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851.
J. Mistry 《Journal of environmental management》1998,54(4):321-334
Today, fire in the Braziliancerrado(savanna) is predominantly caused by farmers. They use fire during the dry season to promote fresh grass regrowth in pastures for their cattle and to clear areas of planting ready for cultivation in the wet season. This study researched fire use by farmers in thecerradoof the Distrito Federal, central Brazil, in order to investigate what influences their fire management decision-making. The results show that the two main factors limiting the choice of feasible options for farmers to meet their objectives are income and time. However, perceptions also play a major role in the decision-making process, and for many farmers this alone determines whether fire is used. Various fire practices involved with timing, frequency and size, as well as precautions taken before and during the burn, and the factors influencing these decisions are presented. This study shows that it is vital to understand factors determining fire use if effective fire management plans and policies are to be developed.1998 Academic Press 相似文献
852.
853.
Victor Mashinsky 《Journal of Environmental Planning and Management》1990,33(2):91-100
Contemporary urban planning is characterised by the following: (a) a large amount of specific research gives a large quantity of facts, but like stones of the mosaic do hot make an entire picture; (b) in the basis of these researches no one finds entire creative conceptions; (c) the theories lose touch with practical design matter; (d) in contradiction to the classical architectural epoch, urban planning loses touch with the construction of buildings; (e) the practice of urban planning and the construction of buildings lose touch with historical traditions. The corollary of these academic and unnatural specialisations is a break not only from “the tie of times” but also from the ties inside the profession. This situation has an effect on the practice of urban planning and architecture; society returns to destructive criticism. It is impossible to get away from this fact. The author makes an attempt to change this situation for the better — at least in some measures. On the basis of many years study of the results of research this paper presents a concept of contemporary urban planning. This concept is not in the form of hard recommendations, but expedient methods for the solution of problems. It is proved by the author's projects. 相似文献
854.
Summary. Workers of the amblyoponine species Mystrium rogeri employ trail communication during recruitment to food sources and new nest sites. The trail pheromone originates from a hitherto
unknown sternal gland located in the 7th abdominal sternite. The recruiting ant deposits the gland secretions by a special
gaster-dragging behavior. The recruitment behavior can be complemented by a rapid vertical body shaking performed by some
recruiting ants inside the nest. M. rogeri workers possess a large pygidial gland, the secretion of which elicits a repellent response in other ant species.
Received 25 May 1998; accepted 15 June 1998. 相似文献
855.
Woodpigeon damage to spring cabbage on two farms in different years was greatly reduced when a large kite was flown over the fields. Protection continued for over 3 months with no sign of habituation to the kite by pigeons. Woodpigeons avoided flying or settling within 250 m of the kite. Damage in fields with a gas banger exceeded that in fields with a kite, especially in severe winter weather. “Humming line” proved ineffectual in reducing damage. On these lowland farms it was necessary to launch the kite on most mornings, but if such launching can be carried out, kites can be effective in reducing damage by woodpigeons. 相似文献
856.
C.A. Davos 《Journal of environmental management》1998,52(4):379-387
Coastal-zone sustainability policies are socially constructed. It follows that their effective implementation depends on the sustainable voluntary co-operation of stakeholders with competing interests and priorities. No form of integrated coastal-zone management can nurture such co-operation as long as the objective is to determine ‘best’ policies, derived by expert-based rational analysis, instead of seeking to identify ‘correct’ policies, ones that can draw the maximum possible stakeholder support. The latter task requires a co-operative coastal-zone management that incorporates the relevant public discourse into the policy formation process in a direct, proactive and conflict minimizing manner. Towards this end, four major challenges are examined for maximizing the stakeholders' motivation for voluntary co-operation: (1) optimism about the level of optimism; (2) agenda setting; (3) value discourse; and (4) information and empowerment. 相似文献
857.
R.B. Grayson C. Kenyon B.L. Finlayson C.J. Gippel 《Journal of environmental management》1998,52(4):361-372
In this study, an analysis of bathymetric surveys of the Latrobe River delta conducted in 1879 and 1992 is combined with pollen analysis of cores from the delta sediments to assist in setting management priorities for the Latrobe River catchment, a 5000 km2catchment in the south-east of Australia. Reconstructed delta surfaces from 1879 (not long after European settlement of the area) and 1992 were compared to quantify areas of net erosion and deposition. These were compared to post-European deposition depths determined by the presence of exotic pollen species in the sediment. The results indicated that: (1) average sedimentation rates in the receiving lake for the Latrobe River are less than 1 mm yr−1; (2) the deposited material is fine with no material considered as bedload; and (3) the fine nature of the deposited material makes it suitable for carrying a large load of nutrients. These results created a shift in management focus from concern over sedimentation and erosion in general to a greater emphasis on nutrients. While the integrated management of catchments is implicitly contemporary, it should always be performed within a historical context. Failure to do this can lead to management priorities that do not concur with the facts of catchment response and can therefore result in inefficient resource allocation. The use of studies which provide a historical perspective on the problem are therefore critical. 相似文献
858.
矿物包裹体研究表明,武义萤石矿床是含矿地热水活动的产物。其形成温度为130°±27℃,压力为47.23-426.96×10~5帕。属于低温浅成热液矿床。冷渗流大气降水在深处受地热影响加热活化,发生水—岩化学反应和物质交换,导致含矿地热水的形成。它在构造作用和热力及压力梯度驱动下回返上升,于地表—近地表裂隙带与大气降水混合,温压骤降,加以冷的含CO_2和O_2的大气降水界入,使成矿物质自溶液中沉淀析出。 相似文献
859.
860.
以武汉市某住宅的智能化系统设计为实例,从需求分析、投资额度、系统选择、设备配置等方面对楼宇对讲系统、视频监控系统、机房工程、电子围栏系统、弱电管网等进行了论述,并就施工中出现的问题进行了说明,以期为类似工程项目提供参考。 相似文献