The aliens have landed! What are the justifications for ‘native only’ policies in landscape plantings?

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Abstract

Interest in landscaping with native plants has grown rapidly in recent decades, but there is also a rise in ‘native only’ policies where attempts are made to exclude introduced and exotic species from landscape schemes. This paper reviews the issues associated with the use of native and exotic plants in the landscape by looking at a range of philosophical as well as technical issues. The definitions of native and alien status reveal that the concept is not founded on hard science, as often implied, but reflects a set of value judgements about the timescales of environmental change and forms of human impact regarded as acceptable within the landscape. However, the definitions can be said to generate conflicts that cannot be resolved as environmental change and human impacts are inevitable.

Native plants are believed to be superior to introduced species because of their better growth, reduced likelihood to become invasive, their indirect and direct biodiversity value and their contribution to local sense of place. In all cases there are exceptions where non-native species play an important role.

Introduction

Interest in landscaping with native plants has grown rapidly in recent decades, but there is also a rise in ‘native only’ policies where attempts are made to exclude introduced and exotic species from landscape schemes (Kendle and Forbes, 1997). This paper reviews the issues associated with the use of native and exotic plants in the landscape by looking at a range of philosophical as well as technical issues. As will become evident, these cannot be separated, indeed it is the determination to do so that is sometimes at the root of many environmental problems and false solutions.

The subject merits an initial consideration of the very concept and definitions of ‘native’. We tend to use the terminology of native and exotic or alien as if these words represent a concrete reality that needs no explanation, but actually there are complex issues that need to be addressed. The very search for a definition that people feel accurately reflects their position tells us much about their implicit values and assumptions, and it is beyond doubt that this is a subject that is heavily value-laden.

Section snippets

What are the definitions of native?

Whilst everyone recognises the broad meaning of the concept of native, finding agreement about the definition in a way that allows for consensus about detail is not easy. Webb (1985) reviewed the issue of how native is defined within the context of the UK and Ireland and proposed the following that seems to encompass the generally accepted usage of the term native in the UK: a native plant is one that has arrived before neolithic times, or has arrived since without human agency.

This definition

Functional implications of nativeness

Of course definitions and philosophies are often muddy when dealing with the complex realities of the natural world and arguably the more important issue is the functional importance of the native/alien classification. Let us, therefore, accept even the most conservative concept of native. Why is the distinction significant?

There are five common arguments that are forwarded concerning the importance of native plants and the dangers of introduced aliens or exotic species (Hitchmough and Dunnett,

Conclusions

The above functional critique of the importance of native plants in the landscape amounts mostly to an illustration of how, in a complex environment superimposed with equally complex human history, culture, values and aspirations, it is impossible to characterise one group of plants as ‘superior’ than others. This is especially true when the classification system is as nebulous and as value-laden as our definition of native. In essence it is clear that all of the arguments given to favour the

Anthony (Tony) D. Kendle is lecturer in landscape management in the Department of Horticulture and Landscape of the University of Reading, UK. He holds a Ph.D. in restoration ecology from the University of Liverpool and a B.Sc. (Hons) in Horticulture from the University of Bath. He is a member of the Institute of Ecology and Environmental Management and sites on the research sub-committee of the Landscape Institute UK. Research interests include restoration of conservation value on degraded

References (65)

  • J.S. Dukes et al.

    Does global change increase the success of biological invaders?

    Trends Ecol. Evolution

    (1999)
  • Akeroyd, J., 1994. Seeds of destruction. Plantlife,...
  • Anon, 1991. Plant more British trees says Society. Horticulture Week 209 (24)...
  • N. Brown

    Re-defining native woodland

    Forestry

    (1997)
  • Brown, P., 1999. Moorland succombs to advance of purple grass. The Guardian 7th...
  • Budiansky, S., 1995. Nature’s Keepers. Weidenfeld and Nicholson,...
  • M.A. Burgess

    Cultural responsibility in the preservation of local economic plant resources

    Biodiversity and Conservation

    (1994)
  • J.B. Callicott

    The wilderness idea revisited: the sustainable development alternative

    Environ. Professional

    (1991)
  • Cleveland-Peck, P., 1999. Summoned by Bells. The Sunday Express Magazine, 23rd May 1999, pp....
  • J.E. Cottrell et al.

    The use of RAPD analysis to study diversity in British black poplar (Populus nigra L. subsp. betulifolia (Pursh) W. Wettst. (Salicaceae)) in Great Britain

    Watsonia

    (1997)
  • J.E. Cousens

    Variation of some diagnostic characters of the sessile and pedunculate oaks and their hybrids in Scotland

    Watsonia

    (1963)
  • M.B. Davis

    Lags in vegetation response to greengouse warming

    Climatic Change

    (1989)
  • Duffey, E., 1974. Nature Reserves and Wildlife. Heinemann Educational Books, London,...
  • Fenster, C.B., Dudash, M.R., 1994. Genetic considerations for plant restoration. In: Bowles, M.L., Whelan, C.J. (Eds.),...
  • Flora Locale, 1997a. Definitions: British native-origin plants for landscaping, conservation, forestry and amenity...
  • Flora Locale, 1997b. Putting wild plants back where they belong: what to plant and where to plant it (restoring native...
  • Forestry Commission, 1997. Consultation Paper on Sources of Planting Material for Native Woodlands. Forestry...
  • R.A. Garrott et al.

    Overabundance: an issue for conservation biologists?

    Conservation Biol.

    (1993)
  • Gilbert, O.L., 1989. The Ecology Of Urban Habitats. Chapman & Hall,...
  • Gilbert, O.L., Anderson, P., 1998. Habitat Creation and Repair. Oxford University Press,...
  • Gordon, A., 1998. Whence British trees? Tree News Autumn, 1998, p....
  • Green, B., 1996. Countryside Conservation, 3rd Edition. E & FN...
  • Harding, P.T., Rose, F., 1986. Pasture Woodlands in Lowland Britain. Institute of Terrestrial Ecology, Abbots...
  • K. Havens

    The genetics of plant restoration: an overview and a surprise

    Restoration and Management Notes

    (1998)
  • J. Hitchmough et al.

    Sustainable planting schemes. Landscape Design

    (1996)
  • G. Hottentrèger

    New flowers new gardens

    J. Garden History

    (1992)
  • Huenneke, L.F., 1991. Ecological implications of genetic variation in plant populations. In: Falk, D.A., Holsinger,...
  • Jordan, W.R., 1994. ‘Sunflower forest’: ecological restoration as the basis for a new conservation paradigm. In:...
  • A.T. Jones et al.

    A comparison of the growth and morphology of native and commercially obtained continental European Cratagus monogyna Jacq. (Hawthorn) at an upland site

    Watsonia

    (1994)
  • Katz, C., 1998. Whose nature, whose culture? Private productions of space and the ‘preservation’ of nature. In: Braun,...
  • M. Kellman

    Redefining roles: plant community reorganization and species preservation in fragmented systems

    Global Ecol. Biogeography Lett.

    (1996)
  • Kendle, A.D., Forbes, S., 1997. Urban Nature Conservation. E & FN Spon,...
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    Anthony (Tony) D. Kendle is lecturer in landscape management in the Department of Horticulture and Landscape of the University of Reading, UK. He holds a Ph.D. in restoration ecology from the University of Liverpool and a B.Sc. (Hons) in Horticulture from the University of Bath. He is a member of the Institute of Ecology and Environmental Management and sites on the research sub-committee of the Landscape Institute UK. Research interests include restoration of conservation value on degraded land and urban nature conservation.

    Juliet E. Rose is a Ph.D. research student in the Department of Horticulture and Landscape of the University of Reading, UK. She holds an M.Sc. Degree in Horticulture (Distinction) from Reading, and a B.Sc. (Hons) in Biological Sciences with specialisation in Plant Sciences from Kings College, the University of London. Her areas of research address the restoration of degraded and desertified land on islands, and the response to changing environments and land use capabilities.

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