| 摘要: |
| [目的]模拟林内光气候状况,探讨防护林林下的遮荫胁地效应.[方法]在精确计算实验区太阳视运动轨迹的基础上,采用椭球体模型,用光量子计测量了36个试验点的太阳辐射强度值,并统计了林下太阳辐射强度的日分布.建立了毛白杨树冠投影模型,模拟了树荫的年内投影变化以及林下光气候状况.[结果]试验区树荫运动轨迹呈蝶形弧带变化,树高影响投影外弧线位置,枝下高影响投影内弧线位置;在树体东、西侧1倍树高、北侧0.6倍树高范嗣内,透光率小于90%,在该区域发生林木遮荫胁地效应,距树底点较近区域的胁地效应较强.遮荫面积在树体东、西侧最大,南侧最小.[结论]在北回归线以北地区,防护林带应尽量以东西走向成行种植,南北成行种植时,树底点与农作物应相隔一定距离,以减小胁地效应;对现存的防护林带,应及时、适当地修剪防护林带的下部枝条,减少遮荫胁地面积. |
| 关键词: 防护林 毛白杨 树荫轨迹 辐射分布 动态仿真 |
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| 基金项目:“十一五”国家科技支撑计划项目（2006BAD03A03）；北京林业大学研究生基金项目(06JJ024) |
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| Dynamic emulation of the effects from individual tree to lower solar radiation distribution |
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| Abstract: |
| 【Objective】 The study was to simulate the condition of light climate and research the function that umbrage hazard in shelter forest. 【Method】 Based on the calculation of apparent trajectory of solar motion in the experimental area,and using quote ellipsoid distribution and the Monsi model,the radiation values of 36 experimental sites by light quantum mater were measured and statistics of daily solar radiation distribution from the values were calculated.Then the crown projection model was built,and the light climate condition in forest was simulated.【Result】 The trajectory of umbrage motion shaped a butterfly arc belt.The situations of outside and inner arc belt were influenced by height of tree (H) and the height below branch respectively.In the area of 1.0×H(in east and west of tree) and 0.6 ×H(in north of tree),transmittancy was below 90%,which meant umbrage hazard effect happened in this area.Additionally,the effect was stronger at bottom of the tree.The umbrage hazard area in the east and west of the tree was biggest,and smallest in the south.【Conclusion】 The shelter forest should be planted as much as possible toward east west,and keep a certain distance between crops and forest when the shelter forest is north-south direction.Therefore,the umbrage hazard will be decreased in the north to the tropic of cancer.Cutting out the below branches of the existing shelter forest suitably and timely can reduce the area of umbrage. |
| Key words: protection forest Populus tomentosa Carr. variation of umbrage solar radiation distribution dynamic emulation |
