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351.
352.
Contributing to the debate on the causes of Himalayan environmental degradation, the status and management of four watersheds
in the Upper Pokhara Valley were studied using information available from land use analysis, household surveys conducted in
1989 and 1992, deliberations held with villagers, and field observations. Accordingly, areas under forests and grazing lands
were found being depleted at relatively high rates between 1957 and 1978 due mainly to the government policy of increasing
national revenue by expansion of agricultural lands, nationalization of forests, steadily growing population, and dwindling
household economy. Despite the steady growth of population, this process had remarkably slackened since 1978, owing primarily
to remaining forests being located in very, steep slopes and implementation of the community forestry program. Forests with
relatively sparase tree density, however, and grazing lands in the vicinity of settlements have been undergoing degradation
due to fuelwood and fodder collection and livestock grazing. In many instances, this is aggravated by weak resource management
institutions. Being particularly aware of the economic implication of land degradation, farmers have adopted assorted land
management practices. Still a substantial proportion ofbari lands in the hill slopes is vulnerable to accelerating degradation, as the arable cropping system is being practiced there
as well. The perpetuation of the local subsistence economy is certain to lead, to a further deterioration of the socioeconomic
and environmental conditions of watersheds. To facilitate environmental conservation and ecorestructuring for sustainable
development, a broad watershed management strategy is outlined with focus on alleviating pressure on natural resources. 相似文献
353.
Karl H.E. Kroemer 《Journal of Safety Research》1983,14(3):131-136
Body dimensions are main determiners of equipment dimensions. Design for the “average user” is not suitable. Selected percentile values at the lower and upper extremes of the variable distribution determine minimum and maximum equipment dimensions or adjustment ranges. Interactions among design variables must be considered. This paper applies this rationale to the determination of major equipment dimensions of video display terminal (VDT) workstations. While the approach is generally usable, the specific data describing the U.S. population used in this paper indicate design ranges appropriate for North America. Since American body dimensions are quite comparable to most European data, the equipment dimensions should also be suitable for use in Europe. 相似文献
354.
Karl Herrmann 《Die Naturwissenschaften》1958,45(5):111-112
355.
The present study was conducted to determine the effects of airborne herbicides on the photosynthesis and growth of non-target plants. Sunflowers at different growth stages were used as test plants and exposed for 24 h in a wind tunnel to a range of concentrations of bromoxynil-octanoate and metribuzin. The quantum yield (phiPSII) and the dry weight were used as response parameters. Results indicate that young sunflower plants are affected by sublethal concentrations of both herbicides, whereas metribuzin proved to be more phytotoxic. Bromoxynil-octanoate and metribuzin concentrations > 0.265 and >0.135 microg/m(3) impair the photosynthetic activity of exposed leaves and concentrations >0.780 and >0.641 microg/m(3) of leaves developed after exposure. Effects on dry weight indicate that younger plants were more susceptible, whereby the response to metribuzin proved to be more dependent on growth stage. Based on these results and considering herbicide concentrations in ambient air, there is a reasonable probability that non-target plants are temporarily at risk of being affected. 相似文献
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