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Why Biodiversity is Important Introduction
| What is biodiversity? | Nature's
services to humans There is a great concern over the loss of biological diversity, but at the same time few people know in any detail what is happening to the planet's diversity or can really say why they believe it is important. This page details some of the ways in which diversity is important, from concrete economic reasons to equally important but more philosophical reasons.
When it comes to conserving biodiversity, the definition that we use for it becomes extremely important. Simply defining it as "nature" is too nebulous, and makes deciding what actions to take difficult. Besides, both a rainforest and a desert are part of nature, although their diversity is obviously very different. The definitions given in the introduction to this site, despite being formed by governments and international organizations, are fairly vague. Finer definitions have their own problems, though, as much of what one might consider diversity ends up not being included in these definitions. Is it even necessary to define biodiversity? Perhaps it is better to define it as needed for a particular area of study; as long as the definition and its limitations are kept in mind, this may be the most appropriate way of dealing with this problem. A major concern with this approach is that if the context is not kept in mind, later conclusions can be reached that are drastically different from those intended. For this section, the definition of biodiversity is deliberately left vague, as is appropriate for such a large issue. Biodiversity seems a concept that is better explained than defined.
Because these services are largely invisible to us and difficult to give monetary values to, they tend to be given little weight when compared to development and policy decisions. The value of provided services has been calculated for small areas, but it was only a few years ago that an attempt to calculate the value of these services over the entire world was performed. They estimated that these services are worth at least 33 trillion (10^12) dollars, about twice the total economic output of the world! Although this estimate is crude and its exact value is debatable, it is very useful in pointing out just how important diversity is to us and how it should be taken more seriously in policy decisions than it is. Priorities for conservation are easier to decide upon if there is some basis for comparing, and these lists and estimates at least provide a way to make the comparisons.
Modern crops are extremely specialized strains of naturally occurring species, and the land they grow on is the result of the natural systems that they have displaced. Agriculture in Canada is worth $18 billion dollars per year (as farm receipts) and farm livestock contributes $11 billion dollars a year, but farming techniques reduce biodiversity by replacing natural communities with extremely artificial systems (see page 3 of this section for details). Recreation brings in even more money; benefits derived from Canada's natural areas such as national parks totaled an estimated $12 billion in expenditures and an additional $5 billion dollars in tax revenue in 1996. As ecotourism becomes more popular this value will increase in Canada, and internationally this source of income could be extremely important in the economies of developing nations.
Many pharmaceutical companies
are currently engaged in bioprospecting, which consists of testing plant
species Many parts of the natural world prevent or slow rapid change. One example would be forests, which prevent erosion and also prevent heavy rains from turning into floods. To some extent the climate is naturally held somewhat constant as well. This does not require diversity as much as nature; a forest with low diversity will prevent erosion as well as one with high diversity. Our current infrastructure is specialized enough to require this sort of stability. The cost of repairing damage caused by flooding is enormous. Agricultural crops are specialized to grow extremely well, but only under specific conditions. If those conditions were to change, we would be forced to either move the crops to a region where those conditions exist or develop new strains of crops, both of which would be a sizeable drain on resources. Road, buildings, bridges, all are designed for a particular type of climate. It the climate changes, these structures will begin to crumble. Aesthetic and Philosophical Importance
Unfortunately, religions and philosophies don't say much about diversity and nature. One religious tradition that fairly directly mentions biodiversity is Judeo-Christianity, which promotes wise stewardship of the Earth. Philosophies are usually focused on issues internal to ourselves, and don't truly deal with diversity either. Still, most religions and philosophies believe that destruction without just cause is wrong; as humans are responsible for most of the loss of diversity, we have a responsibility to stop doing harm and to repair as much of our damage as we can. Nature, and by extension diversity, also has an aesthetic quality. When people go hiking and canoeing it contributes to the economy in various ways but also enriches their lives. People experience nature in a way that goes beyond economics and also beyond nature's beauty. How does one say exactly how beautiful a forest is, or how much one enjoyed a hike? Because this enjoyment cannot reasonably be quantified, it tends to be ignored in debates about conservation. Only the economic revenues associated with people getting to natural areas can be measured, and it's at best a poor replacement.
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Nature
and biodiversity provide services that we take for granted. Clean water
to drink, clean air to breathe, soil for agriculture, the pollinating
effect of many insects and much more is provided for us (see Daily 1997
for extensive descriptions), but we tend not to pay much attention to
these services. 
Nature
provides huge direct and indirect economic benefits. In 1990 lumber cut
in Canada (mostly from natural stands) had a value of $7.5 billion (10^9),
while fishery catches were worth $1.5 billion. These values are for harvesting
natural resources, and are limited by the natural productivity of nature.
As can be seen by the recent crashes in the Atlantic fisheries, exceeding
what nature can provide is economically dangerous, to say nothing of the
ecological impacts. 
Out
of the top 150 prescription drugs, 118 originally came from living creatures,
mostly plants. Overall, seventy percent of pharmaceuticals now being used
come from or are derived from natural products. Three substances that
have been produced from the barks of tree species include: aspirin, from
willow trees; quinine, which helps prevent malaria and is found in the
bark of the quina tree; and taxol, a cancer-fighting drug derived from
the bark of the Pacific yew tree. Digitalis, used to treat heart conditions,
comes from the foxglove plant. The list goes on and on. 
With
the obvious health and financial importance of plant products, the destruction
of biodiversity is a terrible waste. No one knows how many com
pounds
in plants and animals can be used. Even if only a small fraction of plants
and organisms produce useful medicinal products, it is a potential boon
that we can't ignore and shouldn't destroy.
for potentially useful compounds, sometimes signing agreements with national
governments for permission. How many compounds are being lost before they
are found is a mystery, but the number of potentially useful compounds
found has been large.
The
long list of concrete benefits that diversity and nature provide should
be enough to convince anyone of its importance, but there are also more
esoteric, though no less important, reasons.