In an ideal world, a sustainable landscape is one which is low maintenance, does not require substantive amounts of watering and includes a diverse range of flora and fauna. It should also use recycled materials where possible. But the entire picture is a much more complicated affair.
"A sustainable landscape must first be functional and maintainable. In addition, the proper design of plants and related hardscapes greatly affects the quality of that landscape over its entire life. For example, a philosophy of 'right plant right place', as well as 'right plant right purpose' can dictate the amount of environmental, disease and insect stress that a plant can tolerate,' says Guy Sturt, director and principal landscape architect at Sturt Associates.
"A plant continually in stress will require more maintenance. That means more labour, fertiliser, pesticides, water and ultimately cost."
Although knowledge about sustainable buildings has grown exponentially in the past five years, Sturt says this knowledge has not transferred to landscapes. "Most commercial clients, and especially their marketing arms, still believe landscapes should reflect a garden-esque vision complete with green lawns and greener hedges," he says.
"In addition, the perception is that all landscapes are green and therefore they are sustainable by nature. The public sector, however, in large part has embraced sustainable landscapes, and Sydney Olympic Park is an excellent example of the public sector leading the way."
Climate and location are two of the most crucial factors in sustainable landscape design – how the landscape responds and reacts to the natural elements such as the wind, sun, rain and topography. "A successful design must harness and exploit all of the site’s natural resources in a sustainable fashion," says Marc Conlon, director at Conlon Birrell Landscape Architects.
"Landscapes should naturally be self sustaining and should not require any off-site energy or maintenance. People should also be encouraged to maintain their landscapes, as it creates a healthy affinity with their natural surroundings."
Conlon approaches his projects from a sustainable, economical and cultural perspective. "The idea of a sense of place is at the centre of this. Protecting our local fauna and flora will give each region within Australia its own identity," he says.
To address issues such as flora and fauna impacts, Conlon uses native and endemic flora, fresh water retention ponds and on-site composting. In one project he was involved in, an on-site fresh water pond holds native flora and fauna, including three different species of native plants and two native species of fish.
When it comes to water retention and infiltration, Conlon favours the complete approach, including retention and timed release within materials such as sub soil crystals and recycled rubber materials. He includes this in addition to plants that do not require water during normal climatic conditions and installing systems for grey water recycling.
An innovative way Conlon has dealt with the problem of run off and storm water loading is by creating a turf driveway. The 100 per cent recycled polypropylene soil module and 100 per cent recycled rubber top dressing was used to reinforce the
permeable turf driveway.
"The rubber top dressing reinforces the turf and allows for better water retention, lowering the evaporation rate. Fifty per cent of the turf’s water usage is absorbed and slowly released by water crystals that were installed deep into the soil to also encourage root growth," he says.
Conlon also likes to use recycled materials when possible, such as jetty timber, which he used in a project to build a front gate and letter box.
Using locally sourced and recycled materials also reduces energy costs associated with the transport of materials. But Joshua Zeunert, senior landscape architect at McGregor Coxall, concedes using recycled materials usually attracts an added cost implication and requires a dedicated client to be realised.
Working with – and not against – existing landscapes can add considerably to a landscape’s sustainable outcomes. Sturt
Associates has worked on a number of creekline rehabilitation and restoration projects where the project outcome has been to reinstate degraded creeklines into fully functioning ecological systems.
It has largely dealt with these projects by working with the existing landscape. It created a creek flow path that is resilient and appears natural, whilst also satisfying hydraulic and flood management requirements. It also revegetated endemic plant communities to replicate the original communities existing on the sites and also recreated soil profiles that support plant growth and minimise erosion potential.
Although there are currently numerous environmental rating systems for buildings, there is no Green Star equivalent in the landscape industry. However, McGregor Coxall has developed its own ‘rating’ system which it works by. It created Biocity Studio in 2006 to track local and global environmental issues through undertaking special projects. It then publishes those results to staff, clients, consultant partners and the community.
The model is built on 12 major urban systems: biodiversity, built form, culture/education, economy, energy, food, governance, health, pollution/chemicals, transport, waste and water.
"Due to the lack of sustainability rating systems for landscape architecture and urban design, at McGregor Coxall we developed a comprehensive rating system based on the 12 Biocity categories," Zeunert says.
"A series of sub categories under each of the 12 systems is rated: 0/10 = business as usual, up to 10/10 = world leadership. We have approached some organisations and clients in the attempt to use our rating system as a pilot for becoming a widespread landscape tool – unfortunately with no uptake to date."
But as with building sustainability, sustainable landscapes will grow in popularity as the benefits are realised. Zeunert says: "Many people are beginning to realise that sustainable design often results in cost savings, and often this is the reason sustainable initiatives are realised."
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