Environmental Horticulture

Science and Management of Green Landscapes

Ross Cameron, James Hitchmough

• Publisher: CAB International
• Year: 2016
• ISBN:
  9781789244724
• Topic: Biowissenschaften
• Subtopic: Gartenbau

Environmental horticulture - also referred to as landscape horticulture and amenity horticulture - is the umbrella term for the horticulture that we encounter in our daily lives. This includes parks, botanic gardens, sports facilities, landscape gardens, roundabouts, cemeteries, and shopping centres - any public space which has grass, planting and trees. A complete and comprehensive guide to an area most of us take for granted, Environmental Horticulture: - Comments and critiques contemporary thinking on the subject- Explores the role, value and application of horticulture in different landscapes- Reviews the importance and impact of horticulture on the wider environment- Covers practical management advice for categories of environmental horticulture such as turf grass, bedding plants, trees, grasslands and green roofsA vital resource for undergraduate and postgraduate students, this book is also a valuable addition to academic departments with an interest in green space management and wider environmental issues.

1 Introduction to Environmental Horticulture: Issues and Future

JAMES D. HITCHMOUGH

Key Questions

• What is environmental horticulture?

• What is urban green infrastructure?

• How does environmental horticulture differ from conventional ecological thinking and concepts?

• What is meant by native and non-native flora – what are the potential problems associated with defining plant populations by national/political boundaries?

• What might you consider as ‘ethical’ and ‘non-ethical’ planting?

• What are some of the challenges that the environmental horticultural profession faces?

1.1 Defining Environmental Horticulture

This chapter attempts to put environmental horticulture into context. What are the core values of this discipline? Where does it come from? Where does its future lie? The expression ‘environmental horticulture’ first begins to appear in the literature and educational course terminology in the 1980s, particularly in North America. It is gradually adopted as a term for the subset of horticulture that is concerned with the use and management of plants in public and semi-public environments. In some parts of the world it replaces the term ‘urban horticulture’, although in many cases these descriptors co-exist for long periods of time, and in essence cover the same territory. In the UK, the words ‘environmental’ and ‘urban’ never really catch on as course descriptors, with the much older term ‘amenity horticulture’ tending to persist right up to the present day. These days in North America and elsewhere, ‘landscape horticulture’ is often the preferred term used to cover the planting and maintenance of landscape plants in public or private space.

At one level these terms are just about marketing and branding, trying to present a modern, culturally responsive face to compete in the educational marketplace for students. At another level these newer names signify changing ideas within this branch of horticulture. In the UK the term ‘amenity horticulture’ first emerges in the 1970s to denote the horticulture that is concerned with public and semi-public landscape spaces, as opposed to various forms of crop production. This particular term develops at the same time as recreation and leisure management and reflects a view of the world where this strand of horticulture exists to provide leisure or amenity benefits to citizens through the cultivation of plants in public landscapes (largely urban) visited by the public. The 1970s and 1980s witnessed substantial changes in how horticulture interacted with plants in public spaces. The emergence of landscape architecture as the dominant design discipline in public spaces greatly reduced the role of horticulturalists in plant use decisions, particularly on new build, or other capital intensive projects. There were also significant changes within, for example, local authority parks departments, which led to a diminution of horticultural ambition and capacity.

The first of these changes in the UK were a result of the Bains report (1972) which identified just how inefficient the delivery of many local authority services were, including parks. This led to experimentation with new forms of service delivery that has continued because of changing political philosophies, up to the present day (Byrne, 1994). The first of these was the shift from the standard day labour model, an approach modelled on the hierarchical organization of private estates of the landed gentry in the 19th century towards incentive bonus schemes. The former traditional organizational structures are based around chains of command, designed to highlight who is responsible for what, whilst developing horticultural skill. These systems did not necessarily maximize work rate, and hence the Bains report led to incentive bonus schemes. These were derived from 20th century industrial work study and placed much more emphasis on productivity; all tasks were allotted a time tariff for how long it should take to complete them. Staff received bonus payments where they demonstrated they had undertaken these tasks more quickly than the tariff. This attempt at modernization of service delivery also involved new forms of organization; horticultural service providers ceased to be fully in charge of their own future, in many cases becoming components of much larger departments, concerned with amenity and leisure in a much broader context. These changes can be seen in the marked shift in the content and tone of the articles published in the Parks and Recreation Journal in the UK during this time; from being dominated by detailed horticultural matters to much greater emphasis on the ‘management of the recreational experience’ in which horticulture becomes a relatively minor part.

With the benefit of hindsight, incentive bonus schemes proved to be unsuccessful in improving productivity in a way that was useful, with a tendency to be highly bureaucratic and to corrupt work priorities by favouring tasks that attracted the highest bonus payments.

In other parts of the world, such as North America, which have different horticultural traditions, based less on the gardenesque style of park of 19th century Britain, urban horticulture develops in the 1970s. From the personal perspective of the author, at this time, urban horticulture seemed more modern in its perspective. The name explicitly recognized that urban places were often more biologically challenging places in which to grow plants than were ‘gardens’ or ‘green sward parks’. This was due to, for example, higher levels of atmospheric pollution, soils destroyed by engineering and construction activities, sealed surfaces, changed urban climatic regimes, and sometimes hostile social contexts such as vandalism and other forms of antisocial behaviour. Urban horticulture also explicitly made connections with the human social, cultural and psychological realm. Horticulture is engaged in and practised because it can make us feel better about our lives; it provides complex stimuli in both time and space that constructively moderates the fundamentally highly artificial experience of living in cities. In cities (and indeed in rural areas too), horticulture, whether practised by green-space professionals or home gardeners, is likely to provide the most immediate experience of ‘nature’, the patterns and processes associated with interactions between the physical world of our planet and the living organisms that have evolved in response to this.

Environmental horticulture is intrinsically linked too to the management of urban green space or green infrastructure, although these terms (see Box 1.1) may encompass woodland and other less intensively managed areas. As such they may not be the exclusive ‘domain of the horticulturalist’.

What about ‘environmental horticulture’? The exact origin of this term is uncertain, but it seems to represent an attempt to reposition horticulture to become more open to many of the ideas that developed from the 1990s onwards about biodiversity and ecological processes as well as the previously discussed human-centred ideas. In countries where the emergence of ecological consciousness had begun to lead to a wedge between ecological and horticultural thought, environmental horticulture provided a new paradigm whereby the practices involved in cultivation could be applied to systems that might, for example, consist of entirely native plants that would be seen as appropriate by ecologists. There is also an undercurrent that environmental horticulture should and does embrace more ‘environmentally benign’ actions and procedures that conform to an environmentally sustainable agenda. This includes reduced use of pesticides, use of biological control methods and seeking alternatives to peat and other ‘non-sustainable’ resources. Environmental horticulture has also been linked to ecosystem services, and the ability to deliver benefits to humans through the use of plants. This is particularly relevant to an urban environment, where ‘horticultural’ landscapes and plantings may be used to regulate water flow, improve water quality, alter microclimate or provide cultural services through opportunities for education, physical exercise, contemplation or creativity. Although environmental horticulture is not large-scale commercial field crop production, it does embrace food/human linkages through the likes of community gardens, allotments, edible walls and guerrilla gardening.

Box 1.1. What is meant by open space, green space and green infrastructure?

Open space is any open piece of land that is undeveloped (has no buildings or other built structures) and is generally accepted as being accessible to the public. Typical open spaces are school playgrounds, public squares and plazas, pathways, public seating areas, and vacant areas of even brownfield (ex- industrial) sites.

Green space is a form of open space. This is land that is partly or completely covered with grass, trees, shrubs, or other vegetation. Green space includes parks, community gardens and cemeteries. Green space, however, also comprises land that may not be always open to the public, such as private gardens and certain sports facilities, e.g. golf courses or soccer pitches.

Green infrastructure is the term used to combine different forms (typologies) of green space and is often used in conjunction with urban green spaces, i.e. as a juxtaposition to built (grey) infrastructure. It implies a matrix of green spaces and typologies, and increasingly one that is intentionally or strategically planned. It also alludes to the services such spaces should provide to local (human) populations. This includes its role in housing and economic growth, the regeneration of urban areas and the protection (or creation) of environmental assets and the underpinning of the sustainability of a town or city.

Natural England, the Government body in England, UK, tasked with nature conservation and the management of National Nature Reserves defines green infrastructure as: ‘a network of multi-functional green space, both new and existing, both rural and urban, which supports the natural and ecological processes and is integral to the health and quality of life of sustainable communities’.

Included within green infrastructure typology are:

• Natural and semi-natural urban green spaces

○ woodland and shrubs, grassland (e.g. downland and meadow), heath or moor, wetlands, open and running water, wastelands and disturbed ground, bare rock habitats (e.g. cliffs and quarries)

• Parks and gardens

○ Urban parks, country and regional parks, formal gardens

• Amenity green space

○ Informal recreation spaces, housing green spaces, domestic gardens, village greens, urban commons, pocket parks, other incidental space, green roofs, green walls

• Green (and blue) corridors

○ Rivers and canals, including their banks, road and rail corridors, cycling routes, pedestrian paths, bridleways and other rights of way

• Other areas

○ Allotments, community gardens, urban farms, cemeteries and churchyards

1.2 Horticulture Involves Human Agency

Whilst environmental horticulture covers a wide range of theoretical and practical territory, at its core lie the same practices and understandings of cultivating plants to achieve clearly defined goals. Implicit in the idea of cultivation is that human decision making, ‘agency’, is consciously applied, both as thought and action. This agency may vary from being very occasional through to frequent, but potentially significantly impacting the life of a given plant and/or synthetic plant community that it is part of. This agency process often commences through making decisions on which plants can be used in which environment, indeed in a rational world environmental conditions of the planting site should be one of the main factors in plant selection, and this is discussed further subsequently in this chapter. Agency is applied in varying degrees to different circumstances, often involving the manipulation of water, nutrients, light and physical removal of plant tissues to control the rate and form of growth, the degree to which plants flower and fruit, and how plants are likely to be perceived by people. The use of these manipulation levers can be either intensive or extensive, sophisticated or crude, i.e. there are inherent gradients across which decision making can or must be made, depending on the needs of the location or context, and the resources that are available to decision makers.

At the low intensity end of the spectrum rather blunt forms of management, such as the non-selective cutting off of plant parts, may be used to nudge a plant or a plant community in a chosen direction. This issue of choice and decision making is critical to understanding the horticultural mind-set. Within horticulture, choice, agency, or decision making, call it what you will, is seen as an intrinsic part of the process; essentially as a ‘good’, whilst recognizing that no one input or outcome is appropriate in all situations.

Environmental horticulture and relationships with pure (purist) ecology

The involvement of human agency within environmental horticulture is the prime distinction from parallel disciplines that are concerned with plants, for example conservation ecology or restoration ecology. Depending on who is practising these activities, and in what context, there is also a gradient in terms of how much human agency can be applied, but in general it is much less in total, and often restricted to forms of management which work to kick-start or direct an ecological process, for example, increasing light at ground level in a plant community to benefit particular species by canopy removal. These processes inevitably disadvantage some species in order to benefit others. There are winners and losers, at least temporally.

Horticulturalists tend to find this a little disturbing; in the horticultural paradigm there is a desire to achieve some form of equivalence of benefit, i.e. managing in order to avoid the creation of obvious losers. This notion of ‘care’ is much more remote in conservation ecology or restoration ecology than in environmental horticulture, even when the latter are practising these same activities. Indeed, because these former disciplines are philosophically deeply rooted in the idea that human agency typically corrupts or damages the organisms and processes that we call nature, they are fundamentally uncomfortable or even hostile to the application of human agency to vegetated systems. This is most strongly developed in large, recently settled (by Europeans) countries with a strong ‘wilderness construct’. It is least developed (but still present) in countries with a long and obvious inter-relationship between the natural vegetation and people through various forms of low intensity agricultural exploitation and management.

Within ecological science dialogues, ‘gardening’, i.e. the intense and prolonged application of agency to plants, is often used as a pejorative, rather than a positive concept. These polar views explain why traditional ecological science is sometimes philosophically uncomfortable with the horticultural utilization of plants; it seems at best pointless and at worst almost decadent.

Horticulture, by contrast, is not at all embarrassed by human agency; it recognizes that human beings can obtain great pleasure and sometimes much deeper psychological states such as meaning, through application of their own agency and that of others. By adding another trophic level of interaction (human agency) to the ecological food web, it is possible to achieve endpoints that are impossible through the rather narrow and blinkered processes that underpin conventional ecosystem development. Within the limits of what is possible, horticulture can choose, it does not have to be insular and dogmatic!

But choose what? Within ecology and botany, the development of increasingly comparative taxonomy linked to effective field survey and vegetation sampling from the early 18th century onwards, allows the construction of reliable lists of the native plants that make up the plant communities of a given region. These lists or ‘floras’ do, within a strictly ecological view of the world, circumscribe our choices for us. Deviation from these lists, in terms of species selection, is increasingly seen in the contemporary world of biodiversity as inappropriate, unethical or even plain ‘bad’. In the ‘wilderness’ countries recently settled by Europeans – such as the USA, Australia and New Zealand – this process has been in operation to some degree since at least the 1970s, but is increasingly prevalent even in long-settled countries as a re...