Life on Earth

Class 09 Social Science

The word biome is made up of the word bio, derived from the Greek word bios, meaning ‘life’, and -ome, a suffix used in biology to denote a group of a specific type of biological constituents.

Biomes are large natural regions of the world where certain types of plants and animals live under similar climatic conditions. For example, icy tundras, hot deserts, green forests, and vast grasslands are all different types of biomes.

Types of Biomes

Different biomes support diverse plant and animal life and can be categorised into terrestrial (land-based) and aquatic biomes (water-based).

There are several factors that determine which types of plants and animals can survive and thrive in a biome. These include temperature, precipitation patterns, dominant plant species, growth forms of vegetation, etc.

Terrestrial Biomes

Terrestrial biomes are classified into forests, grasslands, deserts, and tundra, based on their climate.

Forest Biome

A forest biome is like nature’s giant green umbrella - warm, wet, and bursting with life at every level, from the tallest trees to the damp forest floor. Tropical rainforests are mainly found near the Equator, between the Tropic of Cancer and the Tropic of Capricorn (23.5° N to 23.5° S).

The largest tropical rainforests are located in the Amazon Basin in South America, the Congo Basin in Africa, and parts of Southeast Asia, such as Indonesia and Malaysia. Smaller rainforest regions are also found in Central America, as well as in India’s Andaman & Nicobar Islands, and the Northeastern states. Together, these areas form the world’s richest storehouse of biodiversity with rich genetic resources.

Grassland Biome

Grasslands are large open areas covered mainly with grass and very few trees. These develop in regions that receive moderate rainfall, which is not enough to support dense forests. Temperate grasslands (such as the prairies in North America and the steppes in Asia) have fertile soil and are often used for farming.

Tropical grasslands, also known as Savannas (as in Africa), have scattered trees and are home to large animals such as lions, elephants, and giraffes. Grasslands support grazing animals and are important for human activities like agriculture and livestock rearing.

Desert Biome

Deserts are the driest biomes, receiving very little rainfall. They can be hot, like the Sahara in Africa, or cold, like the Gobi in Asia. The Rann of Kutch in Gujarat is one of the world’s largest salt deserts, turning into a marshy wetland during the monsoon and a vast white salt desert during the dry season.

The extreme conditions of a desert make it difficult for life to survive; however, plants like cacti and animals such as camels, lizards, and snakes are specially adapted to these conditions. They can store water and withstand heat and dryness. Deserts often have sandy soil and sparse vegetation. Despite their harshness, they are home to unique ecosystems, and many of them also provide valuable resources such as minerals and oil.

Tundra Biome

The tundra biome is the coldest of all and is found near the Arctic and Antarctic regions. It has very long, harsh winters and short summers. The soil is frozen almost year-round - a condition called permafrost - which makes it difficult for trees to grow.

The vegetation is limited to mosses, lichens, and small shrubs. And animals, such as reindeer, arctic foxes, and polar bears, which are well adapted to survive freezing temperatures, are often found here. The tundra is fragile, and even small temperature changes can affect its ecosystem.

Aquatic Biomes

Aquatic biomes cover about three-fourths of the Earth’s surface and are divided into freshwater and marine biomes.

Freshwater biomes include rivers, lakes, ponds, and wetlands. These are crucial for agriculture, getting access to drinking water, and supporting species, such as fish, frogs, and insects.

Marine biomes include oceans, seas, and coral reefs, which are rich in biodiversity and influence the Earth’s climate by storing and distributing heat. They are also home to countless species, including whales, dolphins, fish, and plankton, and provide food and livelihood for millions of people.

Biome Pyramid

A biome pyramid is a graphical representation that illustrates the relationship between different organisms within a biome, usually in terms of energy, number, or biomass.

At the base of the pyramid are the producers, such as plants and algae, which capture solar energy through photosynthesis. The next levels consist of herbivores (primary consumers), carnivores (secondary consumers), and top predators (tertiary consumers). As we move up the pyramid, the number of organisms, biomass, and available energy decrease as energy is lost at each trophic level as heat during metabolic processes. Thus, a biome pyramid helps in understanding the structure of ecosystems, the flow of energy, and the balance between different living organisms in a biome.

Interconnectedness between Biomes and Living Beings

Biomes are closely connected to living beings because they provide a natural environment where plants, animals, and humans can survive and interact. At the same time, living beings also influence biomes - animals help in pollination and seed dispersal, humans modify landscapes for farming or cities, and microorganisms recycle nutrients. In this way, biomes and living beings are interconnected systems that depend on one another to maintain ecological balance and biodiversity.

Biodiversity

Biodiversity is the variety of life on Earth, including plants, animals, microorganisms, and the ecosystems they inhabit. It refers not only to the number of different species but also to the genetic differences within species and the variety of habitats and ecological processes that sustain life. In simple terms, biodiversity means the richness of life forms and the natural balance they create, which is essential for maintaining healthy ecosystems and supporting human survival.

Forests and Livelihoods

People, particularly rural and tribal communities, rely heavily on forests for their livelihoods. Forests provide essential resources such as food, fuel, fodder, medicine, shelter, timber, bamboo, and firewood. Non-timber forest products, such as honey, fruits, nuts, resins, and medicinal plants, help families meet daily needs and earn income.

Several communities including the Gonds and Bhils perform rituals to honour the forest deities before collecting resources, reflecting sustainable cultural practices and a deep respect for nature. Forests also support livestock grazing, small forest-based industries, ecotourism, and employment, making them vital for the livelihood, culture, and survival of many.