Ecosystem: Structure, Functions, Units and Types

Definition Of Ecosystem

An ecosystem may be defined as a community of living organisms interacting with one another and their nonliving environment in some area. These interactions give rise to a complicated web of relationships that sustains the ecosystem through the flow of energy and cycling of nutrients.

Importance Of Ecosystems

Ecosystems are, therefore, mandatory in keeping life on earth. They offer very important services like food, water, oxygen, and raw materials production. They control the climate, reuse nutrients, and protect biodiversity. Healthy, diverse ecosystems ensure survival.

Structure Of An Ecosystem

The ecosystem is divided into two main components

Biotic Components

All living organisms that coexist, interrelate, and interact with one another, as well as the abiotic factors of the ecosystem, are termed the biotic components. Those can be producers, consumers, and decomposers. All of these contribute to balancing the ecosystem.

Producers (Autotrophs)

Producers are organisms able to obtain their food from photosynthesis or chemosynthesis and form the first trophic level in an ecosystem. They are therefore the energy sources for all other organisms.

Photosynthetic Producers: Plants, algae, and certain bacteria—for example, cyanobacteria. They use sunlight, carbon dioxide, and water to synthesise glucose and oxygen. For example, primary producers are green plants, grass, trees, and phytoplankton in aquatic ecosystems.

Chemosynthetic Producers: Connected mostly to extreme environments, for example, deep-sea vents, these include some bacteria that produce food through chemical reactions between inorganic molecules.

Consumers (Heterotrophs)

Consumers are organisms that cannot prepare their food and obtain energy by consuming other organisms. Consumers are categorised based on their diets as follows:

Primary Consumers (Herbivores): These are organisms that get energy directly from producers. Examples of these are cows, deer, and caterpillars that eat plants.

Secondary Consumers (Carnivores): These are the organisms that consume the primary consumers. Examples are lions, snakes, and frogs that eat herbivores.

Tertiary Consumers (Top Predators): These are carnivores that feed on other carnivores. Examples are eagles, sharks, and orcas, which feed on the secondary consumers.

Omnivores: These are consumers who developed the trait of consuming both plants and animals. Examples are humans, bears, and pigs.

Decomposers (Detritivores)

Decomposers, or detritivores, form a core constituent of an ecosystem and serve to break down dead organic material to return the nutrients to the environment. In this way, the process is important in maintaining self-sustaining and healthy ecosystems by guaranteeing a constant supply of basic elements required by producers.

Bacteria: These microorganisms are very effective decomposers that are almost found everywhere on the planet. They are crucial in degrading complex organic compounds, namely proteins, carbohydrates, and lipids, into simpler molecules. In the case of cellulose, for example, which is a polymeric compound, one of the chief constituents of plant cell walls, and indigestible to most animals, there are some specialised bacteria involved in breaking it down.

• Aerobic bacteria: These are organisms that require oxygen to live and multiply in, for instance, soil and water conditions with adequate availability of oxygen. They decompose the organic matter quickly and produce carbon dioxide, water, and minerals.

• Anaerobic bacteria: do not use oxygen for their survival and are found in places such as deep sediments, waterlogged soils, or in the digestive tracts of animals. They decompose organic material more slowly with byproducts that are methane and other gases.

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This Story also Contains

1. Definition Of Ecosystem
2. Importance Of Ecosystems
3. Structure Of An Ecosystem
4. Functions Of An Ecosystem
5. Units Of An Ecosystem
6. Types Of Ecosystems
7. Important Ecological Concepts
8. Human Impact On Ecosystems

Fungi: They release enzymes that break down complicated organic materials like lignin and cellulose into simpler compounds. Fungi can degrade some of the most resistant plant materials and are extremely important in forest ecosystems, which break down fallen logs and leaf litter.

• Saprophytic Fungi: These fungi derive nutriment from dead or decaying organic matter. A wide network of thread-like hyphae, penetrates the organic material, releasing enzymes outside that hydrolyse it before finally getting absorbed.

• Mycorrhizal Fungi: These are symbionts with plant roots. Although they don't themselves act as decomposers, they assist in nutrient cycling by breaking down organic matter into the soil, where they become more readily available to plants.

Detritivores: Earthworms are Detritivores by nature. They ingest high amounts of soil along with organic litter, break it in the digestive systems, and excrete it in the form of casting rich in nutrients. This aerates the soil, improves its structure, and enhances nutrient availability to plants.

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Abiotic Components

Abiotic factors are the nonliving parts of an ecosystem that have a huge effect on living organisms within it. The factors create an environment in which biotic ones operate and play a very important role in shaping the structure and functionality of the ecosystem. Abiotic factors can be broadly classified into two major groups: physical and chemical factors.

Physical Factors

Sunlight is the fundamental source of energy in almost every ecosystem. It triggers photosynthesis—such is the process whereby producers like plants and algae turn light energy into chemical energy for storage in glucose.

Temperature appears to be one of the major controlling factors for metabolic rates, enzyme activity, and other physiological functions of living organisms.

Water is indispensable for all living organisms because it is the primary constituent of cells and a medium for the majority of biochemical reactions. The types of vegetation and the different species of animals are a function of the water availability.

Soil is a very complex mixture of mineral particles, organic matter, water, air, and living organisms. Its composition varies widely and influences the types of plants that may be grown in it.

Chemical Factors

• pH is the measure of acidity or alkalinity of substances. It ranges on a scale from 0 to 14, where 7 is considered neutral, below 7 is acidic, and above 7 is alkaline.

• Minerals are inorganic elements essential for various physiological functions both in plants and animals. Common minerals include calcium, magnesium, potassium, and iron.

• Gases: The type of organisms that are found in either water or soil can at times be determined by the availability of oxygen. In aquatic ecosystems, this could result in hypoxia. It can affect the rate of photosynthesis and thus the productivity of an ecosystem. CO2 concentration within the atmosphere controls the greenhouse effect and global climate patterns.

Functions Of An Ecosystem

Energy Flow

• The energy flow in an ecosystem begins with the ability of producers to capture solar energy by photosynthesis.

• Plants convert solar energy into chemical energy, and the latter is passed on to the consumers.

• The transference of energy from the producers to primary consumers is to the secondary consumers carnivores, and finally to the tertiary consumers, the top predators.

Nutrient Cycling

• Nutrient cycles refer to those processes that work towards the balancing of major elements within an ecosystem.

• The carbon cycle reports on the movements of carbon between the atmosphere, hydrosphere, lithosphere, and biosphere.

• The nitrogen cycle shows how nitrogen is converted into various chemical forms as it moves through the atmosphere terrestrial, and marine ecosystems.

• Water Cycle describes the continuous movement of water on, above, and below the surface of the Earth.

• The phosphorus cycle describes the pathway phosphorus takes through rocks, water, soil, and living organisms.

Units Of An Ecosystem

Habitat

• A habitat is the natural environment in which an organism lives and thrives.

• It comprises both the biotic and abiotic elements that an organism needs to have to survive, like food, water, or shelter.

• For example, forests are habitats to a uniquely large diversity of species, from birds and mammals to insects and plants, while deserts provide habitat for organisms like cacti, lizards, and scorpions.

Niche

• A niche means the function and status a species occupies in its environment, encompassing all interactions between the species, biotic, and abiotic variables.

• What the species eats and how it procures food, how it interacts with other organisms—these make a niche.

• For instance, pollination, collection of nectar, and pollen are the niche activities of the bee.

Community

• A community consists of different species that live together in a common habitat, but the interactions among its members define the structure and dynamics.

Population

• A population may be defined as a group of interbreeding individuals of the same species that either is or has the potential to be, isolated in some particular locale.

• Population dynamics investigate changes in these populations over time and space, due to events such as birth, death, immigration, and emigration.

• For example, some models describe the growth of a population, like exponential growth models that describe very fast-growing populations with no limiting factors, or logistic growth models that stabilise the carrying capacity of the environment due to limiting factors such as food and space.

Types Of Ecosystems

The ecosystem is mainly divided into two parts

Terrestrial Ecosystems

The terrestrial ecosystem is composed of different forms:

Forest Ecosystems

• Forest ecosystems include tropical, temperate, and boreal forests, which are riddled with a wide variety of flora and fauna.

• In a tropical forest, there is a thick vegetation of plants in warm and wet climates.

• The temperate forest is spread in areas with varying seasonal changes, including deciduous and coniferous trees.

• The boreal forest has a domination of coniferous trees with cold climates, long winters, and short summers and is often referred to as taigas

Grassland Ecosystems

• Grassland ecosystems, including savannas and prairies, are dominated by large expanses of grasses and few trees.

• Savannas occur naturally in warm climates with scattered trees and the presence of big herbivorous species like elephants and zebras.

• Species found in the prairie ecosystems, typically temperate, include bison and prairie dogs.

Desert Ecosystems

• These are the ecosystems of hot and cold deserts that represent highly adverse conditions and specialised organisms.

• In hot deserts, the temperature is very high and dry with system organisms such as cacti and camels, which include adaptations to save water.

• On the other hand, in cold deserts, there are low temperatures, as in Antarctica, along with flora and fauna adapted to them. Examples include lichens and arctic foxes.

Tundra Ecosystems

• The tundra ecosystems include the Arctic and alpine tundra, which represent cold climatic conditions, unique in their vegetation.

• Arctic tundra is characterised by permafrost, low-growing plants like mosses and lichens, and a hard, cold, and dry environment.

• Comparable vegetation exists in alpine tundras at high altitudes, adapted to cold and windy environments.

Aquatic Ecosystems

An aquatic ecosystem is mainly composed of three forms:

Freshwater Ecosystems

• Freshwater ecosystems include lakes, rivers, and ponds that all host their diversity of aquatic life.

• Lakes are bodies of standing water, differing in size and depth, hosting fish, amphibians, and aquatic plants.

• Rivers are flowing water systems and provide habitats for species like salmon and otters.

• Ponds are smaller, shallower, and support a large diversity of plants and microorganisms that are aquatic.

Marine Ecosystems

• Marine ecosystems would include oceans, coral reefs, and estuaries.

• Insects could be characterized by their high degree of biodiversity, with the ocean being the largest body of saltwater where life ranges from plankton to whales.

• Coral reefs are undersea structures, rich in marine biodiversity, that support high varieties of fish and marine invertebrates.

• Estuaries are areas where freshwater meets saltwater and are abundant in nutrients, hence supporting a lot of species of different kinds.

Wetland Ecosystems

• Wetland ecosystems are generally considered a region saturated either on or very near the land surface.

• The swamp is dominated by trees and offers habitat for alligators, waterfowl, and other organisms.

• Marshes are dominated by herbaceous plants, like sedges and grasses, offering support for amphibians and birds.

Important Ecological Concepts

Ecological concepts help in understanding the connection of organisms with their environment and balance maintenance that keeps an ecosystem thriving.

Food Chain

A food chain is a linear sequence that shows the flow of energy and nutrients from one organism to the next in an ecosystem.

• Producers: The very bottom of the food chain; usually plants or algae photosynthesizing for energy.

• Primary Consumers: Herbivores that consume producers.

• Secondary Consumers: Carnivores consume primary consumers.

• Tertiary Consumers: Higher-level carnivores which consume the secondary consumers

• Decomposers: Organisms, mostly bacteria and fungi, involved in the breaking of dead organisms to return nutrients to the ecosystem.

Diagram: Food Chain

Ecological Pyramids

An ecological pyramid is a graphic representation that details or highlights the different trophic levels of an ecosystem in a specific locality.

• Pyramid of Numbers: The number of individual organisms in each trophic level is described. Often shows vast numbers of producers and progressively fewer consumers.

• Pyramid of Biomass: It describes the total mass of living tissue associated with each trophic level. There is a decrease in the biomass from producers via intermediate consumers to final consumers.

• Pyramid of Energy: It describes energy at each trophic level. It shows that energy is lost at each level (approximately 90%) because it is utilised for respiration and metabolic processes.

Food Web

A food web is the complete network of interconnected food chains within an ecosystem, illustrating the various routes energy and nutrients can take.

• Connected Chains: Multiple food chains overlap and intersect with one another.

• Biodiversity: Identifies the feeding diversity of relationships and dependencies among different organisms.

• Stability: The stability of the ecosystem is shown by giving alternative feeding options to organisms.

It means more realistic modelling of energy and nutrient flow compared to a simple food chain and allows for multiple trophic levels and interactions.

Human Impact On Ecosystems

Pollution, whether it be in the air, water, or soil, pertains to the inclusion of deleterious elements into an ecosystem, hence changing the natural self-proceeding and therefore affecting biodiversity. Air pollution through emissions gives rise to acid rain, while water pollution contaminates aquatic environments and soil pollution causes the degradation of land quality. These pollutants harm organisms and disrupt the food chains and functions of ecosystems.

Deforestation from logging and agriculture is followed by habitat loss and changes in diversity. It also causes soil erosion as a result. Climate change, on the other hand, results in an increase in the level of CO2 in the atmosphere. Rising temperatures, resulting from climate change, alter species distribution and disrupts ecosystem health. The mitigation approaches are by reducing the emission of greenhouse gases through renewable energy sources.

Conservation Efforts

Conservation may involve the creation of protected areas, say national parks, and maintenance of biodiversity through sustainable agriculture, forestry, and sea fishing. On the other hand, restoration ecology targets rehabilitating degraded ecosystems to almost their natural state to ensure that there is enrichment of biodiversity and improvement in ecosystems that provide services. This helps to reduce the impact of a human and ensures the health of the ecosystem.