Ecosystems and material cycles Flashcards
What is an ecosystem
An ecosystem is the interaction between a community of living organisms and their environment
Define population
Population is all the organisms of the same or closely related species
Define habitat
A habitat is the place an organism lives
Define community
Two or more populations of organisms
Define the levels of organisation within an ecosystem
Producer, Primary consumer (Herbivores), Secondary consumers, and tertiary consumers.
Abiotic factors affecting the abundance and distribution of organisms.
Light intensity - Some plants have evolved for optimum growth in bright sunlight. Others have evolved to grow in shade.
Temperature - Both animals and plants have evolved to grow at optimum temperatures,
Moisture levels - If a plant is over-watered they cant survive in water logged soils, and the roots are unable to respire, they rot and the plant dies.
Carbon dioxide - Reactant in photosynthesis which means plants need it to survive.
Bioindicators of Pollution levels in water
Clean - Stonefly nymph, mayfly larva.
Some - Freshwater shrimp, caddis fly larva.
High - Sludge worm, red tailed maggot
Biotic factors affecting the abundance of organisms
Availability of food
All animals require food to live. The availability of food is a major factor in how many animals live in an ecosystem. Areas like rainforests with rich food supplies have more species of life than other areas like deserts and the Polar Regions where there is less food.
New predators
The arrival of new predators in an ecosystem can have a devastating effect. In balanced ecosystems, predators and prey have evolved together. Predators can catch enough prey to survive, but not so many that they kill all of their food.
The arrival of a new predator can upset this balance. An example of this is the introduction of the red fox to Australia, which has caused concern over their effect on native birds and small mammals. Introducing new predators can cause a rapid decline in the numbers of prey, which then reduces the food supply for existing predators.
New pathogens
When organisms inhabit new ecosystems they often bring new pathogens. As an example, Europeans first colonised North America, and introduced new pathogens, like the influenza virus. Many Native Americans had not developed immunity to new diseases such as this, and so many were killed by them. There are many examples of new pathogens being introduced to the UK. Ash dieback is a disease caused by a fungus which has killed many ash trees since it was first found in the UK in 2012.
Competion in animals
Food
All animals require food which provides them with energy and raw materials to complete life processes, without which they may die. Because of these, competition for food can be fierce. There are many birds which eat insects in our gardens, and some have evolved to only eat certain types of insect to reduce competition from other species. Others like the blue tit and great tit compete with other members of their own species and as well as others for different insects. Because food is so vital, many animals will fight for it.
Mates
Male deer compete for mates by locking antlers and pushing their opponent - the strongest usually wins
Animals within a species also compete for mates. This is essential so they can pass on their genes to their offspring. Animals have evolved to have an innate or natural drive to reproduce, and this competition often results in fights. This is seen each year when animals like red deer group together at the start of the mating season. Large male deer fight with each other by locking antlers and pushing hard, which is called a rut. In deer, and many others species, these fights competing for mates can often result in serious injury or death, but benefits the population as only the strongest pass on their genes to the next generation.
Territory
The territories of animals contain all of the resources and conditions they need to survive. These include abiotic factors such as light, temperature and water, and oxygen for aquatic animals. These are also biotic factors such as food and predators. Many animals, including the cats in back gardens, will fight for territory.
An example of intraspecific competition over territory would be between lions on the grass plains of Africa whereas interspecific competition would occur when another predator like leopards lived close to the lions.
Inderdependance in a community
All organisms in an ecosystem depend upon eachother, if one population rises or falls then this can affect the rest of the ecosystem. This means all the organisms in an ecosystem are interdependant.
Parasitism
Parasites live on or in another organism, and feed off its resources. The host does not benefit here
Mutulism
Both species help eachother, eg Bees eat the nectar, bee pollunates another plant.
Levels of organisation
Producers - Plants that photosynthesise and provide food for Primary consumers - Herbivores who eat the producers.
Secondary consumers, usually carnivores, who eat the primary consumers.
Waste management
As the human population increases, the amount of pollution and waste increases Modern society is more consumable and isnt very sustainable.
Water pollution
Open sewers and use of fertilisers wash into rivers and other water reserves. Because of these extra nutrients eutrophication can occur
