Ecology

• An ecosystem is made up of living (biotic) and non-living (abiotic) parts. In an ecosystem, there are different levels of organisation
• Individual organisms are the smallest part of the ecosystem.
• Population of individual species make up a single species
• Community - all populations that live together within one habitat
• Animals often compete for food, mates and territory
• Plants also compete for water, mineral ions, light and space.
• There is interdependence between different species. This means that one species may rely on another species for different things, such as:

  Pollination

  Shelter

  Seed dispersal

  food
• Interdependence means that one species relies on another species for different things.
• A stable community is when all the species and environmental factors are balanced and population sizes stay more or less constant.
• A community is stable when populations stay more or less constant.
• Order of the food chain:

  Producer

  Primary consumer

  Secondary Consumer

  Tertiary consumer

  Apex predator
• Food chains nearly always begin with a producer that makes its own food. This is usually a green plant or algae that can photosynthesise
• Which of these words best describes the nature of predator-prey dynamics in stable communities?

  Cyclic
• Predator-prey graphs show the cyclical nature of predator and prey populations in stable communities.
• Environmental change affects the distribution (spread) of species, and in extreme cases, their longevity (how long they survive). 
• Environmental changes include:

  Water

  Temperature

  Atmospheric gases
• What atmospheric gas dissolves in water and makes it more acidic?

  Co2
• Environmental changes can come about for many different reasons, including:

  Humans

  Geological Activity

  Seasons
• Which revolution resulted in the initial spike in human activities that were detrimental to biodiversity?

  Industrial Revolution
• How is human development reducing biodiversity?

  destruction of habitats

  we use land for buildings, farming and disposing waste

  pollution

  deforestation
• Biodiversity is a variety of species of organisms that exist in an ecosystem.
• Sulfur dioxide can dissolve in moisture in the air (atmosphere) to make acid rain. Acid negatively impacts forest, freshwater and soil ecosystems as well as human health.
• The human population has rapidly expanded in recent decades. Resource use has increased accordingly, leading to huge amounts of industrial waste and pollution.
• Industrial waste and pollution affect:

  Water

  Air

  land
• Peat bog destruction has a negative impact on the environment as it releases carbon dioxide which is a greenhouse gas and the loss of biodiversity.
• Peat bogs are destroyed because:

  to free up land for farming

  burn peat for fuel

  sell the peat for garden compost
• Peat demand can be reduced by farmers buying peat-free compost.
• Deforestation is the cutting, clearing and removal of forests in order to free up land for biofuels as well as cattle and rice fields- destroys many animals' habitats
• Deforestation results in the loss of the following ecosystem services:

  Erosion prevention

  Flood control

  Food provision
• Carbon dioxide is a greenhouse gas. Therefore, it is important to keep its atmospheric concentration at suitable levels
• How is carbon dioxide released into the atmosphere?

  Respiration

  Burning of fossil fuels
• The greenhouse effect describes how greenhouse gases act as a natural, insulating layer in the atmosphere, re-radiating most of the heat energy which has been reflected off the Earth’s surface back towards Earth.
• How is carbon dioxide removed from the atmosphere?

  Photosynthesis

  Dissolving in water

  Absorbing into peat bogs
• Farmers are being incentivised to maintain field margins and hedgerows, as these habitats that can support a high biodiversity.
• Decomposer- Responsible for recycling organic matter within an ecosystem and represents the final stop for all food chains
• Decomposers, such as bacteria and fungi, break down dead organisms and return nutrients to the soil.
• Sampling Calculation

  total population size= total area/area sampled x number of organisms counted in the sample
• To look at ecosystems and their population sizes we use Quadrats and Transects.
•  Two cycles that are particularly important for living organisms are:

  Carbon cycle

  Water cycle
• Carbon cycle