Wildland fire management directly affects the forces of natural selection to which plant taxa become adapted. Changes in a fire regime will often result in changes in the relative abundance of particular species, and may cause the extinction of some of them. Life-history characteristics are important indicators of adaptation to recurrent disturbance, such as may be produced by fire. The incorporation of these characteristics in a computer simulation allows of the projection of species abundance under different fire regimes.

Through prescribed burning and fire suppression, fire interval and fire intensity can be controlled to some extent. The fire intensity for given sets of fuel, site, and meteoro-logical conditions, representing given fire-intervals, is calculated with the use of a fire behaviour computer simulation. These results are incorporated in computer simulation of the demographic competition of the five dominant shrub species of coastal sage-scrub in the Santa Monica Mountains of southern California: Artemisia californica, Encelia californica, Eriogonum cinereum, Salvia leucophylla, and S. mellifera. The model incorporates resprouting proportions, seedling establishment, and growth, and assumes survivorship rates in simulating scramble competition for space. Foliar cover-values of the five species are projected for nine different fire regimes. Short fire-intervals of the order of 10–20 years, such as might occur under a regime of prescribed burning, may eliminate or greatly reduce some species, whereas longer intervals allow the maintenance of a more diverse community especially of shrubs. Fixed and variable interval-lengths do not produce appreciably different results.

This study suggests that prescribed burning at 10–20 years' intervals should not be used indiscriminately to reduce wildland fire hazard in southern California. The fire intervals that will reduce the hazard, may eliminate some dominant native shrub species. A ‘natural’ fire regime which would maintain the natural vegetation while constituting only a minimum hazard to homesites may, unfortunately, be mutually exclusive goals in the coastal sage-scrub of southern California.

During 1975 to 1984, a particularly divisive debate accompanied proposals to conserve Polar Bear Pass, NWT. Virtually all interests that participated in the debate supported a more comprehensive approach towards conservation of natural areas than had hitherto prevailed, and criticized the ad hoc manner in which conservation proposals were being handled by the Federal Government of Canada.

Chastened by the experience with Polar Bear Pass, and suffering land-use allocation problems in many locations, the Department of Indian Affairs and Northern Development responded with a Northern Land-use Planning Policy (Diand, 1981a, 1981b), and is now developing a comprehensive conservation policy.

Future conservation reserves in northern Canada are likely to be established as a result of regional land-use planning. It is important, however, that conservation of natural areas in both Territories support northern political development and devolution of resource management authority to northern governments, and settlement of landclaims made by native peoples.

In this paper we present documentation for the realistic assessment of the concept of peat as an energy alternative in the United States. A proposal to mine peat in north-central Florida provides the framework from which a community worksheet for the evaluation of a peat-mining proposal has been developed. Documentation is also given of crucial local and regional environmental impacts that would result from large-scale disturbance of peatlands and the subsequent removal of peat, among which are:

1) toxic-metal release from peat,

2) eutrophication of surface waters,

3) increased runoff (including flooding and impacts on fisheries),

4) release of organic pollutants,

5) changes of salt and freshwater systems,

6) changes in ground-water supply, and

7) air pollution and fires.

Other community concerns, such as zoning regulations, sewage disposal impacts, and disruption of stable industries, must also be considered.

The two best-documented studies of annual rates of clearing of tropical forests appear to come to very different conclusions; the published FAO/UNEP estimate is 7.4 × 106 ha cleared annually during the late 1970s, and the NAS (National Academy of Sciences) estimate is 22.0 × 106 ha disturbed annually during the same period. Closer examination reveals that when corrections are made for differences in forest types included in the studies, and for differences in definitions of ‘deforestation’ (FAO/UNEP) and ‘conversion’ (NAS), there appears to be general agreement on the rate of deforestation in tropical closed broad-leafed forests: 5.9 × 106 ha (FAO/UNEP) and 7.5 × 106 ha (NAS) per year for the late 1970s. ‘Deforestation’ is defined according to the FAO/UNEP report and is the transformation of closed tropical-broad-leafed forests to either land in the shifting-cultivation cycle or permanently-cleared land.

‘Deforestation’ sensu FAO/UNEP is a more restricted term than the term ‘conversion’ used in the NAS report. ‘Conversion’ includes ‘deforestation’ sensu FAO/UNEP as well as: (1) the temporary clearing of fallow-cycle vegetation from land already in the shifting-cultivation cycle for short-term subsistence agriculture; and (2) the permanent clearing of fallow-cycle vegetation and thus the removal of land from the shifting-cultivation cycle.

The Hanford Reach of the Columbia River has experienced a great deal of human-imposed environmental change within the past 40 years, as has much of the adjacent land. The major disturbances have been from hydroelectric dams' construction and an intensive expansion of irrigated agriculture. A notable exception to the steady expansion of agriculture and dam-building has been the 1,400 km2 Hanford Site, which was established in 1943. Today, the Hanford Site consists mostly of undeveloped land that still supports native vegetation. It is free from agricultural practices, and has also been essentially free from livestock grazing and the shooting of animal wildlife. This conservative land-use has favoured populations of native wildlife that use the riverine habitats of the Hanford Reach of the Columbia River—e.g. Mule Deer, Canada Goose, and Great Blue Heron, are notable instances.

The Hanford Reach supports the only mainstem Chinook Salmon spawning habitat on the Columbia River. This population is maintained by a combination of natural spawning and artificial propagation in concert with a regulated harvest of returning adults. Numbers of mainstem spawning Salmon have increased markedly in the past 10 years, and this has attracted increasing numbers of wintering Bald Eagles to the Hanford Reach.

This paper introduces the concept of ‘ecological engineering’, which is based on two fundamental functions that play leading roles in the dynamic processes of ecosystems. These functions are maintaining ‘the general eco-balance resulting from the harmonization of well-coordinated structures with functions in the ecosystems’, and the transformation and regeneration ‘of substances based on the multi-layer trophic structures’ that are common to most ecosystems.

The Jonglei Canal Project should be weighed against its socio-economic impacts as well as environmental considerations. If taken in a short- or long-term cost-benefit perspective, the Project we think is a justified undertaking.

One might argue: ‘let everything well alone; change is another word for disaster’. We are not contending that the Jonglei Canal Project, if duly completed, would not bring about a new mode of life for both Man and domestic and other animals. We are contending that the new mode will be a more satisfactory on than that which exists at present. Sudan aims at the transformation of traditional communities to better social and economic horizons, and not the intentional destruction of the traditional way of life. Many overlook the fact that the Nilotes are already changing, and that it is beyond the powers of the political and social systems to confine them to the past.

Nevertheless there are indications that ecologists and environmentalists are far from agreed among themselves as to whether the Jonglei canal is, on balance, a good or a bad idea. But in any case we would like to stress in conclusion that the Jonglei Canal Project is being executed at a relatively fortunate time in Man's history of awareness of the way in which he should be using his natural resources.

The Soviet Union's Crimean peninsula in the Black Sea has the northernmost occurrence of Mediterranean-type climate and vegetation, particularly in its narrow southern coastal strip which has been almost entirely developed for the tourist and health resort trade. Three inland mountain ranges and their vegetation, both forest and steppe, exert a protective influence over the microclimates of the coast and are thus being extensively studied by scientists at the Ministry of Agriculture's Nikita Botanical Garden and at Simferopol State University. Inland of these ranges lies an expanse of former meadow-steppe that is now under cultivation.

In order to protect and study the high concentrations of remaining native and relict taxa of flora and fauna of the peninsula, three Nature preserves have been established on it–two in the mountain zone and northern coastal islands, and one along the southern coast and adjacent lower slopes. Here human access is restricted while long-term ecological studies are undertaken.

The Nikita Botanical Garden is involved in both conservation and exploitation of natural resources, and in improving health conditions of the resort. These tasks are integrated through a programme of mass seed propagation and ecological studies of wild-growing plants, the results of which are then used in landscaping the resort zone and producing industrial plant materials.

Hydroelectric dams have markedly altered the extensive floodplain of Zambia's Kafue River Flats. Before the dams were built in the 1970s, some 6,000 km2 of floodplain were under water for several months each year, permitting a dense growth of grasses and forbs that supported large populations of ungulates and waterbirds. Now a dam at the lower end of the Flats has permanently inundated parts of the floodplain, and a dam at the upper end has reduced the seasonal flooding, so that much of the floodplain is now probably permanently dry. When the Flats was revisited in 1983, the effect of the dams was obscured by the effects of drought, hunting, and human use.

In 1983, plant growth in most places was much less luxuriant than it had been before impoundment. Bird populations seemed much smaller than formerly, and populations of at least some ungulates had declined. The most abundant ungulate, the Lechwe (Kobus leche), is reported to have declined by about half in the last eight years.

The Communal Lands—occupied by peasant farmers—of the upper catchment of the Sabi River (which drains the southeastern portion of Zimbabwe) are severely deforested, overgrazed, and eroded. Siltation of the river channel has increased the risk of overbank flooding at a downstream irrigation scheme, and a rise in annual outflow from the catchment over the last three decades has additional implications for irrigation development, as well as for the availability of ground-water reserves in the areas of dryland peasant farming.

In a study area within one of the Communal Lands, the average rate of soil loss from fields of gentle slope is estimated to be such that the next generation of peasant farmers will be unable to achieve crop-yields above a very low ‘subsistence’ level. The degraded environment is the inevitable consequence of the expansion of a primitive system of cultivation—in a region of low inherent potential for crop production—under the pressure of rapid population growth. While the peasants are aware of many of the consequences of their exploitative methods of land-use, and recognize the importance of basic conservation measures such as erosion-control terraces, they generally feel that remedial action is beyond their means.

The effective implementation of available technical solutions to the deterioration of the land resources, will depend upon the provision of greater financial incentives for intensified production, as well as upon more positive political influences, than exist at present. The eventual stabilization of the situation is achievable only if population growth is reduced; but much might be done to improve production, and promote conservation, through field research into appropriate farming systems for peasant agriculture in the Sabi catchment and similar environments.

An examination of the relationship between human needs (above and beyond the basic physiological needs and concomitant consumption of resources) has re-emphasized the importance of control of human population in order to meet several other, also important, human needs. Development of human resources to their fullest potential requires utilization of additional resources beyond those necessary for the provision of basic physiological needs.

A preliminary model of resource requirements to meet human needs suggests that resource requirements for meeting the human needs for safety are considerable, those for meeting the cognitive and esteem needs are moderate, while those for meeting belongingness and love, aesthetic, and self-actualization, needs are minimal. Both industrialized and non-industrialized societies can adequately meet basic human needs, but industrialized societies may the better meet some of the higher human needs.

Footpath erosion in mountain wilderness areas is generally undesirable, and maintenance and rehabilitation of eroded paths are costly. Although path erosion results from a complex interactioin between recreational and geomorphological forces and each path's resistance, the processes involved are not well understood.

Economic considerations cannot be invoked to justify long-term protection of the environment. The appeal to posterity, as Goethe pointed out, springs from ‘the pure, strong feeling of the existence of something imperishable; something that will, in the end, be gratified by finding the minority turn into a majority’. There is nothing new in the paradox expounded in the opening paragraphs of this account: Goethe also wrote that there is nothing worth thinking but it has been thought before; we must only try to think it again. In answer to the question, ‘What is your duty?’ he replied, ‘the claims of the day’.

We should not expect to find a logical reason in the future for doing what seems right now. We should do what appears to be our duty in relation to the environment, as in all else, just because it seems right to do so, and in deference to future generations. We may not be justified in believing that there can be objective vindication of our subjective feelings; but this should never allow us to close our ears to the whispering of our inner conscience. There is much that is true which cannot be assessed, yet it is on the strength of truths such as these that actions have sometimes to be based: to ignore the future would make nonsense of the present.

Many of the federal agencies of the United States (e.g. US Forest Service and the Bureau of Land Management) are involved in making decisions that alter land-use on a massive scale. Subsequently, these land-use changes may have deleterious or beneficial effects on wildlife habitat and its ability to support wildlife species, both plant and animal. There exists an urgent need to develop methodologies that are capable of predicting the consequences, for wildlife species, of regional land-use changes. This study develops one such methodology to predict the distribution and abundance of animal species at a regional level.

In an era of increasing land-use demands, it is getting ever-more-difficult to set aside lands for parks or equivalent units where protection rather than (multiple) use of the resource is the goal. Developing a sufficient justification for establishing an area of parkland is directly related to the proper use of well-recognized ecological principles—particularly to the fact that the area included should encompass a unique or nationally significant resource (Polunin & Eidsvik, 1979).

This paper discusses four basic criteria that were used to evaluate potential boundary and resource-management alternatives for a seven-million-ha region in south-central Alaska, much of which was eventually included in the Wrangell-St Elias National Park and Preserve. The necessity or basing the planning decisions on sound data cannot be overemphasized. The paper discusses the different data-types used in the planning process. It was the feeling of all involved in the planning process that more was known about the natural and social resources of the new Alaskan parks than had been known about any other new areas that had been added to the system. The need for good data is particularly acute when the establishment of the parks involves considerable controversy and opposition, as was the case here.

Petroleum refineries are major sources of air pollution, giving off particulate matter, volatile hydrocarbons, and oxides of sulphur and nitrogen. The field-study here reported was conducted in the vicinity of Barauni Petroleum Refinery, in the Begusarai district of Bihar, India, with the objects of measuring the level of pollution through phytomonitoring and assessing the overall impact of the Refinery's emissions on vegetation.