The Amazon Rainforest: Earth's Most Biodiverse Ecosystem Spanning 5.5 Million Square Kilometres
The Amazon rainforest is the world's biggest tropical rainforest and most biodiverse terrestrial environment, comprising over 5.5 million square kilometres (2.1 million square miles) across nine countries, with roughly 60% of that area in Brazil. The Amazon forest is home to about 40,000 plant species, 2,200 fish species, 1,294 bird species, 427 mammal species, 428 amphibian species, and 378 reptile species, with scientists estimating 2.5 million insect species, many of which are still scientifically unknown. The Amazon is home to one out of every 10 known species on the planet, making it invaluable in understanding Earth's biological richness. A single hectare (2.5 acres) can support 500+ tree species, while a single shrub may have more ant species than the entire British Isles—statistics that demonstrate the inconceivable biological richness squeezed inside tropical rainforest habitats. While the Amazon is the crown jewel of biodiversity, Brazil also protects the Pantanal, the world's largest tropical wetland, which offers an equally vital but more accessible view of South American wildlife.
The Amazon's formation was the consequence of millions of years of geological and ecological development. The Amazon Basin, which extends from Peru's Andes Mountains to Brazil's Atlantic coast, is a massive lowland depression formed by ancient tectonic subsidence. The Amazon River, the world's largest by water discharge (about 209,000 cubic meters or 7.4 million cubic feet per second), cuts through the landscape, draining around 40% of South America's precipitation from across the basin. The forest's three distinct structural layers—the emergent canopy (trees over 50 meters / 164 feet), the mid-canopy (30-50 meters / 98-164 feet trees forming a continuous green roof visible from space), and the understory (trees under 30 meters / 98 feet existing in dim light)—create microecosystems with specialised plants and animals adapted to specific light and moisture conditions. The towering canopy shuts off nearly 99% of sunlight, resulting in permanent twilight conditions on the forest floor, where specialised plants adapted to intense shade thrive.
The Amazon's ecological functions are global. The forest provides around 20% of world's oxygen through photosynthesis while also sequestering massive amounts of carbon in biomass—an estimated 150-200 billion tonnes of carbon contained in forest biomass. The forest's transpiration (water released by plants) produces atmospheric moisture, which influences rainfall patterns throughout South America and beyond. Deforestation jeopardises these functions: from 2000 to 2020, Brazil lost around 1.5 million hectares (3.7 million acres) of Amazon forest per year, with cumulative losses exceeding 17% of the total forest extent. Scientists warn that if deforestation continues at a rate of 20-25% total forest loss, the Amazon may reach a tipping point and transition from rainforest to savanna—a catastrophic transformation that would devastate global biodiversity, release massive carbon stocks, and fundamentally alter global climate patterns. Conservation efforts remain critical: protected areas and indigenous territories (where land rights are recognised) have considerably lower rates of deforestation, demonstrating that combining legal protection with indigenous land stewardship is the most successful conservation method.
