A significant factor contributing to deforestation is the expanding human populations' increasing demands on forests and forest products. In many areas, rural households rely solely on fuelwood collected from the forest for their domestic energy supply. Fuel-saving stoves, or improved cook-stoves, have been introduced to reduce fuelwood consumption and thus alleviate deforestation, but there is frequently little or no formal monitoring and evaluation of programmes; their success as both a development and a resource-conservation tool is therefore undetermined. A programme was implemented in communities surrounding two national parks in western Uganda to compare domestic fuelwood consumption of an improved cook-stove and the traditional cooking fire, and assess the attitudes of stove users and non-users towards the improved stove and resource conservation. A kitchen performance test conducted in 100 households in Kiziba, Kahangi and Matayisa/Bundinyama parishes showed that fuelwood consumption did not differ significantly between improved and traditional stoves under actual field conditions. Household surveys showed that respondents in all three parishes had positive perceptions of the improved cook-stove. Perceived advantages of the improved stove included the ability to cook more than one item at once, fuelwood savings, quick cooking, and smoke/accident reduction. Many problems cited with the stove were technical, such as chimney malfunctions and pot-holes being too large or small to accommodate cooking pots. Cost of the stove was the primary reason for non-adoption. Improved-stove users were more concerned with forest conservation than were non-users. The need for monitoring and evaluation of improved-stove programmes is strongly indicated if they are to continue to be implemented as tools for resource conservation.

The emergence of commercial aquaculture in estuaries along the coast of Karnataka, India, has resulted in the breakdown of traditional methods of resource management and adverse impacts on the coastal environment. Based on field survey, personal discussions and published literature, we analyzed the evolution of different market (economic), traditional, and regulatory institutions governing the use of estuarine resources in the study area over the last three decades, and identified the environmental and social impacts of this evolution. In the past, informal associations of farmers in the estuarine floodplains had managed lands for raising crops and brackish-water fish in a sustainable way. In recent years, under economic and political pressures, landowners leased their lands to commercial shrimp-producers. A rapid growth in the production of commercial shrimp, employment of unsustainable production technologies, and laxity in environmental regulation have caused negative ecological and economic impacts on communities dependent on estuarine resources. Through a recent order from the Indian Supreme Court, environmentalists and the affected communities have sought to ban commercial aquaculture in ecologically-sensitive areas. While this court order awaits implementation, several policy options are here suggested for local, state and central governments in India in order to protect the estuarine environment.

Many coral reefs in the Caribbean, and elsewhere, have undergone changes from hard coral to fleshy algal dominance over the past two decades which has often been interpreted as a localized response to eutrophication and fishing. Here, data on the abundance of hard corals and algae from lagoonal patch reefs distributed throughout a large (260 km2) remote reef atoll located approximately 30 km offshore from the sparsely-populated coast of Belize, Central America, are compared with a study of these patch reefs conducted 25 years previously. Data and observations indicate that these patch reefs have undergone a major change in their ecology associated with a 75% reduction in total hard coral, a 99% loss in the cover of Acropora cervicornis and A. palmata, and a 315% increase in algae, which are mostly erect brown algae species in the genera Lobophora, Dictyota, Turbinaria and Sargassum. Such changes have been reported from other Caribbean reefs during the 1980s, but not on such a remote reef and the present changes may be attributed primarily to both a disease that began killing Acropora in this region in the mid 1980s and a reduction in herbivory. The low level of herbivory may be attributable to the disease-induced loss of the sea urchin Diadema antillarum in 1983, or fishing of herbivorous fishes, but both explanations are speculative. The present density of fisherfolk is low, and their efforts are not targetted at herbivorous fishes, and population densities of D. antillarum 14 years after the mortality are <1 individual per 1000 m2, but there is no comparative data from before the die off. There is, however, no indication that these major changes occurred on the fore reef, because A. palmata is abundant and erect algal abundance is low. We suggest that reported changes in other Caribbean reefs are not necessarily or exclusively influenced by local human factors such as localized intense eutrophication or fishing.

The destruction of forest ecosystems appears economically rational because many of the values of intact ecosystems are not recognized in land-use decisions. Many authors have suggested that the conservation of intact ecosystems requires that markets be extended to increase economic benefits derived from the standing forest to the point where they out-compete alternative, destructive land-uses. Three such strategies for market-oriented forest conservation are natural forest management for high-value timber, the collection of non-timber forest products, and biodiversity prospecting. In each case the proposed use of the ecosystem is likely to prove socially and economically unsustainable, or to generate significant alterations in ecosystem structure which endanger its diversity, or both. The success of market-oriented conservation requires that sustainable extraction of useful organisms over the long term yields more profit than destructive activities. The market-oriented conservation strategies examined, however, appear to yield too little profit to out-perform alternatives such as agricultural production or the replacement of forests by pastures or plantations. In each case, key factors limit profits. The slow growth rates of natural forests combined with discounting hinders natural forest management. In the case of non-timber forest products, the typically low density of resources in tropical forests creates disincentives for sustainable commercial production. The profitability of biodiversity prospecting is undermined by the low probability of discovering species with medicinal properties and developing countries' inability to capture the information value of the genetic content of species. Furthermore, each of the three strategies also has potentially negative ecological impacts. In the drive to increase profits, each is likely to degrade ecosystems through over-exploitation of the resource, and prompt simplification of the ecosystem through forest management designed to increase the density of profitable species. Ultimately, such activities are likely to lead to the loss of biodiversity.

Several conditions must be met for market-oriented conservation to be effective. Scientific understanding of forest ecosystems, and the ecological knowledge of both users and regulators must be sufficiently advanced to allow appropriate management regimes to be designed to assure maintenance of the forest ecosystem despite alterations caused by resource harvesting. The natural reproduction rate of the harvested resource must also be sufficiently rapid to justify leaving most of the resource undisturbed to guarantee its reproduction. Furthermore, the resource must be more cheaply and reliably produced in a natural forest than in a plantation, than by a synthetic substitute, or replacement through domestication. Finally, even where ecological and economic conditions support market-oriented conservation, those making land-use decisions must be in a position to benefit from the sustainable harvest of forest resources. If they are unable to enforce exclusive rights to the forests, the conservation effect of market-oriented strategies is likely to prove elusive.

Nevertheless, strategies for market-oriented forest conservation are a vital component of efforts to conserve biodiversity, and they must be improved to harness their full conservation potential. Resource management regulations, strong enforcement, and stable and secure property rights are essential preconditions. In addition, land-use planning should identify ecosystems with lower biological diversity where marketable products are concentrated at economic densities. Areas of high biological diversity will require non-market mechanisms to ensure their protection. In this context, there is no substitute for fully protected areas, and their expansion is vital.

Trees in cities face a severe limitation of plantable space and an exceptionally stressful growing environment. In Hong Kong, shortage of developable land has relegated trees to a lower priority and intensified urban impacts on them, relative to other cities. The vicissitudes of urban growth and trees since the founding of Hong Kong are reviewed, and eleven specific conflicts between urbanization and trees in Hong Kong are described. Redevelopment of existing buildings has raised site coverage by impervious surface and taken away ground-level planting space within and around affected lots. Infilling of relatively low-density areas mainly for government and institutional land-uses has increased development density and removed existing greenery and planting spaces. Road construction and improvement has widely damaged roadside trees and removed valuable and conspicuous greenery. Proliferation of underground utilities has fuelled the contest for usable space and precluded planting in many places. Widespread and frequent roadside trenching, associated with utilities and the laying of cable television and telecommunication networks has incurred massive root damage at roadsides. Poor soil quality commonly beset by chemical and physical constraints has caused chronic poor tree performance. Intrusion into urban parks and other green enclaves by buildings and roads has usurped the limited stock of green spaces. Encroachment into peri-urban woodlands has deprived the city of fringing mature greenery with conservation, landscape and amenity worth. Plantable space in reclaimed lands has been intensively used with inadequate allocation for trees. Protection and preservation of champion specimens has lacked statutory means and a coordinated policy. Reinforcement and demolition of stone walls has destroyed many large trees on unique mural habitats. Quality of arboricultural practice is poor, particularly in the private sector. Possible solutions to these limitations in Hong Kong are suggested, and have implications for other cities facing similar problems.

Wild animals often destroy standing crops and prey on livestock, causing economic losses to farmers. Crop and wildlife damage are becoming serious for many Indian protected areas, and this study aimed to characterize the problem in villages in and around the Sariska Tiger Reserve (STR), Rajasthan, India. Data were collected using a semi-structured questionnaire in 37 villages followed by a semi-structured questionnaire administered to 180 households, quadrat sampling and focus group discussions. Crop and livestock depredation evidently affected nearly half of the households in villages adjacent to the STR, but damage varied considerably amongst villages and with distance from the Reserve border. Wild animal distribution and protection measures which people adopted also influenced the damage. Nilgai (Boselaphus tragocamelus() and wild boar ((Sus scrofa() were reported to be responsible for at least half of the total damage to the major crops caused by wild animals. Tigers and leopards were the main livestock predators; the former preyed mostly on larger livestock and the latter on smaller animals such as goats and sheep. More than two-thirds of the villagers spent considerable time and money guarding crops and protecting livestock. Guarding was the most popular means followed by physical fences around fields. In spite of damage to crops and livestock, the local people still had a positive attitude towards the STR, because of tangible benefits derived from the Reserve in terms of fodder and fuelwood, and cultural/religious attitudes towards wild animals. Settlement of rights to collect fuelwood and fodder within the Reserve appears to be one acceptable measure to compensate for losses besides an immediate review of hunting policy. Suggestions given by local people to minimize losses have implications for the long term sustainability of the STR as a protected area.