Key Terms

📖 Key Terms

deforestation — The large-scale, permanent removal of forest cover, typically for agriculture, logging, mining, or settlement. Since 1970, approximately 17% of the Amazon has been deforested.

biodiversity — The variety of living species within an area. The Amazon contains around 10% of all species on Earth despite occupying 4% of the land surface.

nutrient cycling — The continuous movement of nutrients (nitrogen, phosphorus, potassium etc.) through an ecosystem — from soil, into plants, into animals, back into soil via decomposition. In rainforests, this cycle is very rapid and keeps almost all nutrients in the living biomass.

interdependence — The close mutual reliance of all components of an ecosystem. In a rainforest, remove one species and the effects cascade: the bromeliad example shows 250 species depending on a single plant.

emergent layer — The uppermost layer of a rainforest, where the tallest trees (40–60 m) poke above the main canopy into full sunlight. Species adapted to extreme heat, wind, and desiccation survive here.

epiphyte — A plant that grows on another plant without taking nutrients from it, instead anchoring itself to bark and gathering nutrients from the air, rain, and debris. Orchids and bromeliads are common Amazon epiphytes.

transpiration — The process by which water absorbed by plant roots is released as water vapour through tiny pores (stomata) in leaves. Amazon trees collectively release 20 billion tonnes of water vapour per day — the "flying rivers."

carbon sink — A natural system that absorbs more carbon dioxide than it releases, removing CO₂ from the atmosphere. The Amazon is one of Earth's most important carbon sinks, storing 150–200 billion tonnes of carbon. If significantly damaged, it could become a carbon source, accelerating climate change.

tipping point — A threshold beyond which a system changes irreversibly. For the Amazon, the estimated tipping point is 20–25% deforestation, beyond which the forest may convert permanently to savanna grassland.

REDD+ — Reducing Emissions from Deforestation and Forest Degradation. An international mechanism that pays tropical countries to protect their forests as a means of reducing global carbon emissions. Norway paid Brazil $1.2 billion through the Amazon Fund (2008–2015).

ecotourism — Sustainable tourism to natural areas that generates income for local communities while minimising environmental damage. Provides an economic alternative to clearing the forest for agriculture.

indigenous — Describes the original peoples of a region, whose cultures and livelihoods are tied to the land. The Amazon has over 400 distinct indigenous tribes; around 70 have had no contact with the outside world.

laterite — The hard, iron-rich, infertile reddish soil that remains after tropical forest is cleared and nutrients are washed away by leaching. Most cleared Amazon land becomes laterite within a few years of deforestation.