The great living
belts of the Earth.
who notices the wildlife.
What a biome actually is.
A biome is a very large region of the Earth defined by its climate and the kinds of plants and animals that live there. It is bigger than a single wood or a single river — it is a whole belt of the planet that shares the same broad conditions. The tropical rainforest is a biome. So is the desert, the temperate forest, the grassland, and the cold tundra near the poles.
What decides where each biome sits is, above all, climate — chiefly two things: how much heat a place gets, and how much rainfall. And those follow the lines of latitude. The equator is hot and wet, so a band of rainforest wraps around it. A little further out, dry air sinking from the sky bakes the land into desert. Further still come the temperate forests and grasslands, and finally, near the poles, the freezing tundra. The pattern is not random — it is the climate, drawn in living things.
Three words that nest inside one another. A biome is the huge belt — say, the rainforest. An ecosystem is a community of living things and their surroundings working together — a single patch of that forest, with its plants, animals, soil and water. A habitat is the particular place one creature lives — the bit of the forest a tree frog calls home.
A climate graph, and how to read it.
Geographers describe a biome's climate with a single picture: a climate graph. It packs a whole year into one chart. Temperature is drawn as a red line, read off the axis on the right. Rainfall is drawn as blue bars, read off the axis on the left. One glance tells you whether a place is hot or cold, wet or dry, steady or seasonal.
How to read a climate graph (tropical rainforest)
This particular graph belongs to a tropical rainforest. See how the red line stays high and almost flat — around 27 °C every month, no real seasons — and the blue bars are tall in every month too: rain all year round. A desert graph would be the opposite: a red line swinging high and low, and barely a blue bar in sight. Once you can read the shape, you can name the biome.
The Amazon rainforest makes much of its own rain. Water evaporates off the leaves, forms clouds, falls again, and the same water can be recycled through the forest five or six times before it ever reaches the sea.
Five biomes, from the equator to the poles.
Here are the five biomes worth knowing on sight, in order from the hot wet equator outwards to the cold poles. For each one, hold two things in your head: its climate, and how its plants and animals are adapted to survive it.
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Adaptation — built to fit the climate.
An adaptation is a feature of a plant or animal that helps it survive where it lives. The same problem — too much heat, too little water, too much cold — produces clever and very different solutions in each biome. Here are a few worth knowing.
In the rainforest
- Drip-tips — leaves end in a point so heavy rain runs off quickly and doesn't rot the leaf.
- Buttress roots — huge flared roots brace tall trees in the thin forest soil.
- Tall, straight trunks — trees race upwards to reach the light at the top of the canopy.
In the hot desert
- Water storage — a cactus holds water in a fat, fleshy stem for the long dry spells.
- Spines, not leaves — tiny spines lose far less water than broad leaves, and fend off thirsty animals.
- Long roots — some reach deep for hidden water; others spread wide to grab any rain fast.
In the tundra
- Low and close to the ground — plants stay short to shelter from the bitter, drying wind.
- Thick fur and fat — animals like the Arctic fox keep warmth in with a deep coat and a layer of blubber.
- White winter coats — for camouflage in the snow, hiding hunter and hunted alike.
In the grassland
- Deep grass roots — survive fire and drought, then spring back when the rains come.
- Speed — grazing animals on open plains, like gazelle, survive by outrunning the predators.
- Living in herds — many eyes spot danger sooner on the open ground.
A saguaro cactus can drink up so much rain in one storm that it gains hundreds of kilograms in a single day, swelling like an accordion. It then lives off that stored water for many dry months.
Food chains, food webs, and the flow of energy.
Every living thing in a biome needs energy, and that energy starts in one place: the Sun. A food chain traces how it passes from one living thing to the next. Plants — the producers — capture sunlight and make their own food. Animals that eat the plants are consumers; animals that eat those animals are consumers too, further along the chain. And when anything dies, decomposers (fungi and bacteria) break it down and return its goodness to the soil.
Plants and algae. They make their own food from sunlight by photosynthesis — the base of every food chain.
Animals. They cannot make their own food, so they eat plants (herbivores) or other animals (carnivores).
Fungi and bacteria. They break down dead plants and animals, recycling the nutrients back into the soil.
A single straight food chain is a tidy idea, but the real world is messier. Most animals eat more than one thing, and are eaten by more than one thing. When you join all the chains together you get a food web — a tangle of who-eats-whom across the whole ecosystem. The web matters because it shows how connected everything is: pull out one strand, and others wobble.
A simple grassland food web
Threats — and why deforestation matters.
Biomes are under pressure from people. Grasslands are ploughed for farms, tundra is disturbed for oil and gas, reefs are bleached by warming seas. But the threat you most need to understand is deforestation — the clearing of forest, above all the tropical rainforest, for timber, cattle ranching, and crops like soya and palm oil.
Why does it matter so much? Three reasons stack up. First, biodiversity: the rainforest holds more kinds of living thing than anywhere else on Earth, and clearing it drives countless species towards extinction. Second, climate: forests lock away vast amounts of carbon, and burning them releases it, warming the planet. Third, the soil: rainforest soil is surprisingly thin, and once the trees that held it are gone, the rain quickly washes it away, leaving land that will not easily grow back.
Forests can come back. Where land is protected and replanted, and where people are paid to keep trees standing rather than fell them, the forest recovers — slowly, but it recovers. The choices are not all made yet, and that is the point of learning this.
What mainly decides where a biome sits?
Read the climate graph.
Name the adaptation.
There may be more kinds of insect on a single large rainforest tree than there are species of bird in all of Britain. Some trees have never been fully catalogued — new beetles are still being found by shaking a branch over a sheet.
Which way does the arrow point?
Whose job is it?
Name the threat.
Fresh one. A plant or animal feature that helps it survive where it lives — a cactus storing water, an Arctic fox's thick fur. What is this feature called?
Name the roles in the chain.
Four living things in this food chain are numbered. Pick a chip from the pool, then tap the number it belongs to — label each one by its role. Two of the chips don't belong on this chain at all — read each one before you place it.
Match each label to its pin
Explain why.
This is the kind of question that rewards you generously when you write in full sentences and develop your points — you say something, then you say why, then you say so what. Aim for 100–150 words. No bullet points.
Explain why deforestation of the tropical rainforest causes problems far beyond the patch of forest that is cleared.
Use the words biodiversity, carbon and soil. Give a reason for each, not just a list.
A few thoughts on your answer, Florence
strong You reached for all three of the big ideas — the species, the carbon, the soil — and a marker is looking for exactly that spread. Naming the carbon being released, rather than just “it's bad for the climate”, is the kind of precise cause this question rewards.
try this One of your points stops at what without reaching why. You wrote that soil is washed away — carry it one step on: the trees held the thin soil in place, so once they are gone the rain strips it, and the land won't easily grow back. The second half of the sentence is where the mark lives.
to add A strong closing line ties it together: this is why clearing one patch matters to the whole planet, not just that patch. One sentence of “so what” at the end lifts a list into an argument.
Worth watching.
A short film to watch alongside today's lesson.
The words from today.
- Biome
- A very large region of the Earth defined by its climate and the plants and animals that live there.
- Ecosystem
- A community of living things and their surroundings, all working together in one place.
- Adaptation
- A feature of a plant or animal that helps it survive where it lives — a cactus's spines, a fox's thick fur.
- Producer
- A plant or alga that makes its own food from sunlight — the base of every food chain.
- Decomposer
- A fungus or bacterium that breaks down dead matter and returns its nutrients to the soil.
- Deforestation
- The clearing of forest, mostly rainforest, which harms biodiversity, releases carbon, and exposes the soil.
You can read the living map.
You know now that a biome is climate made visible — heat and rain, drawn in living things. You can name the great belts from the equator to the poles, read a climate graph, and explain how plants and animals are built to fit their home. You can follow energy along a food web, and you understand why losing a forest reaches far beyond its edge. Look out of the window, Florence — you're standing in the temperate forest biome right now.
There is roughly the same length of tree roots and fungal threads beneath a single forest as there are roads on the whole of the Earth's surface. Underground, the trees are quietly wired together — passing water, warnings and even food along a living network.
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