27 July 2012 by Nigel Dunnett and James Hitchmough
The Olympics will come and go, but their legacy will permanently transform the landscape of east London and the variety of plants and animals it supports. Horticultural ecologists Nigel Dunnett and James Hitchmough describe their contribution.
The London Olympic Park in Stratford is the largest new urban park to be developed in Europe for 150 years. It is highly innovative, based on an ambitious long-term vision to create a world-class visitor destination and then to transform it into a park for local communities.
One of the many things that set this project apart from a typical city park is that the whole plan, including the planting strategy, is dictated by the park's Biodiversity Action Plan (BAP), which sets out the range of habitats and species the park needs to support.
One of the planning conditions for the park was that it must provide 50 hectares of new habitat. In reality this means that most of the green space on the site must in some way contribute to the BAP. Given that the park and sporting venues will receive several million day-visitors over the period of the Olympics and Paralympics, this is a major challenge; we have to meet ecological goals and visitors' aesthetic and recreational needs at the same time.
Luckily this is an area we know a lot about. Much of our work focuses on delivering ecological benefits in everyday environments like parks, highways, gardens, schools and commercial areas, rather than in designated nature reserves or nature gardens which some people might never visit. This means we're used to giving equal weight to aesthetics and ecological concerns.
We were invited to be the park's horticultural and planting design consultants in 2008, working with landscape architecture consortium LDA/Hargreaves. Our role has been to develop a planting strategy for the whole site for both 2012 and the subsequent two-year 'transformation' period, when the park will be converted to public use.
Two parks in one
The Olympic Park has two distinct areas. The north park is bigger and has an informal 'country park' approach, while the south park, which includes the main Olympic stadium, has a more urban, 'festival' feel. The vegetation and design of the two areas reflect these different characters.
The vegetation in the north park is dominated by designed versions of native UK habitats, and celebrates native biodiversity. These habitats include species-rich meadows of different types, the largest area of wet woodland habitat in the UK, reedbeds, woodlands, flowering lawns and sustainable urban drainage features like rain gardens and bioswales (plant-filled depressions that help slow and clean water as it runs off the land).
The south park focuses on visual drama. The Stadium Meadows are the largest areas of direct-sown annual meadows ever created in the UK and have seas of annual asters and daisies that are a magnet to pollinating insects. The 2012 Gardens are almost a square kilometre of stunning perennial plantings that celebrate the British gardening tradition and its exceptionally rich diversity of plants.
Being able to work on site for the past two years has given us the opportunity for some trial and error, letting us make sure the park will be at its best when the games take place, in late July and August 2012. It hasn't been easy, because most native flowers are past their best by this time, so we've focused our experiments on cutting back the meadows in spring to delay flowering into late summer.
We've based our design and species choices on scientific research. Evidence for the value of urban gardens and native/exotic vegetation mixes to native invertebrates has come from projects like Biodiversity in Urban Gardens (BUGS), which investigated the variety of living things that city gardens support, and the complex relationships between them. We have also drawn on our own research projects and trials, such as work on the Bibury dataset - the longest-running continuously-monitored experiment on herbaceous plant communities.
Planting for the long game
So how will we resolve the conflict between the immediate visitor experience and meeting BAP requirements over the longer term? The plan is for the vegetation to evolve and adapt, both naturally and through specific management plans, between the year of the games and the long-term legacy phase, from 2014 onwards.
During the transformation phase much of the hard infrastructure built for the games will be removed, and a number of things will happen to the vegetation once it has gone.
For example, species-rich meadows have been created for 2012, containing little or no grass to maximise their flowering impact. During the transformation phase these will be oversown with more grass and other species so that they meet BAP requirements. The high-intensity spectator lawns sown for the games will also be made more diverse with a mix of oversowing and plug planting of more grass species.
A second strategy is to create dramatic hotspots of colourful, non-native plants in both the north and south parks. Despite their drama and complexity, these are very naturalistic - closer to groups of plants in the wild than to typical garden planting schemes. This means they don't need much maintenance at all compared to traditional park flowerbeds, and they support a wealth of biodiversity. In fact, there are no municipal-style park plantings in our design at all; all the vegetation is innovative and sustainable.
The Olympic Development Authority's vision was that the park should play a central role in the London Olympics and beyond. The Olympic Park is unique in the UK, with innovation, sustainability, science, art and biodiversity all at its heart. It represents a potential turning-point in the way urban parks and green space are designed and managed. We hope it will become the benchmark for a new generation of urban green spaces that are both ecologically-informed and beautiful.
Professors James Hitchmough and Nigel Dunnett are members of the Department of Landscape at the University of Sheffield.