The Amazon rainforest is the largest tropical forest on Earth, spread mainly across Brazil and neighboring countries of the Amazon basin. Warmth, heavy rain, and a long growing season stack life in layers: emergents above the canopy, a dim understory, a floor that recycles fallen leaves almost as fast as they drop. Nutrients often live in the vegetation more than in the soil. Cut the trees, and the land can bake and wash away. Rivers the size of seas wander through, flooding forests for months, carrying sediment from the Andes toward the Atlantic.

Diversity here is not a slogan. Thousands of tree species can occupy a single region. Insects, birds, frogs, and fish fill niches that do not exist in a temperate wood. Indigenous peoples have shaped patches of this forest for millennia with fire, planting, and dark earth, so wilderness and garden are not always separate.

The forest makes much of its own rain by pumping water into the air. Lose enough canopy and the climate can dry, threatening what remains. Cattle, soy, gold, and roads drive clearing. Carbon stored in wood and soil, once released, adds to the greenhouse load. The Amazon is not the lungs of the planet in a simple sense — oceans produce much of the oxygen — but it is a vast living reservoir of water, carbon, and species that the rest of the world does not get to rebuild if it is spent.
