🌍 Ecosystem
An ecosystem includes all the living things in an area plus their physical environment. It's like a natural community where everything is connected. Examples include a pond, a forest, or even a rotting log.
Ecosystems and Populations » Ecological Terminology
What you'll learn this session
Study time: 30 minutes
- Define key ecological terms including ecosystem, habitat, population and community
- Understand the difference between biotic and abiotic factors
- Explore food chains, food webs and trophic levels
- Learn about ecological niches and species interactions
- Examine real-world examples of ecological concepts
- Understand how energy flows through ecosystems
🔒 Unlock Full Course Content
Sign up to access the complete lesson and track your progress!
Unlock This CourseIntroduction to Ecological Terminology
Ecology is the study of how living things interact with each other and their environment. To understand these complex relationships, we need to learn the special language that ecologists use. Think of it like learning the rules of a game - once you know the terms, everything starts to make sense!
Every organism on Earth lives in a web of relationships. A lion depends on zebras for food, zebras depend on grass and grass depends on soil nutrients and sunlight. Understanding these connections helps us protect our natural world.
Key Definitions:
- Ecology: The study of relationships between living organisms and their environment.
- Environment: All the conditions that surround a living organism.
- Organism: Any individual living thing, from a tiny bacterium to a massive whale.
Building Blocks of Ecosystems
Ecosystems are made up of different levels of organisation, from individual organisms to entire communities. Let's explore these building blocks step by step.
Population and Community
A population is all the individuals of the same species living in the same area at the same time. For example, all the robins in your local park form a population. When we look at all the different populations together - the robins, squirrels, oak trees and grass - we call this a community.
🐔 Population
All members of one species in an area. Example: All the foxes in Epping Forest.
🌲 Community
All the different populations living together. Example: Foxes, rabbits, oak trees and ferns in the same forest.
🌳 Ecosystem
The community plus the physical environment. Example: The forest community plus soil, climate and water.
Habitat and Niche
Every organism has a specific place where it lives and a particular role it plays in its ecosystem. These concepts help us understand how species fit into the natural world.
🏠 Habitat
A habitat is where an organism lives - its address in nature. It provides everything the organism needs: food, water, shelter and space to reproduce. A pond is a habitat for frogs, whilst tree bark is a habitat for many insects.
Ecological Niche
An ecological niche is much more than just where an animal lives - it's its entire way of life. Think of it as the organism's job description in nature. It includes what it eats, when it's active, how it reproduces and how it interacts with other species.
Case Study Focus: Red Squirrels vs Grey Squirrels
In Britain, red squirrels and grey squirrels have very similar niches - they both eat nuts, live in trees and are active during the day. This overlap has led to competition, with grey squirrels often outcompeting red squirrels for resources. This shows how two species cannot occupy exactly the same niche in the same place for long.
Biotic and Abiotic Factors
Everything in an ecosystem can be classified as either living or non-living. These factors work together to create the conditions that determine which organisms can survive in a particular place.
🐻 Biotic Factors
These are all the living parts of an ecosystem. They include other organisms that affect an individual through competition, predation, disease, or cooperation. Examples: predators, prey, parasites, competitors and decomposers.
🌡 Abiotic Factors
These are the non-living physical and chemical factors. They include temperature, light, water, soil pH, oxygen levels and nutrients. These factors often determine which species can survive in an area.
Food Chains and Food Webs
Energy flows through ecosystems in predictable patterns. Understanding these patterns helps us see how all life is connected and dependent on the sun's energy.
Trophic Levels
Organisms can be grouped into different feeding levels called trophic levels. Each level represents a step in the transfer of energy through an ecosystem.
🌱 Producers
Plants and algae that make their own food using sunlight. They form the base of all food chains.
🐇 Primary Consumers
Herbivores that eat plants. Examples include rabbits, caterpillars and zebras.
🦁 Secondary Consumers
Carnivores that eat herbivores. Examples include foxes, birds of prey and small fish.
Tertiary consumers are carnivores that eat other carnivores, like lions eating hyenas. At the top are apex predators - animals with no natural predators when fully grown, such as polar bears or great white sharks.
Case Study Focus: Yellowstone Wolves
When wolves were reintroduced to Yellowstone National Park in 1995, they didn't just affect deer populations. The wolves changed deer behaviour, allowing trees to grow back along rivers. This changed the shape of the rivers themselves! This shows how apex predators can affect entire ecosystems - a concept called a trophic cascade.
Species Interactions
Organisms don't live in isolation - they constantly interact with other species. These interactions can benefit one or both species, or can be harmful.
Types of Species Interactions
Competition occurs when two or more species need the same limited resource. This could be food, water, space, or mates. Competition can happen between different species (interspecific) or within the same species (intraspecific).
Predation is when one organism (the predator) kills and eats another (the prey). This relationship drives evolution - prey species develop better defences whilst predators develop better hunting abilities.
Symbiosis describes close relationships between different species. There are three main types:
- Mutualism: Both species benefit. Example: bees get nectar from flowers whilst helping plants reproduce by carrying pollen.
- Commensalism: One species benefits, the other is unaffected. Example: small fish following sharks to eat scraps.
- Parasitism: One species benefits, the other is harmed. Example: tapeworms living in animal intestines.
Energy Flow and Nutrient Cycling
Ecosystems need a constant input of energy from the sun, but nutrients are recycled. Understanding these processes helps explain why ecosystems work the way they do.
⚡ Energy Flow
Energy enters ecosystems as sunlight and flows through food chains. At each level, about 90% of energy is lost as heat. This explains why there are fewer predators than prey - there isn't enough energy to support large numbers of top predators.
Decomposers: Nature's Recyclers
Decomposers like bacteria and fungi break down dead organisms and waste products. They're essential because they return nutrients to the soil, making them available for plants to use again. Without decomposers, nutrients would be locked up in dead material and ecosystems would collapse.
Case Study Focus: The Amazon Rainforest
The Amazon rainforest demonstrates many ecological concepts. It has incredible biodiversity with millions of species occupying different niches. The forest floor's rapid decomposition quickly recycles nutrients in the poor tropical soils. The complex food webs include everything from leaf-cutter ants farming fungi to jaguars hunting caimans. This ecosystem shows how all these ecological terms work together in the real world.