Ecology

• An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment
• Organisms require a supply of materials from their surroundings and from the other living organisms there to survive and reproduce
• Plants in a community or habitat often compete for light, space, water, and mineral ions from the soil
• Animals in a community compete with each other for food, mates, and territory
• Within a community, each species depends on others for food, shelter, pollination, seed dispersal, etc
• If one species is removed from a community, it can affect the whole community
• The relationship between different species in a community or habitat is called interdependence
• A stable community has all the species and environmental factors in balance so that population sizes remain fairly constant
• Abiotic factors that affect a community include light intensity, temperature, moisture levels, soil pH and mineral content, wind intensity and direction, carbon dioxide levels for plants, and oxygen levels for aquatic animals
• Biotic factors that affect a community include availability of food, new predators arriving, new pathogens, and one species outcompeting another so the numbers are no longer sufficient to breed
• Organisms have adaptations that enable them to survive in their habitat, which may take the form of structural, behavioural, or functional adaptations
• Extremophiles are organisms that live in extreme environments such as high temperature, pressure, or salt concentrations
• Feeding relationships are represented by food chains, which all begin with a producer, usually green plants or algae
• Methods ecologists use to measure the environment include transects, quadrats, pooters, habitat sensors, and cameras/recording equipment
• In a food chain, primary consumers consume producers, and secondary consumers consume primary consumers
• Consumers that eat other animals are called predators, while animals eaten by consumers are called prey
• In a stable community, the number of predators and prey rise and fall in cycles
• Once an organism dies, all materials in the living world are recycled to provide the building blocks for future organisms
• The carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis
• The water cycle provides fresh water for plants and animals on land before draining into the seas
• Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem
• Great biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for food, shelter, and the maintenance of the physical environment
• A good level of biodiversity impacts the future of the human species on Earth
• More resources (and waste) are being used and created due to rapid growth in the human population and an increase in the standard of living
• Pollution will continue to increase because waste and chemical materials need to be properly handled and are currently not
• Pollution can occur in water from sewage, fertilizer, or toxic chemicals, in air from smoke and acidic gases, and on land from landfill and toxic chemicals
• Pollution kills plants and animals, reducing biodiversity
• Humans reduce the amount of land available to plants and animals by building, quarrying, farming, and dumping waste
• The destruction of peat bogs and other compost areas reduces the area of this habitat and the variety of different plant, animal, and microorganism species that live there (biodiversity)
• The decay or burning of peat releases carbon dioxide into the atmosphere
• Large scale deforestation is done to provide land for cattle and rice fields, and to grow crops for biofuels
• Increased levels of carbon dioxide and methane lead to 'global warming' in the atmosphere
• Programmes in place to protect ecosystems include breeding programmes for endangered species, protection and regeneration of rare habitats, reintroduction of field margins and hedgerows in agricultural areas, reduction of deforestation and carbon dioxide emissions by some governments, and recycling resources rather than dumping waste in landfill