Professor Nigel Dunnett

My research activity is strongly interdisciplinary, focusing on the interface between ecology, design and horticulture in urban green space and built development, and has an active interaction with industry, national agencies, and local community groups. My research falls into four major areas:

• development of sustainable and innovative vegetation and planting design techniques
• the vegetation, planting and ecology of green roof systems
• rain Gardens and other landscape rainwater management features; d) long-term ecological monitoring

Current projects

2009 – 2013. EU Marie-Curie Industry Academia `Green Roof Systems´. Principal Investigator and Project Coordinator. £1.2 million over four years. 6 early career researchers (including 3 PhDs), 3 experienced researchers, and the exchange of permanent staff between the University of Sheffield and its industry partner in Germany, ZinCo GmbH.

2006 – 2009. EU Objective 1. `Green Roof Infrastructure Development Programme´. Principal Investigator and Project Coordinator. £820,000 over three years.

2010 – EPSRC Proof of Concept Fund. £825,000 over two years. Invesitgator.

Sustainable Planting Design

For the past 15 years I have worked to develop techniques for the application of ecological ideas, principles and techniques in the use of plants and vegetation in mainstream urban landscape contexts. This approach to urban planting, which combines native and non-native plant species in low-input systems based on semi-natural vegetation types, such as meadows, woodlands and wetlands, has come to be known as `The Sheffield School´ of planting design.

This work, undertaken in close collaboration with Professor James Hitchmough, has received much national and world-wide attention. The key concepts behind this approach are outlined in the book for which I was the principal editor and contributing author: Dunnett, N. & Hitchmough, L. (2003) The Dynamic Landscape: the ecology, design and management of naturalistic urban planting (Routledge, London).

The key aspects of this work, which differentiates it from that of other planting design specialists in the field of contemporary naturalistic planting design approaches, is that it is specifically focused on urban greenspace, and that it addresses the major practical issues involved in such a context: limited budgets and resources, and a relatively low skills base in terms of maintenance.

Working in an urban context at a wide range of scales means that biodiversity considerations are also highly important. However, in addition to satisfying environmental sustainability objectives, social sustainability is equally important: plantings, vegetations, spaces must be aesthetically acceptable.

Beauty, colour, seasonal change are prime considerations. By applying horticultural concepts to ecological plantings, and ecological concepts to horticultural plantings, the result can be very low-input plantings, with a very long season of visual interest, high biodiversity value, but which also, crucially, have a very high level of public approval.

In general this work involves species selection, research into establishment and maintenance techniques, the development of successful mixes of species to achieve aesthetic and functional objectives. Much of this work involves developing approaches to vegetating landscapes that are seed-based as well as plant-based.

I developed the concept of `Pictorial Meadows´ to describe the intention of a planting approach that was highly aesthetically driven, but which also had the dynamics, biodiversity and management advantages of meadow systems.

The concept works across the board in terms of developing alternatives to traditional herbaceous and perennial planting approaches: directly-sown annuals and perennials that produce dramatic, exciting and very colourful long-lasting displays in a very wide range of contexts, from small gardens through to extensive areas in urban parks, alongside highways and in housing areas.

Research work involves trialing and screening of suitable species, development of seed mixtures for different visual effects, testing establishment and management methods, and crucially, assessing public responses. The resulting seed mixtures are now used widely in the UK and other countries, and receive a great deal of media interest. I developed the concept Current work involves ongoing plant trails and selection, development of new mixes, and the application of technological approaches to delivering such plantings, such as the use of pre-grown vegetation mats.

Another field of activity is Mixed Shrub and Herbaceous Plantings. I have pioneered the use of coppicing as a maintenance technique in shrub plantings to enable long-season mixtures of woody plants and herbaceous perennials to co-exist. Current interests involve applying similar naturalistic principles that are now popular for perennial and ornamental grass plantings to mixed plantings of shrubs and perennials, and to the establishment of woodland ground flora amongst ornamental shrub

The planting and Ecology of Green Roofs

My main focus in this research is to investigate the potential of vegetation and planting on roof and building surfaces. Research ranges from work with native plant communities and species, through to vegetations composed entirely of non-native plants – and all combinations in between.

In 2000 I established the first trials and experimentation with green roof plants in the UK, with the aim of selecting plant species suitable for the UK climate. This work has led to an extensive programme of plant-based research.

At Sheffield we now have the largest international green roof plant screening programme, and are currently working on the biggest re-evaluation of green roof systems since the technology was first developed in Germany, to develop new vegetations and other components of the system to meet the challenges of climate change.

In 2004 I published with Noel Kingsbury the first English language book devoted solely to extensive green roofs (Planting Green Roofs and Living Walls, Timber Press). In 2003 the Department of Landscape hosted the first National Green Roof Conference in the UK, followed by a highly successful second conference in 2006.

In 2006 I secured EU funding to establish the Green Roof Research and Demonstration Centre at the University of Sheffield, which is now the UK´s main centre for multi-disciplinary green roof research. In 2009 I secured further EU funding (£1.2 million) for the project `Green Roof Systems´, which seeks a fundamental re-evaluation of green roofs in the context of global climate change.

This project supports 6 early career researchers (including 3 PhDs), 3 experienced researchers, and the exchange of permanent staff between the University of Sheffield and its industry partner in Germany, ZinCo GmbH. In addition to the Marie Curie students, at least 5 other PG students are doing green roof research at the University of Sheffield.

Plant evaluation projects relate to plant tolerance of substrate depth and moisture regime. Particular focus is on species from dry meadow communities in the UK, North America and continental Europe, and in plants from calcareous grasslands across the temperate world. Other work is investigating the long-term dynamics of green roof systems, and exploring the influence of vegetation type on green roof performance

Rain Gardens

This area of investigation explores the potential of managing rainwater runoff in a range of urban situations to promote rich and diverse plantings. Unlike many SUDS or low-impact applications, the focus of this research is on what can be done in limited space alongside buildings, and is closely linked to the green roof work.

I wrote, with Andy Clayden, the first international book on this topic (Rain Gardens: Sustainable Management of Water in the Garden and Designed Landscape, Timber Press, 2007).

Long-term dynamics of herbaceous vegetation

I am the current recorder and database manager for the Bibury long-term data-set (initiated 1958) - the most comprehensive long-term monitoring study of semi-natural grassland vegetation in the world. The work initially formed the basis of my PhD in collaboration with Professor Arthur Willis or the Department of Animal and Plant Sciences.

With the death of Arthur Willis in 2006 I am now the lead investigator. Leverhulme funding gained in 2004 to undertake detailed investigation of the database. The findings from this research are of direct relevance to the application of ecological ideas to the design and management of herbaceous plantings in parks and gardens.