1. What is Biodiversity?
The word 'biodiversity' is a contraction of biological diversity. Diversity is a concept which refers to the range of variation
or differences among some set of entities; biological diversity thus refers to variety within the living world. The term
'biodiversity' is indeed commonly used to describe the number, variety and variability of living organisms. This very broad
usage, embracing many different parameters, is essentially a synonym of 'Life on Earth'.
Management requires measurement, and measures of diversity only become possible when a quantitative value can be
ascribed to them and these values can be compared. It is thus necessary to try and disentangle some of the separate
elements of which biodiversity is composed.
It has become a widespread practice to define biodiversity in terms of genes, species and ecosystems, corresponding to
three fundamental and hierarchically-related levels of biological organisation.
Genetic diversity
This represents the heritable variation within and between populations of organisms. Ultimately, this resides in variations
in the sequence of the four base-pairs which, as components of nucleic acids, constitute the genetic code.
Species diversity
Perhaps because the living world is most widely considered in terms of species, biodiversity is very commonly used as a
synonym of species diversity, in particular of 'species richness', which is the number of species in a site or habitat.
Discussion of global biodiversity is typically presented in terms of global numbers of species in different taxonomic
groups. An estimated 1.8 million species have been described to date; estimates for the total number of species existing
on earth at present vary from 5 milliion to nearly 100 million. A conservative working estimate suggests there might be
around 12.5 million. In terms of species numbers alone, life on earth appears to consist essentially of insects and
microorganisms.
Ecosystem diversity
The quantitative assessment of diversity at the ecosystem, habitat or community level remains problematic. Whilst it is
possible to define what is in principle meant by genetic and species diversity, and to produce various measures thereof,
there is no unique definition and classification of ecosystems at the global level, and it is thus difficult in practice to assess
ecosystem diversity other than on a local or regional basis and then only largely in terms of vegetation. Ecosystems
further differ from genes and species in that they explicitly include abiotic components, being partly determined by soil
parent material and climate.
Why is Biodiversity Important?
The complex web of inter-dependent ecosystems which constitute life on Earth includes us. We are part of that web and
are entirely dependent on clean air, fresh water and healthy food for our survival. Some people would argue that as the
species at the top of the food chain capable of acting on the planet's ecosystems to create profound change, we have a
responsibility to act as stewards of the planet, protecting nature for its own sake and ensuring our consumption levels are
sustainable.
Others take a more utlitarian approach and argue that we should protect nature on the basis of the present and potential
use of elements of biodiversity as biological resources, and focus on maintaining the biosphere in a state which supports
human life.
While some may prefer the 'nature for nature's sake' approach, many of the individuals, organisations and corporations
whose activities are putting the planet's ecosystems under immense pressure are more responsive to utilitarian
arguments framed in concrete and measurable terms.
Current corporate accounting systems tend to ignores costs to nature, and look only at the short-term economic benefit
of development to a small group of individuals. This incentivises indifference to the environment, at best, and maximum
exploitation for profit, at worst. In order to counteract this, scientists have been working on the development of clear and
transparent ways of assigning a monetary value to some of the ecosystem functions on which we depend, such as the
activity of bees and other pollinators, the treatment of water and purification of waste, or the carbon sequestration and
climate regulation role of plants, in particular tropical rainforests.