Presenter note: This presentation is part of a unit designed to help the class investigate trees and the way they work.

Transcription

1 Title slide - The secret life of trees Presenter note: This presentation is part of a unit designed to help the class investigate trees and the way they work. Today we are going to investigate the secret life of trees. Not only are trees the longest living organisms on Earth but they help to purify the air we breath and are essential for our lives. They re all around us and help us do lots of things everyday. 1

2 All looks serene and tranquil on the surface but inside each tree, there s so much going on. All the time, trees are a hive of activity. 2

3 Ask the class: If you stand and stare at a tree, what can you see going on? Well, not an awful lot at first glance but let s look a little bit harder. Let s look at what s happening in different parts of a tree. Photo: Tree in Hackfall, near Masham copyright Woodland Trust 3

4 Well, not an awful lot at first glance but let s look a little bit harder. Let s look at what s happening in different parts of a tree. Photo: Trees copyright Woodland Trust 4

5 There are thousands of leaves on a tree but what are they all doing? What are leaves for? Ask the class: Any ideas? 5

6 There s lots going on in leaves. The main thing is making food for the rest of the tree. Each leaf is like a mini food factory! How does it work? The Sun s warmth and light is trapped in the leaf (by a green chemical called chlorophyll). This energy is used to combine carbon dioxide from the air and water to make yummy tree food of sugars and starches. This process is called photosynthesis. The most essential components of this process include direct sunlight, water, carbon dioxide and chlorophyll. Water + Carbon Dioxide + Light Energy -> Glucose + Oxygen. There are chemicals produced by the process that trees don t need. They are moisture (water) and oxygen (the gas we need to breath lucky us!). Each leaf releases these into the atmosphere. 6

7 Ask the class: What s all this food being made for? The food helps the tree to grow new wood in it s trunk (called cambium) and some is stored for later. How does the food get to the rest of the tree? 7

8 How does the food get to the rest of the tree? The inner bark (called the phloem pronounced flow-em ) carries the food made in the leaves to other parts of the tree just like trucks on a motorway going down the tree. The trunk supports the tree and helps to stop it falling over. When the transport cells get old, they fill with a hard chemical. They are called heartwood. They re no longer alive but help to provide strength in high winds and storms. They re like scaffolding inside the tree. 8

9 Where does the tree keep any spare food? 9

10 The motorways (phloem) take spare food to be stored, for example, in big fat roots. They re just like warehouses. Ask the class: Why do you think spare food is needed? The food is stored until it s needed, for example in hot dry conditions when the tree can t make as much new food. Advanced question: Why can t the tree make as much food in hot dry conditions? The big fat roots also help to keep the tree from falling over, the same as the trunk. They are the foundations of a tree and like anchors. 10

11 There is a massive network of tiny roots too that mine their way through the soil. Ask the class: Any ideas what these do? 11

12 The tiny roots or root hairs sup up water and nutrients from the soil. They re just like thousands of drinking straws. There s lots and lots of tiny ones to give the tree a better chance of getting more out of the soil. Advanced question: Why would having lots of tiny root hairs rather than a few really big roots help the tree to get more water and nutrients? Having lots of small root hairs provides a greater surface area through which to absorb nutrients and a greater area of soil the roots can penetrate and be in contact with. The water and nutrients help the tree to make new food and live. They are transported around the tree and to the leaf factories by another motorway system called the xylem. 12

13 Each tree has its own bark, just like we have fingerprints but it s not just pretty, bark does a serious job! Ask the class: Does anyone have any ideas about what the bark does for a tree? 13

14 The bark is just like a security team for the tree. It fights off intruders with bark security. The bark protects the tree from insects, mammals, diseases, bad weather and injuries. 14

15 All trees have flowers or cones. These make seeds or fruits or nuts that have seeds inside them. 15

16 The seeds or fruits or nuts that have seeds inside them help make new trees. They re just like a hospital maternity ward. The flowers or cones on a tree are pollinated, for example by busy bees. They then make seeds which contain everything needed to make a new tree. Seeds are sometimes hidden inside a nut or fruit to keep them safe and to help them get from a branch to a new place to grow. Ask the class: How many different types of tree nuts and seeds can we think of? We even eat some of them! 16

17 Let s look at the whole tree there s lots happening! Review the parts of a tree: Leaves like food factories Inside the trunk like motorways and scaffolding Big, fat roots like food warehouses and anchors Tiny root hairs like drinking straws Bark like the security team Flowers, fruits, nuts and seeds like a hospital maternity ward Presenter note: At this point, hand out the tree diagram for pupils to label each part of the tree. 17

18 Exit title slide the secret life of trees. Now it s time to investigate the secret life of trees. Presenter note: See teachers notes for ideas for investigations indoors and outdoors. 18

19 The secret life of trees This resource has been developed by the Woodland Trust and is free for educational use. Acknowledgements Thank you to the Heritage Lottery Fund, Hackfall Trust, Nidderdale Aarea of Outstanding Natural Beauty. Resources designed and developed by Kate Measures Consulting at 19