World models are still in the early phases of development, and the majority of the ones built so far do not deal with the resources and environment sectors adequately. Of the models available, only the Leontief input-output model considers these two sectors in some detail. Even then the results should be taken as ordersof-magnitude guesses rather than as figures that can be used in an operational sense. Furthermore, the Leontief model suffers from a basic defect: it is a pollution abatement model. From the resources and environmental standpoint, it would be much more preferable to consider this as a sector within an overall management framework in which pollution control could play an important part.

Modelling of world problematique is still in an early stage of development, and much work remains to be done to improve its basic structures, underlying assumptions, and data availability. Because of the difficulties—both conceptual and practical—many important areas are not considered in the resources and environment fields, or, if considered, are dealt with only superficially. An example is the consideration of the extent of recycling, conservation, and materials substitution, as prices of individual resources increase—owing either to economic market forces or man-made factors. While the general direction of the main thrusts are known, it is still difficult to define limits and determine interlinkages with any high degree of confidence. Much further work will be necessary to establish these interrelationships, the components of which will also need to have an adequate data-base.

Scientific research funds appear to be distributed according to The Cesspool Hypothesis: ‘All research can be done in environments directly impacted by human activities or managed for human designs’. This is a misleading thesis; several important reasons exist for research in natural areas. Four of these are outlined as (1) natural areas may function as reserves of ‘miners' canaries’, giving advance warning of danger while escape or remedy should still be possible, (2) natural areas will be essential for testing and examining the effects of development and other human activities, (3) natural areas provide dependable data on nutrient and hydrological cycles in ecosystems, and (4) natural areas provide the only mechanism possible for ecosystems to retain a reasonably diverse reservoir of wild genes.

The U.S. Atomic Energy Commission and its successor the Energy Research and Development Administration (now the Department of Energy), has acknowledged these reasons. In a slow but steady progression of land-use landuse decisions, four large National Environmental Research Parks, totalling 530,000 ha, have been added to the 2,096,000 ha of areas previously dedicated for research.

The central role of ecology in park planning and management is now so well recognized that the establishment of park programmes without ecological advice seems unthinkable. Yet attempts to link ecological principles and planning principles are still fraught with difficulty. Communications between interdisciplinary teams are complex.

The Authors of this paper illustrate how the principles of ecology and the practices of park management are interconnected and interdependent. The need for resource inventories as a foundation of park management is explored and emphasized as essential, as is the need for constant monitoring to ensure that conservation goals are attained. Underlying the article are basic convictions that dynamic ecosystems require dynamic management, and that management in the future will be required increasingly to attain specific conservation objectives.

Investigations into the relationship between the number of fish species in small coral communities and the area of those communities have suggested ties between the theories of terrestrial island biogeography and the functioning of the closely-spaced archipelagos of ‘underwater islands’ that make up the Great Barrier Reef of Australia. The value of these theories to the marine park planner and resource manager may be considerable where quantitative information on minimum reserve size and the degree of isolation and exchange are needed in the decision-making process. There also follow a number of biogeographic principles which can form a set of practices for the establishment and management of marine reserves wherever the marine ecosystem is subdivided into collections of isolated or semiisolated parts.

A total of 2,816 questionnaires were completed in the Dalby Forest Area in the period from March 1975 to March 1976. The answers to six questions were combined into a Wildlife Interest Index Value for each interviewee (Everett, 1977). The variations in the mean of this value are considered to indicate the wildlife interest of visitors in groups based on the following characteristics: income, occupation, age, party size, the visitors' attitude to the number of people present, their membership of wildlife organizations, the elements of the area that the visitors enjoyed, their activities, the benefits that the interviewees felt from visiting the area, the components of the area that were necessary to their enjoyment, the number of times that they visited the Dalby Forest Area per year, the day of the week, the month, the weather, the location of the interview, and the relationship to the visitor's home.

The effects of snowmobile traffic on the winter home-ranges, movements, and activity patterns, of White-tailed Deer (Odocoileus virginianus), were studied during two winters in northern Wisconsin. There were no significant differences in home-range size and habitat use of the Deer in areas with and without snowmobiling. However, snowmobiling caused some Deer to leave the immediate vicinity of the snowmobile trail. Deer were most affected when they were within 61 m of the snowmobile trail.

The Bureau of Land Management, the land agency that administers much of the federal rangeland in the American West, has frequently been characterized as excessively responsive to the desires of ranchers, with resulting land deterioration and loss of resource values. Both the generally poor condition of the public domain, and the Bureau's attempt to maintain stocking levels while improving the range, support this characterization.

Several policies and programmes over the last decade, however, suggest that the Bureau today is less strongly tied to the livestock industry, and certainly its lands are being increasingly coveted by groups other than grazers. This recent trend towards a more ‘multiple use’ agency has been strengthened by Congressional passage of the Federal Land Policy and Management Act in 1976. Whether or not diversification of land policies will continue into the future is, however, at present unclear.

The aquatic weed Salvinia molesta (syn. S. auriculata) has spread to many parts of the tropics and subtropics. In Kerala, it has become established as a dreadful weed occupying large areas of open water, causing navigational problems, interfering with irrigation and fishing, rendering the water unfit for human consumption, and facilitating mosquito breeding, etc. The H2S generated in the decaying weed-mass in the water is destructive of generative equipment in hydroelectric installations, blocks intake apertures of ships, and damages engines of small motor-boats. In addition, the weeds cause reduction in the stored water of reservoirs, owing to excessive evapotranspiration, while thick mats of Salvinia, which later form large floating islands supporting secondary and tertiary colonizers, may be instrumental in the gradual drying up of natural and man-made water-bodies. These are very serious matters which have to be tackled effectively.