Showing papers in "Environmental Conservation in 1997"

A review of methods for the assessment of prediction errors in conservation presence/absence models

Abstract: Predicting the distribution of endangered species from habitat data is frequently perceived to be a useful technique. Models that predict the presence or absence of a species are normally judged by the number of prediction errors. These may be of two types: false positives and false negatives. Many of the prediction errors can be traced to ecological processes such as unsaturated habitat and species interactions. Consequently, if prediction errors are not placed in an ecological context the results of the model may be misleading. The simplest, and most widely used, measure of prediction accuracy is the number of correctly classified cases. There are other measures of prediction success that may be more appropriate. Strategies for assessing the causes and costs of these errors are discussed. A range of techniques for measuring error in presence/absence models, including some that are seldom used by ecologists (e.g. ROC plots and cost matrices), are described. A new approach to estimating prediction error, which is based on the spatial characteristics of the errors, is proposed. Thirteen recommendations are made to enable the objective selection of an error assessment technique for ecological presence/absence models.

Livestock depredation by large carnivores in the Indian trans-Himalaya: conflict perceptions and conservation prospects

Abstract: Summary Livestock depredation by the snow leopard, Uncia uncia, and the wolf, Canis lupus, has resulted in a human-wildlife conflict that hinders the conservation of these globally-threatened species throughout their range This paper analyses the alleged economic loss due to livestock depredation by these carnivores, and the retaliatory responses of an agro-pastoral community around Kibber Wildlife Sanctuary in the Indian trans-Himalaya The three villages studied (80 households) attributed a total of 189 livestock deaths (18% of the livestock holding) over a period of 18 months to wild predators, and this would amount to a loss per household equivalent to half the average annual per capita income The financial compensation received by the villagers from the Government amounted to 3% of the perceived annual loss Recent intensification of the conflict seems related to a 377% increase in livestock holding in the last decade Villagers have been killing the wolf, though apparently not the snow leopard A self-financed compensation scheme, and modification of existing livestock pens are suggested as area-specific short-term measures to reduce the conflict The need to address the problem of increasing livestock holding in the long run is emphasized

The effects of traditional fisheries management on fisheries yields and the coral-reef ecosystems of southern Kenya

Abstract: Many traditions of coastal peoples may be viewed as traditional forms of marine conservation because, like modern fisheries management, they restrict fishing gear, fishing times, and places, but their effects are little studied in practice. A study was undertaken of human culture and fisheries resources in an area of southern Kenya, designated as a national marine reserve, to determine the effect of the existing 'traditional management' on fisheries yields and on the ecological condition of the fished reefs. This area has one of the oldest and most elaborate cultural traditions concerning sacred sites and rituals of sacrifice along the Kenyan coast. The purpose of the customs is, however, to appease spirits rather than to regulate fish stocks which are traditionally seen to fluctuate independently of fishing effort. Many of these traditions have decayed in recent times as Islamization of the culture has occurred, and authority has shifted towards national organizations, weakening the effectiveness of the traditional leaders. Coincidentally, fishers have adopted new or foreign gear, colleagues, and traditions. Two adjacent landing sites (Mvuleni and Mwanyaza) have, however, successfully stopped pull seiners from landing their catch at their sites for over 20 years through passive means. Other landing sites have adopted pull seining. Both landing areas use arguments based on tradition to justify their use of gear. The two landings that restrict pull seining have higher per capita fish catches than those that do not. Nonetheless, there were no obvious differences in the ecological condition of the reefs at these two management areas; both areas were amongst the most degraded reefs reported in East Africa. Biological diversity and coral cover were reduced greatly in all these areas compared to other fished or fully-protected marine park or reserve sites established by the national government. Presently, traditional management is not effective in protecting species diversity or ecological functions, which was probably never the intention of the customs. The conflict between national organizations and local fishers arises because some resource users are concerned that the management proposed by the national organizations will eventually lead to the total loss of access to, and control of the resource by local fishers. There is, therefore, a need to resolve conflicts concerning gear use and regulation, and a need to increase awareness of the expectations and management programmes among the national and local organizations. Many of the traditional forms of management are compatible with the policies of national organizations, but confusion and conflict occur concerning enforcement and its benefits. To solve these conflicts discussions are required between traditional and national fisheries leaders to develop mutually-acceptable policies that augment and share the power of management.

Environmental carrying capacity and tourism development in the Maldives and Nepal

Abstract: Tourism is regarded by many countries, particularly resource-poor countries, as a potential stimulus to the economy. Yet tourism, by the nature of the activities involved, is constrained by the natural resource base and infrastructure, and by the pollution and other environmental and social impacts of tourist numbers. Tourism development strategies of national governments have been diverse in the face of this complex relationship between the economic costs and benefits of tourism. This paper examines tourist development based on concepts of open access and renewable natural resources. The experiences of two economies highly dependent on tourism, the Maldives and Nepal, are compared and contrasted. Although these countries offer very different attractions to tourists, they are faced with similar problems in terms of adverse environmental impacts of tourism. The dominant impacts in both areas are those associated with solid waste disposal and water resources, compounded by the depletion of natural resources. Both countries are currently employing 'dispersal' techniques to overcome the adverse impacts of tourism, but such strategies do not address the fundamental problem of maintaining tourism revenues whilst minimizing environmental damage. Even if an ecological carrying capacity can be defined, the experiences of these two countries indicate that impacts on local communities may well exceed so-called cultural carrying capacity.

Co-management of New Zealand's conservation estate by Maori and Pakeha: a review

Abstract: Despite direction by the Conservation Act (1987) to give effect to the principles of the Treaty of Waitangi, New Zealand's Department of Conservation has few formal collaborative management arrangements with Maori. Obstacles to establishing agreements that involve Maori in equitable conservation decision-making roles include divergent philosophies (preservation versus conservation for future use), institutional inertia, a lack of concrete models of co-management to evaluate success or otherwise to promote conservation, a lack of resources and opportunities for capacity building and scientific research amongst Maori, opposition and a lack of trust from conservation non-governmental organizations that are predominantly euro-centric in approach and membership, and a fundamental reluctance of some to share power with Maori. Recent examples of work towards co-management emphasize the need for innovative methods to build trust and explore common ground and differences. Meetings on marae (traditional Maori gathering places) have established guiding principles, lengthy dialogue, and a collective symbol as a metaphor for co-management. These were valuable steps towards building trust and understanding required for the restoration of coastal lakes and a river, and the potential joint management of two national parks on the west coast of the North Island. Establishment of a research project to assess the sustainability of a traditional harvest of a sea-bird (Puffinus griseus) by Rakiura Maori was facilitated by drawing up a 'cultural safety' contract. This contract underscored the role of Maori as directors of the research, protected their intellectual property rights to their traditional environmental knowledge, guaranteed continuity of the collaborative research project and regulated how results were to be communicated. The scientific ethics of a university ecological research team were safeguarded by the contract, which ensured that they could publish their inferences without erasure or interference. The New Zealand experience shows that even when legislation signals from the top down that the doorway is open for co-management with indigenous people, this by itself is unlikely to make it happen. Active facilitation by innovative middle-level agreements and the creation of new administrative structures are needed to govern co-management of a broad spectrum of resource issues. Bottom-up initiatives involving single, or very localized, resource uses may also trigger co-management. Models for successful co-management involving indigenous peoples must focus more strongly on issues of equity or power sharing, and therefore may be very different from models directed at a single conservation outcome.

Arrested succession in pastures hinders regeneration of Tropandean forests and shreds mountain landscapes

Abstract: Arrested succession is conspicuous in the abandoned pastures of the Andean piedmont that have encroached upon the tropical montane forests toward higher limits and steeper slopes. Habitat 'shredding' is analysed to depict the current spatial configuration of tropical Andean landscapes, based on fragmentation patterns prompted by seed dispersal ecology and pasture encroachment.Seed dispersal was studied to address the hypo-thesis that seed input constrains the recruitment of montane forest seedlings, thus impeding pasture conversion to forest. It turns out that a better competitor, the tussock grass Setaria sphacelata, is limiting dispersal success due to its bioarchitecture and planting patterns. Because of the variegation of fragments, the area is in danger of landscape homogeneity within a matrix of degraded pasture. Currently, protection of fragmented remnants and restoration of original landscape structure and function are urgent needs for land-use planning toward sustainable development in the region.Restoration ecology is plausible as a means of conservation for degraded Tropandean forests, since human impacts have shredded landscapes entirely. Dispersal ecology may be used to facilitate pasture conversion to forest in equatorial landscapes, but the proactive approach of pasture removal or planting strategy should differ from that for lowland Amazonia, where abandoned pastures are different from those of montane environs. However, the region may be proactively managed only if political decisions include conservation as a goal of development.

Greenhouse-gas emissions from Amazonian hydroelectric reservoirs: the example of Brazil's Tucuruí Dam as compared to fossil fuel alternatives

Abstract: Hydroelectric dams in tropical forest areas emit carbon dioxide and methane. How these emissions and their impacts should be calculated, and how comparisons should be made with global warming contributions of alternative energy sources such as fossil fuels, can lead to sharp differences in conclusions on the relative advantages of these options. The example of Brazil's Tucurui Dam is examined to clarify these differences. The present paper extends an earlier analysis to 100 years and explores the differences between these and comparable fossil fuel emissions.Factors considered here in calculating emissions for Tucurui Dam include the initial stock and distribution of carbon, decay rates and pathways (leading to carbon dioxide and methane), and losses of power in transmission lines. Factors not considered include forest degradation on islands and reservoir shores, nitrous oxide sources in drawdown zones and transmission lines, additional methane emission pathways for release from standing trees, water passing through the turbines, etc. Construction-phase emissions are also not included; neither are emissions from deforestation by people displaced by and attracted to the project. A complete accounting of the alternative landscape is also lacking. Standardization of the level of reliability of the electricity supply is needed to compare hydroelectric and thermoelectric options.Types of emission calculations commonly used include the ultimate contribution to emissions, the annual balance of emissions in a given year, and emissions over a long time horizon (such as 100 years). The timing of emissions differs between hydroelectric and thermal generation, hydro producing a large pulse of carbon dioxide emissions in the first years after filling the reservoir while thermal produces a constant flux of gases in proportion to the power generated. The impacts of emissions are related to the atmospheric load (stocks) of the gases rather than to the emissions (flows), and therefore last over a long time. According to the calculations in the present paper, the average carbon dioxide molecule in the atmospheric load contributed by Tucurui was present in the atmosphere 15 years earlier than the average molecule in the comparable load from fossil fuel generation. This means that, considering a 100-year time horizon, a tonne of CO2 emitted by Tucurui has 15% more global warming impact than a tonne emitted by fossil fuel, assuming no discounting. If discounting is applied, then the relative impact of the hydroelectric option is increased.Time preference, either by discounting or by an alternative procedure, is a key factor affecting the attractiveness of hydroelectric power. At low annual discount rates (say 1–2%), the attractiveness of Tucurui, although less than without discounting, is still 3–4 times better than fossil-fuel generation. If the discount rate reaches 15%, the situation is reversed, and fossil-fuel generation becomes more attractive from a global-warming perspective. Tucurui, with a power density (installed capacity/reservoir area) of 1.63 W m-2 is better than both the 0.81 W m-2 average for Brazilian Amazonia's 5500 km2 of existing reservoirs and the 1 W m-2 estimated by Brazil's electrical authorities as the mean for all planned hydroelectric development in the region.

Ecotourism and conservation in Amazonian Perú: short-term and long-term challenges

Abstract: Several authors have suggested that ecotourism can enhance the value of intact wildlands and thereby promote conservation. Two rainforest lodges dating from the 1970s and located in southeastern Amazonian Peru have been held up as early success stories in tourism-driven conservation, but a more recent assessment reveals that both lodges have since lost their rainforest reserves to encroachment. One of the major reasons for failure was that the national land laws in effect at the time did not allow the purchase of land titles. Recently, Peru has instituted a process for the purchase of land titles in the rainforest. One lodge has used the new land tenure laws with some success to create a rainforest reserve. The very attempt to buy land for purposes of conservation can promote encroachment and land-buying speculation, and the lodge's current agreement with its neighbours to provide a school in exchange for non-encroachment is fraught with moral hazards and appears unstable over the long term. Tourism can promote conservation primarily at the national level, and ecotourism projects in the Peruvian Amazon can stabilize land-use patterns at least in the short term. However, the conservation of habitat over the long-term will rest primarily on the ability of the State to enforce a consistent land use policy with regard to land tenure and Park protection.

Sustainable development: modern elixir or sack dress?

Abstract: Over the past two decades 'sustainable development' has grown from a term expressing concern for social and environmental problems to an international craze. The concept purportedly offers cures for the many and diverse problems afflicting modern society, and because it involves an integrated approach, the sustainable development fashion has resulted in much-needed collaboration between specialists from diverse backgrounds, to work on the complex problems involved in the interactions between society and environment. However, the term is rarely defined, and, being stylish and institutionalized, the 'sustainability movement' now directs the way much science and policy for biological conservation and development are designed, executed and evaluated. Occult, but basic, in nearly all discourses of sustainable development is the axiom of continual growth; and, in most cases, instead of offering a true solution to contemporary problems, the term is a source of confusion, contention and even deception. It is imperative that the use of this term, especially in multidisciplinary, international and scientific spheres, be based on clear understanding of its meaning, and that the issue of growth and the concept of limits be clearly incorporated into the core of the discussion.

Poverty, technology, and wildlife hunting in Palawan

Abstract: Tropical forest destruction jeopardizes wildlife habitat. In many countries, hunting by low-income households also poses a direct threat to many species. This paper reports a study of the wildlife hunting practices of an indigenous cultural community in the Philippine province of Palawan. A survey of hunting practices was conducted among farmers living along the forest margin. The survey collected information on hunting frequency, hunting techniques, and species hunted. These data were combined with household income and demographic data to learn how socioeconomic factors influence hunting patterns and practices. Descriptive statistical procedures and regression analysis show that hunting pressure during the study period was typically greatest among resource-poor households. Poor households used the widest range of hunting implements, including modern implements such as air rifles, and low living standards were associated with greater hunting effort. Households with small farms were more likely to hunt, and were also more likely to expend greater hunting effort. Hunting was a supplementary source of food acquisition for most farmers and was found to be inferior to agricultural production, in the sense that households with large farms tended to hunt less often than households with small farms. Indirect evidence suggests that higher population pressure correlates positively with hunting pressure, and that non-agricultural employment negatively correlates with hunting probability and intensity.

Forced migration, environmental change and woodfuel issues in the Senegal River Valley

Abstract: Summary There is increasing international concern about the environmental impacts of refugees on host areas, with governments calling for compensation for environmental damage, particularly concerning the loss of woodland resources as a result of demand for wood for fuel. In addition to an obvious increase in the population of host areas, concern about refugees’ woodfueluse centres on the notion that they are ‘exceptional resource degraders’. Since they view their stay as temporary, it is argued, they therefore do not have any incentive to use resources in a way that is sustainable in the long-term. This study examined refugee migration to the middle valley of the Senegal River, and com

Trampling associated with bait-collection for sandprawns Callianassa kraussi Stebbing: effects on the biota of an intertidal sandflat

Abstract: Previous studies have inferred that the side effects of physical disturbance associated with bait-collecting for the sandprawn Callianassa kraussi are more deleterious than the actual removal of the prawns. The present study was specifically designed to disentangle the side-effects of trampling and disturbance associated with using suction pumps for bait-collecting. Separate areas were sucked over with a prawn pump at three different intensities, and the prawns collected from these areas subsequently returned to them. A parallel treatment involved trampling the sediment at levels comparable to the 'sucking' intensities, without removing the prawns. The responses of the meiofauna, macrofauna and microflora were assessed six weeks after this disturbance. Prawn densities were depressed six weeks following both sucking and trampling but recovered by 32 weeks. The meiofauna responded positively to some of the disturbance treatments; macrofaunal numbers on the other hand, declined in most treatment areas, and similarity analysis and multidimensional scaling showed that macrofaunal community composition in the most-disturbed areas was distinct from that in other areas. Chlorophyll levels were reduced at the more intensely-disturbed sites. The results corroborate the conclusion that trampling per se has almost the same effect as sucking for prawns, on both the prawns and on the associated biota. This has important implications in terms of managing the use of lagoonal and estuarine ecosystems.

A comparison of the enforcement of access restrictions between Xishuangbanna Nature Reserve (China) and Khao Yai National Park (Thailand)

Abstract: Given limited budgets to enforce access restrictions, protected area (PA) managers and non-governmental organizations (NGOs) in developing countries employ a range of policy instruments to conserve the area's natural resources. Natural characteristics of the PA combine with the managers' enforcement activities and other policy instruments to create a set of incentives to which local people respond in making decisions about extracting resources from the PA. The different management approaches employed in the Xishuangbanna Nature Reserve (XNR; China) and the Khao Yai National Park (KYNP; Thailand) and the reaction to the incentives which they create are compared. KYNP managers use policing and punishment mechanisms, in conjunction with limited NGO-supported income-generation projects, to deter resource use. In contrast, XNR managers rely on extensive cooperation with local people and trade-offs between current resource degradation and increased rural incomes.As predicted by the economic enforcement literature, rural people respond to the threat of punishment, and its reduction of the expected benefit of an illegal activity, by reducing that activity, but may undertake socially-costly avoidance activities to avoid punishment. This literature also correctly predicts that XNR managers will concentrate less on pure enforcement than KYNP managers because, as a result of a difference in government mandates, the XNR managers consider the value of the extracted products and the non-PA productivity in their decisions while the KYNP managers do not. In both PAs, rural people's actions affect the quality of resource conservation. In KYNP, natural characteristics and the policing activities deter resource extraction and encroachment in the central core of the Park. Even NGO projects, however, have not controlled extraction, and even agricultural encroachment, in the outer third of the Park, which has caused over-extraction of some resources and has left a ring of highly-degraded land. In contrast, XNR's cooperative management approach has generated more control over the amount and the spatial configuration of resource degradation. XNR's control, however, comes at the cost of reduced area and level of current conservation.

Effects of rainfall and grazing on vegetation yield and cover of two arid rangelands in Kuwait

Abstract: Increasing human pressure has presumably led to a decrease in the cover and herbage yield of Kuwaiti desert vegetation, but, to date, there has been little detailed study on such human impacts. A study of Rhanterium epapposum (local name arfaj) and Haloxylon salicornicum (local name remeth) steppe was therefore effected to determine the seasonal variation in above-ground phytomass and percentage cover, and to investigate differences between protected and adjacent grazed areas.An average seasonal precipitation of 90 mm supported a mean of 223 kg ha-1 in arfaj steppe in 1979–1989, whereas an average mean seasonal precipitation of 73 mm during 1983–1989 maintained a mean phytomass of 102 kg ha-1 in the remeth steppe. Annual forbs and perennial shrubs were the greatest producers of dry matter per kg of phytomass in the arfaj and remeth steppes, respectively. The seasonal production of dry matter was related directly to the seasonal precipitation in the arfaj steppe, whereas the remeth steppe did not show an obvious relationship to the precipitation. The plant cover was 83% and 70% less, and herbage production was 76% and 91% less in grazed areas than in protected areas in the arfaj and remeth steppes, respectively.

Human perturbations and conservation strategies for San Pedro Mártir Island, Islas del Golfo de California Reserve, México

Abstract: Summary Many sea-birds are dependent for breeding on islands free from both mammalian predators and high levels of human disturbance. Yet human use of small islands appears to be increasing in many parts of the world, including the >150 islands in the Gulf of California, Mexico. For this reason, the frequency and activities of human visitors to San Pedro Martir Island, one of the most important sea-bird nesting sites in Mexico, were studied over the course of 14 months of field work between 1990 and 1992. On average >350 people per month visited the near-shore waters. The most important visitors were: (1) commercial fishers in small open boats called pangas; (2) commercial fishers in larger ships; (3) private sport-fishers; and (4) commercial environmental-tourism groups. Private sportfishing boats were most frequently observed, but private sport-fishers rarely landed on shore and caused little apparent disturbance to nesting or roosting sea-birds or California sea-lions (Zalophus californicus). Commercial companies concerned with environmental tourism also caused little apparent disturbance to sea-birds or sea-lions, but only because the company that brought the majority of ‘ecotourists’ developed and followed guidelines to minimize disturbance. Disturbance caused by all tourists can be reduced at minimal cost to both tourists and protected-area managers. Commercial fishers were responsible for most of the apparent disturbances to sea-birds and sea-lions; decreasing this apparent impact will be more difficult. Most apparent human impact was found to be short term and localized. However, commercial fishers and scientific researchers have the potential to cause long-term changes to the terrestrial ecology of the island by introducing exotic species.

Effects of oil and other surface-active organic pollutants on aquatic birds

Abstract: A variety of organic contaminants can potentially have impact on aquatic birds by their affecting surface tension. Avian plumage constitutes a porous barrier to water and the air trapped between the feathers serves as thermal insulation. When the air is displaced, the birds expend extra energy to maintain a normal body temperature, but this response cannot be sustained for long, especially at low environmental temperatures. When energy stores are depleted, hypothermia and death ensue. Surface tension is the force that resists infiltration of water into the plumage. The critical surface tension for feather wetting is conservatively estimated to be in the range 38–50 mN m-1. The hypothesis that surface-active organic contaminants can have significant detrimental effects on aquatic birds was evaluated. New data obtained in a study of water penetration pressures in Lesser Scaup contour feathers show that the 'wettability safety factor' is reduced by about half during moult. That is, the critical surface tension was raised to approximately 49–58 mN m-1 in moulting Lesser Scaup. The energetic and behavioural effects of oil contamination are reviewed, and it is concluded that even small quantities of organic material may confer significant physiological cost. The available data generally support the hypothesis that waterfowl face a potential risk associated with chronic or periodic mild depression of water surface tension due to organic pollutants, including oils and detergents. However, much of the evidence is indirect and further research, especially long-term assessment of surface tension in marine, estuarine and freshwater habitats, is needed to determine whether a real environmental problem exists.

Conservation status of forests and wildlife in the Eastern Ghats, India

Abstract: The Eastern Ghats (EGs) comprise a chain of ancient low hills in the state of Andhra Pradesh adjoining the east coast of India. These hill ranges are well known for a rich array of tropical forests with great conservation significance which support large human populations. A series of protected areas (PAs) have been established by the government along these ranges to conserve the regional biodiversity, but their effectiveness is often questionable. In order to assess the ecological status of the forests both within and outside the PAs and to assess the impacts of ongoing forestry practices a survey was conducted along the EGs. Plant species richness, and density of shrubs and trees, were estimated along disturbance gradients (core, buffer and fringe situations) using random plots of 10-m radius for trees, and 5-m radius (nested) plots for shrubs and saplings. Indirect evidence (spoor) of domestic and wild animals was recorded within the sample plots to compare habitat use by the animals.Srivenkateshwara National Park in the Seshachalam Hills, Gundlabrahmeshwaram Sanctuary in Nallamalais and some parts of Srisailam-Nagarjunasagar Tiger Reserve, had the least degraded forests due to their PA status. However, collection of non-timber forest products, bamboo harvesting and livestock grazing continues in all areas irrespective of legal status. All bamboo areas have been heavily worked. It is recommended that bamboo working should be stopped in core areas of the PAs and reduced from nine to six months (October to March) in the buffer zones. Summer is a period of potential water shortage for wild animals and bamboo workers' camps near water courses may affect habitat use by these species.The proposed Gudem Maripakhala Sanctuary, well known for its biogeographical value and diverse flora, is seriously threatened as a result of to extensive 'podu' (slash and burn) cultivation. It is suggested that an integrated approach to biodiversity conservation and better agricultural practices, should be adopted in this area. Some of the primary and old growth forests should be identified, mapped and given immediate protection, until a scientifically-based management plan is developed.

Contrasts in conservation attitudes and agricultural practices between farmers operating in wetlands and a plain in Macedonia, Greece

Abstract: Conservation projects around the world have been impeded by conflicting land uses. In Greece, although agriculture is considered to have significant impacts on wetlands and adversely to have affected conservation, the attitudes of Greek farmers to wetlands and conservation have not been assessed. Data on demographic variables of farm operators, characteristics of the farming operation, irrigation practices, attitudes towards environment and the wetland resources, knowledge on the impact of agriculture on the local environment and opinions on the Common Agricultural Policy reform, were collected through a survey using personal interviews from a random sample of 196 farmers operating in two wetlands, Lakes Mikri Prespa and Kerkini (Ramsar sites), and 141 farmers operating in a plain, in Macedonia, northern Greece.Analysis of the data revealed that farmers practise crop and stock agriculture more intensively in wetlands than in the plain, and exploit wetland resources excessively. Hunting, fishing and wood harvesting are practised, and lake water is used intensively for irrigation by both groups of farmers, with no care for loss of the resources. Alternative methods of irrigation for improving efficiency of water use or alleviating hydrological pressures on the wetlands are not considered. Sustainability of agriculture is at risk as present practices result in impoverished soils, salinization of the fields and waste of water resources. Wetland farmers seemed to have a more negative attitude toward the wetland resources and seemed to be more ignorant of conservation issues or the impact of their practices on the environment than plain farmers. Moreover, their awareness and willingness to adopt an environmentally-friendly type of farming was very low.

Shelf life of stock-piled topsoil of an opencast coal mine

Abstract: Topsoil is essential to abandoned mines and has to be stock-piled separately for post-mining land reclamation. If the storage period exceeds the 'shelf life' of the topsoil, it cannot be preserved by technical reclamation only. Opencast coal mining production in India is predicted to increase from the present level of 180 million tonnes per year to approximately 256 million tonnes per year by the year 2000. At that time about 60 km2 of land per year would be damaged by direct coal mines and 75 km2 per year would be affected by external overburden dumps and topsoil dumps. A large opencast coal mine was studied to evaluate the effect of stock-piling topsoil. Soil characteristics of soil dumps of six different ages (1, 3, 4, 6, 9 and 10 years old) were compared with those of surrounding unmined sites. Soil profiles were found to change greatly with age. Physico-chemical characteristics of soil dumps were found to deteriorate with respect to unmined soil. It was observed that, as the age of soil dumps increased from one to 10 years, the concentrations of suitable plant growth nutrients in soil gradually decreased and, after six years, the soils were found to be stagnant. This may be considered to be the 'shelf life' of topsoil. Biological reclamation must be adopted to preserve the topsoil if the storage period exceeds the shelf life period. The methodology provides guidelines for assessing the shelf life of topsoil in other areas.

Human carrying capacity estimation in Brazilian Amazonia as a basis for sustainable development

Abstract: Sustainable development requires that population and consumption remain within the limits of carrying capacity, while preventing a decline in the carrying capacity of an area requires that productive systems implanted through development be sustainable. Zoning can be a valuable tool in influencing land-use decisions, but we cannot expect government decrees to be capable of causing the landscape to evolve toward the sustainable patterns which have been recommended through zoning. A prerequisite for influencing land-use change is understanding the social processes involved in land-use decisions, beginning with deforestation dynamics. Work to estimate carrying capacity needs to embrace the wide variety of production systems used and contemplated for Amazonia and to be able to interpret this information at scales ranging from local communities to the region as a whole. This will require not only studies of different land-use systems in rural areas, but also integration with studies of energy use and support limits of urban populations. Risks of environmental impacts must be quantified under different development scenarios, and limits of acceptable risk identified and integrated into analyses of carrying capacity.Tapping the value of environmental services of standing forest represents a promising means of sustaining Amazonia's population over the long term, but numerous obstacles exist. These include halting deforestation before opportunities are lost and supporting the population in non-damaging ways while the institutional groundwork is laid for using the environmental services involved. Research is needed to quantify the magnitude of services and the appropriate monetary value per unit of service. Diplomatic agreement must be reached on these values, which can be expected to be quite different from estimates of the 'true' values based on research. A series of social arrangements must be proposed and implemented if the value derived from environmental services is to fulfil its dual role of maintaining both the forest and the human population in Amazonia.

Engineering a large sustainable world fishery

Abstract: Mankind is faced with three interconnected problems, those of rising population, the provision of adequate food and the increasing level of waste carbon dioxide in the atmosphere. The ocean plays an important role at present by annually providing c. 90 Mt of high protein food and absorbing about 1000 Mt of carbon dioxide (CO2) from the atmosphere. By the year 2100 it is predicted by the United Nations (1992) that the world population will have more than doubled its 1990 level of 5.2 thousand million people and will approach 11.5 thousand million. Most of this population increase will occur in the developing countries.

The UK transition from nature preservation to ‘creative conservation’

Abstract: A half century has elapsed since the appointment of an official body, the Nature Conservancy, in 1949, and the beginnings of what might be described as the modern nature conservation movement in the UK. Whilst ecologists perceived the 'heritage of wild nature' to be largely the outcome of past land use, and that the nature reserves would have to be managed consciously if their wildlife interest were to be sustained, there was only the most rudimentary understanding of how this might be achieved. Drawing for the most part on projects affecting wetlands, the paper illustrates the early steps taken to bring greater scientific rigour to reserve management. Whilst the potential for habitat restoration was recognized, there was little opportunity for its practice in the intensively-farmed countryside until grant aid was made available for such purpose from the agricultural budget in the 1980s. Where nature conservation had begun to subsume nature preservation, some fifty years ago, notions of 'creative conservation' have similarly encouraged reassessment of the purpose and practice of wildlife-resource management. This time however the challenge is being met in both the wider countryside and the built environment.

Plant succession and its optimization on tar-polluted coasts in the Arabian Gulf region

Abstract: Summary Coastal ecosystems in the Arabian Gulf region are under increasing pressures from hostilities and other developmental activities; the region has a long history of crude-oil pollution. Because of the high ambient temperature, oil deposited along the coastline or inland evaporates, leaving a semi-solid tar. In Qatar, to clean up the polluted sites, the deposited tar is stripped off and dumped in the coastal marshes as confluent dome-shaped piles. Flowering plant colonization of tar-piles is described here as a chronosequence, ranging in age from 2 to 14 years. The successional patterns in vegetation, seed bank, species diversity and plant growth were predicted from tarpile disturbances with different ages and tar content. The success of natural plant colonization and the establishment of plant communities on the tar-pile disturbances depend upon: (1) age of the tar-pile disturbances, (2) tar content of the piles and soil physicochemical properties, (3) soil moisture content, (4) structure of plant communities in the surrounding landscape, (5) size of the disposal sites and the method of dumping, and (6) prevailing environmental conditions. A management and restoration framework is proposed to optimize the natural recolonization of tarpiles. To retain these ecosystems in a self-sustaining state, some native plant species might be used including: Aeloropus lagopoides, Aizoon canariense, Anabasis setifera, Fagonia indica, Mesembryanthemum nodiflorum, Reichardia tingitana, Salsola imbricata, Suaeda aegyptiaca, Senecio glaucus, Sporobolus arabicus, Zygophyllum quatarense, and Zygophyllum simplex. To clarify the biological and chemical aspects of the problem, further research on the chemistry of tar-polluted soil and its vegetation in relation to the food web is needed.

Interpreting puma ( Puma concolor ) population estimates for theory and management

Abstract: Estimates of population size have been essential for ecological theory and wildlife management, but they depend on spatial scales of observation. Reported aspects of study and interpretive design were tested to see if they could explain variation in puma (Puma concolor) density. Comparison of puma studies revealed information shortfalls and possible confounding effects in research trends. Vegetation descriptions and other biological and physical aspects of the study site explained none of the 30-fold range of variation in puma density, nor did sampling and estimation methods and other aspects of study and interpretive design. Most (78%) of the variation in puma density estimates can be explained by the spatial extent of study area. Given the effect of scale, puma density estimates have been inappropriately extrapolated to larger geographic areas for management purposes. Due to spatial shifting of local population clusters, conventional density estimates cannot contribute to assessments of puma population trend without study at multiple sites over longer periods of time. Field studies would contribute more to knowledge of puma by spanning larger areas, a greater variety of land uses and habitats, and more of puma's range of distribution.

Protection of mahogany: a catalytic species in the destruction of rain forests in the american tropics

Abstract: Mahogany as a catalytic species. Logging of American (bigleaf ) mahogany (Swietenia spp.) initiates a series of events that leads to degradation and later destruction of tropical forests in the New World. It also is a spear-point for penetration of indigenous areas by loggers, who inflict both social and environmental impacts on the tribes. Mahogany populations are declining and are not being replenished by natural regener-ation; the situation of the species continues to worsen in the field.

A long-term record of human impacts on an urban ecosystem in the sediments of Töölönlahti Bay in Helsinki, Finland

Abstract: Ecological impacts of urbanization are receiving increasing scientific attention, yet few data sets permit long-term effects on terrestrial and aquatic ecosystems to be assessed. Toolonlahti Bay, in the centre of Helsinki, Finland, provided on opportunity to characterize recent human impacts especially by means of chemical and biostratigraphical analyses of a sediment core. Periods of coniferous forest, forest clearance, urbanization and the development of parks, can be distinguished in the pollen record of the core. Palynological diversity was highest before the forest clearance at the turn of the century. The character of the sediment and the water have changed substantially in response to rapid population growth, the construction of sewage systems and building within the catchment of the bay. This is reflected in marked increases in organic matter, phosphorus and heavy metal (Cd, Cu, Ni, Zn and Pb) concentrations between 1890 and 1960, accompanied by a rapid increase in diatom species indicative of eutrophication and a decline in diatom species diversity. Since the cessation of waste-water disposal in the 1960s, concentrations of a number of pollutants have declined and water quality has gradually improved, but conditions are still affected by internal and atmospheric loadings. As a consequence of land uplift (2 mm per year) and the rapid sedimentation rate (6 mm per year), the volume of the bay is decreasing. Within 200 years, the shallow bay, which is skirted by extensive parks and famous cultural buildings such as the Finlandia and the Opera Houses, will fill with sediment unless it is dredged.

Evolution of the system of protected areas in Western Australia

Abstract: The Western Australian system of protected areas (PAs) covers more than 15 million ha and is the second largest conservation estate of the Australian continent. An analysis of the history of the creation of PAs in Western Australia shows that the concept of nature conservation through reserves was slow to emerge. During the early decades of the century, reserves were mainly created for their recreation values. The lack of governmental interest in nature conservation led to a belated development of reserve coverage up to the 1950s, while vast areas of land were opened to farming and pastoralism. Following two scientifically-based reviews of the PA system, the number and coverage of PAs increased dramatically up to the late 1970s. The rationalization of the vesting and managerial responsibilities for PAs was only finalized in the 1980s. Since then, there has not been any large increase in PA area but a consolidation of the PA coverage. The development of the system of PAs has been impeded by the belated response of Western Australian governments to conservation concerns and a 'worthless' land approach to conservation as a land use. While large-scale land alienation for agriculture has now stopped, other types of land uses such as mining and other aspirations over land management and vesting, such as Aboriginal land claims and forestry are now constraining any large expansion of the PA system. Only an approach embracing the whole landscape can overcome the political and social limitations of the concept of PAs and the further degradation of developed land in Western Australia.