Ch. 8 - The Study of a Habitat

• Ecology


  The study of how plants and animals interact with each other and with their surroundings (or environment)
• The importance of ecology


  •  It provides information about how the world works.
  •  It provides evidence of consequences of human interaction on the environment and how we can protect the environment for future generations.
• Ecosystem


  a group of plants, animals and other organisms that interact with each other and with their environment

  Examples of major ecosystems include:

  • Grassland
  • Deserts
  • Tropical Rainforests
  • Seashores
• Habitat

  the place where an organism lives. It is carefully selected by an organism based on food, water, climate and predators.

  Examples:

  1. A robin lives in a nest in a tree.

  2. A rabbit lives in a burrow in the ground.

  3. A blackberry plant lives in the hedgerow.
• There are a wide variety of habitats that can be studied. These include:


  • Grassland
  • Rocky seashore
  • Bog
  • School field
  • Hedgerow
  • Woodland
  • Local park
  • Pond
• How to carry out a habitat study


  • The study of a local habitat is called fieldwork
  • if possible, the habitat should be visited during different seasons
  • this will show how the habitat changes over the course of a year
  • there is a recognised countryside code, and when investigating any habitat, it is important to follow this code
• The Countryside Code


  • Get permission to enter private property
  • Close gates behind you
  • Do not disturb livestock
  • Do not damage gates, fences or crops
  • Do not light fires
  • Do not leave litter
  • Where possible you should ‘ Seven leave only footprints and take only memories’
• The Study of a Habitat involves 5 steps


  1. Draw a simple map of the habitat (or photograph it, if possible)
  2. Measure and record the environmental, or non-living, features in the habitat
  3. Identify and name all the organisms in the habitat
  4. Collect samples of those organisms in the habitat that cannot be identified
  5. Estimate the number of each type of plant in the habitat
• Step 1: Map the Habitat


  Draw a simple map to show the main features of the habitat, e.g. walls, fences, ponds, large trees, hedges or paths. If possible, photograph the habitat.
• Step 2: Measure Environmental Features


  The environmental (non-living) features of a habitat are called abiotic factors

  • you should measure and record as many of these factors as possible

  
• Step 3: Identify the Organisms

  • If possible, organisms in the habitat should be named and listed on site
  • Plants and animals should be removed from the habitat only if they cannot be identified there and then
  • Organisms can be identified by comparing them to drawings or pictures in a book or by using a suitable key
• Step 4: Collect Organisms for Identification in the Laboratory


  • Plants are easy to collect as they do not move away
  • Slow or non-moving animals can be collected easily
  • Most animals will have to be trapped or collected using special devices
• How can we collect plants and animals in a habitat?

  
• Step 5: Estimate the Number of Plants


  • it is not normally possible to count all the plants in a habitat
  • Instead, the number of plants is calculated from samples taken at random in the habitat
  • We can then calculate how often a plant is likely to be found in the habitat (i.e. its frequency)
  • The most common method of calculating plant numbers is to use a quadrat
  • A quadrat is a square frame that is thrown at random in the habitat
  • they come in different sizes (e.g. their asides may measure 0.5m or 0.25m)
  • they may be made of wood, metal or plastic, or they can be marked out using string/rope
• Community


  consists of all the organisms living in a particular area
• Adaptation


  a structure or behaviour that helps an organism to survive in its habitat or within its community
• Adaptations are..


  Changes that allow organisms to live longer and produce more offspring, which are passed on to the next generation
• Adaptations are central to the process of evolution by natural selection
• Adaptations shown by grassland organisms


  • Plants such as primroses grow and produce flowers early in the spring
  • Grasses grow from the base (most plants grow at their tips)
  • Grasses have very branched roots
  • Caterpillars have a similar colour to the plants they feed on
  • Caterpillars have strong mouth parts
  • Butterflies have long tubular mouth parts
• Primroses

  • grow and produce flowers early in the spring
  • this means they get more light and grow better than other plants in their habitat, because the other plants have not produced their leaves in early spring
• Grasses

  • Grow from the base (most plants grow at their tips)
  • Can survive when grazed by animals
  • Have very branched roots
  • Are not easily pulled out of the ground
• Caterpillars

  • Are well camouflaged
  • Can bite and chew leaves
• Butterflies

  • Can drink nectar (sugary water) from flowers
• Competition


  Takes place when 2 or more organisms actively demand something that is in scarce supply. In any habitat:

  • animals compete for space, food, water, and partners
  • plants compete for light, space, water and minerals from the soil
• Intra-specific Competition


  this occurs between plants and animals of the same type (species), for example:

  • grasses compete with each other for light and space
  • foxes compete with each other for food
• Inter-specific Competition


  this occurs between different types (species) of plants and animals, for example:

  • Grass and dandelions compete with each other for light
  • Robins and blackbirds compete with each other for food
• Interdependence


  means that all the organisms in a habitat depend on other organisms for their survival.
• Examples of how Plants and Animals are Interdependent include:


  • Animals depend on plants, e.g. Rabbits depend on grass for food
  • Plants depend on animals, e.g. The grass depends on the rabbit for its nutrients in their urine and faeces (fertiliser) e.g. Flowers depend on bees for pollination
  • Plants depend on each other, e.g. Plants depend on each other for shelter
  • Animals depend on other animals, e.g. Foxes depend on rabbits for food
• Other examples of interdependence include:


  • Birds use twigs for nests
  • Foxes hide in long grass
  • Spiders use plants on which to build their webs
  • Squirrels spread the seeds of trees
  • Dead plants (detritus) are decayed by decomposers such as bacteria and fungi to release minerals into the soil for new plants to absorb
• Food Interdependence


  One of the main ways in which living things depend on each other is for food. Organisms get their food in different ways, and can be categorised as:

  • Producers
  • Consumers
  • Decomposers
• Producers (autotrophs)


  Green plants that make their own food (using light energy from the sun). Examples include:

  • Grasses
  • Buttercups
  • Dandelions
  • Daisies
  • Nettles
• Consumers (heterotrophs)


  organisms that take in food

  • Animals do not make their own food
  • Instead, they get their food by eating (or consuming) plants or other animals
  • For this reason, animals are called consumers
  • Depending on what they eat, consumers can be placed into three different groups (next card)
• Herbivores


  animals that eat plants only

  Examples:

  • Rabbits
  • Sheep
  • Slugs
  • Snails
• Carnivores


  animals that eat other animals

  Examples:

  • Foxes
  • Hawks
  • Ladybirds
• Omnivores


  animals that eat both plants and other animals

  Examples:

  • Badgers
  • Thrushes
  • Blackbirds
  • humans
• Decomposers


  organisms that feed on and break down dead plants and animals.

  • They include a range of small animals (such as woodlice and earthworms) along with bacteria and fungi
  • Decomposers are of great value as they release chemicals back into the environment
  • This allows other organisms to use these chemicals
  • this means decomposers allow recycling
• Food Chain


  A list of organisms in which each organism is eaten by the next one in the chain

  • A food chain is a simple way of explaining how energy and nutrients pass from one thing to another
  • The arrows in a food chain show the direction in which the energy and nutrients pass
  • An example of a simple food chain is where grass is eaten by a rabbit and the rabbit is eaten by a fox (shown below)

  
• Do food chains involve decomposers?


  • Another way to show a food chain is to refer to the decomposers
  • Decomposers act on dead plants and animals and on the waste products (such as urine and faeces) of animals

  
• Food Chains pt. 2

  • food chains are simple way to show how organisms feed in a habitat
  • For example, the simple food chain described earlier (grass -> rabbit -> fox) suggests that grass is eaten only by rabbits
  • It also suggests that rabbits are eaten only by foxes
  • Both of these are untrue
• Food Web


  consists of a number of interlinked food chains

  • A food web provides a more complete and realistic explanation of the way in which organisms in a habitat feed
  • In all food webs, the dead plants and animals are broken down by decomposers
  • Examples: