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In the autumn of 1995, coordinated national lake surveys were conducted in the Nordic countries, including Russian Kola. The 11 metals (Pb, Cd, As, Zn, Cu, Ni, Co, Fe, Mn, Cr, V) investigated in nearly 3000 lakes have generally low concentrations and distinct geographical patterns. Direct and indirect influence of long-range transported air pollution is the major important factor for distribution of Pb, Cd, Zn and to a certain degree Co. Total organic carbon (TOC) concentrations in lakes are important for Fe and Mn but also to a certain degree for As, Cr and V. Bedrock geology is the major controlling factor for Cu and Ni, with the exception of areas around the smelters in the Kola peninsula, where the Cu and Ni concentrations in lakes are very high due to local airborne pollution. Bedrock and surficial geology is also an important factor for controlling the concentrations of As, Co, Cr and V. The results indicate that heavy metal pollution in lakes is a minor ecological problem on a regional scale in the Nordic countries.
Concentrations of Sb, Hg, Bi, Cd, Mo, As, Co, Ni, Cr, Cu, V, Pb and Zn in surface and preindustrial sediments from 210 lakes in Norway were used for studying modern atmospheric depositions of these elements. Surface sediments had considerably higher concentrations of Sb, Hg, Bi, Cd, As, Pb than preindustrial sediments. The differences decreased with latitude and altitude. A multivariate analysis including the trace elements and the major constituents (organic matter, Si, Al, Fe and Mn) of surface sediments suggested the following relationships: Sb, Hg, Bi, As, and Pb formed a group with strong associations to organic matter. Ni, Cr and Cu formed a second group, weakly associated to the inorganic sediment fraction (Si and Al). Zn and Cd formed a third group with weak associations to organic matter. Co was associated to Mn, whereas Mo and V showed no important covariations with any other trace elements or major components.
Acidification represents a growing threat to certain developing country ecosystems in tropical and subtropical climates. A methodology investigating the extent of acidification risks from sulfur emissions on a global scale is presented. Atmospheric transfer models have been used to calculate transfer and deposition of sulfur (using emissions for 1990 and a projection for 2050) and alkaline soil dust. A method to derive the relative sensitivity of terrestrial ecosystems is explained and preliminary critical load values are assigned. A range of values for critical loads and base cation deposition have been used to investigate uncertainty in maps depicting the excess of deposition above critical loads. These show an increasing risk of acidification in 2050 in extended regions of southern and eastern Asia, as well as parts of southern Africa, in comparison to 1990. Certain areas, especially in Asia, are shown at risk even when high values of critical load and base cation deposition are used.
The southern Namib is characterized by high biodiversity, changes in winter and summer rainfall, extreme climatic conditions and associated geomorphologic processes, a paucity of ecological knowledge, and multiple environmental threats posed by conflicting development options. With the long-term view to establish a research initiative focussing on restoration ecology in the southern Namib Desert, this article provides a review of current ecological knowledge and proposes potential research priorities. The aims of a research initiative would be two-fold. On the academic side, understanding processes operating at different scales will be critical to develop methods of ecological restoration suitable for southern Namib ecosystems. On the practical side, the development of appropriate methods will focus on facilitating ecological processes such as restoration of biologically active substrate, natural succession, and concentration of limited resources. The function of landscapes, plant-soil interface, soil-, vegetation- and plant population dynamics will likely provide some of the answers for ecological restoration.
In Orissa 100 thousand ha of village plantations were established from 1985 to 1992 as an aid project to support the subsistence needs of rural poor and to relieve heavy pressure on the natural forests. The aim of this paper is to examine the welfare and environmental effects of these village plantations. To do this, extensive data collection was needed which included both household utilization of different sources of biomass as well as remote-sensing information, to establish the status of the vegetation and it's spatial location vis-a-vis the users. The study shows that plantations have the potential for substantial welfare improvements for the target population, especially women, through increased consumption of biomass, decreased time for collection and decreased pressure on natural forests. However, interventions need to be very selective in order to be successful, with special consideration given to plantation location compared to natural forest.
This paper reviews the application of satellite remote sensing to management of Singapore's coastal environment. Remotely sensed data have been used for marine habitat mapping, water quality monitoring, ship and ship-wake detection, oil spill detection, red tide monitoring, and mapping of reclamation activities. While these applications clearly cover most of the range of opportunities for use of remotely sensed data in the coastal zone, there is still a need for more complete baseline studies of natural resources and habitats, and monitoring of the impacts of development on the coastal and marine environment. There is also a requirement for more management-oriented research and continued development and revision of the available datasets. Integration and exchange of information between management agencies and research groups is also an important aspect of sustainable management of Singapore's coastal environment and marine resources.
In many countries where the economy has shifted from mainly agricultural to industrial, abandoned agricultural lands are lost to urbanization. For more than 4 centuries the Puerto Rican economy depended almost entirely on agriculture, but sociopolitical changes early in the 20th century resulted in a shift to industry. This shift in the economy, and an increase in population, has resulted in an increase in urban areas. This study describes the rate and distribution of urban growth on the island of Puerto Rico from 1977 to 1994 and the resulting influence on potential agricultural lands. Urban extent and growth were determined by interpreting aerial photographs and satellite imagery. The 1994 urban coverage was combined with a soil coverage based on agricultural potential to determine the distribution of urban areas relative to potential farmlands. Analyses showed that in 1977, 11.3% of Puerto Rico was classified as urban. After 17 years, urban areas had increased by 27.4% and urban growth on soils suitable for agriculture had increased by 41.6%. This represents a loss of 6% of potential agricultural lands. If this pattern of encroachment by urban growth into potential farmlands continues, Puerto Rico's potential for food production in the future could be greatly limited.
How can governments in developing countries act together with local people to promote sustainable forest land use? Based upon an initial review of man's use of natural resources in Southeast Asia over 100 years, an interdisciplinary approach to strategic planning based on interaction among stakeholders is outlined. A case study in a water catchment area in Laos, dominated by shifting cultivation, is used to test and illustrate the approach, which includes interviews with local people about historical events and socioeconomic and environmental conditions. The study also includes field point sampling, remote sensing, official records and a simulation tool (the Area Production Model), for verification, calibration and supplementation of the information provided by villagers. By presenting the consolidated data to the villagers and giving them opportunities to consider their landuse and explain discrepancies, and comment on the conclusions, a dialogue on land-use strategies was initiated.