Trees create microclimate under their crowns in comparison to the outside ambient atmospheric temperature. Sun is the pivotal source of radiant energy reaching the earth atmosphere of which heat is more important than...Trees create microclimate under their crowns in comparison to the outside ambient atmospheric temperature. Sun is the pivotal source of radiant energy reaching the earth atmosphere of which heat is more important than light. The radiant energy reaches the ground without any barricade whereas the tree crown impedes it in reaching the earth’s surface. During the day, when insolation impinges on tree crown, a portion of it is reflected back to the space, other portion is absorbed by the canopy increasing the temperature of leaves and the remaining part reaches the ground penetrating through the crown. Thus, a significant coolness is experienced under the shade of trees in comparison to open sunshine, with qualitative variations. The cooling produced by trees under their shades varies with species to species due to variation in several anatomical, structural and physiological attributes of the species. Climate is changing more rapidly prominently due to human activities especially indiscriminate felling of trees and it is feared that it will create problems on availability of energy, water and food security. Economic value takes over ecological benefits in selection of species in plantation programmes and this might have been due to the lack of scientific data about varying effectiveness of ecological services bestowed by different species. In the present study, an endeavor has been made to understand as to how a tree is integrated to the effects on atmosphere and responses to changing conditions with respect to differential cooling produced by five selected forestry tree species belonging to different categories. Analysis of data has come out with gradation of the sample species in respect to their cooling effect in the atmosphere in terms of yearly, quarterly, monthly and diurnal basis.展开更多
Coffea cultivation with shade tree is used for improving soil health,increasing coffea production,sustaining agro ecology.The study was attended in two kebele,on 36 farmers’fields,at Gololcha district of East Arsi zo...Coffea cultivation with shade tree is used for improving soil health,increasing coffea production,sustaining agro ecology.The study was attended in two kebele,on 36 farmers’fields,at Gololcha district of East Arsi zone.The study was intended to assess the influence of coffea shade trees on farm lands versus mountainous area.Household interviews were used to get imperative separately,i.e.from old farmers,middle age farmers and young farmers.Significant difference value was observed between farm land and mountainous area coverage.Based on this respondents’idea,before 25-30 years;the‘condition of tree coverage at mountainous’area in Arsi Gololcha district was‘medium condition’but not normal that means as deforestation of mountainous area have been starting before 30 years’time;while the condition of tree coverage at farmland area also has been starting before 30 years’time.The third respondents’idea was interpreted with the real situation of the district,that it gave us a constructive inspiration on the role of coffea shade tree to enable the farm land to be taken as regular natural forest.The existing coffea shade trees are Cordia africana followed by Erythrina abyssinica and Acacia senegal.Farmers accounted 95%of coffea shade users and 4.6%without shade users.The respondents said that even if the rainfall intensity is increasing at farmland rather than mountainous area occasionally due to shade tree effect.On the contrary side,mountainous area exposed to deforestation since the farmers have been shifting to hilly side for their livelihood dependency.展开更多
为了探究行道树的微气候调节能力,以肇庆市城东新区部分城市主干道为研究对象,通过实地调查和观测,统计分析行道树株高、冠高、枝下高等生物学特性,研究其对温度、湿度、太阳辐射强度等微气候的调节作用。并进一步采用RayMan Pro 3.1计...为了探究行道树的微气候调节能力,以肇庆市城东新区部分城市主干道为研究对象,通过实地调查和观测,统计分析行道树株高、冠高、枝下高等生物学特性,研究其对温度、湿度、太阳辐射强度等微气候的调节作用。并进一步采用RayMan Pro 3.1计算出热舒适性指标,以此为依据评价热舒适性,分析行道树与热舒适性的相关性及其对行人热舒适性的影响。结果表明,从改善热舒适性的角度出发,树种间的生物学特性与树木遮荫能力和调节微气候能力密切相关。细叶榕、非洲楝、天桃木、小叶榄仁、菠萝蜜为调节微气候能力良好的树种,树体高大、树冠宽大浓密的行道树能更好发挥遮荫性能并调节道路空间微气候,有效提升行人的热舒适性水平。展开更多
文摘Trees create microclimate under their crowns in comparison to the outside ambient atmospheric temperature. Sun is the pivotal source of radiant energy reaching the earth atmosphere of which heat is more important than light. The radiant energy reaches the ground without any barricade whereas the tree crown impedes it in reaching the earth’s surface. During the day, when insolation impinges on tree crown, a portion of it is reflected back to the space, other portion is absorbed by the canopy increasing the temperature of leaves and the remaining part reaches the ground penetrating through the crown. Thus, a significant coolness is experienced under the shade of trees in comparison to open sunshine, with qualitative variations. The cooling produced by trees under their shades varies with species to species due to variation in several anatomical, structural and physiological attributes of the species. Climate is changing more rapidly prominently due to human activities especially indiscriminate felling of trees and it is feared that it will create problems on availability of energy, water and food security. Economic value takes over ecological benefits in selection of species in plantation programmes and this might have been due to the lack of scientific data about varying effectiveness of ecological services bestowed by different species. In the present study, an endeavor has been made to understand as to how a tree is integrated to the effects on atmosphere and responses to changing conditions with respect to differential cooling produced by five selected forestry tree species belonging to different categories. Analysis of data has come out with gradation of the sample species in respect to their cooling effect in the atmosphere in terms of yearly, quarterly, monthly and diurnal basis.
文摘Coffea cultivation with shade tree is used for improving soil health,increasing coffea production,sustaining agro ecology.The study was attended in two kebele,on 36 farmers’fields,at Gololcha district of East Arsi zone.The study was intended to assess the influence of coffea shade trees on farm lands versus mountainous area.Household interviews were used to get imperative separately,i.e.from old farmers,middle age farmers and young farmers.Significant difference value was observed between farm land and mountainous area coverage.Based on this respondents’idea,before 25-30 years;the‘condition of tree coverage at mountainous’area in Arsi Gololcha district was‘medium condition’but not normal that means as deforestation of mountainous area have been starting before 30 years’time;while the condition of tree coverage at farmland area also has been starting before 30 years’time.The third respondents’idea was interpreted with the real situation of the district,that it gave us a constructive inspiration on the role of coffea shade tree to enable the farm land to be taken as regular natural forest.The existing coffea shade trees are Cordia africana followed by Erythrina abyssinica and Acacia senegal.Farmers accounted 95%of coffea shade users and 4.6%without shade users.The respondents said that even if the rainfall intensity is increasing at farmland rather than mountainous area occasionally due to shade tree effect.On the contrary side,mountainous area exposed to deforestation since the farmers have been shifting to hilly side for their livelihood dependency.
文摘为了探究行道树的微气候调节能力,以肇庆市城东新区部分城市主干道为研究对象,通过实地调查和观测,统计分析行道树株高、冠高、枝下高等生物学特性,研究其对温度、湿度、太阳辐射强度等微气候的调节作用。并进一步采用RayMan Pro 3.1计算出热舒适性指标,以此为依据评价热舒适性,分析行道树与热舒适性的相关性及其对行人热舒适性的影响。结果表明,从改善热舒适性的角度出发,树种间的生物学特性与树木遮荫能力和调节微气候能力密切相关。细叶榕、非洲楝、天桃木、小叶榄仁、菠萝蜜为调节微气候能力良好的树种,树体高大、树冠宽大浓密的行道树能更好发挥遮荫性能并调节道路空间微气候,有效提升行人的热舒适性水平。
