Biodiversity is the variety of all life forms, the genes
they contain and the ecosystems of which they form a part.
What is it?
There are three aspects to biodiversity:
species diversity, genetic diversity and ecosystem diversity. Species
diversity refers to the variety of plants, animals
and micro-organisms. About 1.8 million different species
of living things have been identified to date. Scientists
estimate that 6 to 12 million are still waiting to be discovered
and described.
Genetic diversity refers to the variations between
individuals of a species — characteristics passed down
from parents to their offspring. Genetic
diversity allows for continuing adaptation and evolution. Ecosystem diversity refers to the great variety
of ecological communities produced by the interactions
of the living (animals and plants) and non-living world
(water, wind, landforms, soil, and rocks).
The biodiversity on the Earth today is the outcome of
billions of years of evolution, shaped by natural processes
and, increasingly, by the influence of humans. Globally,
the estimated current rate of species extinction is
100-1000 times the average ‘natural’ rate. One-half
of all species could be lost over the next 100 years.
Why is it important?
“Biodiversity is both essential for our existence
and intrinsically valuable in its own right.” “Biodiversity is our life. We humans are a part of
nature, not apart from it. Just like the other species
on this planet, we rely on biodiversity for our food,
our shelter, our health and all aspects of our well-being.”
Fundamental ecological functions and life support
Biological diversity plays a vital
role in sustaining life on Earth. Plants, animals
and living systems interact with the physical environment
powered by the sun’s energy to make this planet habitable.
For example:
Plants renew the earth's oxygen, trap sunlight and
carbon, and produce food for other species.
Fungi and micro-organisms create and maintain soils.
Birds, insects and mammals pollinate plants and maintain
nutrient cycles.
Large-scale ecological processes assimilate waste,
moderate climate, and recycle life-essential nutrients
such as carbon, nitrogen and phosphorus.
Biodiversity influences climate at local, regional and
global scales. For example, growing evidence suggests that
undisturbed forest helps to maintain 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. Plants extract carbon
from the atmosphere for long-term storage in wood and soils,
thereby mitigating climate change. Biodiversity enhances
the effectiveness of the biological pump that moves carbon
from the surface ocean and sequesters it in deep waters
and sediments.
Biodiversity confers resilience on ecosystems and organisms,
enhancing their ability to recover from natural and human-caused
disturbances. Conversely, loss of a species or reduction
in a gene pool could affect the functioning of many other
components of the ecosystem. “This layer of living organisms—the biosphere—through the collective metabolic
activities of its innumerable plants, animals, and microbes physically and
chemically unites the atmosphere, geosphere, and hydrosphere into one environmental
system within which millions of species, including humans, have thrived. Breathable
air, potable water, fertile soils, productive lands, bountiful seas, the equitable
climate of Earth’s recent history, and other ecosystem services are manifestations
of the workings of life.”
Human health, wealth and wellbeing
Our personal health, and the health of our economy and
human society, depend on the continued functioning of ecological
processes and ecosystems. Many of these natural processes
are simply impossible, or prohibitively expensive to replace
with artificial systems.
Living organisms provide us with food, fuel, fibre, building
materials, medicines, wood products and ornamental plants.
We currently use a limited range of species, but the genetic
diversity remaining in wild populations is an important
resource for disease resistance, improved productivity
and different environmental tolerances in crop varieties
and livestock breeds.
Box 1. Diversifying food
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…
There is 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 investigated,
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 right. 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.
Biological systems provide us with
diverse and essential benefits. Both plants and soil
micro-organisms are involved in cleaning the air we breathe.
Vegetation protects water catchments from erosion, mitigates
flooding and helps to regulate underground water tables.
Wetland vegetation and forests act as water purifying
systems. Biological diversity helps in the formation
and maintenance of soil structure and fertility, thus
protecting the productive capacity of soils for crops
and pastures. Pest species are controlled by predatory
species and competitors. Components of ecosystems from
bacteria to higher life forms are involved in the breakdown
and absorption of wastes and pollutants such as sewage,
garbage and oil spills. Biological communities can prevent
landslides, safeguard coastlines and riverbanks, and
prevent the degradation of coral reefs and fisheries
due to siltation.
People enjoy a range of social, cultural and health benefits
from biological diversity. Natural environments can reduce
stress levels, improve mental health, enhance emotional
development and a sense of belonging. The diversity of
living forms inspires artists, poets, writers, architects
and musicians. These living forms provide icons and symbols
of cultural significance. Nature is of great spiritual
value to many people, whether or not this is part of their
religious beliefs. For example, Australia’s biodiversity
is of deep spiritual and cultural importance to Indigenous
Australians.
Biological diversity is a feature of many areas valued
for tourism and recreational purposes, which make substantial
contributions to regional and national economies. Pursuits
such as birdwatching, nature photography, diving and snorkelling
are directly dependent on biodiversity.
The study of biology and ecology provides intellectual
stimulation: “Trying to understand the incredible complexity of biological systems and
how organisms have evolved over more than 3.5 billion years is for some of
us the most challenging, fascinating, and fulfilling way we could ever imagine
to use our powers of observation and our intellects.”
Why protect biodiversity?
Arguments for protecting biodiversity fall into two basic
categories:
(1) biodiversity has an intrinsic
value for its own sake simply because it exists,
that is worth protecting regardless of its value to humans,
and (2) humans depend on biodiversity for many aspects of our
health, wellbeing and livelihoods (as outlined above).
Environmental ethicists also stress that humans
should protect biodiversity because they are the cause of most of the recent
loss of biodiversity through loss of habitat, overexploitation and other perturbations.
Another ethical argument relates to inter-generational equity, which obliges
us to pass on to the next generation a planet that is at least as ecologically
healthy as it was for our generation.
With regard to human dependence on biodiversity, the Millenium
Ecosystem Assessment found
that biodiversity loss and deteriorating ecosystem processes
contribute - directly or indirectly - to worsening health,
higher food insecurity, increasing vulnerability, lower
material wealth, worsening social relations, and less freedom
for choice and action. “Protecting biodiversity is in our self-interest. Biological resources
are the pillars upon which we build civilizations. Nature's products support
such diverse industries as agriculture, cosmetics, pharmaceuticals, pulp and
paper, horticulture, construction and waste treatment. The loss of biodiversity
threatens our food supplies, opportunities for recreation and tourism, and
sources of wood, medicines and energy. It also interferes with essential ecological
functions.”
Biodiversity provides some insurance against disease, climate
change, fire and drought, ensuring that there are some
more robust species or organisms that can survive and rebuild
ecosystems.
Another reason for biodiversity conservation is the avoidance
of the rising costs of inaction. In Australia and elsewhere,
ecological degradation already results in significant losses
in production, and environmental repair is very costly.
Biodiversity represents unexplored options for the future.
Wild plant, animal and micro-organism resources are of
great importance in the search for new medically-active
compounds, and the potential of Australian biota to contribute
to modern medicine has scarcely begun to be realised. Examples
of 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.
The complex and interdependent network of relationships
between organisms that constitute the web of life are underpinned
by biological diversity at genetic, species and ecosystem
levels. The loss of a single species can set off a chain
reaction that reverberates throughout the system. The total
impact of loss of biodiversity is not always apparent and
is difficult to predict, as our understanding of ecological
relationships is rudimentary. But it is probably safe to
say that the clearing of a patch of bush, contraction in
range of a species or pollution of a coral reef all contribute
to the de-stabilising of planetary life-support systems.
Scientists have stated recently that the current rate of
biodiversity loss cannot continue without significantly
eroding the resilience of major components of Earth-system
functioning. This could have consequences that are detrimental
or even catastrophic for large parts of the world and associated
human populations.
Further reading
E. Chivian, & A. Bernstein,
(eds) Sustaining Life:
How human health depends on biodiversity. Oxford
University Press, New York, 2008.
Department of the Environment, Sport & Territories, Biodiversity
and its value. Biodiversity Series, Paper no.1, Canberra,
1993. Available at www.environment.gov.au/biodiversity/publications/series/paper1/why.html
2010 International Year of Biodiversity website www.cbd.int/2010/biodiversity/
Millennium Ecosystem Assessment, Ecosystems and Human
Well-being: Biodiversity Synthesis. World Resources
Institute, Washington DC, 2005. Available at www.maweb.org
