What does the impact of climate change mean for those responsible for planting in public spaces? And how should they plan their response?

If there is one topic that is likely to become dated rapidly it is the question of how we amend our landscape planting in response to climate change. Can anyone remember the dire predictions in the 1970s about how we were going to run out of oil and other fossil fuels by the end of the century? At the time, before global warming had been recognised, I seem to recall that climate predictions then were of an impending new ice age rather than rapid meltdown. Even now, a strand of opinion proposes that a potential effect of climate change is the diversion of the Gulf Stream, plunging us not into Mediterranean conditions, but a prolonged Siberian winter.

Three or four years ago, after we had suffered a run of torrential summer and autumn downpours and extreme flooding events, the talk was of plantings tolerant of soggy summers. Now, after two exceptionally dry winters, we are seriously considering adopting the xeriscape concept from the arid southwestern United States.

The point is that, while climate change, and a trend towards warmer drier conditions, is widely accepted, it is still not clear how it will play out. An associated increase in the frequency of extreme weather events may mean that we will have to deal both with the problem and paradox of too little water (drought) and too much water (heavy summer storms) in the same place.

One thing is sure – it can only mean good news for those of us who believe in the ecologically-informed approach to landscape planting and design as the exciting and creative driving force for the profession. It is already becoming economically feasible and desirable to adopt ‘green’ solutions to engineering problems – that until very recently were still seen as radical and idealistic.

At the heart of many of these approaches is the use of plants and planting to replace concrete and steel. Sustainable Urban Drainage Systems (SUDS) have become part and parcel of everyday urban planning language.

However, look at what has happened over the past five years or so in American cities such as Chicago, Portland and Seattle. These cities have produced the most inspiring stormwater management design manuals that have brought the skills of landscape architects to bear on civil engineers, with the result that new urban infrastructure is planned with planting at its core. And not just any old planting – diverse, native landscapes that look good, soak up and clean excess stormwater run off, provide wildlife habitat, and need much less intensive maintenance. At last we have a reason to promote high-quality planting, and lots of it – not just because it looks attractive, but because it is essential to the functioning of healthy cities in the era of climate change.

So, we have to accept that climate change is happening. There is no point in being negative about this, because in reality nothing can be done to stop the tide: we can only modify the trend. Yes, certain habitats and native plant communities are threatened, but nature is a dynamic and ever-changing process, and in the place of what is lost, we will gain new plant communities that are better fitted – look at the spontaneous plant communities that colonise our urban wastelands and brownfields.

But the way to do it is to develop approaches that are ‘extensive’ – in other words they do not need intensive care for their survival in the form of irrigation, fertilisers and heavy maintenance. We will have to do this, because it will not be cost effective or resource efficient to do otherwise. This will require a renewed focus on plant knowledge and training and a higher profile for skilled planting design. Putting plants and ecological processes at the core of landscape architecture, where they rightly belong, could be one legacy of the changing climate we are facing.

Nigel Dunnett is senior lecturer in the department of landscape,University of Sheffield.He is co-author of Planting Green Roofs and Living Wallswith Noel Kingsbury,and co-editor of The Dynamic Landscape: ecology,design and maintenance of urbannaturalistic vegetationwith James Hitchmough
Visit:www.shef.ac.uk
Nigel Dunnett
University of Sheffield

Guy Barter - Royal Horticultural Society

The scientific community agrees that weather trends indicate that climate change is with us and will continue to develop for the rest of this century. Summers will be drier and higher temperatures will lead to soil moisture reserves being depleted much earlier in the summer. Winters will be wetter, but the overall annual rainfall will fall. Warmer winters will mean higher evaporation, so less water will accumulate in the soils to replenish rivers and aquifers and plants will run short of water sooner. On the plus side the growing season will be longer, so growth, where there is sufficient water, will be better.

These factors are mediated by soil. Dry sandy and chalky soils will have too little moisture to sustain water- demanding plantings. At the moment, beech is common, but more drought- resistant oak, ash or hornbeam are likely to be suitable for the next 50 years. And after 80 years summer droughts might be such that only drought-resistant trees, such as the Corsican pine currently used in heathland forests, will survive.

Short-term planting, such as shrubs and herbaceous plants, are more readily changed. It may be that late summer plantings that need summer moisture to flower well – phlox and delphiniums, for example – will have to be replaced by drought-resistant plantings such as those used at RHS Garden Hyde Hall.

Lawns will suffer. However, grass breeders are developing more drought- resistant grasses and there is much interest in lawns that have a proportion of clover or other deep-rooted herbs.

Winter rain is forecast to occur in heavy downpours. It will mean more run off, less replenishment of soil moisture reserves, flooding incidents and soil erosion. Planting and landscape design to counter this will be important.

Plant roots can survive cold wet winter soils, but are vulnerable in future warmer soils. Plants, such as ornamental cherries, need cold in winter to promote the formation of flowers and leaf production. Warmer winters may change the timings we currently use, so different choices of flowering plants will be important.

Guy Barter is head of horticultural advisory services at the Royal Horticultural Society

Sarah Fairhurst - National Farmers Union

Climate change offers policy makers and those in the green industries directly affected by it the potential to create opportunities with imaginative designs and new varieties. But we must avoid a situation where climate change issues give those who hold the purse strings the chance to cut back on budgets. Communication is paramount. Those involved with the planting of public spaces must talk to their growers. We can provide suitable plants that look good, and advise on management and maintenance.

Local authorities should use imaginative and water-efficient techniques to produce and maintain displays. This does not mean cutting back to a low-cost, low-input stereotypical display of grasses and pebbles. Grouping plants with similar watering requirements is just one way of increasing water efficiency.

Yes, climate change will impact on planting in public places, but this must be seen as an opportunity. I see many wonderful plants to be used now and in the future. A proactive approach and imaginative thinking will lead to eye-catching designs.

Sarah Fairhurst sits on the NFU National Horticulture Board and the British Bedding and Pot Plant Association technical committee. She is quality controller for Porters Horticultural
Visit:www.portersfuchsias.co.uk and www.nfuonline.com

Paul Stone - Paul Stone Gardens

Back in the 1980s it was my experience as a landscape contractor to receive enquiries from landscape architect practices requiring vast swathes of ornamental ground cover in amenity open spaces and roadside situations. These were often really low-specification schedules of work with little investment in ground preparation, amelioration or protection, and certainly little consideration for choice of drought- tolerant varieties. With low-maintenance regimes added to the mix, the end result was often vast swathes of dead ornamental ground cover.

Since then, there is no doubt the industry has improved its end product and better design, specification and working practice have resulted. However, the climate has continued to produce warmer seasonal temperatures and reduced annual rainfall, so the challenge has increased.

The first signs of response came through the development of technology and such products as mulches, mats, swell gels and membranes, many of them sustainable drought protection aids. Despite initial installation costs these have become standard practice in water conservation. Reduction of maintenance costs and improvements in establishment of plants have been the successful end result.

I am glad to say that the mindset in many landscape design practices now seems firmly engaged on what is ethical, socially and environmentally acceptable in respect of what is delivered for public landscape design. Practical use of grey water; designs that protect planting from water loss and trap and deliver water to where it is needed; the creation of free draining soils from greenwaste products – these are all increasingly the aspirations of designers.

The climate change in Britain has actually made plant specification more exiting. A whole new palate of what were considered exotic and tender plantsare now potentially at the designer’s disposal. Equally though, there remains a good choice of tolerant native species offering important biodiversity opportunities.

The greatest challenge is to tackle the public mindset on what is expected from landscapes. They appear responsive to recycling and conservation initiatives but how are they ever going to accept brown lawns and the disappearance of annual bedding displays?

Paul Stone is principal designer at Paul Stone Gardens and manages landscape projects at the Eden Project Visit:www.paulstonegardens.co.uk

Jessamine Gilchrist - Parks Positive

Sustainability is everything and for some time parks managers have been working with growers, developers (creative and technical/scientific) and suppliers of composts and seeds towards designs and plant material that:

• are resilient to wear and tear from sport, play, general recreation and fun
• need little fertilising, pruning, mowing
• will survive in brutal thoroughfares (ill- designed concrete and general human use and abuse)
• need minimal staff/machinery input
• make the sites look welcoming

Authorities are already taking sensible steps to use green waste more effectively as compost and mulches. Most are aware that the porosity of the soil is crucial to combat dry conditions, as is ph, and that to improve soil structure is paramount, both for holding moisture and nutrients.

It is, of course, impossible to renew every piece of green with more resilient plant material or sward. But it is possible to research more suitable species of trees, shrubs and bedding, for when we have the chance to refurbish and develop. It may be possible to focus on small areas of carpet bedding, which can be stunning, and make use of species that survive in drier situations. Just think, too, of wonderful African marigolds and the many other Mediterranean species that are available as ferns and grasses.

In our parks we have near perfect places and sites to educate and assist in changing the perceptions of the public in what to expect of the ‘natural’ environment now and in the future. It is up to green space managers to make sure that strategies and plans reflect the probable effects of climate change, and that planners and designers also change their perceptions to fit the future. If we don’t get it right at inception, the cost of designing, planning, implementing and maintaining inappropriate schemes, whether within the built environment or in established green space, really will cost us our piece of the earth. Jessamine Gilchrist runs the consultancy Parks Positive.Until earlier this year,she was head of parks, cemeteries and allotments for a district council.

Robin Tacchi - Robin Tacchi Plants

Planting in the public realm has seen a decline in the last few years. The main factors appear to be the lack of plant knowledge in a new generation of designers, making them less confident in the use of plants, and the perceived costs of maintenance and aftercare. The results have been harsh, graffiti-covered urban areas. We need to go back to soft landscaping to create more harmonious and balanced environments, and re- introduce softness, quiet movement and life to solid, dead environs.

The specifiers in 2006 have a new set of demands when choosing and using plant material. Recent dry conditions across the UK have resulted in water authorities taking special measures, while The Met Office also warns of exceptionally wet conditions.

A well-planted area creates its own micro-climate, as well as contributing to the wider locale. Overuse of hard landscaping results in flash flooding in wet conditions and, without areas of soil, rainfall is not channelled into the aquifers and is lost. Solid, sealed ground also leads to extreme temperature differential between cold and hot. In summer, plants help keep the average local temperature cooler and in winter warmth is generated from the soil. Planted areas absorb dust and noise; they are the lungs of a city producing oxygen and absorbing carbon dioxide.

A professionally planned site with careful attention paid to drainage, soil conditions and normal local climatic conditions will always provide the best start for establishing planting. Landscape professionals will have to adapt their plant choices to take into account the immediate needs of newly planted sites and potentially extreme conditions. In these evermore volatile climatic conditions, specifiers need to work with experienced growers at the planning stage for advice on plants. For the present drought situations, there are plants that will cope and thrive, such as the best varieties of lavenders, buddleia, cistus, cortaderia, cotinus, genista and rosmarinus; for hedging escallonia and crataegus; perennials and grasses such as pennisteum and stipa.

A well-planted and thriving micro- climate looks after not only itself and the local fauna but our spiritual health as well. We must not lose sight of the fundamental importance of the contribution of plants to the environment with over anxiety about immediate climate changes. We have a wealth of indigenous plant species to suit different conditions. With no soft landscaping there will a more profound cost than mere money in the end.

Robin Tacchi is managing director of Robin Tacchi Plants in Norfolk.He is a passionate plantsman and has been growing for the landscape industry for over 30 years
Visit:www.robintacchiplants.com

Do you agree?

What is the impact of climate change likely to be on public planting and how should public space professionals be responding? Email: greenplaces@landscape.co.uk