Costa Rica is often incorrectly defined by a single environment, but it is actually a complex mosaic of distinct ecological zones. This small Central American nation contains several major habitats. The country’s geographic location, nestled between the Pacific Ocean and the Caribbean Sea and bisected by mountain ranges, creates diverse microclimates that foster exceptional biodiversity. This varied topography and dual-coastline position prevents any single biome from dominating the landscape.
Lowland Tropical Rainforests
The classic image of a dense, humid jungle is realized in Costa Rica’s lowland tropical rainforests, typically found below 1,000 meters. These areas, particularly along the Caribbean coast and the southern Pacific lowlands, are defined by consistently high temperatures (71°F to 91°F) and high annual rainfall, often exceeding 100 inches (2,540 mm). This constant warmth and moisture support unparalleled biological productivity.
The forest structure is highly stratified, featuring distinct layers from the floor to the emergent layer. The dense canopy absorbs up to 95% of the sunlight, forcing plants below to adapt to low-light conditions. This environment supports large trees like laurel and cedar, which provide habitat for canopy-dwelling mammals such as the three-toed sloth and howler monkeys.
Biodiversity is most concentrated among the epiphytes, insects, and amphibians that thrive in the persistent humidity. Thousands of insect species, along with colorful poison dart frogs and jaguars, make their home here. The constant moisture allows life to flourish without interruption from seasonal drought, making these zones highly biodiverse.
Cloud and Montane Forests
The cooler, perpetually damp cloud and montane forests are found mainly on the slopes of the central mountain ranges. Cloud forests occur between 1,500 and 3,000 meters (4,900 and 9,800 feet) above sea level, where moist trade winds are forced upward, causing the air to cool and condense into a persistent fog. This orographic effect means moisture arrives as horizontal precipitation—mist that drips directly onto the vegetation.
The constant moisture and cooler temperatures, ranging from 50°F to 64°F (10°C–18°C), create a unique ecosystem where tree growth is often stunted compared to the lowlands. Trees are shorter, with gnarled trunks and smaller, waxy leaves, and they are heavily draped in a high concentration of epiphytic plants. These air plants, which include mosses, lichens, bromeliads, and over 500 species of orchids, absorb nutrients and water directly from the misty air.
This specialized environment fosters a high degree of endemism. The cloud forest is a haven for specialized avifauna, including the Resplendent Quetzal and various hummingbirds, which rely on the misty conditions. The dense, sponge-like covering of epiphytes on the trees helps regulate the regional water supply, capturing moisture and slowly releasing it to streams that feed the lower elevations.
Seasonal and Coastal Ecosystems
The northwestern Pacific slope, particularly in the Guanacaste province, hosts the tropical dry forest biome. This environment is characterized by a dry season lasting three to five months, from December to May. The annual rainfall is significantly lower, often less than 79 inches (2,000 mm), which forces plant and animal life to adapt to a cycle of abundance and scarcity.
The most notable adaptation is the deciduous nature of the trees, which shed their leaves during the dry season to conserve water, causing the forest to appear barren and brown. When the heavy rains return, the forest rapidly explodes into a lush green landscape. Animals like white-tailed deer and large mammals must be mobile or adjust their activity to the seasonal availability of water and forage.
Along both the Pacific and Caribbean coastlines, the transition between land and sea creates unique, brackish habitats, most notably the mangrove forests. These coastal wetlands are composed of salt-tolerant trees, such as the red, black, and white mangroves, which possess specialized aerial roots that allow them to breathe in oxygen-poor, muddy soil. Red mangroves, for instance, have prop roots that extend into the water, providing a protective nursery habitat for juvenile fish, crabs, and shrimp.
Mangrove forests also stabilize coastlines with their extensive root systems, buffering the land against erosion and storm surges. These areas are rich in wildlife, serving as feeding grounds for wading birds like herons, and as a habitat for reptiles such as crocodiles and caimans. The largest of these ecosystems is the Térraba-Sierpe National Wetlands on the Pacific coast.