The word biodiversity is used to explain the variety of life on Earth, and is considered at
different levels of biological organization including genes, species and ecosystems.
Biodiversity is most often understood in terms of the number of species or other taxa and can
be considered at different spatial scales such as Whittaker’s definitions of alpha, beta and
gamma diversity. Biodiversity is not distributed evenly over the world, leading to Myers
concept of biodiversity hotspots.
The importance of biodiversity was one of the key subjects of the 1992 World Summit held in
Rio de Janeiro, Brazil, which resulted in the Convention on Biological Diversity (CBD). The
goals of the CBD are “the conservation of biological diversity, the sustainable use of its
components, and the fair and equitable sharing of the benefits from the use of genetic
resources”. Nevertheless, human actions have caused huge losses in biodiversity, including
the disruption of ecosystem processes, habitat destruction, species extinction and the eroding
of genetic diversity within species.
In order to understand and conserve biodiversity we need to measure it effectively, with
species richness being the most frequently used measure of biodiversity. At the moment
around 1.75 million species have been identified and estimates for the total number vary from
3 to 100 million. Identifying, naming and examining the relationships between species
depends on highly skilled taxonomists and the general lack of taxonomic expertise and
infrastructure has been called the taxonomic impediment. The Global Taxonomy Initiative has
developed a programme of work that attempts to reverse this impediment, whilst molecular
techniques such as DNA bar-coding provide an important way forward.
The National Botanic Garden of Wales is given as a case study for the role of a new botanic
garden in conserving biodiversity