Any realistic, workable definition of biodiversity must take multiple factors into account, because biodiversity covers so much of what we know as life.
A good definition of biodiversity must not only take into account that biodiversity covers the air, land and water of Earth and all the animal and plant life thereof. It must take into account that there are three specific types of biodiversity:
Genetic diversity means the variation of genes within a species. It can apply to either distinct populations of the same species (like India’s many different rice varieties) or to the genetic variation within a population (like the many different kinds of jungle cats, with low variation in a particular species, like tigers).
Species diversity is the variety of species within a region. There are many ways to determine this, but no one method has been declared definitive. One of the most often used methods is species richness: the number of species, both plant and animal in an area, but a more precise method is taxonomic diversity. This considers not only the number of species, but their relationships to each other.
Ecosystem diversity is the most difficult kind of diversity to measure because community boundaries, especially in sparsely populated areas are very fluid and almost impossible to determine.
Natural diversity is often synonymous with biological diversity. Scientists word their definition of biodiversity in several ways: First is the number of different species native to an area. Second is the variety of habitats within an ecological area. Third is the variety of interactions between the various species inhabiting an area, and fourth is genetic variation among the individuals of a given species.
Those trying to formulate a realistic working definition of biodiversity are often stopped by the very complexity of the subject. Since biodiversity covers pretty much every aspect of life on Earth, it’s is very difficult to create simple, yet adequate criteria by which to measure or describe the subject concisely. Add in threats such as human depredations (like deforestation or over-fishing) and climate change, and the issue becomes almost indescribable. This leads to patchwork efforts to remedy the damage, which are often too little and often undertaken far too late. If a comprehensive definition of biodiversity cannot be formulated, and soon, the planet’s natural resources will continue to be threatened, because you cannot fix what you cannot name.
In formulating any realistic and workable definition of biodiversity, private agendas must be put aside so that each of the major factors of this multi-faceted topic are given due consideration in balance with the others.