Final Exam Class 5

Question 1

community structue

Answer 1

describes the composition of communities

Question 2

what are the components of community structure

Answer 2

number of species
abundance of species
interactions among species
biotic and abiotic factors

Question 3

species richness describes

Answer 3

the number of species in a community

Question 4

species diversity accounts for

Answer 4

number of species and abundance

Question 5

frederick Clements argues

Answer 5

communities are stable and the result of extensive biotic interactions and coevolution

Question 6

(clements) after disturbance species in an area should reach

Answer 6

climax community which is stable and predictable

Question 7

henry gleason argues

Answer 7

comunities are dynamic and are the result of historical chance and abiotic factors

Question 8

(gleason) unpredictiable

Answer 8

communities are ephermeral

Question 9

how did gleason and clements test their theories?

Answer 9

experimental ponds were built and allowed species to establish themselves over 1 year

Question 10

which theory (clements or gleason) was correct?

Answer 10

both Gleason and clements (different species colonized different ponds therefore communities are unpredictable, but most of the species occurred in all 12 ponds)

Question 11

what is a keystone species?

Answer 11

have a disproportionately large effect on their surrounding ecosystem relative to its own abundance

Question 12

what is a dominant species

Answer 12

can have strong effect just due to high abundance and biomass

Question 13

what is an example of a keystone species

Answer 13

sea otters, starfish
- starfish preys on mollusks and mussles which it competes for space, so when you remove the starfish the mussels just take over which throws the species abundances out of whack

Question 14

the presence of a keystone species can limit

Answer 14

one species from dominating and promoting community diversity
their removal can change communities

Question 15

all communities face

Answer 15

disturbances

Question 16

what is a disturbance

Answer 16

anything that changes the community structure

Question 17

what influences the diversity and ability of organisms adapt to changes?

Answer 17

frequency, duration, and predictablility or disturbances

Question 18

whar are the diffeerent types of predictivablity

Answer 18

daily : tides
seasonal : winter snow monsoons
aseasonal:froughts, forest fires
millennial: volcanoes and earthquakes

Question 19

what is successsion?

Answer 19

the pattern of recovery
-bare rock to lichen moss to annual herb to perennial herb to scrub to forest (climax community)

Question 20

what is primary succession?

Answer 20

when a disurbance removes all organisms in an area and the soil
-caused by glaciers or volcanoes (takes hundreds of years)
-pioneer species to intermediate species to climax community

Question 21

the sequence of succession depends on

Answer 21

the species involved
their interactions
environmental circumstances
disturbance frequency

Question 22

early species tent o be

Answer 22

r selected (weeds)

Question 23

later species tend to be

Answer 23

k selected

Question 24

early species interact with subsequent species 3 different ways

Answer 24

facilitaiton
toerace
inhibition

Question 25

facilitation

Answer 25

makes conditions avorable for new species

Question 26

tolerace

Answer 26

does not positively ornegatively affect new species

Question 27

inhibition

Answer 27

prevents the establishment of a new species

Question 28

exampes of facilitation

Answer 28

protection from the win
increase soil moisture
increase available nutrients and organic matter

Question 29

examples of inhibition

Answer 29

limit sunlight
compete for nutrients
allelochemicals to inhibit growth

Question 30

what is secondary succession?

Answer 30

occurs when a disturbance remove’s some but not all organisms in an area

Question 31

secodary sucession is caused by

Answer 31

fires r storms and recovery can take only a hundred or so years
- can be important to regulate environments and communities

Question 32

many communities are adapted to

Answer 32

specific disturbance regimes and altering these regimes may negatively impact community structure

Question 33

in the early 1910’s

Answer 33

the us forest service began supressing natural forest fires
this reduced frequency of secondary succession that was important for communities adapted to periodic disturbances