Trees fall ill when lacking water. Their temperature would also rise when lacking water.Besides, temperature in different part of the tree is different.
The change of temperature of leaves is the most obvious.
During the daytime, the leaves mainly adjust temperature by transpiration. When there is enough water in the earth, the effect of transpiration is prominent. When there is not enough water, the leaves would close their pores under the sunlight. In this way, the transpiration is decreased and the temperature of the leaves rises.
The temperature of the sick trees would rise like that of men.When people get ill, their temperature rise at night and the fever is reduced in the morning.
However, this is quite contrary to the trees, whose temperature is highest in the morning.
According to the situation of the trees’ fever, the forest rangers could judge out which area of the forest is sick and take effective measures to cure them.
2. When do trees usually have most badly fever? ( )
A. in the morning B. at noon C. at night