The Adelaide Hills in Australia have been a reservoir of some of the rare flora and fauna. The environment of the place has greatly contributed towards making it a nature’s paradise. The need of the hour is to preserve this heritage, slowly falling prey to man’s exploitative attitudes.


Introduction
The Adelaide Hills is like an oasis – a fairly big one – with natural forest and a reasonable rainfall. It extends from Cape Jervois in the south to the Barossa Valley in the north, and from the coast to Mt Barker.
It is about 3000 square kilometres of temperate landscape and it is hundreds of kilometres    to any comparable landscape.
Since colonial times it has been a fertile food source and in recent times it has extended its capability, thanks to the water imported from the Murray River less than one hundred kilometres to the east .

But, off late a crisis has emerged in the area, which demands attention.  Ninety-three per cent of the land has been denuded of its forest cover and only 7% remains as remnant vegetation.
The River Murray as a source of water is no longer reliable and there is no reason to think that it will be a good source for decades ahead considering the rising global warming, climate change and above all government inertia.
It is timely to reconsider how we manage the land and environment within a sustainable economy for South Australia.

A History of Managed Land
The site of the colony of South Australia was chosen as there was a good sea port alongside land with good soil and good water. Unlike much of colonial Australia, it leant itself readily to European agriculture and the colonial dream of ‘civilising’ the land seemed manageable. At first, it was successful with subsistence agriculture – but as communication and transportation brought the nation together, profits flowed from grazing animals and extensive areas were committed to cattle and sheep. The land was extensively cleared of its native vegetation at that time and was replaced by grasses suitable for grazing.

This regime was challenged in the late 20th century by a generation that sought to harmonise with the environment of Australia – not try to mould it to the European ideal. Clearing was halted. ‘Trees for Life’ and others introduced re-vegetation.

The promoters of the re-vegetation effort sought to replace the natural vegetation, but this noble aim is more tricky than it looks at first.

The native forests were not just a ‘natural’ environment but a managed environment especially in the form of ‘fire stick farming’. This made for a stable ecological system under the control of the Kaurna people who resided there. The species mix was stabilized by the regime of fire management. Within a few years of colonial settlement the character of the land changed and in some cases what was open woodland became closed bush thickets.

So the ideal of remaking the pre-colonial vegetation mix was bound to be problematic.
The approximation that was adopted most widely was to create plantations of eucalypts both local and regionally exotic for their value as timber. And, now there are new plantations arising providing ‘carbon offsets’ in the response to climate change.

So what do we want of our land?
I suggest there are a number of requirements which should guide our thinking in creating a valid answer.
We want the land for:
o    Agricultural Productivity
o    Preservation of biodiversity
o    Human amenity
o    Water management
o    Environmental services
But, steps taken to support any one of these aims will interact with the other ones. So our plans have to be carefully balanced.

Productivity
The hills is a productive landscape and we need to ensure that it retains its productivity in the future. The Hills have good soil and with an average rainfall of about 700mm the land is very productive.
With added water the productivity is enhanced. From the middle of the 20th century water has been imported from the Murray River for irrigation and it has allowed hills farmers to become complacent.
However the supply of water from the Murray River is no longer assured, in fact it would be hard to imagine that the environmental and political realities of the River would allow it to be a source at any time soon or in the foreseeable future. With the demise of the supply of irrigation water from the Murray what is to be done?

How can we get the maximum use of the water available from the hills alone?

In setting priorities for production in an environment of limited water it is of interest to note that meat production generates $14 per Megalitre of water, while fruits and vegetables both generate over $1200 per litre (Leamann 2005)
We would certainly do well to increase our production of fruits, vegetables and nuts in place of the grazing currently in vogue.

Water
The deforestation done in the 19th and 20th centuries has left many hillsides for grazing with just a thin cover of grass.
In our Mediterranean climate we see winter rains and little in the warm months.
The rain that falls on the grassy hills runs away unhindered and the water is lost to the immediate environment. Travelling with speed it contributes to the loss of precious top-soil from those hills.  
How much more productive could our land be?
There is no doubt that water is the key to the productive capacity of the land.
How can we maximise the water available?

We need to farm the water itself. Rainfall is unreliable in Australia. This is the dominant reality factor in working with any Australian environment.
The sporadic nature of rainfall on this environment has been established for thousands of years. But, it would seem that rainfall has declined in recent years even beyond the natural variation of the climate. We know that climate change due to green house gases is having an impact but could there be other factors at work?

Tom Lyons (CSIRO) has shown that native vegetation cover in WA has an impact on rainfall. Comparing farm land to native vegetation, the rainfall decreased 10% where there were wheat fields but increased 20% where there was native vegetation.
This is a very significant result and it calls out for further research on the topic.
Could the deforested Hills be drawing less rainfall than the previously forested land?
If vegetation loss makes the rain decline, could appropriate vegetation bring back the rain and even increase rainfall? It has also been claimed that some vegetation is more inviting to rain than others.

Sarkar – the philosopher and seer who has made significant contributions to many fields of study claims that oaks (Quercus sp.) and ferns and certain other species growing on the landscape are more likely to bring rain. This is again a challenge that should be taken up by researchers. Forest cover also creates shade and windbreaks and these factors will help stop water from evaporating.

The technology of storing water is widely implemented in the form of farm dams, but it is also true that the soil itself will hold water where there is a cover of vegetation.
Vegetation is a sponge for water and soil with a rich a carpet of green will hold much of the water that falls on it. A well-balanced flora should see water in the creeks all the year round as demonstrated by Peter Andrews (‘Back from the Brink’)

Biodiversity
Many marsupial species have been lost from the Adelaide Hills. The introduction of foxes and cats has been the biggest contributor to the demise of the bettongs, bandicoots, pottoroos and small wallabies which were lost from the Hills many years ago.

Warrawong sanctuary has made a showcase of some of some of these delightful animals. The (permaculture) Food Forest at Gawler has also shown how they can be protected and make a contribution to sustainable farming in this environment. 

What more can be done to re-introduce and protect these animals?

There are just over 100 bird species, which are indigenous to the hills. According to David Paton of Adelaide University, about half of them are on a trajectory to extinction, and they will decline year by year unless their habitat is cared for. When there are poor seasonal conditions they will decline even faster. Paton promotes re-establishing and maintaining 30% of the Hills land for conservation purposes.

For example, the glossy black cockatoo has been declining for many years and only in recent times has an effort been made to save them. There is a race against time to grow the shea-oaks they need on the Fleurieu Peninsula and get them up to an age where they will set fruit and provide the requirements of the birds which migrate annually. The birds are an aging population and it is not known whether they will still be young enough to be fertile when the trees finally are sufficiently mature. Each species of bird has particular requirements and we should make a priority of  re-creating a satisfactory environment for each and every one of them.

The Adelaide Hills is home to over 2000 indigenous species – comparable to number of species of plants in the entire British Isles! At present 300 plants are listed as endangered or threatened in South Australia, many of which are in the Adelaide Hills. We should make sure suitable sites are available to protect all those species.

The climax species of that environment was the gum tree - in reality twenty or so species of eucalypts that grow in the hills.
Unfortunately, much as we love them, gum trees have their faults.
They have come to dominate the landscape – but it was not always the case. Looking at the evolutionary history of our flora over geological time we can see the special circumstances of the dominance of eucalypts.  “The gradual drying of the continent and depletion of soil nutrients led to the development of a more open forest type, predominantly casuarinas and acacia species. With the arrival of the first humans about 50 thousand years ago, fires became much more frequent and the fire-loving eucalypts soon came to account for roughly 70% of Australia’s forest.” (Wikipedia)
In Thailand, the plantations of eucalypts have been removed from some areas as it gained the reputation of being the ‘selfish tree’. It has deep tap roots which take water from the higher layers of the soil and drives the water table down very deep – too deep for the other plants, which those Thai farmers were trying to grow.

In parts of the Australian landscape – particularly where the land is flatter, gum trees have done service by maintaining the salt levels in the soil down below the surface. Eucalypts removed from this land then becomes prone to problems of salinity. So, the gum tree is not an advantage when trying to increase the useable water.
Another factor here is the flammable nature of a forest of eucalypts. Their volatile oils are very fire prone. They dry the ground out. They leave a litter of broken branches and leaves which become the fuel load creating a hazard for summer.

The recent (2008) fires in the suburbs of Los Angeles blazed across the forests of eucalypts that the folk of California have come to love and are now starting to fear.
Bushfire is a major issue and any revegetation has to be done with fire in mind.
So it may be that our revegetation initiatives would be well advised to steer away from gum trees in the main.
They are also not significant in terms of biodiversity and commentators have noted the lack of birds and insects which are to be found in these plantations. Unfortunately the call for carbon offsetting is easily translated into plantations.  These plantations might not be the best solution to the mix of problems needing to be addressed.

Amenity
Living in Adelaide or in the hills, we experience cold winters and hot summers. It is a blessing to have good shade in summer and some attractive places in the Hills make the most of it. The best shade trees are usually exotic, and there are some very successful examples. In winter sunlight is beneficial and consequently deciduous trees are desirable.
There is scope to develop our culture of gardening for shade in Adelaide and the Hills.
We should increase the tree cover over the Hills – but the threat of fire is a strong disincentive to creating bush and forest.

In the past, clearing was undertaken with a vengeance by the early colonists driven by the desire for pasture land and farming – but also driven by the reality of fire in this forest landscape. Recall that the indigenous population had established a stable ecology under a management regime of regular fires. The European lifestyle of settlement and housing does not fit comfortably under this regime.
Fire remains a disincentive to revegetation efforts.
But we have seen that revegetation is a high priority – how to structure it so that it is as productive as possible?
Some trees are less prone to fire and some more so. Eucalypts are fire lovers – their volatile oils, fallen limbs and leaves – their desiccated immediate environment at ground level are all points which serve to encourage fire.
Native grasses do not dry out in the summer as do the exotic species. So the imported grass species are more dangerous and reintroducing native grasses would be a contribution to fire management as well as a boon to rebuilding biodiversity.
Which other native plants are fire makers and which are fire stoppers? The Boobialla is a shrub which is known as a fire retardant species. Wattles are likely to be damaged by fire but they are not great supporters of fire.
And which exotic trees are fire retardant? Again oak forests have potential: “Oaks woodlands in seasonally dry climates are often fire resistant, particularly if present in open grasslands, as a grass fire is insufficient to ignite the scattered trees. Such is not the case with a eucalypt forest. Besides, we should also try to find out what other large trees would be suitable?

Environmental services
Each of the themes in this study has a complex interaction with the other points.
So, I have already spoken of some of the environmental services.
In the recent past, our society did not know the subtle values of vegetation, but we can now speak of many ways in which plants contribute to the health of the environment.
Vegetation helps filter the water, feed the wildlife birds and insects, support insects which carry out the task of pollinating our fruit trees and grains. They create carbon sinks by capturing carbon dioxide from the atmosphere and help control salinity, acidity, erosion, and pollution. These environmental services have economic benefits and economists are working out ways to factor in their monetary value.

Conclusion
The Adelaide Hills have been denuded of vegetation and there is a pressing need to revegetate the land. To increase the amount of land committed to forest, woodland, orchard and bush, it is to be hoped that the government will do all that it can. But, governments can only do a certain amount. The farming community has to embrace this new direction. This will only be possible if they can see its potential to contribute to productivity, to the health of the soil and the increased capacity to store and utilise water.

The biodiversity – the flora and fauna of the Hills should be secured by planting the plant species at risk and by creating suitable habitat for each bird under threat. More can be done to re-establish the marsupial populations that have been in the region in the past.
Hopefully, the farming community can all make a contribution to these efforts at conservation.

The oasis that is the Adelaide Hills has to be managed in new ways to play its key role into the future for the lives of the people who live there.