2. What Is BIODIVERSITY?
• There are more than 10,000 species of birds, 300,000 and 500,000
species of higher plants (i.e flowering and cone bearing plants)
of which approximately 250,000 have been identified or described,
and almost one million species of insects in the world.
• Example: Family Orchidaceae (the orchids) ~ 30,000 of species
worldwide!
• However, very little reliable biodiversity data on other groups such as
most bacteria, fungi, non-vascular plants, and invertebrates.
• The number of species identified has increased substantially in
recent years, and there are over 1.5 million species currently
known (~due to more discoveries).
• Although this number might seem large, it is actually only a fraction
of the number of species that exist today. New species are being
identified every day, and it is estimated that there are anywhere
between three and fifty million different species living on Earth.
3. What Is BIODIVERSITY?
•Biodiversity also known as biological diversity - is the
variety of life on Earth across all of the different levels of
biological organization.
• Biodiversity is the total variability within and among species
of all living organisms and their habitats.
• On a smaller scale, biodiversity can be used to describe the
variety in the genetic makeup of a species, and on a larger
scale, it can be used to describe the variety of ecosystem types.
• Plant diversity: variety of plant species
• Animal diversity: variety of animal species
4. Plant Diversity
• The diversity of plant life exists for many reasons - a key factor being
adaptive changes which allow different species to thrive in the
many varied environments of the world.
• Plants have developed adaptations for different soil types, methods
of pollination, daylight hours, temperature, altitude, competition with
other plants ~ environmental factors driven.
• Even two plants of the same species, separated by geography will
have a different genetic make-up – allopatric speciation.
• Diversity within any population is vital for that population’s survival. If
humans were all the same, a single strain of a particularly nasty cold
could wipe us all out!
5. • The tropics have the greatest biodiversity on the planet, and, within the tropics, the areas
richest in species are the rainforests.
• It is estimated that tropical forests, comprising only 6% of the world’s surface area
(about 31% of the Earth is covered by forests); contain one-half to three-quarters of the
earth’s species of plants and animals!
• This is in part because the groups of organisms which contain the most species
(arthropods and flowering plants) are found in high concentrations in tropical forests.
• These species, although numerous, tend to have smaller geographical ranges than
temperate species, and there is considerable endemism (the restriction of a species to a
circumscribed area or region).
• Europe north of the Alps has 50 species of trees; eastern North America, 171; but even a
small area of tropical forest may have 100 or 200 species of trees of reasonable size
(Whitmore, 1995). In Borneo, 3200 species of plants can be found in 100 hectares of
rainforest. In fact, a land area of 0.5 km2 in some tropical forests contains more tree
species than does the entire land mass of Europe and North America combined.
How much biodiversity is found in tropical
rainforests?
7. • The tropical rainforests richest in species are those of Southeast Asia; the poorest, those
in Africa.
• This may be because Africa has mainly seasonal forest with relatively low rainfall and a
long history of human intervention. Here there are few palms – only about 100 species
compared to 1400 in Australasia – and 403 known species of orchids, compared to more
than 5000 in Malesia. Other species – epiphytes and lianas, are comparably fewer in
number than in other tropical regions.
• Malesia (the region of Southeast Asia including Malaysia and the western part of
Indonesia), which has many mountains and islands, has at least 30,000 species of plants.
Within this area, Borneo and Peninsular Malaysia have the greatest variety of species.
Here the dominant trees are called dipterocarps, of which Borneo alone has 267 species.
• Indonesia has more species of flowering plants, amphibians, birds and reptiles than all of
Africa.
Biodiversity in tropical forests: A comparison
9. Biodiversity in tropical forests: A comparison
• The Mekong river, which passes through Laos and Vietnam, has more than 110
species of snails, and Asia has more than 80 genera of freshwater crabs and
many turtles. Sri Lanka, although it has only 750 km2 of forest (less than 5% of its
original forest cover), has recently been discovered to have more than 140
species of frogs (Meegaskumbura, et al., 2002).
• Within the Neotropics, the upper Amazon is the richest in the number of species.
Amazonia, which also has an extremely rich flora and fauna, is dominated by
leguminous trees of many genera and species. Here one will find 2000 species of
bromeliads (the pineapple family) and 837 species of palms. There are 1383
known species of fish in Brazil alone and 456 in Central America (as compared to
192 species in Europe).
• Colombia, which is not very large, has perhaps the third most diverse forest in the
world. It has 1815 bird species, 142 of which are endemic; approximately 700
species of amphibia, 367 of which are found nowhere else; and between 45,000
and 51,000 plants species, one-third of which are endemic. It has 10%- 20% of
the worlds orchids.
11. Deforestation
• The Earth’s most varied and most mysterious ecosystem, the tropical rainforest, has been
reduced to half of its original size.
• Deforestation, clearance, or clearing is the removal of a forest or stand of trees from land
which is then converted to a non-forest use.
• It can involve conversion of forest land to farms, ranches, or urban use.
• Deforestation can occur for several reasons: trees can be cut down to be used for building,
furniture and paper production or sold as fuel (sometimes in the form of charcoal or timber),
while cleared land can be used as pasture for livestock (beef production) and plantation (exp:
oil palm plantation, soy plantation).
• The removal of trees without sufficient reforestation has resulted in habitat damage,
biodiversity loss, and aridity. It has adverse impacts on biosequestration of atmospheric
carbon dioxide.
• Most of this loss has taken place over the past five to six decades. Despite increased
awareness of the key role played by the tropical forests in solving the most urgent global
environment and development challenges, the rate of tropical deforestation remains
alarmingly high.
• Looking more closely at developments in the last five to ten years, however, we can note both
significant policy changes and important examples indicating that it is indeed possible to avoid
continued deforestation of the magnitude that has characterized recent decades.
13. Deforestation
• What if you found out that just four commodities—
commodities so pervasive in modern life that we encounter
them daily—are responsible for more than half of the
world’s tropical deforestation?
• What if you learned that many of the other commonly cited
causes of deforestation, such as cocoa, sugar, and coffee,
are now only marginal parts of the global problem?
• Surprisingly, all of this is true. Just four commodities—
beef, soy, palm oil, and wood products—drive the
majority of tropical deforestation!
Union of Concerned Scientist, Inc. (US)
14. Types of Biodiversity
• Biodiversity is a very broad term and is often divided into three types:
i) Species diversity
ii) Genetic diversity
iii) Ecological diversity
• Species diversity is defined as the number and abundance of different species that occupy a location.
To accurately determine species diversity, both the species richness, which is the number of different
species, and the relative abundance, which is the number of individuals within each species, must be
considered. An example of species diversity would be the number and abundance of different types of
mammals in a forest. The first type of biodiversity is species diversity, and this is the type of biodiversity
most people are familiar with.
• Genetic diversity is the amount of variation in genetic material within a species or within a population.
There is a high level of diversity among species, but there is an even higher level of diversity among the
genetic material of the individuals of a specific species. An example of genetic diversity is the variation in
the genes that encode for hair colour in humans. The term genetic diversity also covers distinct
populations of a single species, such as the thousands of breeds of different dogs or the numerous
variety of roses.
15. Types of Biodiversity
• Ecological diversity is the variation in the ecosystems found in a region
or the variation in ecosystems over the whole planet. Ecological diversity
includes the variation in both terrestrial and aquatic ecosystems.
Ecological diversity can also take into account the variation in the
complexity of a biological community, including the number of different
niches, the number of trophic levels and other ecological processes. An
example of ecological diversity on a global scale would be the variation in
ecosystems, such as deserts, forests, grasslands, wetlands and oceans.
Ecological diversity is the largest scale of biodiversity, and within each
ecosystem, there is a great deal of both species and genetic diversity.
16. Community Structure
• A community is an association of interacting species inhabiting some
defined area (exp: deserts, forests, grasslands, wetlands and
oceans, etc.).
• Various abiotic and biotic aspects of the environment influence
the structure of communities.
• Community structure includes attributes such as the number of
species, the relative abundance of species, and the kinds of
species comprising a community.
