Geoscience Reference
In-Depth Information
may be direct or indirect on the living system. The direct
impacts are those which are predictable and one can think
of getting rid of them. Indirect impacts are those which
are very slow to monitor and difficult to predict. They
have a long-lasting and permanent change in the features
of biodiversity.
16.1
Biodiversity
Biodiversity is the degree of variation of life-forms within a
given species, ecosystem, biome or the entire planet. Health of
an ecosystem can be measured by biodiversity, which is a func-
tion of climate. The term biological diversity was used first by
the wildlife scientist and conservationist Raymond F. Dasmann
in 1968 in the topic
A Different Kind of Country.
The term was
widely adopted only after more than a decade, when in the
1980s, it came into common usage in science and environmen-
tal policy. The biological definition of biodiversity is 'totality of
genes, species and ecosystems of a region'. Biological variation
can be identified in four levels:
•
Species diversity: Species diversity is the effective num-
ber of different species that are represented in a collec-
tion of individuals. The effective number of species refers
to the number of equally abundant species needed to
obtain the same mean proportional species abundance as
that observed in the dataset of interest. Species diversity
consists of two components, species richness and species
evenness.
•
Ecosystem diversity
: Ecosystem diversity refers to the
diversity of a place at the level of ecosystems. Ecosystem
diversity means a variety of ecosystems present in a bio-
sphere, the variety of species and ecological processes
that occur in different physical settings.
•
Genetic diversity
: Genetic diversity refers to the extent
of genotypic differences existing in the biological sys-
tem. It may be intraspecific, interspecific and intrage-
neric. In other words, genetic diversity means the inter se
genetic distance among the individuals in the biological
community.
Biodiversity is not evenly distributed; rather, it varies greatly
across the globe as well as within regions. The distribution of
living entities on the Earth depends on climatic and edaphic
