Ecosystems

OBJECTIVES

What is an ecosystem? What are three basic components of an ecosystem?

What are the different classification of the ecosystem? Terrestrial and aquatic/open or closed. What is the structure of the ecosystem? How do energy and matter travel through ecosystems?

In an ecosystem, each organism has its own niche or role to play.

The whole surface of Earth is a series of connected ecosystems.

An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life.

Ecosystems contain biotic, or living parts, as well as abiotic factors, or non-living parts. Biotic factors include plants, animals, and other organisms. Abiotic factors include rocks, temperature, and humidity.

Every factor in an ecosystem depends on every other factor, either directly or indirectly.

An ecosystem is a community of plants and animals interacting with each other in a given area, and also with their non-living environments. Like; Weather Earth Sun Soil Climate Atmosphere.

The ecosystem relates to the way that all these different organisms live in close proximity to each other and how they interact with each other.

These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces.

Ecosystems can be classified into three main scales.

MICRO

A small-scale ecosystem, such as a pond, puddle, tree trunk, under a rock, etc.

MESSO

A medium-scale ecosystem, such as a forest or a large lake.

BIOME

A very large ecosystem or collection of ecosystems with similar biotic and abiotic factors, such as an entire rainforest with millions of animals and trees, with many different water bodies running through them.

Ecosystems are often connected in a larger biome.

Biomes are large sections of land, sea, or atmosphere.

Forests, ponds, reefs, and tundra are all types of biomes, for example.

ECOSYSTEMS COME IN INDEFINITE SIZES

Each ecosystem is unique, but all ecosystems have three basic components: Autotrophs (producers of energy) plants. Heterotrophs (consumers of energy) animals.

Non-living matter ( the soil, sediments, leaf litter, and other organic matter on the ground or at the bottom of an aquatic system.)

THE STRUCTURE OF AN ECOSYSTEM

Basic functional level. Contains primary producers (plants) capable of harvesting energy from the sun through the process called photosynthesis.

This energy then flows through the food chain.

Next-level consumers. Consumers could be: Primary consumers (herbivores) . Secondary consumers (carnivores). These consumers feed on the captured energy.

Decomposers work at the bottom of the food chain.

Dead tissues and waste products are produced at all levels.

Scavengers, detritivores and decomposers not only feed on this energy, but also break organic matter back into its organic constituents.

It is the microbes that finish the job of decomposition and produce organic constituents that can again be used by producers.

Please note that in ecosystems, both matter and energy are conserved.

Energy flows through the system – usually from light to heat – while matter is recycled.

THERE ARE TWO TYPES OF ECOSYSTEMS

Closed – Closed ecosystems are ones that do not have any inputs (exchanges of energy from the surrounding environment) or outputs (exchanges of energy from within the ecosystem).

Open – Open ecosystems are ones that have both inputs and outputs.

Ecosystems can be classified in a variety of ways, but most commonly they are defined as either terrestrial or aquatic. TERRESTRIAL Are those that are found only on land. Six types of terrestrial ecosystems. - Taiga - Tundra, - Deciduous forest - Grasslands - Tropical rain forests - Deserts AQUATIC

Refers to living and non-living parts of a waterbody and the interactions that take place among them.

Three types of aquatic ecosystems. - Freshwater - Marine - Estuarine – places where rivers meet the sea and may be defined as areas where salt water is diluted with fresh water. A freshwater body of water has fewer dissolved compounds, or salts, present. It covers less than one per cent of the earth and are subdivided into lotic (systems with rapid, flowing waters that move in a unidirectional way, such as rivers and streams.), lentic (all standing water habitats, such as lakes and ponds) and wetlands.

A marine body of water has various salts dissolved in it, hence the term ‘salt water’. The average salinity of salt water is around 35 parts per thousand. It covers over 70 per cent of the earth’s surface. Oceans, estuaries, coral reefs and coastal ecosystems are the various kinds of marine ecosystems.

Estuarine areas are those that experience a flux of both fresh and salt water, depending on the tides and water currents.

The area where the Mississippi River meets the Gulf of Mexico is considered estuarine because there is a constant mix of fresh and salt water.

HOW ENERGY AND MATTER TRAVEL THROUGH ECOSYSTEMS

Both energy and matter are conserved, neither created nor destroyed, but take different routes through ecosystems:

Matter is recycled; the same atoms are reused over and over.

Energy flows through the ecosystem, usually entering as light and exiting as heat.

MATTER IS RECYCLED

Through Earth’s ecosystems. Though it may move from one ecosystem to another, as it does when nutrients are washed away into a river.

The same atoms are used over and over again, assembled into different chemical forms and incorporated into the bodies of different organisms.

Now, let’s look at how chemical nutrients move through a terrestrial ecosystem.

A land plant takes in carbon dioxide from the atmosphere and other nutrients, such as nitrogen and phosphorous, from the soil to build the molecules that make up its cells. When an animal eats the plant, it uses the plant’s molecules for energy and as building material for its own cells, often rearranging atoms and molecules into new forms.

When plants and animals break down molecules as fuel, carbon dioxide is released into the atmosphere. Also, when they excrete

used for energy and building material by bacteria and fungi.

These decomposers release simple molecules back into the soil and atmosphere, where they can be taken up anew in the next round of the cycle. Energy cannot be recycled in ecosystems.

It flows through an ecosystem in one way – from light to heat.

It usually enters ecosystems as sunlight and is captured in chemical form by photosynthesizers like plants and algae.

It is then passed through the ecosystem, changing forms as organisms Metabolise Produces waste. Eat one another. Die and decompose. Each time energy changes forms, some of it is converted to heat. Heat still counts as energy, but can’t be used as an energy source by living organisms. Energy that entered the ecosystem as sunlight is dissipated as heat and radiated back into space.

LEVELS OF ORGANISATION IN AN ECOSYSTEM

Ecosystems with higher biodiversity tend to be more stable, with greater resistance and resilience in the face of disturbances, disruptive events.

the next lesson will focus on other components of an ecosystem (human, climate, vegetation, soil).