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Recent interest in the valuation of ecosystem services has provided tools for assessing the costs of invasive species in natural areas. This study evaluates the economic impacts of tamarisk (Tamarix sp.), an invasive woody shrub, on societally-valued ecosystem services in its naturalized range. Tamarisk, intentionally introduced from Eurasia, has invaded most riparian areas of the arid and semiarid western United States. In its naturalized range, tamarisk consumes more water than native vegetation, with significant economic implications in a region marked by water scarcity. Tamarisk also increases sedimentation in river channels, leading to increased frequency and severity of flood damage. Conservative economic estimates of these impacts indicate that the annual costs of tamarisk to the western United States total USD 280–450 ha−1. Eradicating the invader and restoring native riparian communities throughout the region would cost approximately USD 7400 ha−1. Full recovery of these costs, even with a highly conservative benefits estimate, would occur in as few as 17 years, after which the societal, ecological, and economic benefits of restoration would continue to accrue indefinitely.
Ten-day intervals of satellite data between 1982 and 1993 are used to investigate the status of biological productivity on a rangeland in semiarid China exposed to high grazing pressure. Linear trends for 64 km2 pixels are calculated through annual vegetation peak values, constructed by averaging the 6 Normalized Difference Vegetation Index (NDVI) values for August and September each year, and displayed in a GIS exposing the spatial and relative changes of biomass. Biological production, expressed as NDVI, has increased in general over the 12-year period and the correlation between precipitation and NDVI dynamic is tested. High increases are found for irrigated farmland along the Yellow River confirming a trend toward intensified cultivation and increased biomass from planted trees for farmland protection. Production on the rangeland has increased slightly without correspondence in rainfall. Instead, different measures implemented in the area to combat desertification are discussed as being likely explanations for the positive change.
Rainwater harvesting agriculture (RHA), which was first developed by scientists in Gansu province over a decade ago, is an integrated system for water management on rainfed land in semiarid areas. This system consists of three main components including rainwater harvesting system, water-saving irrigation system, and highly effective crop production system. Its main function is to provide farmers in water-limiting environments with access to the water needed to meet domestic and agricultural water needs. The preliminary implementation of RHA in Gansu and other provinces in northwest China suggests that RHA has the potential to improve performance in rainfed farming systems and to address environmental problems such as soil erosion. The small-scale and low cost of RHA systems make application by household farmers simple. However, to be successful RHA needs to be integrated in a comprehensive agricultural-management system; i.e. management of RHA must be combined with other agricultural technologies and management practices. In addition, the spread of RHA over large areas entails consideration of a range of technological, agrohydrological, ecological, social, cultural, economic, and political factors. In particular, there is a need to provide training and extension services to farmers, to develop and disseminate more effective and affordable types of RHA technologies as alternatives and to design and develop alternative policy instruments and social institutions that facilitate adoption of RHA practices.
Small-scale gold mining in southern Ecuador is causing considerable environmental impacts, the most important of which are related to the discharge of metals, metalloids and cyanide into adjacent rivers. In the rivers, these contaminants are generally not present in water-soluble forms, but are instead associated with suspended particles and river bed sediment. However, elevated levels in biota show these contaminants to be readily bioavailable. These results suggest a need to consider the suspended and sediment phases when evaluating water-quality impacts, and in setting appropriate environmental water-quality standards. Contaminant discharges, are almost entirely caused by inadequate management of the waste products derived from mining and processing activities, indicating a failure of policy and public supervision to control the mining activities, as well as a general difficulty in achieving good environmental performance among small-scale miners. These findings suggest that Ecuadorian policy needs to develop to enable small scale and artisanal miners to become larger scale.
Sustainable use of natural resources continues to gain attention, especially in relation to energy and global carbon cycles. Biomass crops may offset fossil fuels and reduce CO2 contributions to greenhouse gases while improving soil and water quality. We review research on biomass crops, with emphasis on their specific characteristics and how their production can affect soil and water quality. Data from regions throughout the world are included, but the focus is primarily on recent research results from biomass crop production in the United States. Research to date shows promising short-term changes in soil and water quality, but responses vary. Short-term studies have demonstrated increases in surface soil organic-matter content, reduction in erosion and nutrient losses in surface runoff. We conclude that while the potential for benefits is present, data are not yet available to determine the long-term changes in soil quality associated with production of biomass crops.
Drainage and peat harvesting may induce considerable changes in the fluxes to the atmosphere of the greenhouse gases CH4 and CO2 in peatlands. In this study, fluxes of CH4 and CO2 were measured with the closed chamber method in 6 Swedish peatlands that are being mined. Fluxes of CH4 were much higher from ditches than from mining “strips”, i.e. emissions from ditches dominated in most peatlands. The total CH4 emission during the growing season (0.41 to 4.5 g CH4 m−2 yr−1) was similar to emissions from virgin peatlands. Emissions from ditches can probably be kept low by keeping the ditches clear from vegetation. Like CH4, CO2 was released to the atmosphere from both ditches and strips in most peatlands. The total emission during the growing season (0.23 to 1.0 kg CO2 m−2 yr−1) was strongly dominated by the strips. Compared to the total peat yield during mining these CO2 emission rates imply that on average ca 6% of the peat carbon is lost by microbial decomposition in the mire.
Based on land-use/land-cover (LU/LC) maps for the 1970s and satellite imagery for the 1990s we estimate LU/LC change and associated C fluxes in 3 subregions of the Selva Lacandona, Chiapas, Mexico. The total area of closed forest was reduced by 31%, whereas secondary forests expanded more than ninefold, secondary shrubs by almost sixfold, and cultivated land and pasture areas expanded 21% and 92%, respectively. However, the LU/LC change was not uniformly distributed over the entire study area. Total mean C densities ranged from 452 Mg C ha−1 for closed mature forests to a low of 120 Mg C ha−1 for pasture. The heavily converted areas lost an estimated 24% of their total 1976 C pools, whereas the low impacted region lost only 3%.
The central part of the Kola Peninsula, severely affected by emissions from a nickel-copper smelter at Monche-gorsk, represents a perfect object for environmental studies. We survey the information collected in this region, with special attention paid to earlier works by Russian researchers. Although some sources are difficult to access, and some of the data should be used with caution, the benefits to be derived from the inclusion of the already collected information in forthcoming environmental projects are obvious; it provides a historical (dynamic) view of landscape deterioration and eliminates redundant work. The perception of environmental contamination by local communities changed from acceptance in the 1950s to ignorance in the 1970s and 1980s; the active protests of the early 1990s have been terminated by economic factors, which have drawn public attention away from problems of the environment and of public health.
Agricultural land expansion is almost eliminating the bamboo forests of Ethiopia, and the biological diversity associated with them. Several bamboo species are endemic to Africa and mainly found in Ethiopia. Consequently, their preservation is of international concern. Urgent and effective action is required to secure their future existence and for their use in systems managed on a sustainable basis. Utilization driven production could ensure their sustainability. Lack of awareness about their multiple use and a paucity of scientific knowledge about their production and main properties are impediments for conservation and utilization. Concerted efforts are needed to generate and adopt the required knowledge and technology in order to promote bamboo forest cultivation in Ethiopia as an economically viable crop, which is of environmental interest.