Estimates say that the rainforests are home to more than half of the world’s species and account for forty percent of the earth’s oxygen.
Extending from 28 degrees north or south of the equator, the tropical rainforests cover around 6-7% of the earth. They cover the parts of Asia, Australia, Africa, South America, Central America, and Mexico. The largest of these rainforests are found in Brazil, the democratic republic of congo, and Indonesia. Parts of the pacific islands are also covered by the same and other tropical rainforests are present in southeast Asia, Hawaii, and Caribbean islands. The Amazon rainforests are the world’s largest rainforest. Almost 2/3rd of the continental United States is covered by the same!
The rainforests are wet all year round. The forests near the equator have no seasons while the ones away from the equator experience only wet and dry seasons. With 175-300 inches of annual precipitation, sunlight remains a limiting factor for these rainforests. They thrive in regions that witness extremes of temperature and precipitation.
480 tree species in a single hectare!
The exact number of species that thrive in the forest isn’t known. But it is estimated that the forests shelter around 50 million species – higher numbers on a per-area basis relative to the other ecosystems.
To be more elaborate, there are more than 480 species of trees in a single hectare of the forest. An amazonian bush accounts for a high number of ant species- perhaps more than the species of ants found in the British Isles.
Lungs of the planet: not just a pretty face!
With a vivid beauty and rich biodiversity, the rainforests are quite significant when it comes to stabilizing the climate. An acre of the rainforest stores more carbon than any other vegetation. Carbon dioxide absorption helps to stabilize the climate while the process of transpiration helps to maintain the world’s water cycle. Scientists claim that the moisture generated in the forests of Africa falls as rain in America. It is believed that the Amazon rainforests account for half of the Earth’s rainwater.
They are comparable to a huge sponge that stores water!
The absence of rainforests is thus no less than a nightmare.
Biodiversity backed by climate – a complex biome
First of all, it is the hot and humid climate that facilitates the existence of rich biodiversity. Humidity ensures the availability of water – the most essential ingredient for survival. There is no dearth of food for the species all year round owing to the availability of sunlight that facilitates the process of photosynthesis. The solar energy is passed on from the plants to the herbivores and then to the carnivores that consume the former. The species are well adapted to the forests and are highly dependent on each other. They interact with each other in different ways. The extinction of a single species endangers the other species.
Narrow niches and well-adapted creatures
The creatures are less with the defense mechanisms and specializations essential for cutting out rivals. The specializations further extend to complex adaptations like feeding habits and symbiotic relationships. It is that not even a single niche is unfilled in the forest. The species, relatively different ones, can coexist in a relatively small area without disturbing their neighbors. With the evolutionary processes, these species are further pushed into the narrower niches hence mastering incredible specializations.No species can adapt to all the available niches- hence there is no dominating class amongst the species. The abundant species however is threatened by its predator.
The grandiose diversity of the rainforests can thus be attributed to the narrow niches.
The defenses: mechanical and biochemical
From thorns, spines and stinging hairs to chemical defenses like the production of alkaloids, tannins, and toxic amino acids, the plant species in the rainforests have mastered the art of defending themselves against an array of predators. But we are all aware of Newton’s third law. As a result of such a mechanism, a counter- mechanism is adopted by the insects. A few of the herbivore insects are capable of detoxifying the chemicals while the others are adapted to feed on a limited plant species.
The biochemical warfare: a doorway to the medicinal extracts
In the way of perfecting their defenses, several plant species have synthesized compounds that protect against parasites and infections. Natural selection has led to the formation of acutely powerful chemicals that are presently contributing to modern medicines. Several species are contributing actively to ethnobotany and bioprospecting.
An interesting association: the tale of the deceptive colors and chemical warfare
The passion flower vines are the producers of cyanide-based compounds which is a defense mechanism against predators. The Heliconius caterpillars are well adapted to these leaves and consume them. The caterpillar on turning into a butterfly retains the cyanide for defense. The butterflies have a distinct color and taste to indicate their toxicity. The passion flower vines have thus counter- adapted in return!
They form nectaries that serve as ant food. The ants thus attack the butterfly eggs and all other intruders. Another counter adaptation is to mimic the eggs of the butterfly. The butterfly gets confused and doesn’t lay eggs on the leaf that already has an egg and moves to the other plant.
Diversity or abundance?
The strikingly subtle lifestyle in the rainforest is the opposite of what one envisions. The sight of a herd of zebras or a group of birds with colorful wings is rare when one visits the rainforest. The diverse nature of species doesn’t ensure their abundance! The tropical rainforest holds the biology of rare species. A few species are on the verge of extinction in the areas where the forests are disturbed. The lack of abundance can be attributed to the high specialization of these species to fit in a particular niche. The offsprings of a particular species that is abundant in a niche tend to colonize a new area in which they are rare.
Canopy niche: the multiplier effect
The trees account for 70-90 percent of life in the rainforest. The canopy of trees ends up creating new niches in the form of shelters for the interaction of species. The species seek places for hiding and food sources under the canopy. Epiphytes can be cited as an example for the same. Several ground-dwelling animals have thus accessed the canopies. Lianas and creepers also create a pathway for these animals.
The tropical rainforest is one of the oldest ecosystems present on earth. The spectacular ecosystem holds immense significance when it comes to tackling present-day climate issues. However, it is a matter of concern that the rate of forest clearing has been accelerated with growing urbanization. The biodiversity is sharply reduced by the degradation of forests. Scientists estimate that we are close to the sixth mass extinction.
The forest logging disturbs the natural canopy and makes room for more sunlight. Thus, the forest dries out and the habitats get destroyed. Studies around the world show decline in species with the logging of forests. Forest fires are a direct consequence of forest degradation.
It’s time to realize the potential of these forests and save them, only then mankind will know peace.