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Patterns of tree buttressing at Lawachara National Park, Bangladesh
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作者 Md. A bu Hanifa Mehedi Chandan Kundu Md. Qumruzzaman Chowdhury 《Journal of Forestry Research》 SCIE CAS CSCD 2012年第3期461-466,共6页
We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park, Bangladesh. Forty-five percent of trees of these 11 species had buttresses. Artocarpus chaplasha Roxb. show... We describe patterns of buttress formation and development in eleven tree species at Lawachara National Park, Bangladesh. Forty-five percent of trees of these 11 species had buttresses. Artocarpus chaplasha Roxb. showed maximum (87%) buttress formation, whereas Alstonia scholaris (L.) R. Br. did not show any buttress. Buttresses were recorded in 20%-40% of trees of six species and 40%-60% of trees in three species. Mean length and height of buttress varied among the species and ranged from 0.37-4.37 m and 0.71-2.13 m, respectively. Buttress height, mean buttress length, total buttress length, and total length plus length of secondaries increased with DBH (diameter at breast height) and tree height. Buttress number did not increase with DBH or tree height. Under-storey and mid-canopy trees produced less developed buttresses than did emergent trees (p〈0.01). Wood density showed moderate effects on buttress characters (p〈0.05), while the slope of the land did not. Canopy category was a primary regulating factor for tree buttressing, suggesting that buttresses are mechanical adaptations of trees to counter physical stresses. 展开更多
关键词 buttresses tree architecture canopy category slope of the ground wood density
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土地扩张对城市边界层风热环境影响的模拟研究——以沈阳市为例 被引量:8
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作者 沈历都 龚强 +3 位作者 徐红 王涛 顾正强 马雁军 《气象与环境学报》 2018年第6期64-74,共11页
利用WRF模式中的UCM+AH城市冠层方案,以2005年8月两个晴天为天气背景,对比研究了1993年与2005年不同下垫面情况下,沈阳市城市扩张对近地层风热环境及边界层的影响。结果表明:UCM+AH方案能够较合理准确地模拟出城市范围的2 m气温与10 m... 利用WRF模式中的UCM+AH城市冠层方案,以2005年8月两个晴天为天气背景,对比研究了1993年与2005年不同下垫面情况下,沈阳市城市扩张对近地层风热环境及边界层的影响。结果表明:UCM+AH方案能够较合理准确地模拟出城市范围的2 m气温与10 m风速的日变化特征,且对2 m气温的模拟效果要优于10 m风速;模拟2 m气温的日较差偏大,模拟10 m风速系统性偏高0.5—1.0 m·s-1;城市土地扩张后,城区普遍增温,且夜间增温幅度较大,扩建城区夜间最大增温能达到7℃,老城区在夜间增温幅度最大可达3℃,上风向增温幅度较大;城区日间增温不明显,在0—1℃;城市土地扩张后,老城区风速普遍减小,但减小值<1 m·s-1;扩建城区风速减小近1 m·s-1,城区内可能出现的高温辐合中心对周围近地层风速有加速作用;城市扩张对边界层最显著的影响体现在午后,城区的扩张增大了湍流动能的影响范围,湍流动能在数值上增加0.2—0.3 m2·s-2;扩建城区上空的边界层高度在14时抬升100—200 m,且下风向边界层内部的局地环流与垂直上升运动增强。 展开更多
关键词 城市扩张 城市冠层模型 土地利用类型 WRF模式
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