Our Abstract

PLC Sydney, PLC Armidale and The Armidale School have taken part in a science pilot
program called the SMART Tree Project. The schools each have a solar powered SAP flow
meter on a tree in their school. These meters measure plant water use, (sap flow). This data
can then be analysed with reference to data obtained on temperature, sunlight, humidity
and wind direction. PLC Sydney has the sap flow meter on a lemon scented gum (Corymbia
citriodara). PLC Armidale has 2 trees with sap flow meters, a Ribbon Gum Tree (Eucalyptus
viminalis) and the introduced, deciduous Poplar (Populus trichocarpa)The Armidale School
monitors Eucalyptus stellulata.

The schools collaborate by sharing data from each of the meters on the trees. Over twelve
months of data have been collected. The sap flow meters use the heat ratio method (HRM)
of measuring the sap flow in xylem tissue. This uses a short pulse of heat as a tracer. By
measuring the rate of heat transferred to two symmetrically placed temperature sensors the
magnitude and direction of water flow can be detected.

PLC Sydney also has an automated weather station which measures wind speed, wind
direction, air temperature, humidity and atmospheric pressure. Last year during a week of
prolonged bushfires, the students analysed the data to determine whether higher pollution,
wind speed and temperature had caused a decrease in sap flow; the sap flow in fact
increased.

PLC Armidale has compared the sap flow in Summer and Winter of the deciduous and
native trees. They have noted a significant decrease in sap flow after an extended drought
period. In addition they have noted that the trees reduce sap flow prior to an extreme
temperature day reduced.

This research could provide data when considering issues such as climate change, drought
policy and natural science management. Presbyterian Ladies’ College Sydney would like to
present their findings at the 10th International Student Science Conference.

At PLC Sydney + Who are we?

Our school is very interested in the SMART Tree Project, and as a side project of our own, we are building a model of the lemon scented gum in our own school library. The junior school will be adding the external structure of the tree and the life found in and around the tree and the senior school will be adding the internal structure, cells xylem phloem and cambium layers. The tree will be built from the ground floor of the library to the second floor.

Currently, we have the scaffold of the tree, some floating oxygen molecules, and various decorations made by Science classes in both the junior and senior schools. Here is a photo of how it looks so far:

We also took some photos to introduce you to the lemon scented gum located in the PLC gardens, which we are using to conduct the SMART Tree Project, and the solar panel which provides the sap flow meter with electricity.

And this is the weather station at our school which collects the other data such as temperature, wind speed and humidity. The weather station is located on the roof of our Performing Arts Centre and it sends radio wave signals to the Macindoe Research Centre (our school library) so that the data may be processed.

And who are we? We are five PLC Sydney Year 10 students who are partaking in the SMART Tree Project which we shall be presenting at the 10th International Student Science Conference later this year at Nankai Highschool in Tianjin in China, accompanied by our Principal, Dr Paul Burgis, a member of the Science staff, Ms Hendricks, and some performers. From left to right, our names are Natalie Teh, Jingtong (Averlie) Wang, Catherine (Katie) Taylor, Emma Carnuccio and Hayley Ng.

Introduction to the SMART Tree Project

Hello everyone,

Welcome to the official blog for the SMART Tree Project. PLC Sydney is participating in a scientific program titled the SMART Tree Project, which involves using a solar powered sap flow meter to measure plant water use, the rising and falling levels of sap flow within a tree on the school grounds. This data lets us analyse it with reference to data obtained on temperature, sunlight, humidity and wind direction; that we collect from the automated weather station at our school. We will use it to investigate the different relationships that sap flow has with each of them. Our school has the sap flow meter installed on a lemon scented gum tree Corymbia citriodara which was planted by our first principal Dr. Marden in approximately 1918.

What is sap?
Sap is the fluid, consisting mainly of water with dissolved sugars and mineral salts, which is found circulating through the vascular system of plants carried by xylem cells.

What is sap flow?

Sap flow is the movement of sap through the plant. It is triggered by heat and light which leads to photosynthesis and transpiration and these two processes cause sap to move inside the plant.

How does the sap flow meter work?
The sap flow meter is an Australian invention which is electrically powered by a solar panel located near the near the tree. The meter takes readings every hour and transmits radio signals to receivers located on the roof of our school library. The data is then further transmitted to the science staff where it can be interpreted and analysed.

Every student in years 7 to 10 is graphing ‘sap flow vs temperature’ and ‘sap flow vs humidity’ for their respective birthdays. This allows us to begin to hypothesise what the relationships between sap flow and these natural phenomenons could be.

For example, take a look at these graphs for the 13th of March in 2013:

From looking at graphs such as these, we hypothesise that as humidity decreases, sap flow increases, and as temperature increases, sap flow also increases. We look forward to obtaining more data and creating more graphs so that we can further analyse our results and test our hypotheses.