understanding biodiversity, its benefits and how it is threatened

By Dr J Floor Anthoni (2001)

Biodiversity is easily understood as the variety of life, an abstract concept measuring the richness of life by its variety. Variety is nature's way to create stability with maximum adaptability. As humans encroach, while altering their surroundings, wildlife disappears at a frightening rate, diminishing biodiversity. What is biodiversity? How is biodiversity measured? How is biodiversity threatened? What are ecosystem services? Can we save the environment? Can we prevent extinctions? What is biosecurity? How do we protect biodiversity?

Biodiversity is the natural biological capital of the Earth.

this long chapter consists or 4 parts: part1 (contents), part2, part3, part4 as shown by colours
biodiversity Biodiversity, the variety of life is at stake as the living space for the remaining ten million species becomes crowded out by humans. This chapter explains what is involved in biodiversity. Benefit to humans, what is not biodiversity, the species, the mechanics of evolution, nature's master plan, succession and climax, hot spots. 
ecosystem services Ultimately, humans depend on the services provided by the natural ecosystems, and these are critical to the life of all creatures on Earth.
 extinction Extinction is forever. What are its major causes? Classification of endangered species. How many species? Extinction is frightening. The mathematics of scarcity. 
 measuring diversity Scientists have made enormous progress in cataloguing the planet's species but they are not even half way there. In the meantime, they have also become better at estimating how many species remain unknown, and how many species must have disappeared recently. Diversity and area size. Factors affecting island reserves. 
marine biodiversity The sea is a totally different place. How does it differ from the land? How many phyla and species? How does it affect marine reserves? How can marine reserves fail? 
 biosecurity Safeguarding the life of native species, crops and livestock against the onslaught of introduced species and disease. 
protecting biodiversity Endangered species are listed in CITES and Red Data Books. 
Internet links biodiversity links: Tufts University biodiversity links, very extensive and academic, by category. the IUCN red list of threatened species has for almost four decades been assessing the conservation status of species, subspecies, varieties and even selected sub-populations on a global scale in order to highlight taxa threatened with extinction, and therefore promote their conservation. Links to important sites relevant to biodiversity (Colorado State Univ IBOY International Biodiversity Observation Year project) the official site of the United Nations Convention on Biological Diversity (CBD) All-Species Inventory, genetically sample every living species of life on Earth  Global Biodiversity Information Facility, aims to become a complete store of all species information. Established in 2001. The Infra Eco Network Europe (IENE) project aims to reduce the environmental impact of infrastructure networks like roads, and conserve biodiversity through research. CREO Committee on Recently Extinct Organisms. American Museum of Natural History. Aimal and Plant Health Inspection Services. APHIS provides leadership in ensuring the health and care of animals and plants, improving agricultural productivity and competitiveness, and contributing to the national economy and the public health. (Biosecurity)
related pages
on this web site
Conservation principles: understanding conservation of the environment and how it can fail (30p)
Resource management: important knowledge for understanding biodiversity and conservation (30p)
Global threats to humans, atmosphere, land and sea. (20 p)
Marine habitats: an introduction to the life-determining factors in the sea. (16 p)
The intertidal rocky shore: principles of the rocky shore zoning, and an identification of shore species. (80p)
Myths and fallacies in marine conservation, marine reserves, MPAs and marine science. (large)
Biorealms of the planet: the major biospheres and their differences. (4 p)
Red Data Book of NZ: a summary of the list of endangered species in New Zealand. (9 p)
Sitemap: discover the gems in the Seafriends web site from our complete site map (11p)
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The word biodiversity has entered the vocabulary of politicians and conservationists as a new buzz-word, still missing from most dictionaries before 1995. It is a maligned word in the sense that conservation of biodiversity is a recently introduced concept which extends conservation from the traditional saving for future human use to the tacit admission that conservation must extend to living organisms not of any use to humans. This just stops short of admitting that those other ten million species have a right to live on this planet.
biodiversity (L: bios=life; diversitas= variety) the variety that exists among organisms and their environments.  The term, short for biological diversity, is used mainly by scientists, conservationists, and others interested in the study, protection, and sustainable use of living things.  Protecting biodiversity is one of the greatest challenges facing humankind.  The scientists who specialize in ways to preserve it are called conservation biologists. (World Book 2000)
Biodiversity is a better word than biological diversity, which literally means variety in the knowledge of life.

The Convention on Biological Diversity (1992) defines biodiversity as: the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.

Biodiversity is an abstract concept. One cannot touch or feel biodiversity, as one can see a habitat or species. It is not a resource, yet it has resource-like benefits. It is often used as a feel-good word, suggesting that people know what it really involves. So what is behind biodiversity?
Benefits to humans
Often, the conservation of biodiversity is defended in terms of how much it can be of use to humans:
Although it is true that humans benefit from the biodiversity around them, conservation of biodiversity is all about stewardship of this planet and keeping it in a form which is still recognisably Planet Earth. If nature can be defined as what is not human or human made, then in order to preserve the integrity of the planet, no more than one third should be used or altered by people. However, as it stands today (2001), humans have already taken over half of the photosynthetic productivity of the planet, while changing over 60% of the land, and their population is still to double.
Amazing biodiversity facts
In 1993, about 80% of the 150 top prescription drugs  used int he USA were synthetic compounds modelled on natural products, semi-synthetic compounds derived from natural products or in a few cases natural products.

In 1988 ecotourism had 235 million people taking part, resulting in economic ativity amounting to US$ 233 billion.

Of the estimated 320,000 vascular plant species, about 25% have edible properties but only about 3000 are regularly used for food. Only about 30 of the 50,000 vertebrate species have been domesticated. Only about 200 species of fish, shellfish, frogs, turtles and algae are grown for food or other products.

Many native grasslands do no longer exist in their natural form. Forests and woodlands have decreased 15%. Tropical rain forest is being lost at 1% per year, since 1970.

Natural extinction rate (background extinction) is 1-3 species per year. Human-induced species decline is 1000 times larger. Natural mammals extinction rate is 1 per century.

Source: UNEP Global Biodiversity Assessment 1995.

What is not biodiversity
In our attempt to define what biodiversity is, it may help to mention also what it is not:
The message here is that the best way of conservation is prevention of degradation of proven natural ecosystems and habitats, with all their species. By preventing habitats from being changed, the largest contribution to conservation can be made at the least cost. An often overlooked fact is the soil, as perhaps the most important part of a habitat or ecosystem. To preserve an ecosystem, means above all, preserving its soil. See our chapter about soil.
The species
Thus biodiversity is not about preserving all species in an artificial way, but about a world or part thereof, unchanged by human beings. Biodiversity is but one aspect of the natural world around us, a web of organisms living together after a very long period of evolution. It is about living and functioning ecosystems in which one organism depends on the services of many others. To get a good feel of the enormity of nature, we'll attempt to look at it from various angles, but first of all we'll introduce the concept of the species:
species (L: specere= to look; species= appearance, beauty, kind) a class of things having some common characteristics. A category in the classification of living organisms consisting of single individuals capable of exchanging genes or capable of inbreeding.

Although the above definition appears simple enough, in practice, it is difficult to tell species apart.
morphological species concept (MSC): species differ if they have different form. However, some species have richly varied forms. In some species, males and females look entirely different. Other species have many colour forms (like flowers).
biological species concept (BSC): species differ if they cannot interbreed. However, many distinct species do interbreed, but their offspring is less successful, sometimes sterile. Often species who could interbreed, are prevented from doing so, because they are isolated from one another.
DNA species concept (DSC): species are distinguished by the differences in their DNA. However, some very distinct species have only very small differences in their DNA. (Human and bonobo chimpansee DNA differ only by 0.013). This method is also used to quantify genetic diversity within a species. However, many invertebrate species and plants reproduce mainly asexually.
sibling species: even though species look alike, they do not interbreed and are truly separate species.
hybrid species: species can be crossed to produce a new species, which is often sterile. If hybrids between two similar species cannot be found in the wild, they must be biologically separate species. But when similar species are geographically separated, this becomes difficult to establish. All breeds of domestic dog can interbreed to produce fertile offspring. It is estimated that up to 10% of all species hybridise in nature.
bacteria: single-celled organisms have different means of reproduction. Viruses play an important role, being able to transmit genetic material from one organism to another. When examining a soil sample, one may visually distinguish a hundred different bacterium species, but DNA techniques applied to the entire sample, find a hundred times more. Are these truly different species? If so, the species diversity of bacteria alone eclipses all others, estimated at 70 million species.

Although it may be difficult to define precisely what is a species, nature has a specific place and function for each.
The mechanics of evolution
Species have diversified by the mechanism of evolution, the most important components of which are:
It is hard to imagine that the sheer variety and beautiful functionality of the 4-30 million species around us, has arisen from such simple strategies as listed above. But it is the unimaginably vast period of time, and the equally unimaginable number of extinct species, that make it seem purposeful, as if a creator were behind it. Although we perceive only the successful species alive today, evolution consists of a long path of failed species. Of all the species that have ever lived, 99.99% are now extinct!

There are three kinds of species, judging by the way their numbers are increasing or decreasing:

Whereas the common species are the most important from a food and functional perspective, the rare ones are the most fascinating. Somehow they have managed to stay alive in small numbers, living far apart, as if flouting the laws of nature. In many cases such organisms have developed advantages (technology) such as camouflage, special defences, being inedible, being poisonous, being able to survive long periods of adversity (famine, cold, drought, etc.) and so on. Surprisingly too, they appear to survive well, individually to an old age, and as a species.

(A separate section on this web site will be devoted to evolution)

f003929: pregnant male seahorse
f003929: a pregnant male seahorse (Hippocampus abdominalis) hangs on to a branch in the tidal current of an estuary in New Zealand. Seahorses have evolved a peculiar way of reproduction. The female lays her eggs into the male's pouch after an affectionate courtship. Inside the pouch they are fertilised. Each egg then attaches to the pouch's lining, drawing food from the father and developing into a tiny seahorse. At 20mm length, the 50-200 young detach and escape to live entirely on their own resources.
f023214: long-tailed stingray and diver
f023214: A male long-tailed stingray (Dasyatis thetidis) tolerates a diver touching his wings. Poor Knights Islands, New Zealand. Stingrays and sharks, considered primitive cartilagious fishes, have evolved a system of internal fertilisation. Males have two penises (claspers), as seen trailing behind the animal above. Females give live birth to two baby stingrays, which are entirely functional and capable of looking after themselves, after birth.
These are two examples of nature's way of reinventing the wheel in different ways.

Nature's master plan
Diversity is one of nature's important strategies to create stable ecosystems. As discussed in the article on resource management, nature's strategies for resilience are: overcapacity + replication + diversity + connectivity (functionality) + adaptability. It achieves this by genetic variation, and by recording successful information in species and ecosystems. Here is nature's master plan (roughly corresponding to the sciences of genetics + ecology + biogeography):
Primary productivity and evapotranspirationIn the above summary of biodiversity, the physical world has been included with the living world, which is not usually done. However, the physical environment has a major influence on biodiversity, and the living and nonliving worlds interact in such profound ways, that it is not possible to separate them. Rainfall and evapotranspiration are the two most important factors to life, as shown in the diagram on right (but notice the logarithmic horizontal evapotranspiration and vertical growth scales). An increase in evapotranspiration of 10x leads to an increase in productivity of 40x. Life in turn, is of influence to rainfall, stabilises the world's climate, has made the world suitable for life, has formed the oceans, and who knows may also be accountable for the drifting of continents on their tectonic plates?
Succession and climax
In the grand scheme of things, it is important to distinguish what comes first. Since all animal life depends on plants, plants must take up the largest biomass, by at least five times. Because plants are able to store energy in woody tissues, which resist being eaten to some extent, their biomass can be very much larger still. 
Once the plants have established themselves, wildlife follows. It is not a stable situation, since plants create soil, with the help of soil animals, fungi and bacteria. As the soil changes, other plants take hold in succession, as do animals and soil creatures. Eventually a relatively stable climax vegetation forms, in which nutrients and energy cycle optimally, with minimal loss, but with very low net productivity (growth). Its total biomass then stays constant, and it won't be able to sequester additional carbondioxide from the air, for lack of moisture or nutrients. In such climax forests, with all their variants and edges, the highest diversity of species is found.

The path of succession to climax vegetation is marked by the following changes:

  1. Soil development: progressive development of the soil, with increasing depth and organic content, and differentiation of layers or horizons.
  2. Increasing biomass: increasing height and massiveness of the plants, while also differentiating the strata or tiers of vegetation.
  3. Storing nutrients & energy: the pool of nutrients and energy held in plant tissues, animals and soil, increases.
  4. Increased productivity: productivity, the rate of formation of organic matter increases.
  5. Microclimate: the microclimate under the canopy becomes determined by the forest, and increases in importance.
  6. Increased biodiversity: species diversity increases from simple succession communities to mature climax communities.
  7. Equilibrium: populations rise and fall, replacing one another until an equilibrium is reached.
  8. Long-lived species: long-lived species begin to dominate.
  9. Stability: the relative stability of the communities increases. Biodiversity climaxes.
At present, ecologists are a bit confused about the climax idea. They observe that fires can take down the work of hundreds of years of development, which makes them think that the situation is more dynamic (subject to change). Indeed many ecosystems are subjected to periodic upheavals such as hurricanes and fires, but the climax idea still holds as it is related to the amount of biodiversity information still available in soils, seeds and structure needed to rebuild the whole.
Note that the climax idea and stability lie at the heart of resilience or the capacity of an ecosystem to rebuild to its original state after an upheaval. When a change becomes permanent, this could only mean that environmental conditions have changed and/or biodiversity information has been lost permanently.
Hot spots
The uneven distribution of species in their environment causes what scientists call clumping. Clumping may have been caused by sheer coincidence of chance effects. When emptying a bag of red and blue marbles, one will notice that they are not evenly spread over the floor, but in some places the reds are dominant, whereas in other places the blues. However, these are not what scientists call hot spots.

Hot spots are places in nature where one notices a remarkable increase in species, often accompanied by an increase in numbers as well. They appear as oases or slices of paradise, even to the untrained eye. Why would this be? Remember that just as a species stores a record of its evolutionary past, an environment does so too. Hot spots therefore, may give clues of a distant past, interesting to be studied, and also valuable to be preserved. Here are some possible causes:

One could easily make the mistake that hotspots should be protected for their biodiversity, and that they give the most value for the least size. It is true that hot spots have proved their resilience over time. However, conservation is about creating sustainable communities, large enough to enable interbreeding while also maintaining a varied gene pool. Size thus remains important.
Clumping by regrouping
In our observations of the underwater damage caused by Cyclone Heta in January 2004, we noticed that much of the damage was caused by individuals and communities being scattered around. After 18 months, the animals found one another again and regrouped, which caused distinct clumping of biodiversity. On a small island surrounded by a large empty blue ocean, with little food to sustain high biodensities, clumping (schooling or grouping) is an important mechanism to form viable and fecund communities where high biodiversity exists all around. When diving in such an environment, every dive discovers a number of species not seen before, and these remain specific to the dive spot. By diving in different places, one also meets different communities, as if Noah's Ark was spread out all along the shore.


Ecosystem services

Over a very long period of time, the life on this planet created an environment suitable for innumerable species and humans. Around us we see nature as a benign place to be, replete (filled) with rich food sources. It is by far, a friendly place, a place we call home. 
We have given ourselves the right to plunder this home, and to change it to our needs. With the help of technology and fossil fuel we now believe that we have become invincible rulers of planet Earth, but nothing could be further from the truth. Like all other creatures, we depend on the life supporting biosphere, which is maintained by the co-operative effort of millions of species other than Homo sapiens. They provide services that humans cannot even think of providing for themselves, services which maintain the biosphere in a state supportive of all forms of life, including human life.
Genetic hot spots for crop speciesThis map shows the genetic hot spots where our major crop species come from, and where their wild varieties are found. These wild species and varieties are important for sustaining the crops' genetic resource base, because our main crops have the tendency to be monocultures of the most successful hybrid varieties only. Unfortunately, these hot spots are also good for cropping, which displaces the wild varieties. A concerted effort must be made to retain the genetic database and their natural habitats.
When living in an artificial environment like a city, with piped water, waste and energy, it is easy to forget that we depend on the part of the planet we have not changed. That part, already less than 50%, is shrinking rapidly.

Intergalactic space travel?
Spurred by our rich imagination, many people have started to believe in the reality of space travel across galaxies to planets with environmental conditions like ours. We could produce our own food from unlimited sources of energy and we could live longer in suspended animation. Human life is just the blooming stage of Gaia, ready to spread its seeds. Intelligence will provide the vehicles to seed life to other planets and other galaxies. Even if Earth may no longer be inhabitable, life and the human species will survive elsewhere. However, this may never be the case.

Observant scientists have pointed out that Earth is a young planet, and our galaxy also. Much older systems exist in space, many millions of years older. Life must have evolved there to bear intelligence incomparably superior to ours. Life-carrying planets should be within a reachable distance, and a thousand years to hop from one outpost to another must be easy for an advanced intelligence. In the millions of years of advantage, they could have seeded every planet in the entire universe, including Earth, long before the advent of Homo sapiens.Yet they have never found us.

We are insufficiently aware that all life on this planet depends on each other; that every species depends on hundreds, perhaps thousands of other species in an invisible network of ecological relationships, from which no species can be removed without an effect on others. Worse still, no species can live outside this network, and so does Man. No species alive today can live on some other world; not even on Earth 100 million years ago or 100 million years in the future, because those are different worlds with different climates and species and ecological relationships. There is no hope to seed life somewhere else. There won't be any planet with an ocean but without life. There is perhaps no planet at all with an ocean. To bring a library of DNA, hoping to rebuild the species from Earth, is flawed because the planet where they came from was created in 4000 million years by myriad successions of other species. The planet where they are introduced is not.

every Earthly species can live on Earth alone
and this includes Man

let's be humble and save this one and only Earth.

 go to part2 <=> go to part3 <=> go to part4