Biodiversity publications archive

Biodiversity and its value

Biodiversity series, Paper no. 1
Biodiversity Unit
Department of the Environment, Sport and Territories
, 1993
ISBN 0 642 19904 3

2. Why is biological diversity important?

Today, as ever, human beings are dependent for their sustenance, health, well-being and enjoyment of life on fundamental biological systems and processes. Humanity derives all of its food and many medicines and industrial products from the wild and domesticated components of biological diversity. Biotic resources also serve recreation and tourism, and underpin the ecosystems which provide us with many services.

While the benefits of such resources are considerable, the value of biological diversity is not restricted to these. The enormous diversity of life in itself is of crucial value, probably giving greater resilience to ecosystems and organisms. Biodiversity also has important social and cultural values.

2.1 The value of biological diversity's components

Generally, benefits arising from the conservation of components of biological diversity can be considered in three groups: ecosystem services, biological resources and social benefits. Some examples of these benefits follow.

Ecosystem services

Protection of water resources

Natural vegetation cover in water catchments helps to maintain hydrological cycles, regulating and stabilising water runoff, and acting as a buffer against extreme events such as flood and drought. Vegetation removal results in siltation of catchment waterways, loss of water yield and quality, and degradation of aquatic habitat, among other things. Vegetation also helps to regulate underground water tables, preventing dryland salinity which affects vast areas of Australia's agricultural lands, at great cost to the community. Wetlands and forests act as water purifying systems, while mangroves trap silt, reducing impacts on marine ecosystems.

These services translate into substantial financial benefits. A Victorian Government sponsored study, for example, calculated the financial benefit of water supplied to Melbourne from forested catchments at $250 million per year. This amount is based on a study which valued water collected in the Thomson Reservoir and supplied to Melbourne at $530 per megalitre, and the fact that the bulk of water supplied to Melbourne is harvested from 80 000 ha of catchment forested with ash-type eucalypts. Annual water yields from these forests vary from six to twelve megalitres per hectare, depending on whether the forest is 30 year old regrowth or old growth more than 200 years old. Presently most of the ash-type eucalypt forest in the catchments is 54 years old. Over the next 50 to 100 years, as the regrowth forests age, the value of water produced each year will increase by $150 million due to natural streamflow increases.14

Soils formation and protection

Biological diversity helps in the formation and maintenance of soil structure and the retention of moisture and nutrient levels. The loss of biological diversity through clearing of vegetation has contributed to the salinisation of soils, leaching of nutrients, laterisation of minerals and accelerated erosion of topsoil, reducing the land's productivity. Trees, on the other hand, lower the water table and remove deposited salt from the upper soil horizons.

Soil protection by maintenance of biological diversity can preserve the productive capacity of the soil, prevent landslides, safeguard coastlines and riverbanks, and prevent the degradation of coral reefs and riverine and coastal fisheries by siltation.

Trees and other vegetation also assist in soil formation. A significant contribution is the introduction of organic matter through litter formation and the decay and regeneration of tiny fibrous roots, both of which facilitate microbial activity. Another contribution is through the effects of root systems which break up soil and rock leading to, amongst other things, penetration of water. Root systems also bring mineral nutrients to the surface through root uptake. Organic matter formed by the decay of tiny fibrous roots can also bind with minerals, such as iron and aluminium, which can reduce the potential deleterious effects of these minerals on other vegetation.15

Nutrient storage and cycling

Ecosystems perform the vital function of recycling nutrients. These nutrients include the elements of the atmosphere as well as those found in the soil, which are necessary for the maintenance of life. Biological diversity is essential in this process. Plants are able to take up nutrients from the soil as well as from the air, and these nutrients can then form the basis of food chains, to be used by a wide range of other life forms. The soil's nutrient status, in turn, is replenished by dead or waste matter which is transformed by microorganisms; this may then feed other species such as earthworms which also mix and aerate the soil and make nutrients more readily available.

Pollution breakdown and absorption

Ecosystems and ecological processes play an important role in the breakdown and absorption of many pollutants created by humans and their activities. These include wastes such as sewage, garbage and oil spills. Components of ecosystems from bacteria to higher life forms are involved in these breakdown and assimilative processes. Excessive quantities of any pollutant, however, can be detrimental to the integrity of ecosystems and their biota.

Some ecosystems, especially wetlands, have qualities that are particularly well suited to breaking down and absorbing pollutants. Natural and artificial wetlands are being used to filter effluents to remove nutrients, heavy metals and suspended solids, reduce the biochemical oxygen demand and destroy potentially harmful microorganisms.

Contribution to climate stability

Vegetation influences climate at the macro and micro levels. Growing evidence suggests that undisturbed forest helps to maintain the rainfall in its immediate vicinity by recycling water vapour at a steady rate back into the atmosphere and through the canopy's effect in promoting atmospheric turbulence. At smaller scales, vegetation has a moderating influence on local climates and may create quite specific micro-climates. Some organisms are dependent on such micro-climates for their existence.

Maintenance of ecosystems

Ecosystem relationships resemble a web of connections from one living thing to many other living and non-living things. They not only allow survival, but also maintain a balance between living things and the resources (such as food and shelter) they need to survive. Vegetation is integral to the maintenance of water and humidity levels and is essential for the maintenance of the oxygen/carbon dioxide balance of the atmosphere. Due to the complex nature of ecosystem relationships, the removal or disturbance of one part of the ecosystem could affect the functioning of many other components of the ecosystem. Our knowledge of these relationships is incomplete, and the results of disturbance are thus to some extent unpredictable.

Maintaining natural habitats helps ecosystem functions over a wider area. Natural habitats afford sanctuary to breeding populations of birds and other predators which help control insect pests in agricultural areas, thus reducing the need for, and cost of artifical control measures. birds and nectar loving insects roost and breed in natural habitats may range some distance and pollinate crops and native flora in surrounding areas.

Recovery from unpredictable events

Maintaining healthy ecosystems improves the chances of recovery of plant and animal populations from unpredictable natural catastrophic events such as fire, flood and cyclones and from disasters caused by humans. Inadequately conserved and isolated populations, and ecosystems which are degraded, are less likely to recover or to recover as quickly, to their former state. Populations of biota may end up with small, possibly non-viable, genetic bases, which can lead to extinctions.

Biological resources

Food

Human existence (and that of most other organisms) is heavily dependent on what biologists call primary producers, mainly plants. Five thousand plant species have been used as food by humans, but less than twenty now feed the majority of the world's population and just three or four carbohydrate crops are staples for a vast majority. One of the important benefits of conservation of biodiversity is the wild plant gene pool which is available to augment the narrow genetic base of these established food crops, providing disease resistance, improved productivity and different environmental tolerances.24 25

Australia's native species are contributing to the global food capacity. Australia has important native fish and crustacean harvesting industries and is the reservoir of genetic diversity for the macadamia and quandong. Such reservoirs increase the opportunities for enhancing agricultural productivity. Australia, for example, has 15 of the world's 16 species of wild soybean. These may prove to be extremely valuable genetic stock in the future because, unlike current commercial varieties, many of these wild plants have genes that help them resist leaf rust diseases.

There is also great food potential in native Australian plants. The nutritional value of 'bush' foods is quite high, some having greater amounts of protein, fats, carbohydrates, minerals and vitamins than cultivated plant foods. For example, acacia seeds, some 50 types of which were used by Aboriginal people for food, are superior to rice and wheat in energy, protein and fats. The potential of Australian acacias to augment diets in Africa is currently being investigated26, and Australian native species of Vigna are being explored to add useful characteristics to the domesticated mung bean, and for their potential as food in their own right27. The seeds of pigweed (Portulaca oleracea), which were commonly eaten by Aboriginal peoples, contain 20 per cent protein, 16 per cent fat, and high levels of iron. A native fig, Ficus platypoda, has very high levels of calcium (4000mg/100g), as well as higher protein and fat content than expected for fruits, while the wild Arnhem Land plum has spectacular amounts of Vitamin C – more than 50 times the level found in exotic citrus fruit.28 29 New chemical structures are being discovered all the time, and the conservation of biological diversity is essential for the continuation of this research.

The short and long-term values of these genetic resources are enormous and most improvements in agriculture and silviculture depend on their preservation. Moreover, the gene pool value of natural habitats will increase as remaining natural habitats become more scarce. These areas are therefore of great value as in situ gene banks, and need to be effectively managed.

Medicinal resources

People have long used biological resources for medicinal purposes. Australian Aboriginal societies made use of many native plants as medicines; at least 70 were used by central Australian Aboriginal people alone.14 30 Examples cover many genera, and include acacias and eremophilas,30 as well as individual species such as Isotoma petraea and the parrot plant (Crotolaria cunninghamii).31 A few Aboriginal medicines have been widely used in western medicine, such as the ubiquitous eucalyptus oil for relief of respiratory tract infections, but many more are now being investigated. A prime example is provided by current research into the bark of a tree found in the Kimberleys, which is known to Aboriginal people as a powerful painkiller.32

A number of Australian species are the basis of medicinal products. Hyoscine (or scopolamine), used to treat motion sickness, stomach disorders and the effects of cancer therapy, is a product of two species of corkwood (Duboisia). One of these, D. leichhardtii, is restricted to Queensland, and the hybrid between the two species produces more hyoscine than any other plant.33. The vine Tylophora is the source of the drug tylocrebrine,34 which has been effective in treating lymphoid leukemia, while the kangaroo apples Solanum aviculare and S. laciniatum, found in Australia and New Zealand and cultivated overseas, provide solasodine, which is easily converted to steroids.33

Wild plant, animal and microorganism resources are also of great importance in the search for new medically active compounds, and the potential of other Australian biota to contribute to modern medicine has scarcely begun to be realised. Many of the drugs presently used are derived from plants; many medicines, in particular antibiotics, are derived from microorganisms, and new chemical structures are being discovered all the time. The native pepper (Piper novae-hollandiae) and the black bean (Castanospermum australe) both offer potential in the treatment of cancer.33 Current work at Macquarie University is exploring the antibiotic potential of secretions from glands of bulldog ants (Myrmecia). The substances have strong antibiotic properties, and kill a wide range of selected bacteria and fungi. Their potential, particularly as industrial biocides, is enormous.35

Studies of various chemicals produced by animals have led to discoveries of medicinally useful substances. A substance called Prostaglandin E2, which could be of importance in the treatment of gastric ulcers, was originally discovered in the two species of gastric brooding frogs (Rheobatrachus) found only in the rainforests of Queensland. Unfortunately, both species have not been sighted for some time, and it is conceivable that one at least (R. silus) is now extinct.36

Wood products

Wood is a basic commodity used worldwide, and is still largely harvested from the wild. It is a primary source of fuel, is used in construction, and forms the basis for paper production.

Australian native plants have been of continued importance in the construction of buildings and furniture, and more recently for paper production. The timber industries form a significant part of our modern economy. The unique nature of Australian species has been well recognised: huon pine (Lagarostrobus franklinii) does not decay; gidgee (Acacia cambagei) and mulga (Acacia aneura sens. lat.) are very hard woods currently being investigated for musical instruments; and the lignotubers of some eucalypts and banksias are favoured for highly decorative furniture. Many Australian species, notably eucalypts, are grown overseas for timber products.

Ornamental plants

Native Australian species are increasingly being used for ornamental and horticultural purposes, with new hybrids and strains being developed and marketed. One well known example is the Grevillea "Robyn Gordon". The cut flower trade of Western Australia is also of great importance, with many species harvested, and some being cultivated for this purpose.

Breeding stocks, population reservoirs

Natural areas provide support systems for commercially valuable environmental benefits and resources.

Some habitats protect crucial life stages or elements of wildlife populations that are widely and profitably harvested outside these habitats, such as spawning areas in mangroves and wetlands. For example, when mangrove areas are cleared for resort and urban development, populations of commercial fish species which rely on mangroves for breeding habitats also diminish. Some of these crucial habitats have been declared protected areas, as their importance for maintaining stocks of fish, crustaceans such as prawns and mud-crabs, and other aquatic fauna has been recognised.37 38

Other habitats act as genetic reservoirs from which seed and other material can be assessed for enhancement of harvested species. The leaf oil content of several Western Australian eucalyptus mallee species, for example, is being assessed from across their natural distributions to identify high yield populations for potential propagation.

Future resources

About 50 per cent of species in Australia are known but only a quarter formally described. 10 As knowledge improves, new bioresources to increase human welfare will be discovered and developed. There is a clear relationship between the conservation of biological diversity and the discovery of new biological resources. The relatively few developed plant species currently cultivated have had a large amount of research and selective breeding applied to them. Many presently under-utilised food crops have the potential to become important in the future. The documentation of indigenous peoples' use of plants is often the source for ideas on developing plant species for wider use and/or economic benefit and there are a large number of as yet undiscovered plant species which could prove useful. 39

Potential products which may be derived from biological resources include sunscreens from corals, light and high tensile fibres from spider silk, and instant adhesives from velvet worms or barnacles. 40 Microorganisms are important in the production of extensive ranges of agrochemicals, protein for animal feed, enzymes and biopolymers.

There is also potential for further development of biotic resources for natural pesticides, similar to the insecticidal microorganism Bacillus thuringiensis, and other useful products such as fats, and oils. 24 The conservation of diversity is also essential for finding effective biological control organisms and for breeding disease resistant species. Genetic engineering of microorganisms promises further advances in the production of new compounds and processes. 25

Social benefits

Research, education and monitoring

There is still much to learn on how to get better use from biological resources, how to maintain the genetic base of harvested biological resources, and how to rehabilitate degraded ecosystems. Natural areas provide excellent living laboratories for such studies, for comparison with other areas under different systems of use, and for valuable research into ecology and evolution. Unaltered habitats are often essential for certain research approaches, providing controls against which the changes brought about by different management regimes may be measured and assessed.

Recreation

Biological diversity is an intrinsic part of many areas valued in Australia for tourism and recreational purposes. The aesthetic qualities of such areas are often strikingly different, in large part due to the range of biological diversity to be found on this continent. People value such areas for a variety of recreational pursuits: film, photographs or literature based on or using wildlife, natural habitats and natural features; birdwatching; and ecological field study and other scientific pursuits. 41 The Australian environment is a major factor in attracting tourists. Studies have shown that over 85 per cent of Japanese visitors and 70 per cent of European and American travellers identified such factors as beautiful scenery and wildlife as key elements of their travel decisions. 42 In addition, it has been conservatively estimated that at least 10 million people visited natural environments in Australia in 1987/88; five million visited parks and reserves, four million visited the four major zoological gardens and one million visited botanical gardens. 43

Cultural values

The cultural value of biological diversity conservation for present and future generations is an important reason for conserving it today. Human cultures coevolve with their environment, and the conservation of biological diversity can be important for cultural identity throughout Australia. The natural environment provides for many of the inspirational, aesthetic, spiritual and educational needs of people, of all cultures, now and in the future. Australian society places great cultural value on the 'bush' while certain species, such as the kangaroo, koala and the emu, have become national icons.

The aesthetic values of our natural ecosystems and landscapes contribute to the emotional and spiritual well-being of a highly urbanised population. The conservation of biological diversity also has ethical benefits. The presence of a wide range of living organisms reminds people that they are but one interdependent part of Earth.

Aboriginal relationships to the land and sea, and its animals and plants are complex. To these people the land and sea has a deep spiritual, economic, social, protective and recreational significance. By hunting and gathering, tribal Aboriginal people are not only supplementing their diet with food very high in nutritional value; they are also confirming their self-sufficiency and, more importantly, educating their children in relationships to the land and to other aspects of their culture. 44 Biological diversity conservation can contribute to the conservation of Aboriginal cultural identity.

Benefits of timely action

Another benefit of conservation is the avoidance of the rising costs of inaction. Already Australia is suffering losses in production from environmental degradation and is spending considerable sums in environmental repair. Land degradation costs in Australia have been estimated at $1150 million annually, 45 and the CSIRO has classified some 52 per cent of the continent as degraded in one way or another and in need of reclamation.46 Salinity related problems in the Murrary-Darling Basin alone are estimated to cost $35 million annually, and losses to agriculture in this region are in the order of $260 million each year. 47 These costs are those identified today. Currently, some $320 million has been directed to the Decade of Landcare, much of which will be for the control of land degradation. 48

Without remedial action degradation will inevitably increase and the costs of repair faced by the community in the future will be much greater. These costs can be reduced by strategic and timely conservation actions.

2.2 The value of diversity

The sheer diversity of life is of inestimable value. It provides a foundation for the continued existence of a healthy planet and our own well-being. Many biologists now believe that ecosystems rich in diversity gain greater resilience and are therefore able to recover more readily from stresses such as drought or human induced habitat degradation. When ecosystems are diverse, there is a range of pathways for primary production and ecological processes such as nutrient cycling, so that if one is damaged or destroyed, an alternative pathway may be used and the ecosystem can continue functioning at its normal level. If biological diversity is greatly diminished, the functioning of ecosystems is put at risk.

Possibly the greatest value of the variety of life may be the opportunities it gives us for adapting to change. The unknown potential of genes, species and ecosystems is of inestimable but certainly high value. Genetic diversity will enable breeders to tailor crops to new climatic conditions, while the Earth's biota is likely to hold still undiscovered cures for known and emerging diseases. A multiplicity of genes, species, and ecosystems is a resource that can be tapped as human needs change.

There is possibly no single particular argument which on its own, provides sufficient grounds for attempting to maintain all existing biological diversity. A more general and pragmatic approach, however, recognises that different but equally valid arguments – resource values, precautionary values, ethics and aesthetics, and simple self-interest – apply in different cases, and between them provide an overwhelmingly powerful and convincing case for the conservation of biological diversity.

The many values of biological diversity and its importance for development indicate why biological diversity conservation differs from traditional nature conservation. Biological diversity conservation entails a shift from a reactive posture – protecting nature from the impacts of development – to a proactive effort seeking to meet peoples' needs from biological resources while ensuring the long-term ecological sustainability of Earth's biotic wealth. On a global level it thus involves not only the protection of wild species and their habitats but also the safeguarding of the genetic diversity of cultivated and domesticated species and their wild relatives.

The conservation of biological diversity seeks to maintain the life-support system provided by nature in all its variety, and the living resources essential for ecologically sustainable development.