Human activity has changed Australia forever. Much irreversible damage has been done, and many of our environmental values are still in decline. While learning from the past, we must nevertheless look forward: there is a great deal at stake. Our challenge is to manage the environmental values that remain and rectify damage where possible. To do this we need to understand and manage the environmental risks arising from our economic and social development.

If we had known earlier what we know now, we may have been able to avoid a lot of damage to natural systems; for example, by not introducing certain destructive exotic plants and animals. Even so, our lifestyles and our habits, our desire for space and transport, and our demand for food, water, energy and manufactured products, would still have put pressure on the environment and on Victoria’s biodiversity.

By the turn of the century Victoria’s population will pass 4.5 million, and we will receive around 1.5 million visitors per year.⁷ The increase in the active and passive use of natural environments that is likely to result will mean that the wise management and sustainable use of our natural resources will become an increasingly complex and important issue in the years ahead.

Within the first few decades of European settlement, many of the species’ extinctions in Australia occurred.

Of the 91 species of non-marine mammals known to have inhabited Victoria since European settlement, 19 are now extinct in the state, and five of these are now totally extinct. Many other species survive with much diminished populations. More than 900 species of Victorian plants are rare or threatened. Satellite maps graphically illustrate the loss of some ecological communities, with 30% of the State’s broad vegetation types having been reduced by 80%. For example, the native grassland complexes of lowland Victoria are now among the most endangered ecological communities in Australia, there being less than 2% left of the pre-1750 area of thousands of square kilometres.

These modern remote sensing techniques show us not only what we have lost: they can also tell us where the surviving communities are located. For example, around two-thirds of the remaining lowland grassland complexes are on private land, and thus the assistance of these private landowners will be critical in preserving these ecosystems. A picture of our losses to date also provides us with a benchmark against which we can measure our effectiveness in halting and, wherever possible, reversing the decline.

Our response to key risks will continue to change as our understanding improves. For example, the recognition of the factors that cause the salinisation of rivers and wetlands and contribute to land salinisation has led to changes in the way water is managed. It has led to the establishment of catchment-based land-use planning, more efficient use of water resources and the reservation of water for environmental purposes in the allocation of water rights.

Meanwhile, protecting the quality of our bays and seas is growing in importance. For example, the risk of introducing marine pests through ballast water rises with the increase in trade.

Similarly, we have to manage the risks of polluted stormwater run-off associated with our spreading urban areas. Our challenge is to manage the environmental risks associated with all our activities. Clearly, the best way to reduce these risks, wherever practicable, is to modify our behaviour and reduce the effect of threatening processes. It is equally clear that we need to allocate our scarce resources carefully, setting priorities and increasing community custodianship and action. There is much we do not know. A central challenge is to recognise the uncertainty associated with our choices and to consciously manage the risks to biodiversity; by doing so we will have a better chance of avoiding further irreversible losses.