1.  Biotic & Abiotic Influences on Ecosystems October 19, 2012 SNC1D1

2. Limiting Factor  Any factor that restricts the size of a population  Can be biotic (competition) or abiotic (access to water, temperature)  Human influences often act as limiting factors

3. Influence of Abiotic Factors  Temperature, light, soil  Tolerance range : the range in which a species is able to survive

4. Tolerance Range  Some species have wide ranges, while others have narrow ranges.  Wide range: widely distributed and easily invade other ecosystems  Narrow range: only found in certain areas  Eg. Buckthorn – wide tolerance range Lady’s slipper orchid – narrow tolerance range

5. Influence of Abiotic Factors in Terrestrial Ecosystems  Distribution of terrestrial plant species limited by temperature, precipitation and light  Eg. Black spruce in North America  Limited to regions with long, cold winters and moderate precipitation

6. Influence of Abiotic Factors in Aquatic Ecosystems  Key abiotic factors:  salt concentration – can be negative  availability of sunlight – decreases with depth  Availability of oxygen – decreases with depth  availability of nutrients - varies

7. Influence of Biotic Factors  Abiotic factors determine where a species can live, but biotic factors determine the success of a species  Eg. Deer can survive in dense forests, but prefer open woodlands

8. Influence of Biotic Factors - 5 main types  Individuals are often in competition with members of their own species and with other species  Compete for limited resources like food, light, space and mates  Eg. Red Squirrels  Compete for pine cones and mates

9. Influence of Biotic Factors - 5 main types  Another interaction is predation.  Occurs when an individual kills and eats another individual  Eg. Wolves and caribou

10. Influence of Biotic Factors - 5 main types  Mutualism occurs when two organisms interact, and both benefit  Eg. Nectar-producing plants and pollinators  Parasitism occurs when one organism lives on or in a host and feeds on it  Eg. Leeches

11. Influence of Biotic Factors - 5 main types  The last type of interaction is commensalism  Occurs when one individual benefits and the other neither benefits or is harmed  Eg. Barnacles on a whale

12. Carrying Capacity  The upper sustainable limit that an ecosystem can support  Maximum number of individuals of a particular species in an ecosystem  Can be altered by human activities  Eg. Removal of wolves = increase in carrying capacity for moose

13. Activity  http://express.smarttech.com/?url=http://exchangedownlo ads.smarttech.com/public/content/9d/9dd67aa1-0a97- 4fa5-bb5b- 43ed6a6d2268/G6_L05_Limiting%20Factors_final_JC.note book# http://express.smarttech.com/?url=http://exchangedownlo ads.smarttech.com/public/content/9d/9dd67aa1-0a97- 4fa5-bb5b- 43ed6a6d2268/G6_L05_Limiting%20Factors_final_JC.note book#  http://exchange.smarttech.com/search.html?q=limiting%2 0factors http://exchange.smarttech.com/search.html?q=limiting%2 0factors