8.7: Disturbances In An Ecosystem

Question 1

What can disturbances in an ecosystem influence?

Answer 1

Species diversity and composition

Question 2

What is a disturbance?

Answer 2

• an event that changes a community by removing organisms from it or altering resource availability
  Ex. Fire, droughts, human activity etc.

Question 3

What is ecological succession?

Answer 3

The gradual process by which the species composition of a community changes and develops over time after a disturbance

Question 4

What are the two types of ecological succession?

Answer 4

Primary and secondary

Question 5

What is primary succession?

Answer 5

• a series of changes on an entirely new (previously lifeless) habitat that has not been colonized

Question 6

What is secondary succession?

Answer 6

• a series of changes that clears an existing community, but leaves the soil intact
  Ex. Fire (seeds are like revived or smth idk)

Question 7

Give some examples of how primary succession would occur.

Answer 7

1. Improvement/increase in soil quality, which allows plants to grow, More nutrients available
   - plants need nutrients like P and N to grow
2. Change in pH, H2O levels, temp, etc.

Question 8

What is the strongest disturbance to an ecosystem?

Answer 8

HUMAN ACTIVITY

Question 9

what are the 4 main threats to biodiversity?

Answer 9

• habitat loss
• invasive species
• over harvesting
• global change

Question 10

Why is habitat loss a threat to biodiversity? (2)

Answer 10

• single greatest threat to biodiversity
• agricultural development and urbanization
  Ex. Clear cutting, cattle grazing, farmland

Question 11

Why are invasive species a threat to biodiversity?

Answer 11

• a nonnative species that can occupy a wide range of habitats and competitively exclude native species from those habitats
  Ex. Zebra mussels (lake wpg) murder hornets (BC) Asian carp (USA)

Question 12

Why is overharvesting a threat to biodiversity?

Answer 12

Organisms are harvested faster than their populations Can rebound
Ex. Harvesting of ivory in elephants (banned now)
Overfishing

Question 13

What is global change, and why is global change a threat to biodiversity?

Answer 13

• alterations to climate, atmospheric chemistry, and ecological systems that reduce the capacity of earth to sustain life
  Ex. Air/water pollution (acid rain), CO2 emissions, ocean acidification (increase CO2 means increase in carbonic acid production)

Question 14

Why are human disturbances the strongest disturbance to an ecosystem? (3)

Answer 14

• significant increase of endangered species
• many species that are now threatened could potentially provide food, medicine, and fibres
• scientist say we are in a mass extinction now

Question 15

What are biogeographical factors?

Answer 15

• large scale factors that contribute to a range of diversity observed

Question 16

What are two types of biogeographical factors?

Answer 16

Latitude and area

Question 17

Why does latitude contribute to biodiversity?

Answer 17

Species are more diverse in tropics (increased vegetation) than at the poles due to climate

Question 18

Why does area contribute to biodiversity?

Answer 18

• larger areas are more diverse because they offer greater diversity of habitats

Question 19

What are pathogens?

Answer 19

Disease- causing organisms and viruses (unicellular, non-living)

Question 20

Why do pathogens affect biodiversity?

Answer 20

• pathogens have the most effect on new habitats or ecosystems with less biodiversity