Foreign Problems in the Desert Landscape: In Australia's Top End, the Growing Problem of Introduced Plant Species Becoming Weeds Is Being Made Worse by a Climate and Urban Culture That Encourages the Planting of Exotic Ornamentals
Goodfellow, Denise Lawungkurr, Ecos
There is a sheltered cove in Darwin where the cliffs are covered with monsoon vine forest. The forest is so badly infested with poinciana (Delonix regia) and other escaped garden plants that many native species are relegated to the understorey.
Poinciana is one of the many 'pretty' exotic garden plants--such as crotons, frangipani and golden cane--that festoon the streets and gardens of Top End towns. While there is no rain in the Top End for up to eight months of the year, local residents prefer these vibrant exotics in their lush, green gardens to less spectacular, drought-tolerant indigenous plants.
The preference is entrenched. For years, Darwin has celebrated bougainvillea at an annual festival. To many Territorians, indigenous flora are viewed as unfamiliar and even alien.
The truth is that 'pretty' introduced plants like poinciana and bougainvillea pose a serious threat to the Top End's environment. For example, exotic plantings such as those outside Bagot, a reserve in Darwin for indigenous people, have even been embraced by Bininj (Top End indigenous people), who are 'always asking whether they can take crotons, etc, back to their homelands', according to a Northern Land Council employee.
Apart from assisting in the spread of exotic weeds, the Bininj are also losing their traditional plant knowledge. Indeed, some have remarked that they look upon the native flora of their homelands as 'rubbish'.
An uphill battle
According to the Australian National Weeds Strategy Executive Committee, 70 per cent of the most invasive Australian weeds are garden escapees. Yet, according to a 2005 World Wildlife
Fund Australia report, (1) more than half of the 720 recognised invasive garden plants were still on sale in nurseries. (2) Further, in a garden guide for new homeowners published recently by a Top End developer, two-thirds of the recommended plants were exotic species and some were invasive weeds.
Innovative landscapers and developers around the world face a huge challenge in overcoming the entrenched preference for green and ornamental gardens. For example, in a US study of garden preference in Phoenix, Arizona, one participant, showing a typical attitude, stated, 'I am from the Midwest and like the green and flowers; I don't like brown and one colour'.
The same study concluded that developers 'anticipate homeowners' tastes and package their homes with desirable dreamscapes'.
It's not surprising to discover that when an innovative Northern Territory developer, Ochre Ltd, attempted to leave some of the original native vegetation in a subdivision to provide home-buyers with minimal care bush gardens, some builders decided to 'tidy up' Ochre's land, clearing every last shrub and tree.
Darwin landscape architect, Marisa Fontes of Outsidesign, says that while she may propose native species for new gardens, exotic alternatives may be suggested by nurseries or landscape contractors who undertake the actual construction.
Ms Fontes feels that garden plant choice is influenced by television shows such as Backyard Blitz, which generally showcase exotics and plants native to eastern Australia. Such plants also dominate the selection at local nurseries, Bunnings and K-Mart stores.
Many tourism operators also believe that visitors to the Top End expect to see colourful tropical vegetation. From Darwin homestays to hotels in Kakadu National Park, most tourist accommodation is surrounded by gardens of crotons, bougainvillea, frangipani and golden cane.
Yet during my 24 years as a local guide, I've found that visitors prefer the local flora, a view shared by Dr Tonia Cochran, Chair of tour operator Wildlife Tourism Australia who take visitors from all corners of the globe to see the majestic Top End.
Long history of introductions
Northern Australia has a long history of plant introductions. …