Ch 3 Introduction to Ecology. Need to know. Define the term: biosphere, ecology, ecosystem, habitat. Name a range of ecosystems Name examples of habitats. What is Ecology?. Ecology is the study of the interaction between groups of organisms and their environment.
Need to know • Define the term: biosphere, ecology, ecosystem, habitat. • Name a range of ecosystems • Name examples of habitats.
What is Ecology? Ecology is the study of the interaction between groups of organisms and their environment. The environmentconsists of: • living e.g. availability of food & • non living parts e.g. amount of rainfall.
What is an Ecosystem? An ecosystem is a community of organisms and their environment.
What is the Biosphere? The biosphere is the part of the earth and its atmosphere in which life can exist.
Types of Organisms in an Ecosystem • Producers – autotrophs: organisms that make their own food. • Consumers – heterotrophs: organisms that can’t make their own food. • Primary consumers – herbivores: animals that eat plants only • Secondary consumers – carnivores: animals that eat animals & omnivores: animals that eat plants & animals
Learning check 1 • What is ecology? • What does the term environment refer to? • What is an Ecosystem? • What is the biosphere? • List the 4 types of Organisms that can be found in an Ecosystem.
Need to know • Distinguish between Abiotic & Biotic factors • Define and give examples of the following as applied to terrestrial (land) and aquatic (water) environments: • Abiotic • Biotic • Climatic • Edaphic factors
Environmental factors that affect organisms There are two broad factors: • Biotic: These are living factors e.g. the plants, animals & decomposers. These include: • competition • predation • symbiosis
Biotic factors include: • Competitors • Predators • Parasites and pathogens • Decomposers • Humans • Pollinators • Prey • Plants for food and shelter
Environmental factors that affect organisms 2. Abiotic: These are non-living factors. They include: • Climatic factors - These are the average weather conditions that affect the community in an ecosystem • Edaphic Factors – related to the soil • Aquatic Factors
Climatic factors include: • Temperature • Rainfall • Humidity • Wind • Light intensity (including seasonal variations) • Day length
Edaphic factors include: • Soil type, • Soil pH, • Available (soil) water, • Air and Mineral content, • Humus, • Soil texture and Structure.
Aquatic Environmental Factors The following are also considered as factors: • Light penetration • Currents • Wave action
Learning check 2 • What are the two broad environmental factors that affect organisms? • What are biotic factors? • What is meant by abiotic factors? • What are climatic factors? • What are edaphic factors? • What are aquatic factors?
1.4.6 Energy Flow Need to know Name the sun as the primary source of energy. Name feeding as the pathway of energy flow. Present a grazing food chain. Present a food web.
Energy Flow in an Ecosystem The sun is the primary source of energy for life on our planet. Energy is transferred from one organism to the next in an ecosystem due to feeding, e.g. along a food chain.
Food Chain Is the feeding relationship between organisms through which energy is transferred. A food chain ends when there is not enough energy to support another organism. grass rabbit fox.
A Grazing food chain is one which begins with a plant. Grass grasshoppers frogs hawks Honeysuckle aphids ladybirds thrushes
A Detritus food chain is one which begins with dead organic matter and animal waste (detritus).
Food Web Consists of two or more interconnecting food chains.
A woodland food web Construct a two food chains (4 ‘links’) from the above food web
Another food web What is the longest food chain you can construct from this food web?
Producers Producersareorganisms capable of making their own food by photosynthesis, e.g. green plants. Food chains always begin with Primary producers
Consumers Consumersare organisms that feed on other organisms. They cannot make their own food. There are three types: • Primary consumers – feed on producers • Secondary consumers – feed on primary consumers • Tertiary consumers – feed on secondary consumers
Primary consumer Secondary consumer Tertiary consumer Producer Woodland food chain Honeysuckle aphids ladybirds thrushes
Caterpillar Earthworm Thrush Blackbird Fox Plant Learning check 3 • Construct 2 simple food chains E.g. Plant caterpillar thrush fox Plant earthworm blackbird fox • Combine them to form a food web E.g.
Trophic Level Is the feeding level in a food chain. • Plants are at the 1st trophic level (T1) and • Herbivores occupy the 2nd trophic level (T2). • Carnivores that eat herbivores are at the 3rd trophic level (T3). • The 4th trophic level (T4) is often occupied by the top carnivore.
Learning check 4 • What is the primary source of energy? • Energy flow/transfer through an ecosystem is achieved by … • What is meant by a Grazing food chain? • Give an example • Explain the following terms: Producer, Consumer, Primary Consumer, Secondary Consumer &Tertiary Consumer • What is meant by trophic level?
Pyramid of NumbersNeed to know • Construct a pyramid of numbers. • Explain the limitations of use regarding the size of organisms • State two inferences (conclusions) that can be made regarding the shape of the pyramid e.g. large tree or parasites • Explain the energy loss shown in the pyramid
Fox Rabbits Grasses Pyramid of Numbers Is used to show the numbers of organisms at each trophic level in a food chain.
Bottom layer is the usually the largest and represents the number of primary producers • The next layer is usually smaller and represents the primary consumers • The next layer – the no. of secondary consumers • The uppermost layer - the no. of tertiary consumer, where there may be only one.
Energy loss in a Food Chain or Ecosystem • From the previous slide we can see when a plant is eaten only 10% of the energy it absorbed from the sun is transferred onto the herbivore. • The herbivore uses up 90% of this energy during respiration, as heat & only passes on 10% to the secondary consumer.
This continues up the food chain, so that at each trophic level, the organisms only pass on 10% of energy that they have received. • Each trophic level contains less energy than the previous one.
The large energy loss from one trophic level to the next explains why • food chains contain no more than four or five levels • the number of organisms declines as you go up the pyramid • the body size of animals increase as you go up the pyramid, as predators need to be larger than their prey.