The key systems that underpin all of ecology.

Biotic and Abiotic components

Definition of Ecosystems

An ecosystem is a complex network of living and non-living components that interact with each other.

Biotic components are the living organisms, such as plants, animals, fungi and bacteria. Abiotic components are the non-living elements in an environment, such as climate, soil type and topography. These two types of components interact to form a dynamic system where energy flows between components.

When an ecosystem is balanced or in equilibrium it is able to remain stable over time. For example, when predators hunt their prey they help keep populations in check so that resources are not depleted too quickly by any single species. This relationship is illustrated well by the Canada Lynx preying on the Snowshoe hare. The tight predator-prey relationship between the two animals mean that the populations are kept in balance. In this way ecosystems can maintain their balance.


Although ecosystems can be resilient, their equilibrium can be threatened when faced with external pressures like climate change or human interference. These can push the system into disequilibrium. For example, if coral reefs are subject to rising temperatures, pollution or ocean acidification, the corals can be damaged – often with disastrous consequences for the reef ecosystem.

Types of Ecosystems

Terrestrial and aquatic ecosystems are two distinct types of ecosystems. Terrestrial ecosystems are those that exist on land, such as forests, grasslands, tundra and deserts. Aquatic ecosystems can be divided into freshwater and marine systems. Freshwater systems include rivers, streams, lakes and wetlands while marine systems encompass oceans and estuaries – a transition between the fresh water of land and the salt water of the ocean.


Freshwater ecosystems have a unique set of characteristics due to their low salinity levels which allow for the growth of different species than in salt water environments. Marine habitats also contain a wide variety of organisms adapted to living in salt water conditions. The diversity of life found in these environments is essential for maintaining healthy oceanic food webs which support larger predators like whales or sharks at the top level.

Terrestrial habitats vary greatly depending on climate conditions with each type providing its own unique resources for plants and animals alike. Tundras, for example, are characterized by cold temperatures but still host an array of wildlife adapted to survive in this environment while deserts may appear barren but actually contain numerous species capable of surviving long periods without rainfall or other forms of moisture.

Components of Ecosystems

Ecosystems are composed of both biotic and abiotic components. Biotic components refer to the living organisms in an environment, such as plants, animals, fungi and bacteria. These can be further divided into producers, consumers and decomposers.

Producers such as plants use energy from the sun or chemical reactions to create their own food sources. Consumers rely on other organisms for sustenance, whether they are plant-eating herbivores such as gazelles, generalist omnivores such as bears or meat-eating predators such as lions.

Decomposers break down organic matter into simpler forms that can then be used by producers again. Many decomposers are microscopic – including bacteria and protozoa. However, some decomposers are large enough to see with the naked eye – including fungi and invertebrates such as earthworms.


Abiotic components are non-living elements in an ecosystem such as climate, soil type and water availability which interact with biotic components to form a dynamic system where energy flows from one component to another. Examples of abiotic factors include temperature, light intensity, humidity levels and nutrient availability which all affect how species interact within an ecosystem.

Food Chains and Food Webs

Food chains are linear pathways of energy flow in an ecosystem, showing how energy is transferred from one organism to another. They begin with a producer, such as a plant or algae, which uses the sun’s energy to create its own food source. This food is then consumed by primary consumers such as herbivores and omnivores.

Secondary consumers feed on these primary consumers and tertiary consumers feed on secondary ones. At each level of the chain, some energy is lost through respiration and excretion processes until it eventually reaches decomposers who break down organic matter into simpler forms that can be used again by producers.

Food webs are more complex than food chains because they show multiple pathways for energy transfer between organisms within an ecosystem. Food webs consist of interconnected food chains that form a network where species interact with each other in different ways depending on their position in the web.

For example, predators may consume prey from several different sources while prey may have multiple predators feeding upon them at once. By understanding how these interactions work together we can gain insight into how ecosystems function.

Trophic levels

Trophic levels describe the hierarchical structure of an ecosystem and energy flow within it. Producers are at the base of this hierarchy and include plants, algae, and other photosynthetic organisms that use sunlight to create their own food source. This category also includes chemotrophs in hostile environments around deep sea vents, which produce energy through oxidation.

Primary consumers feed on these producers and include herbivores such as deer or rabbits. Secondary consumers feed on primary consumers and can be carnivores like wolves or foxes. Tertiary consumers feed on secondary ones, such as hawks or sharks. Decomposers form a separate trophic level in which they break down organic matter into simpler forms that can be used again by producers.

Omnivores consume both plant-based foods from the producer level as well as animal-based foods from higher up in the chain; thus they occupy multiple trophic levels simultaneously.

Additionally, some species may switch between different categories depending on environmental conditions; for example, a bear may act as both a primary consumer when it eats berries but also a tertiary consumer when it hunts fish or small mammals. Understanding how these various components interact is essential for maintaining healthy ecosystems.

Energy Flow

Energy is the lifeblood of an ecosystem, and its flow through the environment is essential for maintaining balance. Photosynthesis is a key process in energy transfer, as it converts light energy from the sun into chemical energy stored in organic molecules. This energy then flows up food webs to higher trophic levels, where organisms use it to power their metabolic processes.

The 10% law states that only about 10% of this energy can be transferred between each trophic level; thus, ecosystems are limited by how much primary production they can support. Odum’s y-shaped model illustrates how grazing and detritus food chains connect at intermediate trophic levels to form a complex web of interactions.

Grazing food chains begin with producers such as plants or algae which are consumed by herbivores like deer or rabbits; these animals are then eaten by carnivores such as wolves or foxes. Detritus food chains start with dead organic matter which decomposers break down into simpler forms that can be used again by producers at the base of the chain.

Together, these two pathways form a continuous cycle of energy flow within an ecosystem that helps maintain balance and biodiversity over time.

Nutrient cycles

Nutrient cycles are essential for the functioning of ecosystems, as they provide organisms with the necessary elements to survive and thrive.

The water cycle is a continuous process in which water evaporates from bodies of water or land surfaces, rises into the atmosphere, condenses into clouds and falls back to Earth as precipitation. This cycle helps maintain moisture levels in an ecosystem and provides plants and animals with the water they need to function.

The carbon cycle involves the exchange of carbon between living organisms and their environment; it begins when producers such as plants take up atmospheric carbon dioxide during photosynthesis, then passes through consumers before being released back into the atmosphere by respiration or decomposition.

Another key nutrient for life on Earth is nitrogen. It cycles between organic molecules like proteins and nucleic acids in living things, soil particles, air molecules, and ocean waters. Nitrogen fixation converts atmospheric nitrogen gas into usable forms that can be taken up by plants; this process is carried out by certain bacteria found in soils or aquatic environments. There are many other nutrient cycles, and all are interconnected and play a vital role in maintaining balance within an ecosystem.

Biomes and their characteristics

Biomes are large-scale communities of plants and animals that can be found across the globe. They are characterized by their climate, vegetation and soil type, which together determine the other types of organisms that live in them. Biomes differ from ecosystems in that they cover a much larger area and all contain more than one ecosystems. Ecosystems are typically more localized.

Tropical forests are biomes located near the equator where temperatures remain warm year round and rainfall is abundant. These forests have high biodiversity due to their favorable conditions for growth; they also provide habitats for numerous species of plants, animals and fungi.

Taiga is a biome found in northern regions such as Canada or Russia; it has cold winters with snowfall, short summers with rain showers, and coniferous trees like pines or spruces dominate its landscape.

Deserts are arid biomes located mainly around 30° latitude north or south of the equator; they receive very little precipitation but still support life – which often has adaptations to such harsh conditions including drought resistance or water storage capabilities. All these major biome types demonstrate the vast diversity of life which our planet can support.

Human impact on ecosystems

Humans have a significant impact on ecosystems, both directly and indirectly. Deforestation is one of the most visible forms of human interference in nature; it involves clearing large areas of land for agricultural or industrial use, often resulting in habitat destruction and species extinction.

Pollution from factories, vehicles and other sources can also damage ecosystems by introducing toxins into the environment that disrupt natural processes such as photosynthesis or nutrient cycling. Climate change is another major factor affecting ecosystems; rising temperatures can cause changes to weather patterns which can lead to droughts, floods or extreme storms that devastate habitats and reduce biodiversity.

Examples of these impacts are seen around the world: rainforest clearing for palm oil plantations has caused extensive deforestation in Southeast Asia, while air pollution from cities has led to acid rain damaging forests across Europe. In addition to these direct effects on ecosystems, humans also contribute to climate change through burning fossil fuels which releases greenhouse gases into the atmosphere leading to global warming.

These activities all have serious consequences for our planet’s health; they threaten species survival and disrupt delicate ecological balances that are essential for life on Earth.

Conservation and restoration of ecosystems

Conservation and restoration of ecosystems is an important part of ecology, as it helps to repair damage caused by human activities. Conservationists use a variety of methods to restore damaged habitats, such as replanting trees or reducing pressure on forests.


Restoration ecology is the practice of restoring degraded ecosystems through active management and intervention. This can involve reintroducing native species, controlling invasive species, improving water quality or soil fertility, and managing land use in order to create more sustainable practices.

For example, conservationists may plant new trees in deforested areas or introduce predators into overpopulated areas in order to reduce herbivore populations. Additionally, they may also work with local communities to promote sustainable farming practices that reduce pressure on natural resources while still providing food for people living nearby.

By taking these steps towards restoring damaged ecosystems, conservationists are helping ensure that our planet remains healthy for future generations.

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