Examined here is the problem of persons compelled to flee from their areas of habitual residence. The number of such displaced persons (refugees), both nationally internal and cross-border, already in the many millions, nonetheless keeps increasing by perhaps 3 millions per year. Many of the uprooted continue to flee owing to persecution, oppression, or war. However, these triggering events appear not to have been worsening markedly in recent years. Other, more strictly environmental, refugees flee from such natural disasters as flooding, drought, and volcanic action, although these triggering events have also not been increasing in frequency or severity.

It is thus suggested here that the continuing increases in refugees result from transgressions of the carrying capacity — that is, of unsustainable increases in human (and associated livestock) numbers, often associated with site deterioration or actual habitat degradation. Such displaced persons have been referred to as ‘environmental refugees’. It is clear that in the long term the poignant dilemma of the ever-increasing numbers of refugees can be addressed only in terms of achieving environmental security within a framework of comprehensive human security.

Trees, as welcome and necessary components of Nature and functional landscape elements in cities, provide a worth-while theme for applied ecological study. Of the different approaches, the micro-scale evaluations of tree—habitat interactions can throw light on practical tree management. The roadside trees in Hong Kong, generally dwelling in a stressful physical and physiological environment, have been surveyed in detail in the field with regard to species composition, tree structure, tree defects, and habitat characteristics.

Despite a diversified floristic composition, the street-tree population is dominated by a small number of common species, of which 12 have been chosen for in-depth evaluations. The recent emphasis on exotic and fast-growing species with limited final dimensions will modify the treescape in the long run. Many existing large specimens have been sacrificed to urban redevelopments. The differential performance of different species with reference to the occurrence of defects has been interpreted. Almost all the trees are inflicted by some structural or physiological problems, and large trees are practically collectors of diverse maladies.

The urban tree habitats of Hong Kong are characterized by gravely cramped and stressful conditions from the soil-level upwards and especially as regards headroom. Tree-habitat correlations and associations suggest a need to plant rapid-growing, tall but narrow-canopied species that are able to resist a maximum proportion of the inevitable tree defects and diseases. The shortage of good-quality habitats with space for tree-growth, and the accompanying unfavourable ecological niches, are crucial factors for tree existence. The prospects of street trees in the long-term urban planning and upgrading for environmental quality, with special reference to the provision and preservation of proper habitats, are elaborated, with Hong Kong as a practical example.

The Summer Villa estate was famous for its wildness, preservation of Nature, pleasant climate, and beautiful scenery in the Qing Dynasty when the natural ecosystems were strictly conserved by the Emperors Kangxi and Qianlong (1703–93). Plants on the estate played an important role in this embellishment, 28 out of the 72 noted scenic sites being named after plants or plant etc. materials. The estate has been seriously destroyed in the last 150 years by wars, fires, and natural disasters, before the foundation of the new China. The damage was especially serious in the Hill Area, comprising some 80% of the estate.

The present vegetation in the Hill Area is the result of reafforestion in the 1950s. Seven different plant communities, composed of natural and artificial elements, are now found there, most extensive of which is the Pinus tabulaeformis artificial forest with Vitex chinensis dominating the shrub layer. Some of these communities are unsuitable for the scenic spots on which they stand, some are not adaptable to the habitats, some have problems such as consisting of single species — so resulting in susceptibility to pests and offering little possibility for birds to make their nests and mammals to colonize.

The natural environment in the estate is becoming widely degraded, with serious SO2 and Pb pollution caused by tourism and urbanization. Plants — especially needleleaf trees — are sensitive to these pollutants.

This paper discusses the process of designing for Nature in the Hill Area of the Summer Villa estate, much of the work being concerned with problems of the present vegetation and the best approach to deal with them. To create Nature for the City of Chengde and at the same time recover the natural beauty in the Summer Villa estate, much attention is paid to the natural characteristics of suitable plants — especially those ‘historical’ natural species which can adapt to the present habitats. Five subsidary landscape areas with different plant characteristics in different habitats have been designed. Maps of the ‘historical’ natural vegetation, the present vegetation, and designs for Nature in the Hill Area, have been drawn and are here reproduced for practical use.

Rawa Aopa is a large swamp in South-East Sulawesi, Indonesia — the only major peat-swamp in this mainly mountainous island. Its vegetation and fauna are still quite poorly known. The existing information is summarized here. With the creation of new villages as part of Indonesia's transmigration programme, the human population in this area has increased very rapidly. Pressure on natural resources — especially soils and forests — is increasing, and primary forests are dwindling rapidly. This in turn increases the threats to Rawa Aopa, as erosion in its catchment area inevitably leads to a rapid silting up of the swamp. The swamp has a potential as a source of food (fish and sago) and income (rattan and other products), and it might to some degree become a tourist attraction.

From a scientific point of view, the gaps in the knowledge about water-regime, vegetation, and fauna, ought to be remedied. In order to attain sustainable utilization of this area, a thorough plan ought to be made for the whole catchment of Rawa Aopa. The most important measure to take is the protection of the forests covering the hills and the surroundings of the swamp. Also important very widely is the protection of soils. Furthermore, it is recommended to include the northern part of the swamp in the already-existing Rawa Aopa—Watumohai National Park.

Kerkini Lake in Greece, a reservoir maintained principally for agricultural irrigation purposes on the Strymon River, has been classified as a ‘Wetland of International Importance’ according to the Ramsar Convention. Hydrological conditions favoured the formation of a shallow, very productive lake, rich in species diversity and biotic abundance. The importance of the wetland lay in its complex zonation of various habitats which mainly consisted of: shallow open water with sand-strips, beaches, and mud-flats; shallow-water areas with communities of emergent vegetation; a lowland hardwood riparian forest mainly of Salix and Tamarix species; a shrub-swamp; and extensive wet meadows. The diversity of habitats supported a rich waterbird fauna for breeding, stationing during migration, and wintering.

Nevertheless, in 1982 a new high-dam was constructed, higher embankments along the banks of the Lake were established, and other works were carried out (to increase the water capacity of the reservoir), in response to irrigation demands. No consideration was given to the wetland resources. Operation of the new dam resulted in changes in the flooding etc. regime, with severe impact on the biotic resources of the wetland, especially by waterlevel increases of more than 5 m in less than 4 months during spring — the critical growing- and breedingseason. Wetland heterogeneity and the mosaic structure of water-land-vegetation were thereby lost.

Now the riparian forest is diminishing in area and declining in productivity, the reed-swamp with emergent macrophytes has been lost, and wet meadows have also disappeared. Deep flooding and the loss of these habitats is reflected in marked decline in the densities of migratory waterbird populations and, most important, in drastic shrinkage in the populations of breeding species. Similar impact is observed in the dramatic decline of fish species diversity and abundance. In general, nowadays, Kerkini presents an alarming example of loss of biodiversity and accelerating impoverishment of its former biotic resources.

In view of the projected plans to increase further the water-storage capacity of the Lake by raising its waterlevel, measures are urgently needed: (a) for preventing such actions; (b) for restoring and maintaining marsh conditions, and (c) for ecologically sound management and sustainable use of the wetland resources.

Rural communities in northern Botswana had negative attitudes towards animal wildlife even though they received benefits from it. The negative attitude was caused by wildlife damage to crops, losses of livestock to predators, loss of land to conservation, and lack of control over animal wildlife resources. The benefits derived from animal wildlife, such as the possibility of hunting, meat, cash income from animal products, and employment in the wildlife industry, were not highly valued, even though these benefits are of considerable importance to the local community (e.g. much of the local employment is wildlife-related).

Respondents who had fewer livestock and were more dependent on wildlife for protein, were more negative than others in their attitudes to animal wildlife. The beneficiaries of the wildlife industry were largely perceived as being the hunting and tourist companies. Respondents who were more affected by animal wildlife, those living closer to higher population-densities, and those having more crop losses, were more negative than others in their attitude to wildlife. The communities were distrustful of government motives and had a poor opinion of the Department of Wildlife and National Parks (DWNP).

It is suggested that the present wildlife development programmes in this region of Botswana are likely to fail unless a change in approach is adopted by the local populace. Essential to our mind for the success of these programmes is the reduction of the negative impacts of animal wildlife, through, for example, fencing of agricultural land, improved control of problem animals, and adequate compensation schemes. It is also essential that local communities be given more control over the wildlife resources than they currently enjoy.

Major oil-spills, such as occurred following the grounding of the tanker Exxon Valdez in March 1989 in Prince William Sound, Alaska, account for only a small fraction of the total anthropogenic input of petroleum to the marine environment. Yet major spills can result in significant and even acute impacts, trigger ecological changes requiring decades for recovery, and command considerable public attention. Thus catastrophic oil-spills in general, and the Exxon Valdez spill in particular, differ from other chronic human alterations of coastal marine systems.

Estimates of the fate of the 38,000 metric tons of crude oil lost by the Exxon Valdez are imprecise, but perhaps 30–40% evaporated, 10–25% was recovered, and the rest remains in the marine environment. Roughly 1,500 km of coastline were oiled in varying degrees. Much of this coastline consists of gravel beaches into which oil penetrated to depths as great as 1 m.

The ecological effects of the spill on the marine environments of Prince William Sound and adjacent coastal areas of the Gulf of Alaska were extensive, but natural recovery, aided by clean-up efforts, is expected. Judging by the consequences of other oil-spills affecting rocky shorelines, as well as previous natural and anthropogenic disturbances to Prince William Sound, it appears likely that most affected biotic communities and ecosystems will recover to approximately their pre-spill functional and structural characteristic within from five to twenty-five years.

This oil-spill had major social effects. Many individuals, whether personally present or viewing the spill around the world on television, were saddened by the environmental damage, and felt that an important public trust had been broken. These feelings, together with dissatisfaction with the results of early clean-up efforts, gave rise to popular sentiment in favour of every possible clean-up and mitigation effort — regardless of cost, effectiveness, or possible negative consequences.

The response to the Exxon Valdez oil-spill by government and the oil industry revealed serious inadequacies in the plans and institutions for dealing with major marine oilspills in the United States. Attempts to recover spilled oil, and to respond to the spill's environmental consequences, were hampered by a low level of preparedness and lack of clear agreement about the goals of response efforts. Attempts are under way to improve oil-spill prevention and response capabilities in Alaska and the rest of the United States. However, these efforts are not yet complete, and it remains to be seen whether an improved response will be made to the next major oil-spill.