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271.
272.
Managing Urban Trees and Their Soil Envelopes in a Contiguously Developed City Environment 总被引:7,自引:0,他引:7
Jim CY 《Environmental management》2001,28(6):819-832
Urban Hong Kong is covered by high building, road, and population densities. Its urban morphology is inherently not conducive
to extensive or high-grade greening. Recent renewal of old areas has squeezed out some limited interstitial plantable space,
although in new development areas modest spaces have been earmarked for greenery. The study aims at evaluating the major constraints
to urban trees and their companion urban soil envelopes and at providing specific recommendations to improve tree management
in the city. The analysis covers the above-ground confinements that dampen tree performance, the less tangible but rather
difficult institutional restrictions that impose a somewhat unnecessary lid on tree planting, the multiplicity of players
and stakeholders involved in urban-tree management that militates against coordination and cooperation, the widespread occupation
of underground space by utility lines often to the exclusion of trees, and the extremely poor quality of urban soils that
are often used without amelioration to support tree growth. The management recommendations furnish practical suggestions and
hints to improve the short- and long-term welfare of trees in terms of quality, quantity, and spatial distribution. The conclusion
enumerates some concrete measures for consideration by decision-makers to upgrade the city's greenery to close the gap between
science and policy. 相似文献
273.
The presence of Whitethroats and their potential invertebrate prey in farmland trees and shrubs was investigated. The management of this vegetation by farmers, and their motivation for that management, was explored using participatory techniques. Whitethroats were associated with Guiera senegalensis, the shrub species which supports most caterpillars and spiders. Farmers reported declines in trees and shrubs since the 1950s, loss of fallow areas, declines in soil fertility and crop yields, and increases in the use of fire for clearing fields. Trees are valued by people for their cultural and medicinal uses and some species used by Whitethroats and other birds have potential for restoring soil fertility, although this was not recognised by farmers. More sustainable use of savanna farmland could have both agronomic and wider conservation benefits, and the provision of information that accommodates farmers' cultural and economic incentives could benefit both farmers and wildlife. 相似文献
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276.
The structure of the crown and branching; the growth, development, and ontogeny of branches; and organogenesis and growth of female shoots in the model Siberian stone pine trees were studied in four types of habitats at the timberline in the central Altai Mountains (1700–2170 m a.s.l.). The results provided evidence that the ecological forms of trees appear due to changes in the pattern of branching as well as to the decreased rate of vegetative (primarily apical) growth. The diameter of the shoot pith is one of the most variable characters reflecting the deterioration of environmental conditions at higher elevations. 相似文献
277.
E. A. Platonova 《Russian Journal of Ecology》2001,32(6):375-381
The distribution of tree species in the landscape was studied using the approach based on the comparison of the ecological requirements of species and the properties of ecotopes distinguished by their position in the relief and peculiarities of basement rocks. The types and specificity of ecological regimes were determined for the typical ecotopes of the southern Karelian ridge landscape. The main environmental and successional factors determining the distribution of seven forest-forming tree species in the ecotopes of this landscape were identified. The results of this work can provide a basis for the prognosis of forest vegetation in the landscape studied. 相似文献
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模糊故障树分析及其应用研究 总被引:15,自引:1,他引:14
基于某些实际情况下系统故障发生概率具有模糊性和不确定性的特点 ,笔者将模糊集理论引入故障树分析并针对自动化立体仓库的故障特征 ,对立体仓库各个环节发生故障时所遇到的各种模糊信息进行了科学的、定量的处理。实例证明 ,该方法是行之有效的 ;它能解决传统故障树分析不能处理同时存在随机不确定性和模糊不确定性的故障事件的问题 相似文献
280.