lec 16- Disturbances and succession

Question 1

what are examples of environmental and biological disturbances in nature?

Answer 1

environmental: lava, fire, glaciation, avalanches, landslides, hurricanes, & floods

biological: beaver dams (blocks water), salmon nest digging (moves sediments away), bioturbation (digging), & herbivory

Question 2

what is primary succession?

Answer 2

when a catastrophic disturbance removes soil and plants from the habitat

Question 3

what is secondary succession?

Answer 3

when a disturbance removes plants but the soil remains intact and nutrients remain

Question 4

which succession occurs faster?

Answer 4

secondary due to nutrients and soil already existing

Question 5

what type of succession is old field succession?

Answer 5

secondary

Question 6

how do you measure successions directly?

Answer 6

-collect data at regular intervals following disturbance
-experimentally induce the dirsturbance or create new habitat and monitor species colonization

Question 7

how do you measure succession indirectly?

Answer 7

chronosequences: compare communities in same location with different start times

Question 8

what is the disturbance for sand dune successions?

Answer 8

water

Question 9

what type of succession is sand dune successions?

Answer 9

primary (has sand instead of soil)

Question 10

what is a pioneer species?

Answer 10

the first species to show up in the habitat that experienced the disturbance, help other species to show up

Question 11

what is a climax community?

Answer 11

the final group of species in the habitat that experienced the disturbance, marks the end point of succession and is assumed to be stable until next disturbance, often inhibit other species from showing up

Question 12

what is an example of pioneer species that facilitate?

Answer 12

alder trees fixate nitrogen for the habitat, letting other species to move in

Question 13

what is the difference between early and late successional plants?

Answer 13

early = better dispersal, rapid growth, early reproduction
late = better at competing with other species

Question 14

how do late successional plant species compete and stop other species from showing up?

Answer 14

by inhibition, preventing other species from growing (e.g. broomsedge stops aster)

Question 15

what were the post eruption conditions of Mt. St. Helens?

Answer 15

-inorganic substrates (rock, ash etc.)
-low soil moisture (=drought)
-high sunlight (no shading)
-high availability of space
-no organic nutrients

Question 16

what limits succession?

Answer 16

-dispersal
-inhospitable conditions

Question 17

what are the traits of the first plants to come back?

Answer 17

-good dispensers, small seeds = longer dispersal distances
-ability to withstand harsh conditions, large seeds = better germination success

Question 18

what was the first plant on Mt. St. Helens after the eruption?

Answer 18

lupine

Question 19

what was the first species of animal on Mt. St. Helens after the eruption?

Answer 19

gopher, mixed soil into the volcanic ash letting lupine to flourish

Question 20

what is intermediate disturbance hypothesis?

Answer 20

low number of species experience low intensity of disturbances and have a stable environment = competetive exclusion, high number of species experience high intensity of disturbances and have high stress = high rates of extinction

Question 21

what is peat?

Answer 21

accumulation of dead plant matter

Question 22

what is the steps to bog succession?

Answer 22

1. lake edge grows plants
2. plants expand across into the lake and accumulate peat
3. expand more into the lake and peat becomes thicker
4. plant expansion eventually covers lake and peat sediments in basin

Question 23

what do detrivores contribute in succession?

Answer 23

nutrients from carcasses