Viewing Planet Earth from the standpoint of modern life as a whole, we recognize three main systems, namely The Biosphere, the sociosphere, and the technosphere, although some authorities prefer to consider the two lastmentioned as forming together a so-called ‘noosphere’ or sphere of human influence. Thus we have The Biosphere, constituting the sphere containing life so far up and down as any form of it exists naturally, the technosphere, constituting the Man-made system of structures set within the space of The Biosphere, and the sociosphere, which is commonly defined as the sphere of Man's influence, and is the Man-engendered system of non-structures (institutions, organizations, movements, etc.) that Man has developed in managing his Biospheral relationships and those with the other two systems.

The ecological consequences of contemporary land-use in the neotropics have important influences on national park management in the region. Historical patterns suggest that major land-use changes have occurred regularly, and that these patterns have recently intensified. Is there a relationship between specific land-uses and specific threats to protected areas? Can this relationship be detected in a population of parks?

In a survey of managers of 183 national parks, 122 returned questionnaires from 19 countries in the neotropics. We found that a range of land-uses, from livestock grazing to quarrying, are occurring in and around the parks. The results of our statistical analysis indicate that many of these activities are associated with specific threats to park resources: for example, poaching for subsistence was statistically associated with each of the ten most-reported threats.

We offer two suggestions for improving our understanding of environmental degradation within parks. First, that research and park management be expanded to acquire a regional focus, namely that the land-transforming activities which threaten park resources can best be understood by incorporating the regional-social and political-economic contexts in the analysis. Second, that the influences of the global economic system be increasingly considered in conceptual frameworks of conservation biology.

The ever-increasing demands for outdoor recreation have caused widespread ecological damages in many parts of the world, so that methods to contain deleterious impacts and maintain the quality of recreational experience must be earnestly sought. Besides the commonlyprescribed preventive and ameliorative actions on the resource-base, visitor management which can provide cost-effective and long-term solutions deserves more attention than hitherto. This paper evaluates a spectrum of relevant options including the subtle (influencing userbehaviour), through the intermediate (redistributing use), to the regulatory (rationing use).

The reduction of per caput impact can, naturally, raise the capacity of an area to accommodate continuing use. Minimum impact techniques can substantially curtail the largely inadvertent damage due to ignorance rather than malice, while recreational planning and management can take into account the changing user preference. Appropriate data to guide management decisions can be acquired through innovative non-contact approaches, including visitor observation, to solicit candid and spontaneous responses. Good-quality information, conveyed through different channels in ample time before a visit, can effectively modify user behaviour and perception. Formal and informal education, to inculcate a responsible attitude towards the natural environment, can bring long-range benefits. Citizen participation can furnish diversified and useroriented perspectives that are important for successful programmes.

An account is given of the unique area comprising Cape St Vincent and the Sagres Peninsula, in southwestern Portugal. It has a variety of plant communities, some of which occur only in this area, and is the home of several endemic plant species. The two promontories are important breeding sites for several bird species, and are a landfall for thousands of migrating birds. Other animal groups of the area are less well-known. The area is subject to increasing visitor pressure, and tourist development is on the increase. The case is pressed for its conservation as a vital ecological resource, and as an asset to Portugal.

Awareness of the environmental implications of different development strategies has grown significantly since the early 1970s. Although much destruction is still being wrought, there are at last hopeful signs that some major multilateral development agencies, governments, and NGOs, are beginning to adopt more environmentally sensitive policies.

Recent advances in environmental and development theory have focused on the concept of sustainable development, arguing that the environment must be seen as an integral part of long-term sustainable development rather than merely as a resource to be exploited or traded for economic development.

This paper reviews recent contributions to the literature on both conceptual and empirical aspects of this topical debate, stressing particularly the ‘Brundtland Commission’ report and the work of Michael Redclift. An historically sensitive political perspective is proposed as most appropriate for embracing not only the more traditional ecological and economic aspects but also the crucial political factors underlying uneven development and underdevelopment in the age of an increasingly integrated global economic system. Although we now have a fairly sophisticated theoretical understanding of sustainable development, appropriate methodologies and techniques for translating this into practice are still required. The paper concludes that a blend of ‘top down’ and ‘bottom up’ approaches would give greatest flexibility, and suggests how the assessment of sustainability at the level of individual agro-ecological systems might be advanced.

The United Nations General Assembly, at its forty-second session, in 1987, adopted the ‘Environmental Perspective to the Year 2000 and Beyond’ as a framework to guide national action and international cooperation for environmentally sound development. The Environmental Perspective had been prepared by member governments in response to the General Assembly resolution 38/161 of 19 December 1983, which called for shared perceptions of long-term environmental issues and of the appropriate efforts needed to deal successfully with the challenge of protecting and enhancing the environment, aspirational goals for the world community, and a long-term agenda for action. The Perspective was prepared through a linked process of direct intergovernmental consultation and review, and the preparation by a Commission of eminent individuals, chaired Dr Gro Harlem Brundtland, Prime Minister of Norway, of the report ‘Our Common Future’.

Mostly for political reasons, rather little research has been done on the environmental impacts of military activities. However, some data on this theme have been collected, especially in North America, the Federal Republic of Germany, and The Netherlands. In this last-mentioned country the overall military environmental impact appears to be considerable, and can be compared qualitatively and quantitatively with the pressures on the environment which other economic sectors impose.

The contribution of the military sector to the world-wide environmental degradation problem is estimated at more than 6%, resulting from its share in the gross international product and the heavy character of military practice in both war and peace-time. In The Netherlands this share appears to be about 2 to 5%, which can be deduced from the military share in the national total consumption of energy. The military use of such poisonous and often rare elements as thallium, thorium, copper, beryllium, cadmium, zinc, and lead, varies from about 10 to 40% of their total national use.