How many different types of trees are there on the planet?
It’s a question a team of scientists, including Australian Andy Marshall, have gone out on a limb to answer.
And the answer is about 73,300.
Professor Marshall, from the University of the Sunshine Coast’s Forest Research Institute, and almost 150 other scientists spent five years compiling the world’s largest forest database. The database contains more than 44 million individual trees at more than 100,000 sites in 90 countries, helping the scientists calculate the total number of species on Earth.
“It’s hugely exciting,” said Professor Marshall, who did most of his fieldwork in East Africa and Australia.
“This new global dataset is a significant piece of the puzzle in ecology* and biodiversity*. It’s based on the identification of trees growing in millions of vegetation plots around the world.”
The estimate of the world’s tree species is about 14 per cent higher than previous estimates.
About 9000 of the 73,300 estimated species are yet to be identified and will need names and scientific descriptions.
A large proportion of the unidentified species are thought to be growing in South America.
South America, which is home to the Amazon rainforest and Andean forests, was found to have 43 per cent of the planet’s tree species and the largest number of rare species, at about 8200.
The research, published in the US National Academy of Sciences journal PNAS, found South America has about 27,000 known tree species and 4000 yet to be identified species. Eurasia* has 14,000 known species and 2000 unknown, followed by Africa with 10,000 known and 1000 unknown, and North America (including Central America) with 9000 known and 2000 unknown species.
Almost 6700 known tree species and 1500 undiscovered species are estimated to be in the Oceania region, including Australia and New Zealand.
The study pinpointed “hot spots*” of likely undiscovered species in the tropical and subtropical moist forests of northeast Australia and the Pacific Islands.
Tree diversity* “hot spots” were also found in tropical and subtropical areas of South America, Central America, Africa and Asia.
The study found that about a third of known species could be classified as rare.
Professor Marshall said that estimating the planet’s total number of tree species helped show how many different ecosystems* existed and gauge* the health of those systems.
“The better the information, the better we can inform national and international plans for conservation priorities and biodiversity targets and management – potentially saving endangered tree species in the process,” he said.
The researchers used methods developed by statisticians* and mathematicians to estimate the number of unknown species based on the abundance* and presence of known species.
While this study did not tally* the total number of individual trees globally, previous research in 2015 that was led by one of the co-authors put that figure at about 3 trillion.
- ecology: the study of the relationship between different organisms and their surrounds
- biodiversity: the variety of plant and animal life
- Eurasia: the continents of Europe and Asia as a whole
- hot spots: places where something is found a lot
- diversity: variety, different types
- ecosystems: interacting organisms and their environment
- gauge: measure
- statisticians: experts who work with statistics
- abundance: large quantity
- tally: add up, measure
- How many tree species are estimated to be on Earth?
- How many of Earth’s tree species are yet to be identified?
- Which university is Professor Andy Marshall from?
- Which two places did Professor Marshall do most of his field work?
- How long did it take the scientists to compile the tree species database?
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1. Species of Trees Graph
From the data presented in the Kids News article relating to the geographical areas and the known and unknown amounts of tree species, create a bar graph displaying this information visually.
Your graph should have a title, labelled axis and a colour coded key to show the “known” and “unknown” species data.
Write three questions for your readers that can be answered by looking at your graph.
Time: allow 25 minutes to complete this activity
Curriculum Links: Mathematics
If scientists estimate that there are 73,300 different species of trees on the planet, what can you compare that to?
For example – a crowd of 70,000 people at the Essendon v Carlton match at the MCG.
Try to explain that vast number to a friend. Remember 73,300 is just the amount of species, last time the amount of individual trees was estimated it was about 3 trillion.
Time: allow 10 minutes to complete this activity
Curriculum Links: English, Science, Critical and creative thinking
Opener Up-Level It
Make a list of all the openers in the article. Pick three that repeat and see if you can replace them with another word, or shuffle the order of the sentence to bring a new opener to the front.
Don’t forget to re-read the sentence to make sure it still makes sense, and that it actually sounds better.