Biodiversity is the variety of life on earth. That is, it is the number of different species of flora and fauna including microorganisms. These organisms can inhabit different ecosystems with, varying conditions like the Rainforests, Coral reefs, Grasslands, Deserts, Tundra, and the Polar icecaps. This variety (Biodiversity) is essential for the wellbeing of our planet and sustenance of life as a whole. The importance of biodiversity can be viewed and measured as:
a)Ecosystem services
b) Biological resources
c) Social benefits of biodiversity
The organization and functioning of ecosystems world over are affected and dependent on biodiversity and its richness. The major functional attributes are:
(i) Continuity of nutrient cycles or biogeochemical cycles (N₂, C, a,o, P, S cycles)
(ii) Soil formation, conditioning or maintenance of soil health (fertility) by soil microbial diversity along with the different trophic members
(iii) Increases ecosystem productivity and provide food resources
(iv) Act as water traps, filters, water flow regulators and water purifiers (forest cover and vegetation)
(v) Climate stability (forests are essential for rainfall, temperature regulation, CO₂ absorption, which in turn regulate the density and type of vegetation)
(vi) Forest resource management and sustainable development
(vii) Maintaining a balance between biotic components
(viii) Cleaning up of pollutants - microbes are the biggest degraders of molecules including many anthropogenic ones which are present in effluents, sewage, garbage and agro-chemicals
(ix) Ecological stability - the varieties and richness of species contribute to ecological stability and survival of species. Biodiverse regions are reservoirs of biological resources like food resources, gene pool, genetic resource, medicinal resources, bioprospecting
(x) To provide unique aesthetic value and hotspots for Ecotourism. Along with forest resources and wildlife, it has commercial significance
(xi) An indicator of the health of the ecosystem. Endemism is a crucial indicator of richness.

(i) Development of human society is inevitable. Natural habitats are destroyed for the purpose of settlement, agriculture, mining, Industries and construction of highways
(ii) As a result species are forced to adapt to the changes in the environment or move to other places. If not, they become victim to predation, starvation, disease and eventually die or results in human animal conflict.
(iii) Over population, urbanization, Industrialization and agricultural advancements require additional land, water and raw materials every year.
(iv) This is made possible only through fragmentation or destruction of natural habitats by filling wetlands, ploughing grasslands, cutting down trees, forest, desilting rivers, constructing transport ways, caving mountains, extracting, ores, changing the course of rivers and filling of seashore.

The term biodiversity was introduced by Walter Rosen (1986). Biodiversity is the assemblage of different life forms. Each species is adapted to live in its specific environments.
The changes in climatic conditions are reflected in the distribution and pattern of biodiversity on our planet. The number of species per unit area declines as we move from tropics towards the poles. The Tundra and Taiga of northern Canada, Alaska, northern Europe and Russia possess less than 12 species of trees. The temperate forests of the United states have 20-35 species of trees, while the tropical forests of Panama have over 110 species of trees in a relatively small area.

Insitu and Exsitu are two types of biodiversity conservation strategies.

(i) Keystone species are those which have an extremely high impact on a particular ecosystem relative to its population. They are critical for the overall structure and function of an ecosystem and influence other and plants and animals that make up that ecosystem. Thus in the absence of a keystone species, many ecosystems will fail to exist.
(ii) Predator-prey relationship is an important example. Small Predators that consume herbivorous species prevent such herbivores from destroying the plant species in the ecosystem and are thus considered as keystone species.
(iii) If the number of predators was to decrease, the herbivore population would increase and the plant species in the ecosystem may perish very fast. In turn, the other organisms dependent on plants may also be impacted.
(iv) Thus extinction of a keystone species will lead to loss of biodiversity. Eg. Sea otter is considered to be a keystone species in the nearshore ecosystem. The Kelp forests are critical habitat for many organisms in nearshore ecosystems. These are fed by sea urchins. The Otters feed a Sea Urchins. In the absence of Otters, the sea urchins will destroy the Kelps forest which in turn will impact several other organisms and lead to loss of biodiversity in the ecosystem.