The variety of life on Earth, its biological diversity is commonly referred to as biodiversity.
The number of species of plants, animals, and microorganisms, the enormous diversity of genes in these species, the different ecosystems on the planet, such as deserts, rainforests and coral reefs are all part of a biologically diverse Earth.
Appropriate conservation and sustainable development strategies attempt to recognize this as being integral to any approach to preserving biodiversity. Almost all cultures have their roots in our biological diversity in some way or form.
Declining biodiversity is therefore a concern for many reasons.
A healthy biodiversity offers many natural services
A healthy biodiversity provides a number of natural services for everyone:
Ecosystem services, such as
Protection of water resources
Soils formation and protection
Nutrient storage and recycling
Pollution breakdown and absorption
Contribution to climate stability
Maintenance of ecosystems
Recovery from unpredictable events
Biological resources, such as
Medicinal resources and pharmaceutical drugs
Breeding stocks, population reservoirs
Diversity in genes, species and ecosystems
Social benefits, such as
Research, education and monitoring
Recreation and tourism
That is quite a lot of services we get for free!
The cost of replacing these (if possible) would be extremely expensive. It therefore makes economic and development sense to move towards sustainability.
A report from Nature magazine also explains that genetic diversity helps to prevent the chances of extinction in the wild (and claims to have shown proof of this).
To prevent the well known and well documented problems of genetic defects caused by in-breeding, species need a variety of genes to ensure successful survival. Without this, the chances of extinction increases.
And as we start destroying, reducing and isolating habitats, the chances for interaction from species with a large gene pool decreases. Side NoteUnfortunately the original link to the Nature.com article no longer works, since their site redesign, and I had not noted the publication details. However, for similar information, you could look at Consequences of changing biodiversity, Nature 405, 234 - 242, 11 May 2000 and Causes, consequences and ethics of biodiversity, Nature 405, 208–211, 11 May 2000.
While there might be survival of the fittest within a given species, each species depends on the services provided by other species to ensure survival. It is a type of cooperation based on mutual survival and is often what a balanced ecosystem refers to.
Soil, bacteria, plants; the Nitrogen Cycle
As an example, consider all the species of animals and organisms involved in a simple field used in agriculture. As summarized from Vandana Shiva, Stolen Harvest (South End Press, 2000), pp 61–62:
Crop byproducts feed cattle
Cattle waste feeds the soil that nourish the crops
Crops, as well as yielding grain also yield straw
Straw provides organic matter and fodder
Crops are therefore food sources for humans and animals
Soil organisms also benefit from crops
Bacteria feed on the cellulose fibers of straw that farmers return to the soil
Amoebas feed on bacteria making lignite fibers available for uptake by plants
Algae provide organic matter and serve as natural nitrogen fixers
Rodents that bore under the fields aerate the soil and improve its water-holding capacity
Spiders, centipedes and insects grind organic matter from the surface soil and leave behind enriched droppings.
Earthworms contribute to soil fertility
They provide aerage, drainage and maintain soil structure.
According to Charles Darwin, It may be doubted whether there are many other animals which have played so important a part in the history of creatures.
The earthworm is like a natural tractor, fertilizer factory and dam, combined!
Industrial-farming techniques would deprive these diverse species of food sources and instead assault them with chemicals, destroying the rich biodiversity in the soil and with it the basis for the renewal of the soil fertility.
Shiva, a prominent Indian scientist and activist goes on to detail the costs associated with destroying this natural diversity and traditional farming techniques which recognize this, and replacing this with industrial processes which go against the nature of diversity sustainability.
As reported by CNN (May 5, 2000), One third of all our food—fruits and vegetables—would not exist without pollinators visiting flowers. But honeybees, the primary species that fertilizes food-producing plants, have suffered dramatic declines in recent years, mostly from afflictions introduced by humans.
More important than human use or biological interest
Many people may support environmental causes to help preserve the beauty of Nature. However, that is in a strange way, not really a justifiable excuse as it is a subjective, human or anthropomorphasized view.
For many decades, various environmentalists, biologists and other scientists, have viewed the entire earth as a massive living organism or system due to the interdependent nature of all species within it. Some cultures have recognized this kind of inter-relationship for a very long time. Some have termed this Gaia.
While there are disagreements and differences on how this works, it suggests that ecological balance and biodiversity are crucial for all of earth, not just humans.
Biodiversity: A Matter of Extinction is a briefing from Panos that highlights the problems that have led to an increasingly alarming rate extinctions, this century alone. Although from 1995, it shows how far back the problem was known (and one can infer that we haven’t therefore done much about the problem since).
Why Conserve Species from Nature Magazine provides a good answer to this question. (Unfortunately, since their site redesign, this URL is no longer valid, and to date a new URL cannot be found.)
Life on the Brink from Earth Magazine, (Kalmbach Publishing Company), April 97 edition, delivers a very interesting answer to why biodiversity is important. (Unfortunately they no longer publish this magazine so the article is no longer online.)