This review of polar marine ecosystems covers both the Arctic and Antarctic, identifying the major threats and, where possible, predicting their possible state(s) in 2025. Although the two polar regions are similar in their extreme photoperiod, low temperatures, and in being heavily influenced by snow and ice, in almost all other respects they are very different. The Arctic Ocean is a basin surrounded by continental landmasses, close to, and influenced by, large populations and industrial activities. In contrast, the Southern Ocean is contiguous with all the other great oceans and surrounds a single land mass; Antarctica is remote from major centres of population and sources of pollution. Marine environments in both polar regions have been highly disturbed by fishing activity, but, in terms of pollution, some areas remain among the most pristine in the world. There are, however, both local and global pressures. Over the 2025 time horizon, the greatest concern for the Arctic is probably the ecological implications of climate change, particularly insofar as sea ice extent and duration are likely to be affected. Such changes are not expected to be as pronounced in the Southern Ocean over this time period, and concerns are related more to direct threats from harvesting of marine living resources, and the ability to manage these fisheries sustainably. In both polar regions, the capacity of marine ecosystems to withstand the cumulative impact of a number of pressures, including climate change, pollution and overexploitation, acting synergistically is of greatest concern.

The deep sea is the world's largest ecosystem by volume and is assumed to have a high assimilative capacity. Natural events, such as the sinking of surface plant and animal material to the seabed, sediment slides, benthic storms and hydrothermal vents can contribute vast amounts of material, both organic and inorganic, to the deep ocean. In the past the deep sea has been used as a repository for sewage, dredge spoil and radioactive waste. In addition, there has been interest in the disposal of large man-made objects and, more recently, the disposal of industrially-produced carbon dioxide. Some of the materials disposed of in the deep sea may have natural analogues. This review examines natural processes in the deep sea including the vertical flux of organic material, turbidity currents and benthic storms, natural gas emissions, hydrothermal vents, natural radionuclides and rocky substrata, and compares them with anthropogenic input including sewage disposal, dredge spoil, carbon dioxide disposal, chemical contamination and the disposal of radioactive waste, wrecks and rigs. The comparison shows what are true analogues and what are false friends. Knowledge of the deep sea is fragmentary and much more needs to be known about this large, biologically-diverse system before any further consideration is given to its use in the disposal of waste.

Conservationists are missing opportunities to protect species at mass tourism sites where wildlife itself is not the main tourist attraction. At such locations are ‘incidental ecotourists’, i.e. tourists with multiple interests who encounter wildlife or fragile ecosystems inadvertently. A case study from Lamanai Archaeological Reserve, Belize, reveals the motivations of incidental ecotourists and their impact on an endangered primate species, the black howler monkey, Alouatta pigra. Four hundred and seventy-one visitors were surveyed to assess their travel goals, conservation commitments, and reactions to viewing howler monkeys. Data were also collected on the behaviour of tourists and monkeys during encounters. More intense tourist interactions with howler monkeys were correlated with the number of tourists and the duration of the encounter; guided parties interacted more intensely than unguided parties. Tourists were largely unaware that these interactions may harm the howler monkeys. Qualitative observations of howler response to tourists suggest short- and long-term negative impacts. These impacts could be mitigated through more effective guide training, limiting tourist group size, and increasing entrance fees at the Reserve. Improving environmental education may reduce impacts and motivate some tourists to become advocates for conservation of endangered species.

There is considerable interest in the fragmentation and loss of natural and semi-natural habitats, but few studies have examined the dynamics and mechanisms of change. A temporal analysis of landscape change on the South Downs in Sussex, UK, provides a clear description of the process of change over the 20 years 1971–1991. Transition probabilities were calculated from digital interpretations of an aerial photography time series of West Sussex. The analysis enabled quantitative comparison of landscape mosaics within different landscape ecoregions and under different management regimes to be made. Past changes in land use have produced a fragmented downland landscape. The key land conversion sequences identified show a substantial transition towards arable production, often at the expense of the internationally and nationally important unimproved grassland systems. A geographical information system facilitated greater understanding of the environmental and topographical characteristics of land converted to arable and other uses, and highlighted areas for protection and potential restoration. The patterns of land-use conversion observed in the study provide a landscape-scale planning tool for assessing the potential impact of agri-environmental policies, plans, and programmes in semi-natural grassland habitats.

Dehesas, rangelands occupied by scattered oak trees and characterized by silvopastoral uses, cover about 3.1 million ha in south-western Spain. There is considerable debate about the long-term persistence of holm oak (Quercus ilex) populations in dehesas, since most stands are overaged and seedlings and saplings are sparse. The forest cycle has been disrupted in most dehesas. Regeneration has been inhibited since stands were opened for agriculture and grazing. Oak diameters from three land-use groups (young dehesa [YD], middle-aged dehesa [MD], and old dehesa [OD]) in Cáceres Province, Spain, were compared. These groups differed in the age of the land-use system, i.e. time since the original Mediterranean forest was cleared. The dehesa systems were established about 80 (YD), 150 (MD) and 500 (OD) years ago. An analysis of 66 holm oak cross sections revealed a close correlation (r2 = 91.2%) between tree rings and diameters, so that diameter seems to be a reliable indicator of tree age. Nested analysis of variance showed significant variation in diameters between the land-use groups. There is generally a positive relationship between tree age and the age of agrosilvopastoral use of the dehesas. Sparse holm oaks in the dehesas are primarily remnants from the first forest cycle. Local differences in growth conditions (for example soil quality and tree density) contribute further significant diameter variation on a between-plot level. Diameter structure of abandoned dehesas showed two peaks and a high proportion of trees in the smallest size class. This indicates that the forest degradation process is reversible. An effective regeneration policy should promote a rotating 20- to 30-year set-aside of dehesa parcels.

Tropical moist forests in Africa are concentrated in the Congo Basin. A variety of animals in these forests, in particular mammals, are hunted for their meat, termed bushmeat. This paper investigates current and future trends of bushmeat protein, and non-bushmeat protein supply, for inhabitants of the main Congo Basin countries. Since most bushmeat is derived from forest mammals, published extraction (E) and production (P) estimates of mammal populations were used to calculate the per person protein supplied by these. Current bushmeat protein supply may range from 30 g person−1 day−1 in the Democratic Republic of Congo, to 180 g person−1 day−1 in Gabon. Future bushmeat protein supplies were predicted for the next 50 years by employing current E:P ratios, and controlling for known deforestation and population growth rates. At current exploitation rates, bushmeat protein supply would drop 81% in all countries in less than 50 years; only three countries would be able to maintain a protein supply above the recommended daily requirement of 52 g person−1 day−1. However, if bushmeat harvests were reduced to a sustainable level, all countries except Gabon would be dramatically affected by the loss of wild protein supply. The dependence on bushmeat protein is emphasized by the fact that four out of the five countries studied do not produce sufficient amounts of non-bushmeat protein to feed their populations. These findings imply that a significant number of forest mammals could become extinct relatively soon, and that protein malnutrition is likely to increase dramatically if food security in the region is not promptly resolved.

This paper illustrates the opportunity for conservation offered by linking traditional agroecological knowledge and advances in adaptive management theory and practice. Drawing on examples from the Banawa-Marawola region of Central Sulawesi, Indonesia, a suite of traditional resource management practices premised on principles of adaptive management are identified and assessed, including: (1) resource management practices and regulations that are associated with the dynamics of complex systems; (2) procedural, planning and decision-making processes that foster learning; (3) sanctions and taboos that act as social mechanisms for the management and conservation of natural resources; and (4) ceremonies and social interactions that promote cultural internalization of the various practices, procedures and mechanisms. In addition, an emerging socio-political movement in the Banawa-Marawola region is explored. Premised on the strengthening of traditional rights and practices, the nascent Kamalise movement potentially provides the socio-political, institutional and organizational context needed to link traditional agroecological knowledge and adaptive management with broader conservation goals. Based on this analysis, two opportunities to enhance conservation in the region are identified: first, maintaining traditional agroecological systems and the associated adaptive resource management strategies used by local groups, and second, building upon the Kamalise movement to forge conservation alliances among communities, non-government and government organizations in which locally-evolved adaptive resource management strategies can be effectively applied. Both opportunities to combine traditional knowledge, adaptive management and conservation, however, are linked to the development aspirations of traditional groups: self-determination, acquisition of land rights and controlling the impacts of changes in livelihood.