Green study on uprooted tree
• TO FIND out more about the "greenhouse effect" and the importance of natural vegetation, a group of junior college students uprooted a rambutan tree last Thursday. They then spent the next 48 hours taking turns measuring the rate at which the 3-m tall tree absorbed water and lost it through its leaves.
The Raffles Junior College students will present their findings at a three-day pre-university seminar on the environment this week.
The seminar is jointly organized by RJC and the Education Ministry to commemorate Earth Day, which falls on Thursday.
Mr Chan Ter Yue, 27, who teaches biology at RJC, said the experiment has been done several times before in Britain, but this is possibly the first time it is being done in the tropics.
The tree was uprooted and placed in water in a tank. The students then took turns adding water every two hours to enable them to record how quickly water was being absorbed. They also recorded the temperature and relative humidity at regular intervals.
The transpired water vapour — which evaporates through the leaves — contributes significantly to cloud formation, which cools the environment and allows the water to fall back to earth as rain elsewhere.
Mr Chan said: "The experiment will show that if one tree alone can evaporate so much water, what about a whole forest of trees?"
Source : The Straits Times, April 21, 1992
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