Enhancement of forest cover is to be viewed as a proactive measure taken to arrest and reverse the current trend of forest decline and degradation. In this context, the world's forests have been under threat and are declining. It is estimated that forests covered four-fifths of the existing area at the beginning of the Eighteenth century. Of this total, approximately half were in tropical regions and half in temperate and boreal regions. However, these forests are declining as a result of deforestation. By the mid-Nineteenth century, it was estimated that global forest cover had decreased to 3,900 million hectares or 30 per cent of the world's land area. The latest figure by the Food and Agriculture Organisation of the United Nations as reflected in the Forest Resources Assessment 1990 had estimated that global forest cover as at the end of 1990 had further decreased to 3,188 million hectares or about 24.4 per cent of the world's land area. Processes of reduction and degradation of forest cover have led to an average annual loss of 0.6 per cent.

Although the annual loss of temperate and boreal forests is said to be negligible in recent time, historically, large- scale deforestration had taken place in Europe during the Industrial Revolution to cater for the needs of agricultural expansion, building materials and industrial development (Hinde, 1985). In fact, it is estimated that almost 200 million hectares or more than 50 per cent of the original forest cover had been lost (UN, 1991).

On the other hand, deforestation in the developing world is a rather recent phenomenon due to poverty, indebtedness and the increasing need for food, shelter and energy to cater for the growing population. In this regard, the four main causes of deforestation in developing countries are shifting cultivation, conversion to agriculture and pasture, wood removals for fuelwood and inappropriate timber utilisation, and the need for infrastructural development. For example, 39.5 per cent of the 1.54 million hectares of closed forest deforested between 1981 and 1990 in Africa was due to agriculture fallow and shifting cultivation, 35.1 per cent due to conversion to mainly permanent agriculture, and the balance 25.4 per cent due to over-exploitation and over-grazing (FAO, 1993a). However, as a result of improved socio-economic development in Africa, the rate of deforestation due to agriculture fallow and shifting cultivation had in fact decreased by 27.2 per cent when compared to 66.7 per cent which was recorded during the period 1976- 1980 (UN, 1991).

Besides the loss of forest cover through deforestation, there has been a general degradation in the quality and health of global forests due to acid rain and other atmospheric pollutants, especially in developed countries, as well as through forest fires, unsustainable use as a result of inappropriate logging and fuelwood exploitation.

The depletion of global forests and their degradation are causes for concern as they involve not only the loss of forest areas, but also the ultimate quality of the forests. If this trend is unchecked, the implications on the world would be catastrophic. Not only would the existence of all forest types be threatened, but the capability of these forests to perform their various roles and functions in perpetuity would also be seriously undermined. Hence, the need to address the decline in global forest areas and its degradation through enhancing forest cover is immediate.

In this context, is the current global forest cover of 24.4 per cent sufficient? If not, what level of forest cover should we aim for in order to ensure that forest resources and forest lands are sustainably managed to meet the needs of the present and future generations?

At the Ministerial Conference on Atmospheric Pollution and Climate Change held in the Netherlands in November, 1989, the Noordwijk Declaration on Climate Change advocated a world net forest growth of 12 million hectares per year by the turn of the century while a global forest cover of 30 per cent by the year 2000 was proposed at the second Ministerial Conference of Developing Countries on Environment and Development held in Malaysia in April, 1992.

There is every indication that the existing global forest cover should be enhanced through greening of the world. In this connection, restoration of all deforested lands in the industrialised world to close to the original levels of forest coverage is improbable, but this does not mean significant reforestation and afforestation are impossible. All countries which aim for a sound environmental future should set themselves a target of a minimum level of forest cover to be maintained in perpetuity. Countries having more than 30 per cent of their land areas under forest cover after taking into account their socio-economic development needs, particularly the developing countries, should be given incentives to improve the quality of their forests, as well as assistance given to reduce their dependence on wood especially as fuel. On the other hand, countries having less than 30 per cent of their land areas under forest cover, but have the means must increase and enhance their forest cover through rehabilitation and afforestation, which may include, in some cases, the conversion of heavily subsidised farms back to forests. As for those countries which are rich but are constrained by physical and climatic conditions to grow trees because of their geographic locations, they could play their roles by assisting the poorer countries in increasing and enhancing their forest cover.

As the future of forests are not only dependent on their quantity, but their quality as well, it is pertinent that all forests, especially those temperate and boreal forests of the developed countries should be protected against air-borne pollutants, particularly that of acid deposition, which are harmful to the health of the forest ecosystems. Appropriate measures should also be taken to protect forests from fire.