Nobody seemed to know much about them so all that lingered with me until recently was a sense of curiosity. Now they are the hottest thing on the cancer ‘beat’, because the slime on which they move contains a group of chemicals, the epothilones, which seem to work on taxol-resistant cancers. Taxol itself is a relatively recent anti-cancer drug which halts tumour growth in ovarian, breast and lung cancer: it was originally isolated from the Pacific yew, a tree in the old-growth forests of the Pacific northwest, that used to be trashed as worthless by clear-cutting loggers.

An unread book
Finding the powers of epothilones and taxol, compounds which play important roles in the life cycles of these organisms, is part of the continuing chain of discovery about living systems derived from biological diversity. As both examples demonstrate, it is hard to predict where such discoveries are likely to be made within the kingdoms of life. It is wondrous really. The role biodiversity plays as the basic library for the life sciences would be reason enough for its conservation. Yet it is only one cause for concern about the accelerating loss of species around the world.

Biological diversity is under assault in virtually every kind of habitat, terrestrial or aquatic. Virtually every environmental problem or stress affects it. So its loss is both a problem in itself and integrates all environmental issues. In essence biological diversity represents the ‘bottom line’ of human impact on the globe.

The impact on forests is dramatic. It is so great that probably more than a billion tonnes of carbon are generated as carbon dioxide (CO₂) in the course of destroying and burning forests each year, compared to 6 billion or so from the burning of fossil fuels. Furthermore, deforestation is usually thought of as the single greatest generator of extinctions, since forests, especially those in the tropics, represent one of the richest natural stores of plant, animal and microorganismal species on the planet.

Biological diversity represents the bottom line of human impact on the globe

One of the many causes of forest loss is the usual lack of recognition of the ecological services that they provide. Take their role in the global carbon cycle and the increasing concentrations of greenhouse gases. We know that reforestation can absorb important amounts of CO₂ and convert it into the carbon the trees need to grow. It now also appears that tropical forests are responding to higher levels of CO₂ in the atmosphere by sequestering more carbon. If natural forest escapes destruction, it prevents an increase in CO₂. So from a biological diversity perspective it would be very desirable for natural forests to be included in the Clean Development Mechanism under the Climate Convention, which would allow payment for this ecological service. Costa Rica already has Certifiable Tradable Offsets ready for sale.

There are of course technical and complex issues to be resolved about what would qualify and how credit should be given, but trees and forests nonetheless represent an easy way to start addressing the CO₂ problem. Further, carbon payments could make a substantial difference to the economics of maintaining natural forest – as opposed to cutting it down – because they can become one of a number of income streams for the same area of forest (provided other income streams do not diminish the forest’s carbon content).

Climate change is likely to have a devastating effect on biological diversity. So carbon offset income for natural forests is probably the single most important measure which can be taken for biological diversity because it conserves it directly and reduces greenhouse gases at the same time.

Disaster prevention
Recent events in Venezuela and Honduras have illuminated yet another ecological service of forests – disaster prevention. Deforestation clearly played a role in aggravating the devastating floods associated with Hurricane Mitch and the ghastly Venezuelan floods and mudslides last December. Both were only partially ‘natural disasters’, ones that will doubtless be visited on other countries with similarly bare hillsides. Quite apart from humane considerations, you do not need a Nobel Prize to conclude that it is better economically to stabilize slopes with forests than to suffer disasters like these.

Then, of course, there is the service that forests provide in supplying reliable flows of clean water. Here, at least, there are signs that the authorities are recognizing their importance. New York City found that it was ten times cheaper to restore its watershed – so that biological diversity could clean its water properly – than to build and operate a treatment plant. In Costa Rica watershed owners, both public and private, are beginning to be recompensed for providing water, whether for drinking or for generating electricity. Quito’s Mayor, Roque Sevilla, calls forests ‘water factories’.