1.4
Looking at leaf function from space
Did you know that?
It is possible to measure plant growth from space. It is done from satellites which measures the colour bands of light which are reflected from the plants: the plants "keep" some parts of the light by chlorophyll to convert into growth (the process of photosynthesis; see story 6.5).
That the Artic shows both greening and browning while most of the Arctic vegetation has not changed.
- Greening, means that Arctic vegetation is getting greener due to plant life thriving. This has been happening in the Arctic tundra more with increasing temperatures providing more hospitable climates for plants (such as shrubs) to grow.
- Browning is when plant growth declines or vegetation is damaged as a result of extreme warm events and fires (see story 5.1). Permafrost thaw can kill plants such as shrubs (see story 3.3). The death of many plants means that there is less vegetation to absorb carbon dioxide from the atmosphere speeding up the effects of climate change (stories 6.4 and 6.5).
- The large areas of vegetation that have not changed are to some extent because some plants have clones that live for thousands of years and have experienced many different weather extremes already.
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From a Leaf to a Forest
How can scientists measure how much carbon dioxide is absorbed by trees?
Inside leaves, there are many small green disks called chloroplasts and they absorb carbon dioxide (CO2), a greenhouse gas in the process of photosynthesis. The chloroplasts turn CO2 into oxygen that we can breathe and sugars that are used by the plants to grow, for example forming new leaves and stems. When the seasons change and the leaves turn red, brown or yellow and start to die, they absorb less and less CO2 but they transport sugars out of the leaves into storage in other part of the plant: this process is called "translocation". However, the plants grow back again in the spring. There are even some plants that don't die at all in the winter. Also, plants vary in the timing of when leaves become active and die: this is called "phenology".
In order to grow, plants need energy through photosynthesis. They also need nutrients from the soil and water. The growth produced can be used to produce new leaves, flowers and storage and support parts such as trunks of trees. You can see how leaves all around the world absorb carbon dioxide and release oxygen throughout the different seasons from this video taken by NASA.
In order to grow, plants need energy through photosynthesis. They also need nutrients from the soil and water. The growth produced can be used to produce new leaves, flowers and storage and support parts such as trunks of trees. You can see how leaves all around the world absorb carbon dioxide and release oxygen throughout the different seasons from this video taken by NASA.
Combatting Climate Change with Plants
While climate change is causing browning in some areas, we are also loosing "the lungs" of planet Earth by cutting down forest such as in Amazonia. We can help to combat this destruction by cutting down on things that produce carbon dioxide and other greenhouse gases, such as driving, having our heating on, building factories, eating less meat and more as well as protecting and planting trees and green areas in general.
Breathing Leaves Activity
Colour the leaves the way they would look for each season and then follow the tasks below.
1
Add a plus (+) if you think the leaf is taking in carbon dioxide (CO2) during its season and a minus (-) if you think the leaf is losing CO2.
2
Add an arrow (→) to show if resources are going into the leaf from the parent plant or going to the parent plant from the leaf.
3
In which season do you think the leaf is able to take in the most CO2? Rank the leaves 1-4, with 1 being the best season for taking in CO2 and 4 being the worst.