My Science School

Tropical rainforests are home to an incredible range of animal life. Over half of the world’s known species exist in the Amazon rainforest alone. Colourful birds, such as toucans, parrots and macaws, live alongside gorillas or other primates, while tigers, pumas and wolves may roam among countless poisonous snakes and insects.

It is said that a single hectare (about two and half acres) of rainforest can contain up to 1500 species of plants plus 750 species of trees. It is this wealth of plant life that attracts and sustains an amazing collection of animals. For example, one in five of all bird species are found in the Amazon rainforest.

Mammals such as Orangutans (in Asia), Gorillas (Africa), Jaguars (South America) and sloths (Central and South America) all call the rainforest home. Sloths spend most of their time in the trees. Their hooked claws and long arms allow them to spend most of their time hanging upside down! Sloths are herbivores and due to their slow movement and metabolism it can take them up to a month to digest their food! Reptiles such as Anacondas, the Emerald Boa Constrictor and the Gaboon Viper slither through the trees and on the forest floor. Insects including cutter ants, tarantulas, scorpions, butterflies and beetles rummage on the forest floor. Amphibians such as frogs and toads live in trees or near bodies of water on the forest floor. Fish including the piranha, Amazonian catfish, fresh water dolphins and stingray inhabit the rivers that run through the rainforests.

Because there are so many animals in the rainforest there is a lot of competition for sunlight, food and space. Animals therefore have to adapt to the environment.

Some animals use camouflage to hide from predators and some predators use camouflage to help them hunt for food. Their colouring or patterned skin help them disappear into the rainforest, blending into the colour of the bark or leaves.

Some animals don’t hide, some use their colouring to warn potential predators away. The poison dart frog is a good example, they may be small but they are one of nature’s most toxic and dangerous creatures. Some local people put the frog’s poisonous toxins on the tips of their blowpipe darts to kill small prey which they then eat.

Picture Credit : Google

With careful planning, areas of rainforest can he re-established, although it takes over a hundred years for the forest to return to its original state. However, it the land is damaged, only scrubby vegetation will grow again.

We all know it takes a long time for cleared rainforests to regenerate, but how long exactly? According to a study focusing on the Brazilian Atlantic forest, certain aspects can return surprisingly quickly – within 65 years. But for the landscape to truly regain its native identity takes a lot longer – up to 4000 years.

The Atlantic forest originally stretched along the southern half of Brazil’s Atlantic coast, covering some 1.2 million square kilometres. Once lush, the forest has been continually exploited for food, wood and space.

Today, land it used to occupy is home to most of the country’s population, including Brazil’s two largest cities, São Paulo and Rio de Janeiro, and only 100,000 square kilometres of forest remain. In 1993, however, the government created several protected areas to conserve the forest’s remnants. To determine how long it would take for the forest to regenerate, Marcia Marques and colleagues at the Federal University of Parana collected data on different parcels of forest that had been virtually cleared and left to recover for varying amounts of time.

The researchers looked at four different measures of forest regrowth: the proportion of tree species whose seeds are dispersed by animals, the proportion of species that can grow in shade, tree height, and the number of native species.

“Animal-dispersed trees sustain a large number of fruit-eating animals, that sustain other animals including large carnivores,” says Marques. “Thus, from the proportion of animal-dispersed trees we can estimate how complex the forest’s ecological web has become.”

Animals are key to the successful regeneration of cleared areas and, typically, 80% of the tree species in a mature tropical rainforest are animal-dispersed. The researchers found that it took just 65 years for a forest to recover to this level.

Picture Credit : Google