Rainforests are complex ecosystems characterized by high annual precipitation, a dense overhead canopy, and extraordinary biological diversity. These forests are sustained by climatic conditions that provide consistent moisture, typically receiving at least 200 centimeters of rainfall each year. Their distribution is determined by the interplay of latitude, temperature, and atmospheric circulation, resulting in two distinct global zones where they flourish.
The Global Divide: Tropical vs. Temperate Zones
The difference in rainforest location is determined by their position relative to the equator, which dictates the prevailing climate. Tropical rainforests are situated within the tropics, a band centered on the equator between the Tropic of Cancer and the Tropic of Capricorn. This equatorial location guarantees consistently high temperatures, typically exceeding 18 degrees Celsius every month of the year. These conditions drive the high rates of evaporation and precipitation necessary to sustain the biome, resulting in a warm, moist, and stable climate year-round.
Temperate rainforests, by contrast, are found in the cooler mid-latitudes, generally between 40 and 60 degrees north and south of the equator. These forests experience the four distinct seasons, though temperatures remain moderate due to oceanic influences. Their existence relies heavily on proximity to the coast, where moisture-laden air provides a constant source of high precipitation and fog. This moisture is often forced out of the air by coastal mountain ranges, a geographic phenomenon known as the orographic effect.
Geographic Pillars of Tropical Rainforests
The majority of the world’s tropical rainforests are concentrated in three massive, geographically distinct blocks that straddle the equator. The largest is the Amazon rainforest, which dominates the northern half of South America. This immense forest covers territory in nine nations, with approximately 60 percent in Brazil. The remainder is distributed across countries including Peru, Colombia, Venezuela, Bolivia, Ecuador, Suriname, Guyana, and French Guiana.
The second major pillar is the Congo Basin, the largest continuous block of tropical forest in Africa. This basin is primarily centered in Central Africa, with the Democratic Republic of the Congo holding the largest share. Significant portions also extend into neighboring countries such as the Republic of the Congo, Gabon, Cameroon, the Central African Republic, and Equatorial Guinea.
The third major concentration is found in the Indo-Malayan Archipelago and parts of Australasia, covering extensive islands and portions of the mainland. This area includes the rainforests of Indonesia and Malaysia, particularly on the islands of Borneo and Sumatra. Further east, the tropical forests of Papua New Guinea also constitute a significant part of this block, which is characterized by fragmentation across thousands of islands.
Locations of Temperate Rainforests
Temperate rainforests are found in widely separated, fragmented coastal areas in both the Northern and Southern Hemispheres. The largest region is the Pacific Northwest of North America, stretching along the coast from Northern California through Oregon, Washington State, British Columbia, and Southeast Alaska. This strip is sustained by moisture from the Pacific Ocean and the barrier created by the Coast Mountains.
In the Southern Hemisphere, a major region is the Valdivian forest, which clings to the western coast of southern Chile and a small portion of Argentina. This forest is wedged between the Pacific Ocean and the Andes Mountains, creating the necessary cool, wet conditions. Other pockets exist in Tasmania, Australia, and on the South Island of New Zealand, particularly in the Fiordland and Westland regions. Small, isolated temperate forests can also be found in specific areas of Europe, such as the Atlantic coast of Norway and the Iberian Peninsula.