Tropical Rainforest Biome – UPSC Environment Notes

In the realm of structure and species variety, the Tropical Rainforest stands out as the most intricate biome globally. Flourishing in optimal conditions characterized by abundant rainfall and perpetual warmth, these forests are designated as Tropical Moist Broadleaf Forest by the World Wildlife Fund. This article aims to elucidate the intricacies of Tropical Rain Forests, offering valuable insights for those preparing for the Environment syllabus in the UPSC Civil Service exam.

Tropical Rain Forests – Distribution

• Tropical rainforests are located in Asia, Australia, Africa, South America, Central America, Mexico, and various Pacific Islands, situated approximately 28 degrees north or south of the equator.
• They encompass approximately 6-7 percent of the earth’s surface and host a staggering half of the planet’s biodiversity.
• The world’s largest rainforests are situated in Brazil (South America), the Democratic Republic of Congo (Africa), and Indonesia.
• Other regions with tropical rainforests include Southeast Asia, Hawaii, and the Caribbean Islands.
• South America’s Amazon rainforest holds the title of the world’s largest, covering an area that is nearly two-thirds the size of the continental United States.

Tropical Rain Forests – Abiotic Components

Abiotic factors constitute the nonliving elements shaping an ecosystem, encompassing elements like climate, temperature, soil, precipitation, and more.

Temperature

• In tropical rainforest regions, the average temperature ranges between 20 and 29 degrees Celsius, with no month falling below 18 degrees Celsius.
• As elevation increases, temperatures become more crucial, with a drop of about 0.5 degrees Celsius for every 100 meters climbed in the humid tropics.
• Despite the perennially hot climate supporting tropical rainforests, extremes seen in drier areas to the north and south of the equatorial belt are absent.

Precipitation

• Moist seasonal tropical forests experience abundant rainfall in warm summers and a drier winter season.
• Annual rainfall varies from 1,800 to 2,500 mm, contributing to poor soils due to nutrient loss from the ground.

Soil

• Tropical rainforest soils are deep but generally not fertile.
• The limited fertility is attributed to significant amounts of mineral nutrients being bound within vegetation, rather than freely available in the soil.
• Tropical red regions form as a result of moist, hot climates causing deep rock weathering, leading to the creation of deep, reddish soil profiles rich in insoluble sesquioxides of iron and aluminum.
• Continuous surplus water, resulting from precipitation surpassing evapotranspiration, leads to nutrient depletion in the soil, rendering it generally infertile.

Tropical Rain Forests- Biotic Components

Biotic factors are the living elements shaping an ecosystem and impacting the resident animals within it. These factors encompass producers, consumers, and decomposers.

• Producers are autotrophs with the ability to manufacture their own food, with green plants being prominent examples utilizing photosynthesis.
• Consumers, on the other hand, are heterotrophs relying on producers for sustenance. This category includes diverse species like goats, zebras, antelopes, lions, etc.
• Decomposers play a vital role by consuming decayed organic matter, primarily facilitated by microorganisms like bacteria.

Producers

• In tropical rainforests, the abundance of all major groups of terrestrial organisms is noteworthy.
• Angiosperms stand out as the most diverse among higher autotrophs, with continuous discoveries of new plant species, including substantial trees.
• Ferns, mosses, liverworts, lichens, and algae also thrive, displaying significant diversity, although they may not be as extensively studied or documented as higher plants.
• Many of these organisms, including ferns and mosses, are epiphytic, attaching themselves to the stems and occasionally leaves of larger plants, especially in the wettest and most humid environments.
• Fungi and other saprophytic plants exhibit diversity, with some playing a crucial role in decomposing dead organic matter on the forest floor. This decomposition releases mineral nutrients, making them available to roots in the top layers of the soil.
• Symbiotic relationships are formed between some fungi and tree roots, known as mycorrhizae.
• The intricate web of life in tropical rainforests involves various consumers interacting within this diverse ecosystem.

Consumers

Consumers play a crucial role in the intricate dynamics of tropical rainforests, relying on the vast array of producers present.

• Various species of animals, such as fruit-eating parrots, pigeons, and seed-eating weevil beetles, contribute to the biodiversity of tropical rainforests.
• While monkeys inhabit both New and Old World tropical rainforests, they are notably absent from New Guinea and its surrounding territories.
• Tree kangaroos and birds-of-paradise are exclusive to the canopies of tropical rainforests in Australia and New Guinea.
• The western rainforests are home to larger mammals like monkeys, deer, pigs, cats, elephants, and rhinoceroses, whereas the eastern rainforests host marsupial mammals such as opossums, cuscuses, dasyurids, tree kangaroos, and bandicoots.
• A few animal species, including bats and rodents, have managed to cross borders and become prevalent in both regions.
• Similar disparities are observed across various animal and plant groups within the same division, although they may be less pronounced.

Significance

Rainforests play a vital role in balancing the global climate by serving as:

• A habitat for numerous plants and animals,
• Guardians of the water cycle, preventing floods, droughts, and erosion,
• A rich source of medicines and foods,
• A supportive environment for tribal people,
• Intriguing destinations for tourist attraction.

Conclusion

Although the temperatures and soil composition of tropical rainforests globally exhibit similarity, each specific regional rainforest possesses its own unique characteristics. Finding identical species across all the world’s tropical rainforests is an impossibility. For instance, the species in African tropical rainforests differ from those in Central American tropical rainforests. However, despite this diversity, the various species within each region fulfill similar roles within their respective rainforests.

FAQs

Q1: Where are tropical rainforests found?

Ans: Tropical rainforests are predominantly found near the equator, spanning regions in Asia, Australia, Africa, South America, Central America, Mexico, and several Pacific Islands. They are generally situated around 28 degrees north or south of the equator.

Q2: Which forest is called a tropical rainforest?

Ans: A tropical rainforest is a type of forest characterized by high annual rainfall and consistently warm temperatures throughout the year. It is often referred to as the Tropical Moist Broadleaf Forest by organizations like the World Wildlife Fund.

Q3: What is the climate of a tropical rainforest?

Ans: The climate of a tropical rainforest is characterized by high temperatures and abundant rainfall. The average temperature typically ranges between 20 and 29 degrees Celsius, with no month having a temperature below 18 degrees Celsius. These forests experience warm summer rainfall and a cooler winter dry season, contributing to their lush and diverse ecosystems.

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