The Study On Analysis Of Building Shadows And Selection Of Greening Plants In Wuhan

As buildings in cities are being more and more intensive and high, large areas of building shadow appear, changing the light condition and affecting the growth of plants significantly.Based on the delineation of fixed regions, lines and points for measuring, the relative light intensity in different orientations around three buildings are measured. And distribution of shadows around buildings in the spring equinox, summer solstice, autumnal equinox and winter solstice are simulated by Sketchup on the base of precision validation, the length and areas of the shadows at8:00,10:00,12:00,14:00and16:00are measured and calculated while the shading time and average shading time in different seasons around the three buildings are calculated. Also, the blossom quantities of several kinds of plants in the south and north of one building are got, at the same time, the light conditions in the north of buildings are simulated by field trials, then the difference in flower amounts, flower size and flower stalk height of three kinds of flowering plants in late winter and early spring are compared. All that done provide reference for the selection of greening plants, and the main results are as follows.(1) The shadows appear in the east, west and north of north-south constructions in Wuhan in the spring equinox, summer solstice, autumnal equinox and winter solstice. There is just a small area covered by the shadow in the summer solstice. The average length of the shadow in the spring equinox, summer solstice, autumnal equinox and winter solstice are being as long as7.3times the height of a building while it is only0.15times in the minimum. The average area of the shadow can be as large as15.32times the building’s basal area, while the minimum is only0.2times. The average shading time can be as long as6.27hours while the minimum is only0hour. The average relative light intensity is100percent at most and35percent at least.(2) The light conditions have a very significant impact on blossom quanties of Lagerstroemia indica,Yucca gloriosa, Impatiens balsamina, Zephyranthes Candida and Hibiscus mutabilis. Zephyranthes candida is suited to slight shading conditions,50to75percent of relative light intensity. Yucca gloriosa has a certain shade tolerance and can grow well in conditions that relative light intensity is more than70percent. Impatiens balsamina, Lagerstroemia indica and Hibiscus mutabilis have a poor shade tolerance and they’re fit for conditions that the relative light intensity is more than80percent.(3) The artificial simulation test of light condition in the north of buildings show that if Viola tricolor and Calendula officinalis(both explode in early spring) are planted in the range of0.75times the height of the building from the foot of a wall in the north (the relative light intensity is less than60percent), their flower amounts and flower size will decrease significantly while flower stalk height will increase, the ornamental reducing. In a word, both of them are not suited to the north of buildings. And if Petunia hybrida is planted in the range of0.75times the height of the building in the north of buildings, the folwer quantities will decrease significantly while its flower size and flower stalk height will decrease a little. So that it can be planted in the north of buildings and had better be far from the buildings.(4) The area around buildings in Wuhan can be devide into4block, the light condition in the same block has little difference, but in different block is very different. At last, we summarized plants can be growed in each block.