Trees and climate (the lesson)
Trees depend on climate as every living creature does, but they also can adapt to change, and may be help prevent climate change.
The observed changes: 1/ narrower water-carrying vessels, 2/ shrinkage in the tissues 3/ blockages in water conducting vessels 4/ thinner leaves in some species.
1. Which of these are adaptations of the trees, and which are simply results of water shortage?. Explain.
2. Thinking of adapting: we say you adapt to the weather donning warmer clothes of carrying an umbrella. But we also say “an animal is adapted to its environment by having camouflage colours”. The word adaptation has a different meaning in those lines. What is the difference?
3. Which type of adaptation do the trees show? Explain.
4. In a moderate climate trees make narrower vessels in autumn. Is this also a way of adapting to water shortage? Explain.
5. In a moderate climate the spring and summer wood has wide vessels. How does the tree ‘know’ that it needs wide vessels?
6.Trees in tropical rainforests usually do not have annual rings. Explain why this was a reason to start this experiment.
7 Willows and poplars in the moderate climate zone usually have wide vessels (and no clear annual rings). Can you explain this thinking of the kind of places where they usually grow?
8. The trees in this experiment grew two years under a plastic cover. Does this mean they could nog get any water at all? The article does not mention the death of these trees, somehow they managed to get enough water to survive. How did they get enough water?
9. The article mentions the interaction between trees, but does not explain this. Which form of cooperation could have been used?
10. Read about the water cycle: http://sustainablefootprint.org/nl/-trees-and-the-water-cycle/
Not only in the tropics trees are important for the climate of the world. Deforestation helps warming up the climate. How does this work? It also stimulates desertification. How?
Where forest has disappearded (sometimes already centruries ago) people are now trying to restore the forest to improve the local climate. Why is it difficult to reforest such areas? What has to be done to make it possible?
12. The role of trees in the water cycle is much bigger than until recently thought. Read http://sustainablefootprint.org/nl/de-verrassende-rol-van-bomen-in-de-noordelijke-waterkringloop/
These trees take much water in spring before the leaves appear. Respiration through the leaves can not play a role yet. Which mechanisme in the roots can make it possible to take up much water so early in spring?
Trees in the city keep the temperature lower on hot summer days. How do they do that? Which other effect make trees in cities good for people?