and are, therefore, the most polluted? Roads marked with double yellow lines and which have broad enough pavements might then be looked at. And why can we not rethink the design of pedestrian crossings? The need for clear sightlines determines that vehicles cannot park on the zig-zag markings to either side of a crossing but planting along the pavement could help to signal the crossing points. Then there are miles of urban canals whose towpaths, often bounded by high walls that serve as canvasses for graffiti, offer potential planting sites.

It would be all too easy to draw up a litany of objections, but with imagination, an appetite to ask the ‘why not’ questions, a collaborative spirit and grass roots community involvement and support that might establish an army of volunteer verderers, we could create and maintain valuable new greenways into and through our towns and cities. On every walk I take I see planting opportunities and ask myself ‘why not there, why not now?’

David Adshead is the Secretary of the Georgian Group