Biodiversity: What is it, where is it, and
why is it important?
Biodiversity reflects the number, variety
and variability of living organisms. It
includes diversity within species, between
species, and among ecosystems. The
concept also covers how this diversity
changes from one location to another and
over time. Indicators such as the number
of species in a given area can help in
monitoring certain aspects of biodiversity
Biodiversity is everywhere, both on land
and in water. It includes all organisms,
from microscopic bacteria to more
complex plants and animals.
Why is biodiversity loss a concern?
Biodiversity loss has negative effects on several aspects of human well-being, such
as food security, vulnerability to natural disasters, energy security, and access to
clean water and raw materials. It also affects human health, social relations, and
freedom of choice.
Society tends to have various competing goals, many of which depend
on biodiversity. When humans modify an ecosystem to improve a service it
provides, this generally also results in changes to other ecosystem services. For
example, actions to increase food production can lead to reduced water availability
for other uses. As a result of such trade-offs, many services have been degraded,
for instance fisheries, water supply, and protection against natural hazards. In the
long term, the value of services lost may greatly exceed the short-term economic
benefits that are gained from transforming ecosystems.
Unlike goods bought and sold in markets, many ecosystem services are not traded
in markets for readily observable prices. This means that the importance
of biodiversity and natural processes in providing benefits to humans is ignored by
financial markets. New methods are being used to assign monetary values to
benefits such as recreation or clean drinking water. Degradation of ecosystem
services could be significantly slowed down or reversed if the full economic value of
these services were taken into account in decision-making.
Over the last century, some people have benefited from the conversion of
natural ecosystems and an increase in international trade, but other people have
suffered from the consequences of biodiversity losses and from restricted access to
resources they depend upon. Changes in ecosystems are harming many of the
world's poorest people, who are the least able to adjust to these changes.
What are the current trends in biodiversity?
Virtually all of Earth’s ecosystems have been dramatically transformed through
human actions and ecosystems continue to be converted for agricultural and other
The current loss of biodiversity and the related changes in the environment are now
faster than ever before in human history and there is no sign of this process slowing
down. Many animal and plant populations have declined in numbers, geographical
spread, or both. Species extinction is a natural part of Earth’s history. Human activity
has increased the extinction rate by at least 100 times compared to the natural rate.
Virtually all of Earth's ecosystems have been dramatically transformed through
human actions, for example, 35% of mangrove and 20% of coral reef areas have
Land areas where the changes have been particularly quick over the past
two decades include:
•the Amazon basin and Southeast Asia (deforestation and expansion of
•Asia (land degradation in drylands); and
•Bangladesh, Indus Valley, parts of Middle East and Central Asia, and the
Great Lakes region of Eastern Africa.
Since 1960, intensification of agricultural systems coupled with
specialization by plant breeders and the harmonizing effects
of globalization have led to a substantial reduction in the genetic
diversity of domesticated plants and animals. Today a third of the 6 500
breeds of domestic species are threatened with extinction.
Comparing different types of measurements of biodiversity loss is not
simple. The rate of change in one aspect of biodiversity, such as loss
of species richness, does not necessarily reflect the change in another,
such as habitat loss.
Furthermore, the fact that the distribution of species on Earth is
becoming more homogeneous as a result of human activities
represents a loss of biodiversity that is often missed when only
considering changes in terms of total numbers of species.
The main cause of the loss of biodiversity can be
attributed to the influence of human beings on the
world’s ecosystem, In fact human beings have
deeply altered the environment, and have modified
the territory, exploiting the species directly, for
example by fishing and hunting, changing the
biogeochemical cycles and transferring species
from one area to another of the Planet. The threats
to biodiversity can be summarized in the following
•Alteration and loss of the habitats: the transformation of
the natural areas determines not only the loss of the
vegetable species, but also a decrease in the animal species
associated to them. Refer to “Alteration and loss of the
•Introduction of exotic species and genetically modified
organisms: species originating from a particular area,
introduced into new natural environments can lead to
different forms of imbalance in the ecological equilibrium.
Refer to, “Introduction of exotic species and genetically
•Climate change: for example, heating of the Earth’s surface affects biodiversity
because it endangers all the species that adapted to the cold due to the latitude
(the Polar species) or the altitude (mountain species).
•Pollution: human activity influences the natural environment producing negative,
direct or indirect, effects that alter the flow of energy, the chemical and physical
constitution of the environment and abundance of the species;
•Overexploitation of resources: when the activities connected with capturing and
harvesting (hunting, fishing, farming) a renewable natural resource in a particular
area is excessively intense, the resource itself may become exhausted, as for
example, is the case of sardines, herrings, cod, tuna and many other species that
man captures without leaving enough time for the organisms to reproduce.
How might biodiversity change in the future under various
The four plausible scenarios explored in this assessment consider two
possible paths of world development: increasing globalization or
The four scenarios are:
Global Orchestration - This scenario depicts a globally-connected society
that focuses on global trade and economic liberalization and takes a
reactive approach to ecosystem problems. Under this scenario, poverty is
reduced, but a number of ecosystem services are deteriorated. While
progress is made on global environmental problems, such as greenhouse
gas emissions and the depletion of marine fish stocks, some local and
regional problems are exacerbated.
Order from Strength - This scenario represents a regionalized and
fragmented world, concerned with security and protection, that and takes
a reactive approach to ecosystem problems. The rich protect their borders,
attempting to confine poverty, conflict, environmental degradation, and
deterioration of ecosystem services to areas outside their borders.
•Adapting Mosaic - In this scenario,
regional ecosystems are the focus of political and
economic activity. Societies develop a local strongly
proactive approach to the management of ecosystems.
Some regions are successful, others learn from them,
but some ecosystems still suffer long-lasting
•TechnoGarden - This scenario depicts a globally-
connected world relying strongly on technology to
provide or improve the provision of ecosystem services.
Under this scenario, environmental problems are dealt
with proactively in an effort to avoid problems. People
push ecosystems to produce as much as possible, but
this often undermines the ability of ecosystems to
support themselves, which in turn can have serious
consequences for human well-being.
Overall, in all four scenarios, agricultural
land will expand and forest cover will
shrink, particularly in developing countries.
This will lead to a continuing decline in local
and global biodiversity, mainly as a result
of habitat loss. More proactive approaches
to the environment will be more successful
in slowing these trends.
Aquatic biodiversity and specific
fish populations are expected to decline
due to factors such as excessive levels
of nutrients, overharvesting, invasion
by alien species, and pollution.
Human well-being will be affected by biodiversity loss both directly and indirectly.
Direct effects include an increased risk of sudden environmental changes such
as fisheries collapses, floods, droughts, wildfires, and disease. Changes will also affect
human well-being indirectly, for instance in the form of conflicts due to scarcer food
and water resources.
Though the average income per person (GDP) is projected to rise in all scenarios, this
can mask increased inequity for instance in terms of food security. Major decisions
will have to address trade-offs between competing goals, for instance between
agricultural production and water quality, or between water use and
aquatic biodiversity. Policies that conserve more biodiversity are also promoting
higher overall human well-being by preserving multiple benefits obtained
What actions can be taken to conserve biodiversity?
Protected areas are an essential part of conservation
programs, but they are not sufficient by themselves
to protect the full range of biodiversity and can be
difficult to enforce. To be successful, sites for
protected areas need to be carefully chosen,
ensuring that all regional ecosystems are well
represented, and the areas need to be well designed
and effectively managed.
Market tools, such as direct payments for ecosystem
services or transfers of ownership rights to private
individuals, can provide economic incentives to
conserve biodiversity and to use ecosystem services
Prevention and early intervention have proven to be the most successful and cost-effective way of
tackling invasive species. Once an invasive species has become established, its control and
particularly its eradication through the use of chemicals or through the introduction of
other species is not necessarily effective and is extremely difficult and costly.
To be conserved, biodiversity must be integrated into the agriculture, fishery, and forestry sectors.
These sectors are directly dependent on biodiversity and affect it directly. The private sector can
make significant contributions, for example by adopting certain agricultural practices. Many
companies now show greater corporate responsibility and are preparing their own biodiversity
Strong institutions at all levels are essential to support biodiversity conservation and the
sustainable use of ecosystems. International agreements need to include enforcement measures
and take into account impacts on biodiversity and possible synergies with other agreements. Most
direct actions to halt or reduce biodiversity loss need to be taken at local or national level. Suitable
laws and policies developed by central governments can enable local levels of government to
provide incentives for sustainable resource management.
Informing all of society about the benefits of conserving biodiversity, and explicitly
considering trade-offs between different options in an integrated way, helps
maximize the benefits to society. Ecosystem restoration is generally far more
expensive than protecting the original ecosystem, but is becoming increasingly
important as more areas become degraded.
Direct and indirect drivers of biodiversity loss must be addressed to better protect
biodiversity and ecosystem services. Possible actions include eliminating harmful
subsidies, promoting sustainable intensification of agriculture, adapting to climate
change, limiting the increase in nutrient levels in soil and water, assessing the
full economic value of ecosystem services, and increasing the transparency of
decision making processes.
Conservation is the scientific study of
the nature and
of Earth's biodiversity with the aim of
protecting species, their habitats,
and ecosystems from excessive rates
of extinction and the erosion of biotic
interactions. It is an interdisciplinary
subject drawing on natural and social
sciences, and the practice of natural
Concepts and foundations
Measuring extinction rates
Extinction rates are measured in a variety of ways. Conservation biologists measure and
apply statistical measures of fossil records, rates of habitat loss, and a multitude of other
variables such as loss of biodiversity as a function of the rate of habitat loss and site occupancy to
obtain such estimates. The Theory of Island Biogeography is possibly the most significant
contribution toward the scientific understanding of both the process and how to measure the
rate of species extinction. The current background extinction rate is estimated to be one species
every few years.
The measure of ongoing species loss is made more complex by the fact that most of the Earth's
species have not been described or evaluated. Estimates vary greatly on how many species
actually exist (estimated range: 3,600,000-111,700,000) to how many have received a species
binomial (estimated range: 1.5-8 million). Less than 1% of all species that have been described
have been studied beyond simply noting its existence. From these figures, the IUCN reports that
23% of vertebrates, 5% of invertebrates and 70% of plants that have been evaluated are
designated as endangered or threatened. Better knowledge is being constructed by The Plant
List for actual numbers of species.
Systematic conservation planning
Systematic conservation planning is an effective way to seek and identify efficient
and effective types of reserve design to capture or sustain the highest priority
biodiversity values and to work with communities in support of local ecosystems.
Margules and Pressey identify six interlinked stages in the systematic planning
1.Compile data on the biodiversity of the planning region
2.Identify conservation goals for the planning region
3.Review existing conservation areas
4.Select additional conservation areas
5.Implement conservation actions
6.Maintain the required values of conservation areas
Conservation biologists regularly prepare detailed conservation plans for grant
proposals or to effectively coordinate their plan of action and to identify best
management practices. Systematic strategies generally employ the services
of Geographic Information Systems to assist in the decision making process.
Conservation physiology: a mechanistic approach to conservation
Conservation Physiology was defined by Steven J. Cooke and colleagues
as: ‘An integrative scientific discipline applying physiological concepts,
tools, and knowledge to characterizing biological diversity and its ecological
implications; understanding and predicting how organisms, populations,
and ecosystems respond to environmental change and stressors; and
solving conservation problems across the broad range of taxa (i.e.
including microbes, plants, and animals). Physiology is considered in the
broadest possible terms to include functional and mechanistic responses at
all scales, and conservation includes the development and refinement of
strategies to rebuild populations, restore ecosystems, inform conservation
policy, generate decision-support tools, and manage natural
resources.’ Conservation physiology is particularly relevant to practitioners
in that it has the potential to generate cause-and-effect relationships and
reveal the factors that contribute to population declines.
Context and trends
Conservation biologists are dealing with and have published evidence from all corners of the planet
indicating that humanity may be causing the sixth and fastest planetary extinction event. It has been
suggested that we are living in an era of unprecedented numbers of species extinctions, also known as
the Holocene extinction event. The global extinction rate may be approximately 100,000 times higher
than the natural background extinction rate. It is estimated that two-thirds of all mammal genera and
one-half of all mammal species weighing at least 44 kilograms (97 lb) have gone extinct in the last 50,000
years. The Global Amphibian Assessment reports that amphibians are declining on a global scale faster
than any other vertebrate group, with over 32% of all surviving species being threatened with extinction.
The surviving populations are in continual decline in 43% of those that are threatened. Since the mid-
1980s the actual rates of extinction have exceeded 211 times rates measured from the fossi
record. However, "The current amphibian extinction rate may range from 25,039 to 45,474 times the
background extinction rate for amphibians." The global extinction trend occurs in every
major vertebrate group that is being monitored. For example, 23% of all mammals and 12% of
all birds are Red Listed by the International Union for Conservation of Nature(IUCN), meaning they too
are threatened with extinction.
Status of oceans and reefs
Global assessments of coral reefs of the world continue to report drastic and
rapid rates of decline. By 2000, 27% of the world's coral reef ecosystems had
effectively collapsed. The largest period of decline occurred in a dramatic
"bleaching" event in 1998, where approximately 16% of all the coral reefs in the
world disappeared in less than a year. Coral bleaching is caused by a mixture
of environmental stresses, including increases in ocean temperatures
and acidity, causing both the release of symbiotic algae and death of
corals. Decline and extinction risk in coral reef biodiversity has risen
dramatically in the past ten years. The loss of coral reefs, which are predicted to
go extinct in the next century, will have huge economic impacts, threatens the
balance of global biodiversity, and endangers food security for hundreds of
millions of people.
The oceans are threatened by acidification due to an increase in
CO2 levels. This is a most serious threat to societies relying heavily
upon oceanic natural resources. A concern is that the majority of
all marine species will not be able to evolve or acclimate in
response to the changes in the ocean chemistry.
Conservation biology of parasites
A large proportion of parasite species are threatened by extinction. A
few of them are being eradicated as pests of humans or domestic
animals, however, most of them are harmless. Threats include the
decline or fragmentation of host populations, or the extinction of host
These things do not imply, however, that human activities
must necessarily cause irreparable harm to the biosphere.
With conservation management and planning for
biodiversity at all levels, from genes to ecosystems, there
are examples where humans mutually coexist in a
sustainable way with nature. However, it may be too late
for human intervention to reverse the current mass