Introduction

An ecosystem comprises all the organisms and also the physical environment with which they interact. Both of these biotic and abiotic components are linked together via nutrient cycles and energy flows. Energy enters the system via photosynthesis and is then incorporated into the plant tissues. After feeding on plants and on one another, animals play a significant role in the movement of matter and energy in the system. They also help in influencing the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back into the atmosphere and facilitate nutrient cycling by converting all the nutrients stored in dead biomass back to a form which can be readily used by plants and microbes.

Natural Ecosystem

The natural ecosystem refers to a community of living and non-living organisms, in which each and every component interacts together as a single unit via biological, physical and chemical processes. The major distinctiveness of natural ecosystems is that their formations are purely natural and are not in any way influenced by any human activity. There are mainly two major types of natural ecosystems prevailing on Earth: aquatic and terrestrial. Each of these categories are broken down further into more different types of ecosystems.

Aquatic Ecosystem

The living things present in an aquatic ecosystem can only survive in the water. There are mainly two types of aquatic ecosystems: freshwater and marine. Freshwater describes any body of water that does not contain saltwater or only possess a small quantity of salt in the water. Marine ecosystems in contrast exist in saltwater. It comprises coral reefs, tidal zones, kelp forests, mangroves, salt marshes, open ocean, rocky shores, deep-sea etc.

Examples of some natural aquatic ecosystems are:

• Natural Ponds and Lakes: The Great Lakes represents five freshwater lakes in east-central North America.
• Natural Rivers and Streams: The Nile River in Africa comprises freshwater and is one of the longest rivers in the world.
• Natural Seas and Oceans: The Earth possesses only one saltwater ocean that is mainly divided into five ocean basins: the Atlantic, Pacific, Indian, Arctic, and Southern oceans.
• Natural Estuaries: places such as the San Francisco Bay in California is the one where freshwater meets saltwater.
• Natural Wetlands: Wetlands are shallow bodies of water like, marshes, swamps, bogs and mudflats. Water flow remains  steady in freshwater wetlands. They help in providing habitat for many plants and animals. E.g. the Bolsa Chica Ecological Reserve in Orange County, California.
• Coral Reefs: these exist in shallow parts of some tropical oceans. Coral reefs are made of calcified remains of coral animals that build up over time and provide habitat for many underwater species. E.g. The Great Barrier Reef of Australia.

Terrestrial Ecosystem

A terrestrial ecosystem refers to a community of living and nonliving things that works together as a single unit on land. They live and grow in the soil and air around them.

There are mainly four types of natural terrestrial ecosystems:

• Forest – it is mostly made up of dense trees and an abundance of plant species.
• Desert – it is marked by an extremely low rainfall, but not necessarily a hot climate.
• Grassland – this includes an almost continuous cover of grasses, but not several taller plants.
• Mountain – mountain features steep elevation changes in the terrain.

These types of ecosystems are further broken down into seven similar types of biomes they are discussed as follows:

• Tropical Rainforest: Hot, moist biomes such as the Amazon jungle in South America receive a lot of precipitation.
• Deciduous Forest: forests in Great Smoky Mountains National Park in North Carolina and Tennessee are mainly made up of trees that lose their leaves only seasonally.
• Coniferous Forest: forests like the ones in Birch River Wildland Provincial Park in Alberta, Canada suffer from cold winters and humid summers. They are entirely filled with trees that produce cones and needles. Coniferous trees are sometimes known as evergreen trees.
• Temperate Grassland: grasslands including many varieties of grasses with hot summers and cold winters, such as the North American prairies.
• Tundra: frozen subsoil restricts tall trees from growing in tundra regions such as the Arctic Tundra.
• Savanna: mixed woodland and grassland regions such as the Serengeti in Tanzania and Kenya comprises trees that are spread far apart.
• Desert: these are the areas with very little precipitation such as the Sahara Desert in Africa makes it tougher for plants and animals to survive.

Components of Natural Ecosystem

Every ecosystem possesses four main components that make it function. These components are as follows:

• Biotic components
• Abiotic components
• Flow of energy
• Cycling of nutrients

Biotic Components of an Ecosystem

The biotic components of any ecosystem represent all the living things present in that group. E.g. of biotic components involves plants, animals, and micro-organisms such as bacteria. All living things present in an ecosystem are classified into producers, consumers, or decomposers. Plants come under producers since they can make their own food and provide food to other living things. Whereas, animals are examples of consumers as they can’t make their own food and have to eat other plants and animals to survive. Fungus comes under decomposers as it mostly eats dead organisms.

Abiotic Components of an Ecosystem

The abiotic components of an ecosystem comprises mainly all the non-living things in that group. These elements provide the living things everything they need to survive and thrive. E.g. of abiotic components include:

• Soil
• Air
• Water
• Rocks
• Temperature
• Sunlight

Energy Flow in an Ecosystem

• The sun is the main source of energy for nearly most of the ecosystems. It acts as the starting point for the flow of energy in an ecosystem.
• Producers use this sunlight to make their own food and convert carbon dioxide into oxygen.
• Some animals like herbivores and omnivores feed upon producers (plants) so that they can live. Energy is being recycled in each step. 
• Some animals like carnivores eat other animals.  
• Herbivores, omnivores and carnivores all leave behind their waste after they eat. Their bodies also become “waste” when they die.
• Decomposers break down the waste and return nutrients to the soil. This leads to the release of energy into the ecosystem.
• Producers again use nutrients from the soil for their survival, and the cycle repeats itself.

Cycling of Nutrients

The chemicals that organisms take pass through the food chain and back to the soil, air, and water. All of these chemicals and the new forms they take as they’re used and spread provides nourishment, or nutrients, to the ecosystem. Example of one such nutrient cycle in an ecosystem is the nitrogen cycle

Conclusion

One of the major points of differences between natural and artificial ecosystems is that the artificial ecosystem needs constant attention as they are not self-sustainable. Examples of such a type of ecosystem include aquariums, crop fields, gardens, dams, etc. Here we come to an end of this topic. We hope that you were able to grasp a clear concept of the topic of the natural ecosystem, its types, characteristics and components.