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51.
This study documents the effects of power utility right-of-way construction and maintenance on the vegetation of a wooded wetland in North Reading, Massachusetts, USA. Neither activity had a substantial, long-term negative impact. Except for differences in size and maturity, the vegetation recovered in two years from nearly total destruction caused by construction. Maintenance that included the periodic removal of high-growing species led to the formation of a plant association different from the one occurring naturally, but as diverse and species rich. 相似文献
52.
Disturbance of natural vegetation by camping: Experimental applications of low-level stress 总被引:3,自引:0,他引:3
David N. Cole 《Environmental management》1995,19(3):405-416
Previously undisturbed sites in four different vegetation types were camped on for one night and for four nights. Changes
in vegetation cover and vegetation height were measured after camping and one year later. Results are presented separately
for different campsite zones—parts of the site where campers slept, cooked meals, and stored their packs. Just one night of
camping was sufficient to cause evident impact in all four vegetation types, although the amount of impact varied significantly
between zones and between vegetation types. Vegetation impact on campsites used four nights was generally less than twice
as severe as impact on the sites used one night. The effects of camping on vegetation were also predicted for 12 other vegetation
types on the basis of vegetational responses to experimental trampling. These results suggest that impact can almost always
be minimized by confining camping to a small number of campsites instead of dispersing use across many campsites. 相似文献
53.
54.
Impacts after four years of experimental trampling on alpine/sub-alpine environments in western Tasmania 总被引:2,自引:0,他引:2
Experimental trials were undertaken over four years to assess the impact of recreational trampling in undisturbed alpine and sub-alpine vegetation communities in the Western Arthur Range, western Tasmania. Data on 'pad' formation due to human trampling were collected using vegetation cover assessments, biomass estimates and detailed cross-sectional surface profiles. In sub-alpine buttongrass and alpine herbfield, prolonged and sustained damage may occur after 100 passes by walkers. The environmental threshold of the flat alpine herbfield site was breached after 200 passes. Plant morphology was one determinant of resistance and resilience, with upright woody shrubs and tall tussock graminoids most vulnerable to sustained trampling damage. Cushions are susceptible to trampling impacts at 500 passes. Loss of vegetation cover peaks 6-12 months after trampling. Our results show that pads formed with as few as 30-100 passes per annum and tracks form at between 100 and 500 passes per annum. Two years after the cessation of trampling, there is some small recovery in vegetation cover after 30 and 100 passes per annum applied for three years, but no evidence of recovery at the 500 pass treatments. The low trampling threshold and slow recovery rates in western Tasmania suggest that concentrating walkers on a minimal number of sites may be the best management option for these untracked alpine and sub-alpine environments. 相似文献
55.
武汉湖泊富营养化遥感调查与评价 总被引:27,自引:5,他引:22
利用武汉东湖各子湖多年可靠的地面监测资料和1999年9月Landsat-7的TM各波段的卫星遥感数据,建立了各子湖的营养状态指数与TMb5图像上的灰度值之间的线性关系模型,并运用该模型对武汉各湖泊进行富营养化评价。同时基于地面监测资料,用日本学者相崎守弘提出的修正富营养化指数法对武汉主要湖泊的富营养化程度进行评价。两种方法评价结果都显示,武汉大多数湖泊呈富营养化状态,一些湖泊已接近甚至达到极富营养化。在用两种方法同时评价的十个湖泊中,有四个湖泊的评价结果完全一致,其余的六个湖泊富营养化程度只相差一个级别。两种方法评价结果存在差异,可能有以下三个原因;(1)遥感方法反映了是图像所在时段的某一个区域上的平均值,营养化指数法反映的是若干个采样站的年平均值;(2)TM图像的获取时间比地面监测的时间晚;(3)遥感影像可能受到云、泥沙等悬浮物、高等水生植物以及湖泊水深等的影响。遥感评价结果与地面监测结果基本一致,利用遥感进行湖泊水体富营养化监测价是可行的,有效的,利用该方法可进行大范围的湖泊富营养化调查评价。 相似文献
56.
上海潜在滨海旅游资源调查及开发研究 总被引:1,自引:0,他引:1
上海市的海岸线蜿蜒460km,涉及5区1县,潜在滨海旅游资源亟待开发。为了更好地了解和掌握潜在上海滨海旅游资源的现状,结合上海独特的自然禀赋和社会经济条件,参照《旅游资源分类、调查与评价(国家标准)》(GB/T18972-2003),在对上海潜在滨海旅游资源普查的基础上,研究了上海潜在滨海旅游资源分类,分析了潜在滨海旅游资源特征和资源富集区状况,选划出上海应重点开发的6大潜在滨海旅游资源区,并分别就各资源区的开发对策与建议提出初步构想。 相似文献
57.
58.
Harald Sverdrup Salim Belyazid Bengt Nihlgård Lars Ericson 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):163-179
The ForSAFE model, designed for modelling biogeochemical cycles (water, acidity, base cation, nitrogen and carbon) in terrestrial
ecosystems, was modified with a vegetation response module (VEG), incorporating the effects of: nitrogen pollution, acidification,
soil moisture, temperature, wind chill exposure, light and shading by trees, grazing by animals, competition between plants,
above ground for light and below ground for water and nutrients. The model calculates the response of number ground vegetation
plant groups. The integrated model was tested and validated at integrated level II forest monitoring sites across Sweden,
four have been shown here, and used to assess the effect of acidification and nitrogen pollution in relation to factors such
as climate change, forest management and changing grazing pressure. The response functions have been derived from single-factor
experiments and integrated through the model structure for use on whole systems. The tests with the model suggest that the
ground vegetation composition is reasonably well predicted, that much research remains before the model is fully tested and
operational, and that the model may serve as a tool for assessing impacts of climate change, acid rain and forest management
on plant biodiversity in forested areas. 相似文献
59.
首都大学生的自然灾害认知调查与减灾教育建议 总被引:11,自引:4,他引:11
2006年国际减灾日的主题是"减灾始于学校",了解学生的灾害认知水平有助于减灾教育工作的有效开展。以北京5所高校的大学生为调查对象,通过问卷方式调查大学生对自然灾害的关注程度、防灾意识、灾害理论知识、应急行为知识以及对减灾教育的看法。问卷统计结果表明:大学生总体的灾害认知水平较低,现行减灾教育方式和内容与学生的期望有较大偏差。在此基础上,提出了减灾教育内容要将学生"该知道的"与"想知道的"相结合,通过演练演习等方式提高学生的防灾应急实际技能等减灾教育建议。 相似文献
60.