Odell, former Head of Landscape and Green Infrastructure at Hertfordshire County Council and current Honorary Secretary of GreenArc, said people sometimes act as if London is an island, particularly when it comes to things green.
He is promoting an upcoming GreenArc conference which will encourage landscape professionals and local authorities to look at how they can link with green infrastructure outside the city's boundaries.
"The All London Green Grid, the proposal for a London Green Infrastructure Board and the National Park for London are all very good at heart, but they share the same weakness that occurs whenever thinking is limited by political geography," Odell said.
"They tend to focus just on London and not reflect that the capital is functionally connected with its hinterland. For a sustainable society, economy and environment, full account must be taken of the needs of the surrounding populations and of its wildlife.
"How long would the capital thrive if London's residents could not go out to the rural fringe and countryside for recreation, if its river catchments ceased to be managed as systems, if there were further severance to essential ecological corridors or if neighbouring local authorities could not co-operate over services?"
GreenArc is an initiative which has sought to connect supply and demand for functional green infrastructure between outer London boroughs and the inner districts of the Home Counties. Odell said GreenArc(NE)'s Strategic Green Infrastructure Plan (2011) essentially extends the All London Green Grid concept into neighbouring areas.
"The demand for green infrastructure planning is rooted in the need to provide what we would now call ecosystem services. They include the need for moderating the urban heat island effect, providing strategic woodland corridors for wildlife, managing water and providing some capacity for large scale recreation."
Kent countryside. Image: Pixabay
As an example, the 2011 plan suggests that Epping Forest and the Broxbourne Woods complex could form a "Woodland Arc" across the north of the city by linking across to Thames Chase and Watling Chase Community Forests.
Focusing on the green credentials of London is another opportunity. The National Park City campaign does this, as do the initiatives of successive Mayors of London and the London Parks and Green Spaces Forum, Odell said.
"But would it not add to London's prestige if it could point beyond the boundary to the support it
gives to a vibrant surrounding network of urban forests, farmland, and river corridors and a collaborative approach with bodies planning for and managing green infrastructure?"
Odell said the starting point for land-use planning around London should be an assessment of the need for and supply of ecosystem services for existing populations.
"This should lead to a well-engineered network of green infrastructure, with plenty of redundant capacity (knowing now how expensive it would be retrofit the equivalent of a Thames Tideway Tunnel). Such a landscape-led approach might also help heal the disconnect seen in the battle over development pressures.
"If we could first cooperate to deliver well-engineered green infrastructure for the rural urban fringe, which should not be so contentious, then apart from taking some of the heat out of the urban heat island it might also take it out of some of the other debates."
Saltmarsh defences in Essex. Image: Pixabay
Odell pointed out his ideas are not new. They go at least as far back as Scottish landscape planner John Loudon (in "Hints for Breathing Places for Metropolis" (PDF), 1829) who proposed for the land around London "park and pleasure-ground scenery...plants, trees, and shrubs which would grow in the open air, with innumerable seats, covered and uncovered, in the sun and in the shade".
During WW2 Ralph Tubbs promoted a system of parks for London which connected to thecountry ("Living in Cities", 1942) and Abercrombie's Green Belt ring was for parks and open space ("Greater London Plan", 1944). Odell pointed to the Lee Valley Regional Park as a great achievement along this path but said there is more still to do.
On 20 July GreenArc(NE) will be exploring both the scope for local cross-boundary collaboration over green infrastructure and the merits of a strategic initiative for the London City Region at its forthcoming conference, being held with the support of the Landscape Institute.
So far more than 40 per cent of local authorities forming the outer London boroughs and inner Home County districts have signed up to attend. They will be encouraged to consider whether there is a case for tying together local ambitions into a strategic initiative for the City Region.
Tickets to Planning for London's Green Doughnut are available at EventBrite.