Types of Ecosystem and its Functions

Key Concepts

• Ecosystem Components

• Different types of ecosystem

• Terrestrial ecosystem

• Aquatic ecosystem

• Functions of ecosystem

Introduction

An ecosystem is a community of living organisms in a particular geographic area. It is composed of biotic (living) and abiotic components (non-living). All living organisms in an ecosystem are dependent on each other either directly or indirectly. The biotic components of an ecosystem can be grouped into two types, namely,  

1. Autotrophic components  

2. Heterotrophic components 

Autotrophic components of an ecosystem include all the green plants that make use of solar energy to produce their food. 

Heterotrophic components of an ecosystem include all animals and non-green plants which take food from autotrophs. 

Types of Ecosystems: 

Ecosystem is the major structural and functional unit of ecology. Ecosystem is defined as the structural and functional unit of the biosphere, comprising living and non-living factors and their interaction. Ecosystem can be classified into different types. 

Ecosystems can be broadly classified into two types, namely,  

1. Natural Ecosystem 

2. Artificial Ecosystem 

Natural Ecosystem: 

Natural ecosystem refers to those ecosystems that occur naturally. These ecosystems do not have any interventions from human beings. Natural ecosystems have the ability to operate and maintain themselves without any human interference. They are classified into aquatic and terrestrial ecosystems. 

Artificial Ecosystem: 

Artificial ecosystem refers to a man-made ecosystem. Artificial ecosystems are observed to have some characteristics of a natural ecosystem. However, they are created and maintained by human beings. 

Example: Crop fields, aquarium, dams, gardens, parks, etc. 

Terrestrial Ecosystem: 

Terrestrial ecosystems are found only on landforms. The terrestrial ecosystem is further divided into four different categories. 

1. Forest ecosystem 

2. Desert ecosystem 

3. Grassland ecosystem 

4. Mountain ecosystem 

Forest Ecosystem:  

The forest ecosystem is rich in flora and fauna. In the forest ecosystem, a large number of organisms live in a small space. In other words, the density of living organisms is higher in this ecosystem. Based on climatic conditions, the forest ecosystem could be further sub-divided into tropical and temperate forests. 

Desert Ecosystem: 

Desert ecosystem occupies around 17% of the total land on earth. The most important features of the desert ecosystem include low precipitation, high temperatures, intense sunlight, and low availability of water. Because of these climatic conditions, flora and fauna are not much developed in the desert ecosystem. Shrubs, bushes, a few types of grass, and trees are the main vegetation found in the desert ecosystem. The stems and leaves of these plants are developed in such a way that they conserve more water. Other living creatures of this ecosystem include camels, reptiles, some insects, and birds. Not all deserts are hot. Deserts could be categorized into four different types, 

1. Hot and dry 

2. Semiarid 

3. Coastal 

4. Cold 

Grassland Ecosystem:                 

Grasslands are a geographic area where the vegetation is dominated by grasses and other herbaceous plants. Grasslands are also known as transitional landscapes. Few or no trees are found in this ecosystem. Grasslands occur naturally on all continents of the Earth except Antarctica. They contribute to around 20% of the total land surface of the Earth. Grasslands are comprised mainly of grasses, and only a very small number of trees and shrubs are found in this ecosystem. The main types of organisms found in this ecosystem include grazing animals, insectivores, and herbivores.  

Mountain Ecosystem: 

Mountain ecosystems are found on the slopes of mountains. The habitat of the mountain ecosystem is scattered and diverse. A large number of plants and animals are found in this ecosystem.  

Aquatic Ecosystem:  

Aquatic ecosystem exists in water. This ecosystem exists within a watery environment. Living organisms that exist in an aquatic environment are dependent on each other and on the surrounding watery environment. The aquatic ecosystem can be broadly classified into two types,  

1. Marine Ecosystem  

2. Freshwater Ecosystem 

Marine Ecosystem: 

Marine ecosystems are the biggest ecosystems. They cover around 71% of the total earth’s surface. The marine ecosystem contains around 97% of the total water present on earth. Marine water contains a high amount of salts and minerals. Saltwater supports different types of species than freshwater. Marine ecosystems are the most abundant types of ecosystems in the world. Marine ecosystems include oceans, tidal zones, estuaries, salt marshes, saltwater swamps, mangroves, and coral reefs.

Freshwater Ecosystem: 

Freshwater ecosystems are the smallest ecosystems. They exist in freshwater environments like lakes, ponds, rivers, streams, springs, wetlands, and swamps. Compared to the marine ecosystem, the area of freshwater ecosystem is very small. They cover only 0.8% of the Earth’s surface. Freshwater ecosystems contribute to 0.009% of the total water present on Earth. Freshwater ecosystems could be classified into three types,  

1. Lentic 

2. Lotic 

3. Wetlands 

Lentic Ecosystem: 

The term lentic is derived from the Latin word lentus (meaning: slow or motionless). Lentic refers to standing water. Lentic ecosystems include still water or slow-moving water. They host various types of plants, amphibians, and insects. In some lakes and ponds, fish species are also artificially introduced by humans. 

Example: Lakes, ponds, seasonal pools. 

Lotic Ecosystem: 

The term lentic is derived from the Latin word lotus (meaning: washing). Lotic refers to running water/flowing water. Lotic ecosystems are fast-moving water. They host various types of plants, amphibians, insects, and small fishes. 

Example: rivers and streams 

Wetland Ecosystem: 

In wetlands, the soil remains saturated for a longer period of time. Wetlands are flooded by water either permanently or seasonally. Wetland ecosystems have variations in soils, landscape, vegetation, climate, etc. Wetland ecosystems can be classified into four types, namely, 

1. Marshes 

2. Swamps 

3. Bogs  

4. Fens 

Wetlands play an important role in preventing soil erosion. They host a wide variety of species, including reptiles, fishes, and amphibians. Wetlands are the most productive ecosystems in the world. Wetlands provide habitat to around 41% of the world’s total fish species. 

Functions of Ecosystem: 

Ecosystems are complex and dynamic in nature. The important functions of ecosystems are as follows,  

1. Productivity 

2. Decomposition 

3. Energy flow 

4. Nutrient Cycling 

Productivity: 

Solar energy is the basic source of energy for the functioning of an ecosystem. Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. Secondary productivity is defined as the rate of formation of new organic matter by consumers. Primary productivity of an ecosystem depends on the plant species inhabiting the ecosystem. Factors that affect primary productivity include photosynthetic capacity of plants, nutrient availability, and several other environmental factors. Therefore, the productivity varies with different types of ecosystems. 

Decomposition: 

Decomposers (e.g.: bacteria, fungi) of the ecosystem break down complex organic materials into simple inorganic products. These inorganic materials are again used by the producers. Detritus of an ecosystem include dead plant remnants such as leaves, bark, flowers, remnants of dead animals, fecal matter, etc. These detritus undergo the process of decomposition through five important steps, namely, 

1. Fragmentation 

2. Leaching 

3. Catabolism 

4. Humification 

5. Mineralization 

Fragmentation refers to the process of breaking down detritus into smaller particles. This process is carried out by detritivores (e.g., earthworm). 

Leaching is the process by which water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.  

Catabolism refers to the process by which bacterial and fungal enzymes degrade detritus into simple inorganic substances. 

Humification and mineralization occur during decomposition in the soil. Humification leads to the accumulation of a dark colored amorphous substance called humus. Humus is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. It is colloidal in nature; it serves as a reservoir of nutrients.  

Mineralization refers to the process by which some microbes degrade humus. Breakdown of humus releases inorganic nutrients into the soil. 

Decomposition is an oxygen-dependent process. Climatic factors and the chemical composition of detritus determine the rate of decomposition. Warm and moist climatic conditions activate soil microbes, thereby enhancing the decomposition process. On the other hand, low temperature and anaerobiosis inhibit the decomposition process. Decomposition rate of detritus rich in nitrogen and water-soluble substances like sugars are faster than detritus rich in lignin and chitin. 

Energy Flow: 

Sun is the source of energy for all ecosystems except the deep-sea hydro-thermal ecosystem. Plants make use of solar energy, and through the process of photosynthesis, they manufacture their food. Energy is transmitted to various trophic levels of an ecosystem through food chain and food web. 

Nutrient Cycle: 

Nutrient cycling refers to the cyclic process through which nutrients from the physical environment gets absorbed into living organisms and then released back to the environment.  

Nutrients in an ecosystem are absorbed by the living organisms in the ecosystem. These nutrients get transferred from one trophic level to the other. After the death and decomposition of these organisms, the nutrient gets released back into the environment. This is again reabsorbed by the producers of the ecosystem. This is a natural nutrient recycling system. 

Microorganisms present in the soil play a significant role in nutrient recycling. The rate of nutrient cycling is dependent on several biotic, physical, and chemical factors.  

The four important nutrient cycles are as follows. 

1. Carbon Cycle 

2. Nitrogen Cycle 

3. Oxygen Cycle 

4. Water Cycle 

Nutrient cycles are very important for the transfer of nutrients at various trophic levels. They play a very important role in maintaining the equilibrium of an ecosystem. In simple terms, nutrient cycles act as a bridge between the biotic and abiotic components of an ecosystem. 

Summary

■ An ecosystem is a community of living organisms in a particular geographic area. It is composed of biotic (living) and abiotic components (non-living).

■ The biotic components of an ecosystem can be grouped into two types, namely, autotrophic components and heterotrophic components.

■ Ecosystems can be broadly classified into two types, namely, natural ecosystem and artificial ecosystem. • Natural ecosystems refer to those ecosystems that occur naturally.

■ Artificial ecosystems refer to man-made ecosystems.

■ Natural ecosystems can be broadly classified into two types, namely, terrestrial, and aquatic ecosystems.

■ Terrestrial ecosystems are found only on landforms. Terrestrial ecosystems are further divided into four different categories – forest, desert, grassland, and mountain.

■ Aquatic ecosystem exists in water. Aquatic ecosystems can be broadly classified into two types – marine ecosystem and freshwater ecosystem.

■ Marine ecosystems are the biggest ecosystems. They cover around 71% of the total earth’s surface. The marine ecosystem contains around 97% of the total water present on Earth. • Freshwater ecosystems are the smallest ecosystems. They exist in freshwater environments like lakes, ponds, rivers, streams, springs, wetlands, and swamps. • Ecosystems are complex and dynamic in nature. The important functions of ecosystems are productivity, decomposition, energy flow and nutrient cycling.