The Role of Architectural Design in Promoting the Social Objectives of Zoos

A Study of Zoo Exhibit Design with Reference to Selected Exhibits in Singapore Zoological Gardens

by Michael Graetz


2.2 Exhibit Planting

This dissertation explores the thesis that the exhibit serves the social objectives of zoos best by depicting animals in as correct a context as possible. Therefore, the planting of such ‘habitats’ must be the most critical element. Given that zoos generally deal with exotic wild animals, exact floristic replication of habitats is not usually possible.

Thus, the principles of planting zoo exhibits involve increasing compromises with the achievement of habitat correctness, using whatever plant material that is available. This chapter reviews some aspects of plant selection and placement for this purpose and refers to other functional uses of plants.

Planting Principles for Landscaping Zoo Habitats

The design of zoo exhibits to represent habitats may be totally unnatural to animals.[1] Plants play a role, specified by the zoologist/curator, in achieving the habitat needs of animals, but enclosures are not true habitats and are not managed in the same way. Planting must give the visual appearance of the habitat and cope with animal management, including increased stocking density and the manipulation of behaviour to ensure visitors can see the animals. What then is required to achieve the appearance and some functionality of wild habitats?

Since nature is the role model, an understanding of the structure of botanical environments is necessary. Then we require a knowledge of the capabilities and impact of the captive animals so that some balance between the two can be found. The large number of species in a typical zoo usually comes from a variety of habitats and niches. An enormous amount of learning is demanded if the designer or horticulturist wishes to be faithful to them all. A strong tendency exists to simplify. For example, Singapore Zoo places West African animals in a generic jungle setting, or East African animals in a savannah. Good habitat simulation requires knowledge got second-hand or, ideally, observations of the habitat made first hand. Creating a visual impression of a natural landscape that the designer has not seen is not easy. Short of this, good graphic and visual media resources are essential.

Natural influences on plant communities. Many factors, from the global to the most local, influence the patterns of vegetation in nature. The underlying rock, often expressed as surface features also characterises the soil types, which in turn influence the flora, and the fauna, in a given region. Soil characteristics important for plants are water holding capacity, drainage and aeration, fertility and mechanical support[2]. Other characteristics include the following: acidity/alkalinity, salinity, organic content, granular structure, colour, soil horizons. The soil horizon may be thin over bedrock or have a thick or thin humus layer.

Tropical rainforests, for example, are characterised by thin topsoil but a great deal of humus. However, forest trees tie up much water, energy and nutrients. Foster states that tropical lowland forest contains significant "edaphic variation" (i.e. due to the influence of soils)[3] and therefore, they are not as uniform as is often supposed.

Spacing, species, succession. In any natural landscape, a characteristic collection of plant species will coexist, forming a plant community. Not only are the species characteristic: so too are the distribution and frequency with which various plant species occur. These patterns are not fixed and change over time. We call this process ‘succession’ in which later colonisers overtake the pioneer species as the latter change the conditions. Eventually, the community will stabilise, but various natural and manmade events will continue to be a cause of change[4].

This introduces the idea that planted landscapes may look natural because they resemble plant communities that have come about through succession.

planted moat edge
Fig. 16 A moat edge concealed by planting

A major difference between many natural and artificial planting schemes is that nature does not arrange plants randomly; nor does it space them regularly. Often, our intuitive idea of randomness is wrong: random dots to many means “equally spaced”. In many instances in nature, however, distances measured between objects--whether plants or pebbles on a beach--vary exponentially, producing the appearance of clustering. Horticulturists often base sound practice on the idea of optimum spacing for the best plant growth, which tends to uniformity. Wild plants grow where their various dispersal techniques find at least minimally acceptable conditions. Ornamental gardeners also favour ‘showy’ plants over ‘weedy’ types, and plant mono-cultural beds or uniform mixes. Typically they have abrupt breaks to beds with different colours or textures. The reason for these arrangements is usually simply ornamental display.

visitor worn planter
Fig. 17 Failure of a plant barrier caused by visitors...
keeper worn planter
Fig. 18 ...and by keepers

Zoos have not applied ornamental horticulture within exhibits so much for several reasons besides the lack of respect many animals have for plants. Until recently, zoos treated areas outside the enclosure proper as divorced from the exhibit. The greatest scope for development of habitat themes in recent times has thus been on the public side of the enclosure barriers. Wourms remarks that, “Immersing the visitor in the exhibit is a straight forward exhibition concept that can be difficult to accomplish”, due to visitor abuse, close examination by visitors and shortage of space[5].

crib wall moat
Fig. 19 A well grown crib moat wall in the Komodo dragon (Varanus komodoensis) exhibit

The greatest difficulty in simulating habitats with planting remains, however, within the enclosure. Polakowski advocates an experimental planting design approach. This should use the “ecological principle of species diversity” as a guideline.[6]

Zoo habitat-type planting represents particular plant communities at a particular stages. Over time, the planted display will itself be subject to succession as the hardier plants overtake weaker plants. The widely practised principle of low maintenance gardening arises from an attempt to go straight to the ‘climax’ vegetation, creating the stable community from the beginning. In most countries, this means working with the local flora as the best adapted to the climate and conditions. Zoos can use this principle strictly only when working with local fauna; however, it is still valid when dealing with exotic fauna, even from different climates, if they use the concept of simulator species--local species resembling plants from the animal's habitat or occupying a similar niche or function in that habitat.

Functional uses of plants. Habitat simulation is the ultimate goal of planting, but several basic needs have to be met along the way. Among these are shade for visitors and animals; cover for the animals, other behavioural needs of animals, depending on the species; visual barriers for animals to avoid other animals; deterrence from escape, in some species; symbolic value; modulation of views and perceptions; and definition of space for people and animals. Plants serve to hide undesirable objects, screen potential cross views and bad views beyond; where screening of barriers etc. is not possible, shading, especially dappled shade, can obscure the object. They can help position animals by controlling animal paths; providing resting perches and/or shade toward the front; and provide limited browse[7].

Another result observed in Singapore Zoo through planting is the control of soil-borne diseases among arboreal primates. Very dense and tall ground cover (typically Napier grass, Pennisetum purpureae) prevents contact with soil and, incidentally, coprophagy on the islands in ‘Primate Kingdom’. This is because the faeces are lost either in the vegetation or, in the enriched botanical environment, the monkeys have lost the desire to consume faeces[8].

rat snake
Fig. 20 Planting for animals' needs: Rat snake (Ptyas korros) sheltering in a pandanus

Selection of Plants for Use in Exhibits

Reference to the Pygmy Hippo display gives an idea of the process of plant selection in Singapore Zoo. The display theme is aquatic and the habitat represented is West African riverine forest. This is broadly similar to the lowland rainforest characteristic of the region in which Singapore is situated. Many plant families have representatives species in both regions, or have pan-tropical species. Furthermore, many plants are introduced species from both tropical Africa and the Americas. This makes a suitable selection relatively easy.








Adenanthera pavonina


Curculigo latifolia


Alstonia scholaris


Musa spp.


Antidesma bunius


Zingiber spp.


Ardisia littoralis (elliptica)*

Costus spp.

Barringtonia asiatica

Putat laut*

Polygonum barbatum

Bauhinia purpurea


Brassaia actinophylla

Austral. ivy palm

Alpinia spp.

Caesalpinia ferrea

Brazilian ironwood

Calathea spp.

Fagraea fragrans


Dracaena fragrans

Ficus elastica

India rubber tree

Dieffenbachia spp.

Ficus lyrata

Monstera deliciosa

Saraca thaipingensis


Spathiphyllum spp.


Pandanus spp.*

Acalypha hispida

Cat's tail

Thaumatococcos danielli

Duranta spp.


Plumbago capensis

Asplenium nidus

Bird's nest fern

Evodia ridleyi

Nephrolepsis exaltata*

Excoecaria bicolor (poisonous)

Platycerium spp.



Cyperus compactus

Monochoria spp.*

Cyperus kyllingea

Cyperus papyrus

Paspalum spp.

Nymphaea spp.

Water lilies*

Ischaemum muticum


Panicum repens

Thunbergia alata

Congea tormentosa

Bignonia spp.

Petraea volubilis

*Local species.

Table II gives a list of readily available plants initially selected for the Pygmy Hippo exhibit in Singapore Zoo. Singapore faces a similar difficulty to that faced by temperate zoos choosing plants for tropical species when displaying a temperate animal. However, as Corner remarks, many a well-known temperate plant, “as one so frequently has to learn, [is] only an outlying representative of a large tropical family”[9]. The oak family is an example. The reverse is also true, as with, for example, conifers--the climax vegetation of certain types of temperate habitats. Araucaria and Podocarpus represent conifers in this region, but some Pinus are introduced1[10]. Cypress pines and Junipers also offer simulation possibilities.

Douc langur
Fig. 21 Douc langurs Pygathrix nemaeus in 'Primate Kingdom'

Habitat simulation serves not only a decorative purpose, but a didactic one too. Plants portray the context of the animal, show the ecological community, and are specimens in their own right. Wall suggests spectacular plants or plants with a “good” story be considered1[11]. A whole, created plant community could extend this story telling idea.

Concluding Remarks

As with zoological issues, the architect will usually have to work with a zoo horticulturist, even when a landscape architect is involved. Finding out the planting practices of the past will be necessary, to discuss their appropriateness for the current project and explore possible alternatives. The consultant team may be eager to implement new approaches, but as with animal management, a great deal of experience resides in the zoo to which the team should listen.

'hartebeest moat
Fig. 7 Moat with temporary fence to condition the animals (hartebeest)

Another relationship is that between architects and landscape architects. They need to attune themselves to the concerns of the other. If both are fully committed zoo designers, all should be well, but both professions otherwise have ingrained belief systems quite different from zoos. Architects, often by training, think of plants as adornments to their buildings. Landscape architects too may be ignorant of the requirements of habitat simulation. Just as architects treat buildings, so they treat landscapes symbolically, imbued with (human) meaning and architectural formalism. Informal naturalism in this context is not necessarily the same as wilderness.

Top Previous Next