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Rainforest


The Rainforest of Tortuguero  

The lowland rainforest is the last part of the unique wet atlantic rainforest, which once covered the whole caribbean coast. Compared to the pacific coast, Tortuguero has no dry season, it rains the whole year. Some months however are drier than other ones, like September, October and February to April. The annual precipitation is around 6000 mm that means six times more than on the east coast of the United States. The annual temperature is about 23 ║C or 76 Fahrenheit. Tortuguero rainforest is still exclusive and highly diverse, despite logging companies that worked thirty years in Tortuguero.

The oldest and tallest trees are the "rainforest almond trees" (Dipteryx panamensis), an attractive construction wood, which is so hard that even termites can't eat it and it is heavier than water. The rainforest almond tree is the most important food source and host tree of the great green macaw (Ara ambigua), whose population in Costa Rica is estimated to only 25 to 30 pairs. The river vegetation is dominated by Raphia palms, fig trees, mimosas, leguminosas like the blood tree (Pterocarpus officinales) and provision trees (Pachira aquatica). Lianas, like Mucuna sp., which is pollinated by bats, hang like curtains over the river vegetation.

Half of the Costa Rican bird species (around 350), 6 species of felines (jaguar, cougar, margay, ocelot, jaguarundi, little spotted cat), tapirs, manatees, peccaries,  monkeys, river otters..., live in Tortuguero and beside that a great diversity of bats, reptiles, amphibians, invertebrates and other mammals. There are 3 monkey species, the mantled howler monkey, central american spider monkey and the white-faced capuchin monkey. The spider monkey is the most endangered, it never goes to the ground and probably for its fruit and flower diet it needs an intact rainforest with a high diversity. Other mammals, like sloth, coatimundi and raccoon are observed more often in young secondary forests. There they find plenty of food, since diversity is low. In Tortuguero their population is more limited, perhaps for more competition and because they have still predators.

In general, as more intact the forest is, as higher the diversity, the smaller the populations. As more plants species (in Tortuguero, around 2000 plant species and 400 tree species) exist, as more specific relationships can evolve between animals and plants. For example, each fig specie is pollinated by another fig wasp specie. Or, in the hairs of three-toed sloth lives green algae. It gives a camouflage to the sloth, but when the sloth climbs in the tree crowns it approaches sunlight, it needs for the photosynthesis. In the hairs of the sloth lives as well a moth which feeds on the algaes, controlling their population. This explains how sensitive the rainforest is to any disturbance.

Beside the sea turtle studies and migratory bird banding, there is no research in Tortuguero. There are two projects planned: an estimation of the jaguar population and the diversity of bat species.  Probably there is still a dense population of jaguars since in turtle season jaguars kill nearly every night a turtle.


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