Introduction to naturalistic herbaceous plant research

Since returning to the UK in 1993 after ten years of working in Australia, I have focused my research on how to create and manage flower (and species) rich naturalistic herbaceous plant communities for use in urban greenspace. Until the late C19th beautiful examples of semi-natural meadows, steppe and prairie were relatively common in many parts of the temperate world, but have mostly now been eliminated by agricultural intensification and urban development. They are now restricted to little visited places in mountainous regions and as fragments on road and railway margins. As a result, most urban people have no actual or even cultural memory of this vegetation other than as a photographic image in "nature" calendars. It is however, often extremely attractive to people when they see it “in the flesh”. This type of vegetation is often highly sustainable under appropriate climatic and edaphic context, and should be of great interest in contemporary urban environments. Scientific understanding of how to create and manage facsimiles of this herbaceous vegetation (“restoration ecology”) is limited but growing.

 

 

Lilium bulbiferum dominated mesic hay meadow, 1500m Val di Fassa, Dolomites, Italy

 

 

 

Iris lutescens and Euphorbia chariacas dry karst meadow, May, 1000m Gargano Peninsula, Puglia, Italy

 

 

 

 

Tall grass prairie in July, near Chicago, dominated by Echinacea pallida

 

 

 

 

Wet Northern hay meadow, dominated by Geranium sylvaticum and Persicaria bistorta, Richmond, UK

 

 

 



Wet meadow of Kniphofia caulescens, near Rhodes, Eastern Cape, South Africa, 2800m. Late January (mid summer).

Whilst I have worked in mainstream restoration ecology research (see Hitchmough et al., 1996 and Hitchmough, 2003) my real interest lies in how to use these naturalistic stereotypes as a framework that can be developed further by  design to create cultural vegetation for urban parks and other designed landscapes with a longer or more intense season of display. In these “synthetic” plant communities additional species may be incorporated that are not present in the original stereotype and species used at exaggerated densities in order to increase the drama of flowering. Alternatively entirely “un-natural” or “novel” combinations of species can be constructed where these have utility in a particular cultural setting. Creating these novel plant communities in practice involves combining design, horticultural and ecological perspectives in the production of new forms of planting design. This work presents a new research paradigm that bridges the traditional divide between ecological and horticultural (“cultural”) vegetation.


I have also attempted to re-think horticultural approaches to plant use which are dominated by the notion of optimising the site for the cultivation of chosen species. In my work the goal is to utilise the site largely as found and to achieve sustainable vegetation by ensuring good fit between plants and the ecological and physical conditions of the site. It is only under the most extreme levels of hostility (or sub-optimality) that this approach is potentially limiting.


These novel plant communities, created primarily by seed sowing in situ, are potentially highly attractive, sustainable, inexpensive to create and manage, and good for native wildlife. This work is seen by some as contentious as it uses exotic as well as native plant species at a time when exotic species are increasingly seen as vermin (see Hitchmough, 2008). Clearly exotic species are a significant ecological threat in many parts of the world and I have adopted a cautious approach in my work, avoiding species that demonstrate invasive traits. In contrast to the nursery industry and conventional landscape practice, I carry out detailed and lengthy (5-10 year) studies into all of the species I work with to assess regeneration from self sown seed, rhizomes etc., before using these species in practice. In the UK, concerns over invasibility are counter-balanced to some degree by the growing understanding developed from the work of Jennifer Owen (Owen, 1991) and the Biodiversity in Urban Gardens Study (BUGS) http://www.bugs.group.shef.ac.uk/BUGS1/bugs1-index.html  (Smith et al. 2005, Loram et al., 2007) of how many exotic species are extremely important for urban nature conservation, as well as being particularly attractive to urban citizens, and providing the opportunity to engage people in the natural world who might not otherwise be engaged. These dialogues have led me to be respond to some of the social and cultural factors underpinning attitudes to the use of native and exotic plants in landscape practice (Hitchmough, 2002). My work is unashamably a celebration of the richness of the cultivated flora and how this can be used to create pleasure and meaning for urban people (Hitchmough, 2006).


The process that I have adopted in the research is illustrated in Figure 1 below. It generally begins by asking some seemingly innocent “blue sky” questions about what types of designed plant community might be useful? and what might they be composed of? It’s important not to be inhibited by knowledge of what has been used in the past, as plantings that failed in the past often did so because of poor ecological understanding, not because they were fundamentally poorly fitted.   In many cases  this  first phase results in identifying individual species or groups of species which might seem of value in constructing a community. It is then necessary to investigate in detail the semi-natural communities from which these species naturally occur to synthesise an understanding of the ecology of these systems, and how these different ecologies can be reconciled (or not) in the new designed community under development. Often this involves identifying examples of the source communities in the wild and visiting them to gain a fuller understanding.
Basing the work at least initially within naturally occurring vegetation communities has the advantage of allowing me to borrow from current ecological research as well as providing an intellectual framework for plant selection and the application of the work to the world of practice. It also facilitates publication of scientific data generated from my work.  Once species of interest have been identified it is necessary to assess their likely availability as seed and then to evaluate germination and emergence requirements; resilience to competition and predation (especially from slugs and snails), and finally the competitive dynamics of these species within a community. This process often involves re-assessment of many genotypes,  as species often respond very differently as members of plant communities subject to potentially intense inter-specific competition, compared to how they perform under managed (i.e. reduced) competition in horticulturally founded plantings.  I have increasingly found it necessary to establish evaluation programmes to make comparative assessments of the various species under consideration as this sort of data is essentially absent from both the horticultural and ecological literature for most species. Where desired species are not commercially available as seed in quantity, I establish and maintain cultivated populations of these species for the purposes of seed production for use later in the research.

Figure 1 Key steps in the process of developing new naturalistic plant communities

The author investigating a grassland containing Dierama latifolium near Nottingham Road, KwaZulu Natal, South Africa.

Work on individual species commences at the scale of the growth cabinet, then moves to pot microcosms and finally to practice scale field experiments which often run for 5-10 years. This time period is necessary in most cases to develop and test effective management strategies to sustain the sown communities in the longer term. It is common to find that species that initially compete and grow well eventually decline, either as a result of competition with other plants or in some cases because herbivores such as slugs increasingly target a species. There is no point in developing new plant communities without also developing commensurate understanding of the detailed maintenance and management techniques necessary for long term sustainability.
Given the lack of skills and financial resources in UK urban parks and greenspace, I have sought to re-think traditional horticultural maintenance as applied to herbaceous plantings. I have looked to replace these principles and practices with far less intensive approaches borrowed from the management of semi-natural native vegetation, for example, cutting or burning (see Hitchmough and de La Fleur, 2006, Hitchmough et al., 2008). Horticultural maintenance can then be overlaid over this background management regime to “polish” communities where this is required.  My expectation is that in the current environment it is unrealistic to expect maintenance staff in practice to be able to distinguish between the sown species and all but the commonest weed species. Hence until this situation improves, techniques are needed whose success depends upon being applied at a particular moment in time rather than a particular point in space as is the case in horticultural maintenance. The focus of the work is therefore on the persistence of the community rather than on a particular individual or species. By making this change many of the resources necessary to maintain traditional herbaceous planting are greatly reduced. For a comprehensive, albeit somewhat dated overview of  the philosophy of the work  Dunnett and Hitchmough (2004) is recommended.
My ability to undertake this work has been greatly enhanced through collaboration with my colleague Dr Nigel Dunnett, and the Royal Horticultural Society who have generously provided space for experiments and in some cases technical support at their gardens at Wisley, Surrey and Harlow Carr in Yorkshire. The Stanley Smith Horticultural Trust has been a generous funder of some of the work. A substantial number of MA students from the Department of Landscape have helped with the research over the past decade and many are mentioned in subsequent web pages.

Dunnett, N., Hitchmough, J.D. (2004) The Dynamic Landscape, Design, Ecology and Manangement of Naturalistic Urban Planting. Taylor and Francis, London.
Hitchmough J.D., Curtain L., Hammersley L., and Kellow J. (1996) The effect of gap width and turf type on the establishment of the Australian forb Bulbine bulbosa. Restoration Ecology, 4,1, 1-9.
Hitchmough, J.D. (2002) Invasion of the habitat snatchers. Landscape Design, 311, 21-24.
Hitchmough, J.D. (2003) Effect of sward height, gap size and slug grazing on the germination and establishment of Trollius europaeus. Restoration Ecology, 11, 1, 20-28.
Hitchmough, J.D. (2006) What value exotic plant species? ECOS, 26, 3/4, 28-32.
Hitchmough, J.D., De la Fleur, M. (2006) Establishing North American prairie vegetation in urban parks in northern England: Effect of management and soil type on long term community development. Landscape and Urban Planning, Online at www.sciencedirect.com
Hitchmough, J.D. (2008) New approaches to ecologically based, designed urban plant communities in Britain: do these have any relevance in the USA? Cities in the Environment, Ecological Landscape Edition
Hitchmough, J.D., Paraskevopoulou, A, and Dunnett, N.  (2008) Influence of grass suppression and sowing rate on the establishment and persistence of forb dominated urban meadows. Urban Ecosystems, 11, 33-4
Loram, A., Tratalos, J., Warren, P.H. and Gaston, P. 2007. Urban domestic gardens. (X): the extent and structure of the resource in five major cities. Landscape Ecology, 22, 4: 601-615.
Owen, J. 1991. The Ecology of a Garden; The first Fifteen Years. Cambridge University Press.

Smith, R.M., Warren, P.H., Thompson, K., Gaston, K.J. (2005) Urban domestic gardens (VI) Environmental correlates of invertebrate species richness. Biodiversity and Conservation, Online First.