Turf trials at by War Graves Commission prepare for climate change

Adapting to climate change will be a challenge for grounds managers, as trials at military cemeteries demonstrate, Gavin McEwan reports.

Oostduinkerke. Image: HW
Oostduinkerke. Image: HW

Ongoing turf and landscaping trials by the Commonwealth War Graves Commission (CWGC) are highlighting the many challenges that grounds managers are likely to face as rainfall and temperature become less predictable in the coming decades.

The commission manages more than 2,500 cemeteries and plots from the UK and mainland Europe to North Africa, the Middle East and Pacific Rim, embracing a huge range of climate conditions. Horticultural manager for Northern Europe Chris Griffiths-Hardman typifies this, having worked for CWGC in east and south-east Asia, so brings a wide perspective on growing conditions.

"We are uniquely placed to consider climate change," he says. "We have always had cemeteries that are dry and suit xerophytic planting. The predictions are that in 30 years' time Belgium will be like Portugal is now - inevitably our planting will change."

In northern Europe, most cemeteries have followed a format of highly maintained turf with herbaceous planting in a border in front of the headstones. In 2008 the commission began a series of trials whose goals were threefold - to gauge reaction to a range of different planting and maintenance schemes, to establish how practices will need to adapt to meet anticipated changes in climate and to assess the viability of present replanting cycles in the trial sites.

Trial sites

All four of the cemeteries selected for the trials, which still have four years to run, are in the France-Belgium border region near the Channel coast, where soil moisture is already an issue. Three have light sandy soils that do not retain moisture or organic material, making it difficult to improve by adding compost. In common with most CWGC sites, none had irrigation systems. But the fourth, Railway Chateau, was prone to flooding - possibly militating against the Mediterranean-style planting that formed part of the trial.

Two are the responsibility of the French office, two fall to the Northern Europe office based in Ieper, Belgium. Both collect and share data on rainfall and temperature in each trial site.

Director of horticulture for France John Tooke also has experience of very different climates, having worked in the CWGC's "Outer Area" ranging from the Balkans to Mauritius. "I see it as a progressive change - we are always looking at ways of being more efficient without losing the original concept," he says. "We want a bit of history before we make big decisions. If we are systematic we will avoid any serious mistakes.

"The overall look hasn't changed. The layman wouldn't necessarily notice the difference. We still have roses and fuchsias in the borders - we want to keep the Gertrude Jekyll look. We don't want to give visitors a surprise. In fact we haven't lost any plants so far this year, even though the winter weather was tough, whereas we would have lost 'dry site' plants."

Deputy horticultural manager Steve Arnold adds: "Climate change isn't happening overnight. The planting has to be able to cope with extremes. It could be warm, cold, dry or wet - it's ever-changing."

The Oye-Plage cemetery was returfed with 100 per cent Barkoel, a variety of crested hairgrass (Koeleria macrantha) bred by turf seed supplier Barenbrug, which has been a partner in the trials. This offers both high drought-tolerance and little need for fertiliser. However, according to Arnold: "Koeleria is harder to establish, and doesn't look as good in winter - it's a summer grass."

Tooke adds: "When established it's a good grass and if you get 100 per cent germination it's fantastic, but you need the right temperature and soil moisture."

In the borders, many roses have been replaced with Geranium endressii and Fuchsia 'Mrs Popple', to reduce pesticide use and improve resistance to drought, although one row of the drought-tolerant 'remembrance' rose was left for comparison.

Also on the French side, at the small cemetery of Les Moeres, one half of the main path was turfed with Barkoel as at Oye Plage, while on the other half, turf was replaced altogether by Marne river pebbles, hemmed in with a metal edge. "It's just to show what can be done," Tooke explains. "We may not stick with the hard landscaping, but it's all reversible."

Over the Belgian border the Oostduinkerke cemetery on the edge of the dune system has similar sandy soil, where turf had "browned out" during the dry summer of 2009. Here Barenbrug's wear-tolerant Splendide mix of tufted tall fescue, rhizomatous tall fescue and Barkoel was trialled, along with single-species plots, with similar results to those on the French side.

"We are looking for turf that will cope with drier conditions, which is why we have been trialling Koeleria," says Griffiths-Hardman. "The trouble is, it's very slow to establish. But that does mean less maintenance. Koeleria only needs 12 cuts a year."

Horticultural supervisor Richard Saynor adds: "Year-on-year the visitor numbers are going up and so wear tolerance is also something we're looking for in the trials."

More drought-tolerant herbaceous planting is also being trialled at the site, including Festuca, Helianthemum, Thymus, Sedum and Sempervivum. "We have to think how this will be in 30 years' time," says Griffiths-Hardman."Plants that do well we can use elsewhere - otherwise, we'll try something else."

An altogether more radical approach was taken at the Railway Chateau cemetery, which fulfilled the trial proposal for a fully hard-landscaped site. Here compacted dolomite limestone gravel was laid over a Terram geotextile membrane, which was felt to better enable wheelchair access than loose gravel. Even though it is a relatively small site, installation took a week.

Here the public response was most marked. A survey on the CWGC website drew more than 250 responses and according to a CWGC report, there was little enthusiasm for the approach. "It doesn't meet people's expectations of a cemetery in northern Europe," says Saynor.

Griffiths-Hardman is philosophical about the result. "It's clearly not an English garden. This was to test public reaction and it was a success in gaining stakeholders' opinions. It may be an option for the future.

Since HW's visit, the Railway Chateau cemetary has been replanted with drought-tolerant Splendide turf used at Oostduinkerke.

REPLANTING APPROACHES AT FOUR CEMETERIES

- Oostduinkerke

The light sandy soil prompted trials of drought-tolerant grass varieties that will also cope with wear, as well as more Meditteranean-style herbaceous planting.

- Railway Chateau

A fully hard-landscaped surface was trialled, but feedback from visitors was largely negative. It has since been returned to turf.

- Oye Plage

A 100 per cent sowing of a Koeleria variety has proved hard to establish, but does offer the promise of lower maintenance.

- Les Moeres

Another form of hard landscaping - pebbles - is being trialled alongside drought-tolerant turf species.


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