Ecosystem Definition

An ecosystem is a community of living and non-living things that interact with each other in a specific environment. It is a complex network of relationships between organisms, their physical surroundings, and the processes that shape and maintain the system. Living organisms, such as plants, animals, and microorganisms, depend on each other and the non-living components of the environment for survival. These non-living components include air, water, soil, and sunlight. Together, these living and non-living components make up an ecosystem's biotic and abiotic elements.

Figure 1. A typical type of ecosystem

The interactions between these elements create the functions of an ecosystem. The food web is called the energy flow through the ecosystem, starting with the sun and moving through plants to herbivores and carnivores. Cycling nutrients, such as carbon, nitrogen, and water, is another important ecosystem function.

Properties of ecosystem

• The ecosystem also helps to maintain homeostasis, which is the ability to resist change and maintain a balance within the system.
• Additionally, ecosystems can recover from disturbances, which is called resilience.
• Ecosystems also provide a variety of services that are essential for human well-being. Biodiversity, the variety of living organisms within an ecosystem, provides goods such as food, medicine, and recreation. Ecosystem services, such as water purification, climate regulation, and pollination, are also provided by biodiversity.
• Human activities have a significant impact on ecosystems. Habitat destruction and fragmentation, caused by activities such as logging and urbanization, can lead to a loss of biodiversity. Climate change and pollution can also severely affect ecosystems and the organisms that depend on them. The loss of biodiversity can also lead to the collapse of ecosystems and the loss of their critical services.
• Ecosystem conservation and management are essential to protect and maintain the planet's health and human well-being. Protected areas and conservation biology are used to conserve biodiversity and ecosystem services. Restoration and rewilding are used to restore degraded ecosystems. Sustainable use and community-based conservation are used to balance the needs of people and the environment.

So, an ecosystem is a complex and interconnected system with living and non-living components that interact to sustain the system's balance, resilience, and biodiversity. The services provided by the ecosystem are crucial for human well-being, and their preservation is vital for the planet's health.

Types of Ecosystem

1. Terrestrial Ecosystem

Terrestrial ecosystems refer to ecosystems that occur on land, as opposed to aquatic ecosystems, which occur in water. These ecosystems are characterized by living organisms, such as plants, animals, and microorganisms, that interact with each other and with the non-living components of the environment, such as soil, water, air, and sunlight.

Figure 2 Terrestrial ecosystems

Some examples of different terrestrial ecosystems include:

• Forest ecosystems

These are characterized by the presence of trees and other vegetation and can be found in regions worldwide, such as tropical rainforests, temperate forests, and boreal forests.

• Grassland ecosystems

These are characterized by grasses and other herbaceous plants and can be found in regions such as the prairies of North America, the savannas of Africa, and the pampas of South America.

• Desert ecosystems

These are characterized by arid conditions, with little precipitation and high temperatures. They can be found in hot and cold regions, such as the Sahara, Gobi, and Atacama deserts.

• Mountain ecosystems: These are characterized by high elevations and can be found in regions such as the Himalayas, the Andes, and the Rockies.

2. Aquatic ecosystems

Aquatic ecosystems are ecosystems based on water, whether saltwater or Freshwater. They support a diverse array of organisms and play a critical role in maintaining the planet's biodiversity and overall ecological health.

Figure3 Aquatic Ecosystems

There are many subparts of aquatic ecosystems:

• Marine ecosystems

Marine ecosystems are found in saltwater environments, such as oceans, coral reefs, and estuaries. They are the largest aquatic ecosystems and cover about 71% of the Earth's surface. Marine ecosystems are characterized by their high productivity, which is driven by the intense solar radiation and the presence of phytoplankton, which form the base of the food web. Marine ecosystems support various organisms, including fish, marine mammals, and plankton. Coral reefs are a unique and important type of marine ecosystem formed by the accumulation of calcium carbonate skeletons of coral animals. Coral reefs support a rich diversity of marine life and are important habitats for many species of fish, mollusks, crustaceans, and other invertebrates.

• Freshwater ecosystems

Freshwater ecosystems are found in Freshwater environments, such as lakes, rivers, and streams. They are smaller and less productive than marine ecosystems but support diverse organisms. Freshwater ecosystems are characterized by their lower salinity and varying dissolved oxygen levels. There are numerous fish species there. Amphibians, aquatic plants, and microorganisms play a vital role in nutrient cycling. Rivers and streams are dynamic ecosystems shaped by the flow of water and the geology of their surroundings. They support various organisms, including fish, insects, and plants. Lakes are relatively stable ecosystems characterized by their relatively calm waters and large size. They support multiple organisms, including fish, amphibians, and aquatic plants.

• Estuarine ecosystems

Estuarine ecosystems are found where Freshwater and saltwater meet, such as in bays, lagoons, and delta areas. They are characterized by their fluctuating salinity levels and support a unique and diverse array of organisms adapted to these conditions. Estuaries are nurseries for many fish and shellfish species and are important habitats for migratory birds. Estuaries are also an important source of food and livelihood for many human communities.

• Wetlands ecosystems

Wetland ecosystems are characterized by water-saturated soils and include marshes, swamps, and bogs. They are highly productive ecosystems that support various organisms, including birds, fish, and amphibians. Wetlands also play a critical role in water purification, flood control, and carbon sequestration.

• Coastal zone

The littoral zone is the shallow zone near the shore, where the water is not very deep, and sunlight can reach the bottom. It is home to many aquatic plants and animals adapted to this environment. Many fish, shellfish, and other aquatic organisms live in the coastal zone and are an important food source for many animals.

• Pelagic zone

The pelagic zone is the deep open water zone in the ocean, where sunlight does not reach the bottom, and the water is very cold and dark. It is home to many fish and other marine organisms adapted to living in this environment.

• Benthic zone

The benthic zone is the zone of the ocean floor, where the bottom is covered by sand, rock, or mud. It is home to many organisms adapted to living in this environment, such as worms, clams, crabs, and starfish.

Important Terms of Ecosystems

1. Biodiversity

The variety of living things is referred to as biodiversity. An ecosystem includes species, genetic diversity within species, and ecosystems. Biodiversity is important for maintaining ecosystems' health and resilience and providing a wide range of ecosystem services.

2. Ecosystem services

Ecosystem services are the advantages humans derive from ecosystems, such as air and water purification, climate regulation, and food production. Ecosystem services are critical for human well-being and sustainable development.

3. Ecological succession

The process of progressive change in the environment of change in an ecosystem's species composition and structure over time. It is driven by the interactions between the organisms in the ecosystem and their physical environment.

4. Food Network

A food network is a diagram showing an ecosystem's flow of energy and nutrients. It illustrates the relationships between the organisms in an ecosystem, including who eats whom and how energy is transferred from one organism to another.

5. Keystone species

A keystone species plays a disproportionately large role in maintaining the structure and function of an ecosystem. Keystone species help regulate populations of other species and help preserve the ecosystem's biodiversity.

6. Niche

A niche is the role and position of a species in an ecosystem, including the range of physical and biological conditions in which a species can survive and the resources it uses.

7. Habitat

Habitat is the physical and biological environment in which a species lives, including the range of conditions that a species needs to survive and reproduce.

8. Adaptation

Adaptation refers to how organisms evolve to survive better and reproduce in their environment. This can include physical, behavioral, and genetic changes that help an organism stay in a specific environment.

9. Climate change

Climate change is the long-term alteration of the typical weather patterns that characterize local, regional, and global climates on Earth. The main human activities contributing to climate change include land use changes, the combustion of fossil fuels, and deforestation.

Interactions in Ecosystems

Interaction in an ecosystem refers to how different organisms and their physical environment interact and influence one another. These interactions can be grouped into several categories.

1. Biotic interactions: Biotic interactions refer to the interactions between living organisms within an ecosystem. These interactions can include competition, predation, symbiosis, and interdependence.

• Competition occurs when two or more organisms are vying for the same limited resource, such as food, water, or mating partners. This can lead to a decrease in population size or a change in the distribution of organisms within the ecosystem. For example, two plant species growing in the same area may compete for sunlight, water, or soil nutrients, affecting their growth and survival.
• Predation occurs when one organism (the predator) hunts and kills another organism (the prey) for food. This relationship can significantly impact the populations of both the predator and the prey. For example, predators such as lions or wolves help control the population of their prey, such as zebras or deer.
• Symbiosis is a close relationship between two or more different organisms. Symbiosis can be mutualistic when both organisms benefit.
• Interdependence is when one organism benefits and the other is neither helped nor harmed, or parasitic is when one organism benefits at the expense of the other. For example, nitrogen-fixing bacteria living in the root nodules of legumes, such as soybeans and peas, help the plant to convert atmospheric nitrogen into a form that the plant can use. In contrast, the bacteria receive a home and nutrients from the plant.

2. Abiotic interactions: Abiotic interactions refer to the interactions between living organisms and the non-living components of the environment, such as temperature, light, water, and nutrient availability. These interactions can affect the survival, growth, and reproduction of organisms. For example, a plant's growth rate and survival are influenced by the amount of sunlight and water it receives. Additionally, the temperature can affect the physiology of an organism; for example, cold-blooded animals are affected by the temperature of their environment, which can affect their metabolism, reproduction, and movements.

Overall, understanding the biotic and abiotic interactions in an ecosystem is crucial for understanding how the ecosystem functions and how it may respond to environmental changes.

Functions of an Ecosystem

1. Energy flow and nutrient cycling

One of the most crucial processes in an ecosystem is the cycling of nutrients and energy. They maintain the ecosystem's stability and balance while ensuring a constant flow of energy and nutrients.

An ecosystem's energy flow is transported from the sun through producers like plants to consumers like herbivores and predators. All life on Earth derives its primary energy from the sun, and through photosynthesis, producers can take this energy and transform it into organic matter. The energy is passed from one organism to another when consumers eat this organic material.

A portion of the energy transferred from one organism to another may be lost as heat. Trophic cascade, a process of energy transmission and loss, ensures that the top consumers in the ecosystem, such as carnivores, only receive a small portion of the sun's energy in the end.

Another crucial ecological process is nutrient cycling. Chemical substances like carbon, nitrogen, phosphorus, and sulfur are examples of nutrients. They circulate continuously from the soil and air to the plants and, eventually, the animals in the ecosystem. By ensuring that they are accessible to all living things, the cycling of these elements contributes to maintaining the ecosystem's balance and health.

Beginning with the release of nutrients from the soil and air by decomposers like bacteria and fungi that break down decaying organic matter, the process of nutrient cycling begins. Plants then absorb the nutrients and incorporate them into their tissues. The nutrients are transferred to the tissues of herbivores when they eat plants and are further transferred up the food chain when carnivores eat them.

For plants to absorb and restart the cycle, nutrients must also be returned to the soil and air as part of the nutrient cycling process. The ecosystem is continuously supplied with the necessary components for all living things thanks to a process known as nutrient cycling.

So, energy flow and nutrient cycling are two crucial ecological processes that guarantee a steady supply of energy and nutrients and support the ecosystem's stability and balance. These processes are vital for the growth and survival of all living things in the ecosystem and are also necessary for the planet's overall health.

2. Biodiversity

Biodiversity, as the name indicates made up of two words, 'bio' and 'diversity', which means" the existence of several different kinds of animals and plants which together make a good and healthy environment."

The variety of life is not evenly spread around the planet; often, it is higher in the tropics because of the warm climate and abundant primary production there. Tropical forest habitats, which occupy less than ten percent of the planet's surface and are home to 90% of all species, are present. More marine biodiversity may frequently be found in the mid-latitudinal band of all oceans and on the Western Pacific coast, where the sea surface temperature is highest. There are latitudinal differences in the diversity of species. The pace of biodiversity has been increasing over time, and it tends to concentrate in hotspots, although it is anticipated to slow down in the next years due to deforestation. Evolution, ecology, and cultural processes are all biological processes that are included.

Acute climate changes are typically the cause of mass extinctions. More than 99.9% of all species that have ever existed on Earth, or five billion, are considered extinct. On Earth today, there are believed to be between 10 million and 14 million species, of which 1.2 million have been discovered, and more than 86% have not yet been given a name. On Earth, there are 5.0 x 1037 linked DNA base pairs, or 50 billion metric tons, according to estimates. According to estimates, the biosphere may hold up to four trillion metric tons of carbon in total. In July 2016, researchers found a collection of 355 genes from the last universal common ancestor (LUCA) of all Earthly life.

3. Habitat and niche

A species' home is the particular environment where it lives and finds the resources and conditions required for life and reproduction. It may be a terrestrial, aquatic, or atmospheric environment and contain various biotic and abiotic elements, including temperature, light, water, soil, and food sources. The environment offers the resources needed for the creature to develop, generate offspring, and perform other life-sustaining activities.

The term "niche" describes an organism's particular function in its ecosystem, including its connections with other creatures, the resources it uses, and the effects it has on the surrounding area. An organism's interactions with its environment and other species within the ecosystem are distinctive and particular. A species may fit into both a predatory and a scavenging niche. For instance, a lion has a niche as both a predator, going after and eating other animals, and a scavenger, going after and eating dead animals. An organism's niche dictates its place in the ecosystem. It affects the environment, including how it participates in the food chain, moves nutrients and energy around the ecosystem, and controls population growth and natural cycles.

4. Regulation of climate and natural cycles

Ecosystems are essential for maintaining natural cycles, such as the cycles of water, carbon, and nutrients, as well as for controlling local and regional climates. This function of ecosystems ensures the stability of the ecosystem over time and aids in keeping the environment in balance.

• Regulation of the water cycle: Plants release water vapor through transpiration, which helps to control the water supply, while roots absorb water, which helps to prevent flooding.
• Controlling carbon cycle: Ecosystems control the carbon cycle by taking carbon dioxide out of the atmosphere through photosynthesis and returning it through respiration and breakdown. This assists in regulating atmospheric carbon dioxide concentrations and reducing the effects of climate change.
• The flow of resources: Ecosystems control the flow of resources by decomposing dead organic matter, releasing nutrients into the soil, and absorbing nutrients through plant roots. These nutrients can then be transferred to other creatures through the food chain. This helps to prevent nutrient pollution and preserve the ecosystem's nutritional balance.

Overall, ecosystems' ability to control the climate and natural cycles is essential to preserving the planet's stability and health.

5. Waste management

Ecosystems naturally treat waste by breaking down waste products and returning nutrients to the environment through various processes, such as decomposition and mineralization. This helps to maintain the balance of nutrients in the ecosystem and prevent pollution.

• Decomposition: Decomposition is the process by which dead organic matter is broken down into smaller components by decomposers, such as bacteria and fungi. It releases essential nutrients into the soil, which plants can take up and recycle into the ecosystem.
• Mineralization: Mineralization is the process by which organic matter is converted into inorganic substances, such as carbon dioxide, nitrogen, and phosphorus, by decomposers. This helps to maintain the balance of nutrients in the ecosystem and prevent nutrient pollution.
• Filtering: Wetlands and other ecosystems can act as filters, removing pollutants and excess nutrients from water before it is returned to the environment. Overall, the waste treatment function of ecosystems helps to maintain the balance of nutrients in the ecosystem and prevent pollution, ensuring the health and stability of the ecosystem over time.