Ecosystem

An ecosystem may be defined as the primary functional and structural unit where various living organisms communicate with one another. In an ecosystem, living organisms and nonliving organisms exist in concurrence with each other. An English botanist named A.G.Tansley coined the term Ecosystem in 1935.

Types of ecosystem

The two basic types of the ecosystem are terrestrial ecosystem and aquatic ecosystem.
Terrestrial ecosystem

All land-based ecosystems belong to the category of terrestrial ecosystem. Based on factors such as food chains, temperature, climate, and energy flow, terrestrial ecosystems are classified into four types. The four types of the terrestrial ecosystem are discussed below.

1. Forest ecosystem: Forests are the fundamental unit of forest ecosystems. The forest ecosystems are densely packed with a wide variety of flora and fauna. The total number of living organisms present per square km is the highest in this ecosystem. Forest ecosystem plays a significant role in conserving biodiversity because they act a habitat for several rare species of animals. All living organisms exist in concurrence with other abiotic factors.

2. Desert ecosystem: Regions that generally receive rainfall less than 25cm are called deserts. With very little rainfall, desserts are generally hot during the daytime and cold during nighttime. Animals living in desert ecosystems are highly resistant to high temperatures. Plants and animals of this ecosystem need less water to survive. The organs of plants are modified so as to adapt to high temperatures. Cactus and camels are commonly seen in desert ecosystems.

3. Mountain ecosystem: A mountain ecosystem consists of regions present at a high altitude greater than the sea level. Similar to the desert ecosystem, the mountain ecosystem also has extreme climate conditions. This ecosystem is generally very cold, and the vegetation is scattered. To survive extreme cold, animals develop thick fur on their skin.

4. Grassland ecosystem: The grassland ecosystem is a little bit similar to the forest ecosystem. However, they are not as dense as forest ecosystems. The temperature of the grassland ecosystem is moderate - neither too cold nor too high. Herbivores, plants, grazing animals, and insectivores are usually found in grassland ecosystems.

Aquatic ecosystem

All water-based ecosystems belong to the category of the aquatic ecosystem. The aquatic ecosystem comprises a huge amount of biodiversity compared to the terrestrial ecosystem. All water bodies together constitute 80% of the total earth’s biodiversity. The two types of aquatic ecosystems are discussed below.

1. Marine ecosystem: Oceans and seas fall under the marine aquatic ecosystem. Almost 97% of the total water present on the earth is marine. The marine ecosystem is characterized by salty or saline water. Marine ecosystems consist of interesting biodiversity ranging from microscopic bacteria to huge whales.

2. Freshwater ecosystem: Rivers, ponds, lakes, and all other water bodies constitute the freshwater ecosystem. The total amount of water accounted for by freshwater ecosystems is 0.8%. Unlike marine ecosystems, freshwater ecosystems do not contain saline water. The freshwater ecosystem is further classified into two categories.

1. Lotic system - Water flows rapidly. Examples of the lotic system include the rivers.
2. Lentic system - Water stays stagnant. Examples of the lentic system include ponds and lakes.

Components of the ecosystem

Every ecosystem consists of two types of components - abiotic and biotic.

1. Abiotic components
Abiotic components of the ecosystem constitute the soil, land, water, and minerals. Abiotic components further include edaphic and climatic factors. All abiotic factors include temperature, pH of the soil, light, rainfall, topography, and wind.

2. Biotic components
All living organisms, irrespective of their size and type, constitute the biotic components of the ecosystem. Biotic components are further classified into four classes based on their ability to synthesize their own food.

• Primary producers: Primary producers represent organisms at the first trophic level. These organisms are capable of producing their own food and are called autotrophs. Examples of primary producers include plants and autotrophic algae.
• Primary consumers: Primary consumers represent organisms at the second trophic level. These organisms depend on other organisms for food. Living organisms belonging to this class are primarily herbivorous. Animals directly or indirectly depend on plants for food. Examples include all herbivorous animals such as goats, elephants, camels, rabbits, and so on.
• Secondary consumers: Secondary consumers represent all organisms at the third trophic level. These organisms depend on other organisms for food. Living organisms belonging to this class are primarily carnivorous. Animals depend on the flesh of other animals for food. Examples include all carnivorous animals such as cats, lions, tigers, etc.
• Tertiary consumers: Tertiary consumers represent all organisms at the fourth trophic level. Animals belonging to this class are omnivorous. Examples include humans, monkeys, etc.