Limiting Factors in Ecosystems PDF

Lesson 7 Unit 2 Ecology SNC1W Limiting Factors in Ecosystems  BIG CONCEPT Various combinations of abiotic and biotic factors cause populations to increase or decrease in a given ecosystem. Example: If there is an unlimited amou...

Lesson 7 Unit 2 Ecology SNC1W Limiting Factors in Ecosystems  BIG CONCEPT Various combinations of abiotic and biotic factors cause populations to increase or decrease in a given ecosystem. Example: If there is an unlimited amount of food, water and space available, populations can grow very quickly. Without any limits, 10 breeding pairs of rabbits could expand to 10 million breeding pairs in only 3 years. ★ In a healthy, properly functioning ecosystem, limiting factors prevent overpopulation from happening! 2  Limiting Factors A limiting factor is any factor that restricts the size of a population or where it can live. These factors can be abiotic or biotic. Human influences can also act as limiting factors. 3  Abiotic Limiting Factors Factors such as temperature and precipitation may influence where a species lives. E.g. Cacti thrive in dry conditions. Too much rainfall could destroy their shallow roots by flooding them or causing them to rot in really wet soil. 4  Abiotic Limiting Factors Each species has a tolerance range: the range of abiotic conditions within which a species can survive. Species with a wide tolerance range tend to live in a variety of ecosystems. E.g. Raccoons can live in hot tropical forests or in colder northern forests. 5 Abiotic Limiting Factors - Terrestrial Ecosystems Key Abiotic Factor Human action and result light availability Fire and tree cutting can remove shade and expose organisms to more light water availability Damming rivers and draining wetlands reduces water availability; irrigation increases water availability nutrient availability Farming practices can change nutrient levels in soil temperature Global warming can reduce available habitat for cool-adapted species 6 Abiotic Limiting Factors - Aquatic Ecosystems Key Abiotic Factor Human action and result light availability Activities that increase erosion or stir up bottom sediments can reduce light at lower depths nutrient availability Fertilizer runoff can increase nutrients in water and cause algal blooms (eutrophication) acidity Pollution from burning fossil fuels increases acid rain in aquatic ecosystems temperature Industries release heated waste water into lakes and rivers, killing fish and other organisms salinity Salting highways and irrigation can increase the concentration of salt 7  Biotic Limiting Factors Abiotic factors usually determine where a species is able to live. Biotic factors often determine how easily a species can survive in an ecosystem. Ex. a specific food source can influence how well a species may survive. Biotic factors include how individuals in a community interact with one another. 8  Biotic Limiting Factors Competition Predation Symbiosis Two individuals seek the One individual feeds on Two species live in/on/near same resource (food, water, another each other light) Ex. lynx prey on snowshoe Ex. There are 3 types of Ex. foxes and coyotes both hares symbiotic relationships…… feed on common prey such as mice Click to see the next slide to find out! 9  Biotic Limiting Factors There are 3 types of symbiotic relationships: A) Mutualism B) Commensalism C) Parasitism Two individuals benefit each One individual benefits One individual lives on or in a other and the other is unaffected host organism and feeds on it Ex. Bacteria living on the Ex. Barnacles on a Ex. Tapeworms are parasites of roots of a soybean plant humpback whale cats and dogs 10  Carrying Capacity As a population grows, it requires more food, water, and space. Eventually, it will reach its carrying capacity – the maximum population size of a species that a given ecosystem can sustain. 11  Carrying Capacity As abiotic and biotic (and human) factors change, the carrying capacity of an ecosystem also changes. Ex. A forest fire decreases the number of trees but new plants will increase as they have more space and light. 12  Carrying Capacity Consider a population of snowshoe hares, which are prey for lynx. As the population of snowshoe hares increases/decreases, so too does the lynx. 13  Human Actions Affect Carrying Capacity 1. Habitat Loss (Deforestation) Humans may destroy natural landscapes as they mine resources and urbanize areas. This is detrimental, as it displaces residing species, reducing available habitats and food sources. 14  Human Actions Affect Carrying Capacity 2. Pollution Can occur from the runoff or disposal of chemical substances, or from energy sources (noise and light pollution). 15  Human Actions Affect Carrying Capacity 3. Invasive Species Humans may unintentionally, or intentionally, introduce a non-native species into an ecosystem. This can negatively affect an ecosystem because the introduced species may outcompete native organisms and displace them. Could there be invasive species in your backyard? 16  Human Actions Affect Carrying Capacity 4. Overexploitation Humans consume large amounts of resources for their own needs. Some examples include the mining of natural resources like coal, the hunting and fishing of animals for food, and the clearing of forests for urbanization and wood use. 17  Human Actions Affect Carrying Capacity 5. Non-renewable Resources Extensive overuse of resources like fossil fuels, can cause great harm to the environment. Recycling products made from nonrenewable resources (such as plastic, which is made from oil) is one way to reduce the negative impacts of this resource exploitation. In addition, the development and use of renewable resources, like solar or wind energy, can help decrease the harmful effects of resource exploitation. 18 Practice Makes it Permanent! Have you been keeping up with the practice work? Do you need to go back and finish from the other lessons? Have you been keeping up with the online videos? Have you been doing the online practice quizzes? Have you tried the Study Jams or Gizmos? 19