It's a dammed fine place to see

There are fewer and fewer pristine wildernesses. Areas of former wilderness have been commercialised, monopolised or overutilised by people or organisations that, more often than not, see only the profits that can be made by exploiting nature. That said, without some outside influences, wilderness areas cannot survive. Once an area becomes economically unsustainable it gets converted to other uses such as farming.

Someone who belongs to the enlightened minority of non-exploiters is Karen Ross, whose passion for nature brought her to one of the world's most diverse natural areas, the Okavango delta in northwestern Botswana. Ross has dedicated more than 15 years to this extraordinary wetland - as is evident in Okavango: Jewel of the Kalahari .

First published in 1987 as a companion to the popular BBC TV documentary series of the same name, it has gone from strength to strength in this new edition.

The Okavango delta is an alluvial fan formed through geological faulting, climatic influences and sedimentation. Its source, the Okavango river, starts its journey in the highlands of southern Angola (where it is known as the Kavango river) and winds its way through wilderness for nearly 1,000km, picking up sediment. Earth movements thousands of years ago produced a huge rift called the Kalahari-Zimbabwe axis, which dammed and diverted the river. Where it enters the Kalahari in Botswana, it slows and drops its load, splitting into myriad channels that depend on the volume of the fluctuating flood waters. The result is a dynamic ecosystem with many contrasts and adaptations.

Ross gives descriptions of the fascinating plant and animal life that, in one way or another, has adapted to this unique environment. Papyrus, for example, is common in the delta. It has the capacity to fix nitrogen from the air with the help of microscopic bacteria and algae that live in its roots, where nutrients are not freely available. Papyrus not only adapts to its environment but also changes it. The stems and roots are very dense and block a huge amount of light. The resultant continual dying of vegetation in turn is responsible for a lower level of oxygen in the water that makes it more acidic. Even so, life still flourishes in the papyrus thickets: aphids live off the dying roots, while beetles and praying mantises prey on them.

Humans have also adapted to life in the Kalahari. The bushmen, or basarwa as they are called in Botswana, are the oldest of Africa's peoples. At one time they occupied most of Africa, but they have slowly lost their land to more aggressive races and, tragically, are still doing so today. They have been persecuted and marginalised and recently were evicted from the Central Kalahari Game Reserve, their last hunting grounds, for reasons that remain unclear. These gentle people have a unique and spiritual bond with the Kalahari, evident in their understanding and use of the bush. Scientists and conservationists have only recently started to understand this intimate knowledge.

Ross gives a startling account of human destruction and thoughtless interference in the Okavango. Until the early 19th century, few people had ventured there, with the exception of the bushmen and a few other African tribes. Then came commercial hunters in search of ivory. The depletion of the wildlife in many areas was paralleled by an increase in the already-large populations of livestock owned by local tribes. Game started to compete for grazing pastures and permanent water sources. Technology then helped to make waterless regions of the Kalahari more accessible; boreholes enabled pastoralists to move their cattle into these areas; and overgrazing followed not far behind.

Then came the erection of cattle fences, which may have incidentally protected the Okavango but put a stop to the movement of wild game in many areas. Most fences were erected to meet European Union beef import regulations and, until recently, were built without any environmental impact assessments.

The fence that forms the northern boundary of the Central Kalahari Game Reserve, called Kuke, was a catastrophe for wildlife. It cut off the northwards migration of wildebeest to the permanent water of the Boteti river system on the western border of the Makgadikgadi salt pans. This "caused the loss of 95 per cent of the Central Kalahari's wildebeest population", Ross writes. Judging from aerial surveys conducted in 1987, an estimated 300,000 wildebeest, 260,000 hartebeest and 60,000 zebra died in those first few years. The fences continue to be a controversial issue and many proposals are under review by the Botswana government to resolve the problem.

Ross also describes the formation, discovery and extraction of diamonds, Botswana's greatest industry, and how this also poses a threat for the water of the Okavango delta. Dredging of the Boro River, to increase water flow for mining, was strongly opposed by conservationists and locals, and was fortunately not executed. She tells of further plans to divert the Okavango to supply Namibia's capital with water and another proposal to harness the river to generate hydroelectricity for Namibia. Amazingly, all these threats have been warded off - for the time being.

Okavango: Jewel of the Kalahari sometimes gets too scientific for the general reader, at whom it is aimed, when describing biological mechanisms.

But this does not detract from a well-researched and well-written text. The more than 170 colour photographs feed the imagination and dare you to go to see the Okavango for yourself.

Bruce Shaun Robinson is lodge manager and guide, Deception Valley Lodge, Botswana.