An ecosystem is a unified system composed of biotic (living) and abiotic (non-living) components, which function together. Examples of ecosystems include littoral zone, coral reef, soil, forest, grassland, pond, and urban areas.
This article gives a comprehensive introduction of the concept of ecosystem, as outlined below;
Ecosystem Meaning and Definition
Ecosystem is a system in which living organisms interact with the non-living features, conditions and processes of their environment.
An ecosystem can also be described as a biological community in which living organisms co-habit and interact with each other, and with their habitat.
It is important to note that the definition of ecosystem may vary, as it is a broad concept that can be viewed from a variety of perspectives.
For example, the term ‘habitat’, as used in the definition of ecosystem above; may be either natural or man-made. The ‘interactions’ which occur in this habitat(s) may also vary from naturally-occurring physical, chemical or biological processes to anthropogenic influences.
However, there are some factors which are commonly considered in any definition of ecosystem. These factors include the components of the system; which are biotic and abiotic; as well as the interactions between these components.
Also, an ecosystem exists only when the interactions between the components of the system are unified; such that these components depend upon, and support; each other.
An ecosystem is commonly viewed as a biological community. In this case, the components of the system are plants, animals and their environment or habitat.
The interactions between these components will also include feeding, reproduction, food production, and finding shelter.
When viewed from a biological perspective, the definition of an ecosystem may involve some other concepts like energy pyramid, symbiosis, parasitism, and commensalism.
There are other perspectives from which ecosystem can be defined. These include the fields of ecology and geography. Within the eco-geographical context, the ecosystem can be seen as a geographic area in which living organisms co-exist.
Components of an Ecosystem
The two components of an ecosystem are biotic (living) and abiotic (non-living) components respectively.
Also known as biotic factors, the biotic components of an ecosystem are the living or organic components of the ecosystem.
Biotic Components are living components which contribute to the processes that occur in an ecosystem. These components influence both the living and non-living aspects of the ecosystem, either directly or indirectly.
There are various ways by which the biotic components of an ecosystem can be categorized. One of these is based on cell structure.
Two categories of biotic components based on cell structure include the Prokaryotes and Eukaryotes.
Eukaryotes on the other hand, are relatively complex organisms, composed of cells whose organelles are typically bounded by membranes. Examples include protists, fungi, plants and animals .
The biotic components of an ecosystem may also be classified on the basis of energy-transfer pathways.
This identifies groups such as Primary Producers (plants), Primary Consumers (herbivores), Secondary Consumers (small carnivores), Tertiary Consumers (large carnivores), Apex Predators (omnivores), and decomposers (e.g.; bacteria).
An overview of the energy flow pattern among these groups is simplified and represented by the energy pyramid.
Biotic components play various roles in an ecosystem. These range from the supply of energy to the system; to the facilitation of several processes that ensure the continuity of the ecosystem as a whole.
Abiotic Components of an ecosystem include all inorganic and non-living factors. Examples of these include water, soil, atmospheric gases and minerals. The features of the environment in which biotic components exist, may all be classified under the abiotic category.
There are also some roles which are played by abiotic components in an ecosystem. These roles include the provision of nutrients which are needed by living organisms, as well as the provision of a habitat for these organisms to live.
Origin and Nature of the Ecosystem Concept
Roy Clapham, who is credited with having coined the term ‘ecosystem’ in 1930 , provides some insight into the original ideology behind the concept. Ecosystem derives from two Ancient Greek words;“οἶκος” (“oîkos”) for “house” and “σύστημα” (“sústēma”) for “organized body”.
This suggests that the concept of the ecosystem relates to an organized unit comprising of interrelated components, which make up a body. Our definitions so far also portray this perspective.
When we consider an ecosystem to an organized unit, we must consider that there are various possible levels of organization. This in turn means that there are various possible definitions of an ecosystem.
Ecosystem may occur at the individual, species, population and community levels.
At the individual level; an ecosystem refers to a system in which an organism interacts with its environment.
At the species level; an ecosystem will include a group of organisms of the same specie which are interacting with each other and with their environment.
At the population level, we may describe an ecosystem as a system comprised of a population of organisms and the processes which affect them in their environment.
At the community level; an ecosystem is simply a unified system which is sustained through the interactions between a biotic community, and the abiotic components of their environment.
In fact, the ultimate goal of sustainable development is to ensure that the processes which lead to continuity of the global ecosystem, continue to occur without significant negative effects on the environment or the living population. These processes are mainly the production, exploitation, distribution and use of natural resources.
An ecosystem does not necessarily have defined boundaries in all cases. This is because it usually occurs as an open system, into, or out of, which energy may flow. What this means is that the entire Earth, and in fact the Universe, is an ecosystem.
However, for the purpose of simplicity, we often impose boundaries on an ecosystem in order to be able to define it. These boundaries may be biological, chemical, physical or geographic.
Based on the boundary-definition approach, there are various types and examples of ecosystems. The latter is discussed in the following section of this article
Examples of Ecosystem
Examples of an ecosystem include a pond, a cave, a river, a forest, a swamp, a desert, a grassland region, and a coral reef.
What these examples suggest, is that an ecosystem is represented by any given environment in which living organisms coexist. Some ecosystem examples are discussed below;
1). Forest Ecosystem
A forest is an example of a natural ecosystem.
It is basically a geographic area (abiotic component) dominated by trees (biotic component).
The trees and the geographic features of this ecosystem constitute a habitat for other living organisms, usually cutting across all or most of the major trophic levels of the energy pyramid (primary producers, primary consumers, secondary consumers, tertiary consumers, and apex predators).
Different types of forest exist. Temperate forests are an example.
Temperate forests represent an ecosystem which comprises of deciduous and coniferous trees, as well as smaller plants, animals and geographic features typical of temperate regions.
The deciduous trees are known to shed their leaves in autumn, while most coniferous trees remain relatively unchanged throughout the year.
Animals in temperate forests include hedgehogs, squirrels, deer, foxes, bears and earthworms. This type of forest ecosystem occurs in parts of Europe, as well as the United States .
Another type of forest ecosystem is the tropical rainforest.
As the name implies, tropical rainforests occur mainly in tropical regions. A high level of diversity can be observed in this ecosystem, in terms of the occurrence of various plant and animal species .
One of the causes of this great diversity, is the presence of relatively abundant precipitation in tropical rainforests. This leads to dense growth of vegetation, so that trees are forced to grow to great heights in order to gain access to sunlight for photosynthesis and survival.
The dense canopy of vegetation creates a suitable environment for various species to thrive. Organisms which commonly occur in tropical forests include sloths, monkeys, apes, snakes and jaguars. Parasitic plants (like Rafflesia) and other types of non-parasitic vegetation that require structural support (like Epiphytes) are also common in tropical rainforests.
Boreal forest or Taiga, is yet another type of forest ecosystem. It occurs predominantly in the cold, northern regions of the world.
Organisms in this ecosystem include coniferous trees like spruce, and animals like red squirrel, elk, caribou, lynx, beaver and black bear.
2). Grassland Ecosystem
As the name implies, grassland ecosystems are geographic regions where the dominant vegetation is grass, alongside other herbaceous plant-species that are closely related to grass .
The climatic condition of grassland ecosystems is usually semi-arid. This prevents large trees and dense population from growing, as is the case in tropical rainforests.
Because of the near-absence of trees across a vast land area, grasslands are also often referred to as plains. This type of ecosystem is estimated to occupy about 20-40 percent of the total land area on Earth.
Organisms which thrive in grassland areas, are those which are adapted to the climate and vegetation in these zones. They include ant, bee, earthworm, ground squirrel, mole, buffalo, giraffe, elephant, hyena, leopard, snake, coyote, fox, and lion.
Grassland ecosystem may occur across various geographic regions including parts of Africa, America and Europe. The growing rate of urbanization and the spread of human settlements is a huge threat to grassland ecosystems, as these areas are easily converted to industrial and residential areas.
A desert ecosystem typically has drier and harsher climatic conditions than grasslands.
Low precipitation and high evaporation (and evapotranspiration) are some major climatic attributes of deserts.
Annual rainfall is usually no more than 10 inches in a desert ecosystem . Temperatures during the day occur at an average of 38°C, while at night these temperatures are at an average of -3.9°C.
A desert ecosystem may occur in temperate or tropical regions. They are characterized by sparse vegetation, and relatively low diversity of organic species. Geographic (environmental) features of deserts include dry soil, dunes, plateaus, plains, and weathered rocks.
Organisms which coexist in deserts include plants such as cactus, agave, brittlebrush, halfmen, aloe vera and tumble weed; and animals such as scorpions, rattlesnakes, lizards, and meercats.
4). Coral Reefs
A coral reef is basically a marine ecosystem formed by corals.
It is known to harbor a wide variety of aquatic species and has been referred to as the rainforest of the ocean .
Only a small portion of less than 1 percent of the ocean floor is occupied by coral reefs .
However, they are said to account for the survival of up to one-quarter (25 percent) of the entire marine population . The dependence of these organisms on coral reefs may be in terms of food, breeding, or shelter, or a combination of these.
With regards to biodiversity, coral reefs serve as a habitat to up to 700 coral species, more than 4,000 fish species , and a large number of crustaceans, mollusks, echinoderms, annelids, and porifera (sponges).
Generally, coral reefs occur at shallow depth in the ocean. This is because they are predominantly composed of carbonaceous material and will dissolve at great depth.
A coral reef ecosystem can also be divided into four categories based on their mode of formation, geometry and relative position. These four categories of coral reefs include fringing reefs, patch reefs, barrier reefs and atolls.
Geographically, tundra ecosystems occur in polar regions and at high altitude .
Climatic conditions in these regions are mostly windy and cold. In spite of the harsh nature of tundra ecosystems, some organisms are known to occur here. These include wildflowers, lichen, arctic hare, caribou, vole, lemming, arctic fox, polar bear, salmon, raven, blackfly and moth.
Most of these organisms are able to thrive in the tundra ecosystem due to the presence of a brief season during which temperatures become less cold.
6). Still-Water Ecosystem
‘Still-water’ can.be used to refer to any aquatic ecosystem in which the water column does not experience any significant flow over long periods of time.
Examples which fall within this category include a swamp, lake, lagoon or marsh.
One of the characteristics of a still-water ecosystem is relatively poor rate of circulation of oxygen and nutrients. However, some organisms are known to thrive in this ecosystem.
Examples of such organisms include plankton, algae, and some aquatic plants like lilies. These organisms are all adapted to the still, oxygen-deficient nature of the ecosystem.
7). Flowing-Water Ecosystem
Obviously, the flowing-water ecosystem is the opposite of still-water ecosystems.
Contrary to still-water, a flowing-water ecosystem is an aquatic ecosystem in which there is a significant amount of water motion over time.
The rate of flow of water may vary from one ecosystem to another. However, in all cases, this flow brings about the distribution of important materials like oxygen and nutrients within the ecosystem. As a result, the flowing-water ecosystem typically has a larger supply of these materials.
Biodiversity in flowing-water ecosystems is usually much broader than that of still-water. This is because the presence of larger amounts of oxygen and nutrients enable more organisms to survive.
Examples which fall under this category include rivers and streams. Organisms which thrive in flowing-water ecosystem include plants like bladderwort and hydrilla, and animals like fish, turtle, crocodile, and crab.
8). Urban Ecosystem
As the name implies; an urban ecosystem is an ecosystem which occurs within an urban area.
It is human-dominated, and comprises of the artificial, developed environment and its occupants.
Another way to describe the urban ecosystem, is as a system which is composed of manmade environmental features and the living organisms which occupy the manmade environment.
Urban areas are cities, which have been altered from their natural configuration by humans who inhabit these areas. The urban ecosystem is relatively complex, as it usually contains various infrastructure which are installed to meet the numerous needs of the population.
Cultivated land, urban forests, and parks, lawns, and artificial resorts all represent the urban ecosystem. This system plays host to other organisms aside humans; including birds, mammals and reptiles.
An ecosystem is a natural or manmade system which comprises of living organisms that interact effectively with each other as well as with their environment.
It is generally a unified system, as all components contribute in one way or another, toward the continuity of the entire system.
There are two main components of an ecosystem. These are the biotic components and the abiotic components.
Biotic components include all living organisms in the ecosystem, such as plants; animals and simpler organisms (prokaryotes).
The abiotic components of the ecosystem include all non-living components of the system such as soil, water and nutrients.
An ecosystem may be defined from a variety of perspectives. Some of these include the individual, population and community levels.
What this implies is that the boundaries of an ecosystem may be defined based on geographic area, species occurrence, population/community occurrence, among other factors.
There are different examples which can be used to describe an ecosystem.
Examples of ecosystem include;
1. Forest Ecosystem
2. Grassland Ecosystem
3. Desert Ecosystem
4. Coral Reefs
5. Tundra Ecosystem
6. Still-Water Ecosystem
7. Flowing-Water Ecosystem
8. Urban Ecosystem
Each of these examples represents a unified system of organisms which coexist in a given environment. The vast disparity between the examples of ecosystems also indicates that an ecosystem can be delineated on the basis of any of a group of multiple factors, as earlier stated.
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