The ongoing fuss over Nairobi's Karura Forest is both bad news and good news. Not good news is the attempt to allocate state forest reserve land for private development as political patronage. Karura has both an intrinsic and symbolic value. Given its high profile location in the capital city – it houses the headquarters of the Forestry Department and is situated on the doorstep of the United Nations Environment Programme – Karura has become a symbolic flagship for the forests of Kenya nationally. From that perspective, the attempt to remove part of it without either social or environmental justification sends a very gloomy signal nationally and internationally that forests reserves can be used as a free land reservoir to be handed out when political considerations demand.

To make matters worse, much of the area in question is not man-made plantation but natural forest unique to the Nairobi region. It consists of indigenous trees and plants – some of them increasingly rare, such as the high quality hardwood Brachylaena – and provides habitat for a variety of wildlife: birds, butterflies, small antelopes and other mammals. And, the thousand hectares (2,500 acres) of Karura represent one of only two major greenbelt reserves within the current limits of a rapidly growing and polluted capital city where most of the urban population lives in congested settlements dismally devoid of trees or green parks.

The good news is the mounting evidence that the Kenyan people are becoming prepared to risk government disapproval by openly demonstrating their concern over forest disappearance; a concern which until now has been mostly confined to professional foresters and conservationists.

The stakes could hardly be higher. Protecting the remaining indigenous forests of Kenya is absolutely vital tot he country's environmental health and in turn to the well being of its human inhabitants. Recognition of this is why varied groups of Kenyans – including students, clergy and members of parliament – have protested at forest disappearance.

They feel the effects would be more adverse for the average Kenyan that the disappearance of elephants, a cause celebre which gripped the imagination of the Western world through the efforts of Richard Leakey and others. Anyone who doubts what the large-scale removal of Kenya's remaining forests would mean should take a close look at neighboring Ethiopia, where the lost of most hill-top forest cover has been a contributory factor in the recurrent pattern of crippling droughts and consequent famines.

This may sound an exaggerated claim, especially when one knows that what are defined as high or closed canopy forests cover only a minute proportion of the country's land area. If there is so little left, then how can its final disappearance have significant national implications beyond the ethical? Two critical features of the distributions of Kenya's natural forests contain the answer.

The first feature explains why most of the natural forest has already disappeared. Unlike in many other parts of the world, the soil and climate conditions favouring rich forest growth in Kenya coincide to a high degree with those areas suitable for the cultivation of the most popular food crops, notably maize. Since agricultural land is the commodity most prized by Kenya's rapidly increasing population, even for the minority who do have alternative sources of sustenance, you do not need a crystal ball to see where a landless person's priorities will lie in any direct land – use contest between forests and agriculture.

These areas are strictly limited: more than two-thirds of Kenya is arid or semi-arid – certainly too dry for forests or maize. Even at its greatest spread, before extensive agricultural settlement and deforestation took place, indigenous forest cover would not have been more than 15 percent of the total land area. Reduction to the present level of just over 1 percent has taken place largely in western Kenya, which was once covered with vast tracts of moist lowland forest but is now densely settled and cultivated by the Luhya and Luo peoples. Today, with the exception of two or three forests of limited size, including Nandi and Kakamega, the lowland forest has all but disappeared.

Not surpassingly, therefore, the second key feature of today's forest distribution is that nearly all the remaining natural forests lie in mountainous areas – they are classified as afromontane type – where they shelter the headwaters of Kenya's major rivers and exercise a natural regulatory control over the river flow. For example, the Mount Kenya forests (200,000 hectares) and the Aberdare forests (150,000 hectares) fulfil this vital function for the Tana and Athi rivers as they flow eastwards to the Indian Ocean. Progressive chipping away at the edge of these forests as parcels are converted to settlement, together with degradation of forest quality through illegal tree removal, is slowly but surely messing things up.

Evaporation increases, leading to less water availability all round; soil loss is exaggerated, so reducing soil fertility; streams once clear become muddier because of their silt content; and extremes of river flow are accentuated. In the west of the country, the inhabitants of the area surrounding the Mount Elgon forest bordering. Uganda has become so concerned as they observe these phenomena that they have made repeated representations to the government to stop forest degradation. If the government either fails to take the necessary action to minimise this process of forest decline nationally or, even worse, is guilty of promoting it, the long-term consequences for Kenya will be dire.

One example can illustrate dramatically the knock-on effects and potentially disastrous consequences of continued failure to protect the afromontane forests. Probably the best known and most sought after wildlife tourist destination in Kenya, and arguably in the whole of Africa, is the Maasai Mara game reserve in the southwestern corner of the country. Justifiably rated as one of the world's great natural wonders, the annual migration makes an unforgettable spectacle, not least the sight of thousands of wildebeest driving themselves across the Mara River. By contrast, few readers of this article – including, I would guess, those who have visited the Mara - will have heard of the Mau forest complex (300,000 hectares) situated along the western escarpment of the Rift Valley.

Yet the future well being of the Mara, and to a lesser extent the neighboring Serengeti National Reserve in Tanzania, is inescapably bound up with the continued existence and well being of the Mau forest complex. And the Mau is increasingly threatened.

The regulation of stream flow in the Mara basin is largely dependent upon the protective role of the Mau forest catchment where dozens of the river's tributaries originate. Substantial forest reduction will trigger multiple negative effects on the downstream system which permeates the game reserve. Low river flows, and in the longer-term even no-flows, will become more common and prolonged, while the risk of damaging flash floods will rise. Water table replenishment will decline, as will the vegetation dependent on it. Inevitably, with less dependable water sources causing deterioration of the grazing and browse, the animal herds will also decline. The effects on tourist revenues will be severe. In the early 1990s the quantifiable catchment protection value of the southwestern sector of the Mau forest complex was conservatively calculated by the UK – funded Kenya Indigenous Forest Conservation Programme (KIFCON) at US $13 million annually; not much perhaps internationally but quite significant to the Kenyan tourist industry. The indirect impact, as the tourist' grapevine' spreads the word of the Mara's decline, will be even more damaging.