Controlling effect of rising temperature by water content in leaves and form shrinkage of leaves in the heating experiments
2007
Iwasaki, T.(Nerima Urban Development Corp., Tokyo (Japan))
Controlling the effect of rising temperature in the water contained in leaves was performed by continuously measuring leaf temperature on the reverse side of the leaf at intervals of two seconds during the heating experiments. Time period to maintain nearly 100 degrees C or less at the reverse side of leaves for 17 species of trees was also shown as the water retention time. It was observed that trees such as Phyllostachys bambusoides, Viburnum awabuki, Hydrangea macrophylla, Camellia japonica spp., etc. had long water retention time, and Acer palmatum var. matumurae, Zelkova serrata, Mellotus japonicus, Prunus jamasakura, etc. had short water retention time. Moreover, the form shrinkage of leaves by heat was measured in relation to the heat interception effect of a leaf. As a result of the heating experiments for 55 species of trees, it was found that the rate of shrinkage of leaves varies from one species of trees to another. It was also found that there is a high positive correlation between the ratio of water content and rate of shrinkage. As a result, it was established that, within the limits of this experiments, evergreen needle-leaf trees demonstrated the smallest shrinkage rate. Evergreen broad-leaved trees such as Photinia glabra, Osmanthus fragrans var. aurantiacus, Pasania edulis, Hedera helix and Euonymus japonicus and deciduous broad-leaved trees such as Ulmus parvifolia, Acer buergerianum, Aphananthe aspera and Cercis chinensis also show smaller shrinkage rate. It is clear that the higher the ratio of form shrinkage, the higher the ratio of water content in the broadleaf trees, especially in deciduous broad-leaved trees. In addition, an opposite relationship can be seen between high water content ratio and the high durability of heat interception in a leaf.
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