Rainforest and savanna biomes
Whether people can use a place without wrecking it depends on how that place works. Tropical rainforest and savanna grassland are a useful pair to study because they lie in similar parts of the world but run on very different climates. Those differences shape their soils, their wildlife and the ways of life of the people who live there.
The largest unit on the ecosystem scale. A biome is a very large area with similar vegetation and animal life, and biomes are classified by their plant cover and their climate.
Every biome is made of abiotic (non-living) parts, such as climate, rock and soil, and biotic (living) parts, the flora (plants) and fauna (animals). These interact, and humans are part of the same system.
The same biome type turns up on several continents. Rainforest is found in the Amazon, and also in Africa and Asia. Savanna grassland stretches across central and southern Africa and parts of South and Southeast Asia.
The two climates differ most in how rain is spread across the year.
- Tropical rainforest: hot all year, with temperatures almost flat at about 27–28°C. Rain falls in every month, from a peak of nearly 300 mm in March down to about 55 mm in August. The yearly total comes to over 2,000 mm.
- Savanna grassland (northern hemisphere): a sharp split between a dry season and a wet season. From November to March almost no rain falls. Then rain builds to a peak of about 285 mm in August. Temperature swings more, from about 18°C in December to about 37°C in April, just before the rains arrive.
Add up the monthly bars and the savanna gets roughly 1,000 mm a year, about half the rainforest total.
Most of it falls in just four months (June to September). Plants and animals there must survive a long dry spell every year, which a rainforest never has.
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