Sustainable landscape design |
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It's our view that every landscape design should follow sustainable principles. We take our cue by studying the way in which natural ecosystems are organized. We could take one of many natural ecosystems as a model, but the figure below shows a patch of Mallee scrub in South Australia. The soil here is poor (it is low in phosphates and trace elements) and the rainfall is less than 350 mm per year. One species of Eucalypt (a multi-trunk Malle tree) dominates the upper story, 2-3 species, an Acacia and Senna artemisoides are the mid level shrubs and Spinifex grasses and Blue bushes (Kochia sedifolia) make up the understory plants. Note the bare areas where competition keeps plants from establishing.
The figure below shows a designed and constructed landscape. The selection of species, placement etc. is modelled on the above. Here a sustainable landscape has been created - one in which the plants are adapted to the local soil and climate conditions so no additional fertilizer or watering is required. The landscape sustains itself, just as the natural one does.
So, to sum up, a sustainable constructed landscape:
Here is some more information on sustainable landscape (much of the following has been adapted from a publication of the Adelaide Botanic Gardens).
Plant selectionOur students get to know their plants very well. Here are a few of our favourite Australian species that grow well in arid areas and contribute to sustainability.
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Senna artemisoides
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This shrub grows up to 3 metres in height. It has pinnate leaves with between 1 and 8 pairs of leaflets and produces an abundance of yellow flowers in winter and spring which are about 1.5 cm in diameter, followed by 2 to 7 cm long flat green pods which age to dark brown. The species adapts to a wide range of climatic conditions, although it is susceptible to frost, particularly when young. It prefers dry, well drained sites with full sun.
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Habitat creation
Through careful design and plant selection, habitat can be provided for a diversity of native fauna. Land clearance in urban areas has led to the decline of many species of birds, insects, lizards, frogs and small mammals. Parks and gardens provide food and shelter for many animals that may inhabit a garden fulltime or use it as a stepping-stone between remnant habitat areas. Native fauna benefit the garden by keeping unwanted pest populations under control, pollinating plants and helping to sustain a mini-ecosystem.
Ways to provide habitat:
• Include a variety of plant species, including some local indigenous plants as they are most likely to provide habitat suitable for local native fauna.
• Ensure that something is flowering all year round and include nectar-producing plants for birds and butterflies.
• Select plants with varying heights and habits to create layers.
• Include some dense prickly shrubs for shelter and protection for small birds.
• Include grasses and daisies for butterflies and caterpillars.
• Fallen branches, logs and rocks provide excellent shelter for small lizards.
• Protect garden habitat from cats and dogs, especially at night.
• Provide a water source, such as birdbath or shady pond.
Pesticides and other chemicals While pesticides may get rid of unwanted animals and plants in your garden, they often affect non-target species as well.
Under storey, groundcover plants and soil provide habitat for many beneficial insects and micro-fauna that keep the soil healthy, recycle dead matter, and provide an essential food source for birds, frogs, lizards and bats.
Over-use of chemicals can also harm local waterways and lead to health problems in humans.
Ways to avoid over-using pesticides and other chemicals:
• Select pest resistant plants that suit local conditions.
• Use organic rather than synthetic fertilisers (organic fertilisers improve soil structure) and avoid over-fertilising plants.
• Identify pests or diseases before selecting a control method and investigate the alternatives.
• Target the identified pest and ensure that chemical product does not come in to contact with anything else.
• Only use chemicals with a low toxicity level, apply the recommended dose and avoid using them before rain or in windy conditions.
Energy
It is a myth to think that a sustainable park or garden will not require any maintenance; every garden needs some looking after. Design, plant selection and choice of
materials will largely determine the level of maintenance required. A sustainable garden is designed to minimise the use of non-renewable energy-powered tools such as lawn mowers, trimmers and chain saws.
To minimise the energy consumption and greenhouse gas emissions from transporting materials over large distances, either from within Australia or from overseas, ensure that your garden products and materials are locally sourced.
Garden materials
A sustainable garden incorporates the thoughtful use of materials such as timber and rock. For example, the removal of moss rocks, river pebbles, rainforest or old growth timber from bushland or waterways can lead to erosion and loss of important habitat. Use of these materials in gardens is unsustainable.
Many innovative recycled products such as soil, mulch, waterwells, pavers, stakes and furniture are now available. Only use local plantation or recycled timbers. Ensure rock and pebble products are sourced from local, licenced suppliers.
Reference: Paper on sustainable landscapes:
Project - sutainable principles in an informal garden
Use GardenCAD to design a space using the priciples set out above.
Project- sustainable principles in a formal design
Construct a GardenCAD drawing based on the image below. Use your own judgement as to sizes, select your own locatin and populate your design with species adapted to the site.
