Kew Garden's Sir Ghillean Prance: A Global View of Biodiversity

Kew Garden's Sir Ghillean Prance:
A Global View of Biodiversity

Biodiversity is one of the planets most precious resources, and the tropical rain forests harbor the bulk of this richness. Among those who have spent their lives studying and documenting the life of the rain forests, few have attained greater prominence than Sir Ghillean Prance, currently director of the Royal Botanic Gardens at Kew, England.

Having completed a first degree and a doctorate in botanical taxonomy in Oxford, Prance joined the New York Botanical Garden in 1963 as a research assistant, gradually working his way up to director of research, then vice-president of research, and finally senior vice-president for science in 1981. He left the Garden in 1988 to become director of Kew. A Fellow of the Royal Society since 1993, Prance was knighted in July, 1995.

"There is a great complexity of interrelationships," say's Sir Ghillean Prance of the Royal Botanic Gardens at Kew, England, describing biodiversity in the Brazilian rain forests and elsewhere. "The loss of species can have surprising consequences."

While working in New York, he spent much of his time leading botanical expeditions in the forests of the Brazilian Amazon, and this has inspired his varied research interests in many aspects of tropical rain- forest ecology, vegetation, and biogeography. He has published papers on subjects that range from fruit dispersal, pollination by monkeys, the biology of Amazonian water lilies, the genetics of the Brazil nut, ethnobotany, and the chemotaxonomy of the Chrysobalanaceae. Perhaps it is this unusually broad base to his research that has brought him such a prominent position as a proponent for the conservation of biodiversity in general and that of the rain forests in particular.

Science Watch correspondent Peter Moore recently spoke with Sir Ghillean Prance at Kew Gardens in London.

How did you first become involved in taxonomy, particularly in tropical forest research?

Prance: I was keen on plants throughout my childhood, with a particular interest in field botany and identification. So it seemed inevitable that I should study botany at university and that I should then gravitate towards taxonomy as a focus for my subsequent research. But I was also interested in habitats, vegetation, biogeography, and so on--the links between animals and plants in such processes as pollination. So I maintained a broad interest in ecology as well as taxonomy.

What was the subject of your doctoral research?

Prance: It was essentially a taxonomic problem--namely, sorting out the generic limits of the pantropical plant family, the Chrysobalanaceae, which has about 500 species. I used quite a lot of numerical techniques in this work, which was one of the early attempts in this direction. I also made use of many different characters, from wood anatomy to pollination ecology, so it was a very broad study. The family was thought at that time possibly to be part of the family Rosaceae, but my work showed definitively that it was not.

So this family presumably led you to your lifelong association with the tropics, but how did you end up in South America rather than Africa or Southeast Asia for your subsequent research?

Prance: My supervisor at Oxford, Frank White, was actually an African specialist, but I found that the center of diversity of the Chrysobalanaceae was South America, so my research led me to focus on that continent. On completing my doctorate I was offered an opportunity to join a New York Botanical Garden expedition to Surinam and then spend a year working up the results. But that appointment actually lasted 25 years! They were very keen to develop a program of research in South America to fill a geographical gap, and I was there in the right place at the right time, eventually taking up the post of curator of Amazonian Botany.

So you were led inexorably to the Amazon, which happens to be the most biodiverse of all the tropical forest regions. What is it about the Amazon basin that has made it so much richer than, say, the African rain forests?

Prance: One reason is that the dry periods of the Pleistocene in South America have not been as dramatic as those of Africa, so there has not been the same level of extinction. It became fragmented, but much more of the forest remained intact than in Africa in riverside patches. The Southeast Asian rain forests also have more diversity than Africa, but not as much as South America.

The value of biodiversity to ecosystems in terms of enhancing their functioning (productivity, nutrient cycling, stability, etc.) is currently a source of much debate. What are your thoughts on this area?

Prance: First of all, we must get away from the idea of climax forest and stability. No ecosystem is stable; it is constantly changing, and the turnover resulting from disturbance is one of the factors that produces diversity in the forest. I have looked at this from the point of view of the interdependency of organisms, pollination, dispersal, mychorrhizal relationships, and so on. So many things are concerned with the maintenance of just one species that it is easy to see that species removal is bound to have wide consequences. Take the Brazil nut, for example; this is a tree that I have studied in great detail. It is pollinated by a bee that in turn needs epiphytic orchids, which attract the female bee and permit mating to take place. So the tree needs the orchids to support the bees. Then an agouti on the forest floor is responsible for dispersing the seeds, and so on. There is a great complexity of interrelationships, and the loss of species can have surprising consequences.
It is also very important to bear in mind the importance of the structured, multi-species forest canopy on a global scale, modifying the chemistry of the atmosphere and world climate patterns. So the biodiversity of this system has an importance that extends beyond the operation of the ecosystem itself, affecting whole global systems. In this way it also extends beyond the more obvious values to humanity as a source of crops and pharmaceuticals. These global values, however, are much more difficult to quantify in economic terms than is the case with forest exploitation for drugs and food.

Sir Ghillean Prance's Most-Cited Papers,
Published Since 1982

Rank	Paper	Citations Through 1997
1	D.G. Campbell, D.C. Daly, G.T. Prance, U.N. Maciel, "Quantitative ecological inventory of terra firme and Varzea tropical forest on the Rio Xingu Brazilian Amazon," Brittonia, 38:369, 1986	29
2	Prance, G.T., "A review of the pyhtographic evidences for Pleistocene climate changes in the neotropics," Ann. Mo. Bot., 69:594. 1982	27
3	KD.M. O'Malley, D.P. Buckley, G.T. Prance, K.S. Bawa, "*Genetics of Brazil nut (Bertholletia excesia* Humb. & Bonpl.:Lecythidadae). 2. Mating system,*" Theor. App. Gen*., 76:929, 1988.	26
4	G.T. Prance, G.B. Schaller, "Preliminary study of some vegetation types of the Pantanal, Mato Grosso, Brazil," Brittonia, 34:228, 1992	18
5	D.P. Buckley, D.M. O'Malley, V. Apsit, G.T. Prance, K.S. Bawa, "*Genetics of Brazil nut (Bertholletia excesia* Humb. & Bonpl.:Lecythidadae). 1. Genetic varation in natural populations,*" Theor. App. Gen*., 76:923, 1988.	14

SOURCE: ISI's Personal Citation Report, 1981-97

You have pointed out that disturbance of the forest is one means of maintaining biodiversity, and I assume that you mean natural disturbance--wind, flood, fire, etc. What of human disturbance? Is this always retrograde?

Prance: Human disturbance does not always prove to be negative. Some of the native tribes in the Amazon do little more than the action of nature itself in terms of scale of disturbance. It is not until one moves in on a commercial scale that the disturbance becomes a negative impact in terms of biodiversity. This does not mean that all the indigenous people look after the forest; many have been as destructive as we have been, but generally the scale of impact has been smaller and hence less harmful.
It is difficult to determine the point at which disturbance becomes a serious factor in the reduction of biodiversity, partly because of lack of information on extinction rates. The National Amazon Research Institute in Manaus, in association with the Smithsonian Institute and the World Wide Fund for Nature, is conducting important research into the dynamics of forest patches, having set up experiments that have now been running for about 25 years. They have recorded the rate of species loss from forest fragments of different sizes, and this work continues. At present we still do not know the precise long-term effects of fragmentation. Undoubtedly, the consequences will vary between species. Birds, for example, are mobile and can cope better than less-mobile species, such as plants. Some animals, like the jaguar, need very large areas to support them. There is also the problem of actually recording extinction. In the case of the Atlantic forests of Brazil, for example, where 90% of the original forest cover has been lost, it is difficult to know whether species are also vanishing. Many of our plant specimens at Kew that were collected in the 1850s have not been found since, so these species may well be extinct, but it is difficult to be absolutely sure because we still do not know the remaining forest well enough. We reckon that around 53% of the plant species of the Brazilian Atlantic forest are endemic to the region, so destruction of this forest is bound to cause extinction at a global level.

What do we actually mean by biodiversity? Is it simply a list of all the organisms present, from elephants to microbes?

Prance: No, it certainly isn't. It is more than species diversity, though it does include that. But is also involves the genetic diversity within those species, ensuring that there is a viable level of variation within populations, and it also involves the diversity of habitats within which species can survive. We are working with some very rare plants at Kew, sometimes where there are only two or three individuals left. We need to know about their genetic constitution--whether it is adequate to maintain the species.

So, determining biodiversity is even more difficult than producing a species list, which is itself very challenging if all organisms are to be included. Are there shortcuts to biodiversity estimation? Can we examine one group of organisms and take it to be generally representative?

Prance: We have to do this. We have to examine the groups that can be assessed, such as birds, butterflies, and plants, because attempts to cover all types of organisms will fail for lack of time and funding. If we don't take this approach then it will be too late. It may well be that, in certain instances, individual groups will prove inadequate or non-representative, so we must study more than one group; but we cannot possibly study them all. I have been involved in locating centers of endemism in Brazil for different groups of organisms, and general patterns do emerge even though there are local differences. Perhaps the best way forward is to examine at least plants, mammals, birds, and an insect group.

Even so, this is an enormous task. Are there enough skilled people around to conduct the work?

Prance: No, there are not. The world is short of taxonomists. We need to create jobs for people to do the work and we need to direct the work so that it is focused on the solution of these problems. At Kew we are trying both to expand scientific knowledge and to train new workers.
Kew is an ideal place to conduct scientific work on plant aspects of global diversity because we have such good collections. We also have a great responsibility for training, currently with 61 graduate students, so we are a major center for the training of the next generation of botanical researchers. I even manage to maintain a group of three research students myself, despite a busy schedule. And, in return, these students provide a vital stimulus to the research at Kew.
Research here now has a much more conservation-oriented flavor than in the past. We even have a conservation legislation unit at Kew, with lawyers working on such issues as the Biodiversity Convention and the CITES treaty. Our research has expanded into molecular systematics so that we can produce molecular fingerprints of plants and fungi. One of our current goals is to coordinate a new classification of the higher plants, incorporating the new molecular information that is available. Obviously, Kew is not alone in this enormous project; it involves botanical institutes from around the world. But we are about to see a major revision in plant classification, parts of which have already been published, but the synthesis of which should be ready by about 2000 or 2001.