Community Ecology Flashcards
ecological succession
the sequential change in species composition of the community over time
what are the two types of ecological succession?
- primary succession
- secondary succession
what is primary succession?
initial establishment of plant and animal communities on substrates lacking living organisms
examples of where primary succession occurs?
bare rock, lava, sand dunes, glacial melt water pond, rainwater
why is alder the first species to grow after a landslide?
rock is nutrient-deficient, alder has nitrogen-fixing bacteria (hemlock do not) and can survive on the rocks.
what type of plants can colonize rock after a landslide?
plants with nitrogen-fixing bacteria can colonize just rock
what is secondary succession?
change of an established community
-> change in a preexisting community
secondary succession: ponds and lakes accumulate _____, _____, ____, and get ______
- sediment, pollen, leaves
- shallower and smaller over time
secondary succession: reeds, grasses and herbs develop on
shoreline
in ecological succession, each sequential community is called a ______
seral stage
_______ seral stages last longer than _____
successive, previous stages
pollen has a ______
low decomposition
it is possible to identify ______ taken from core
pollen species
it is possible to estimate geographical age when plants died using _______
radiocarbon dating
what are carbons three main isotopes?
C12
C13
C14
C14 has a half life of ____ and decays to ______
5730 years, N14
T/F: seral stages are well-defined by ecologists
false, depends on what you are interested in, even then it is pretty loose.
how do we determine the hx of vegetation in secondary successive ecosystems?
pipe in ground (sediment cores)
- used to reconstruct vegetation hx
- when they find that C14 decayed to N14, that is their estimates for when the plants died
- can take the DNA of this plant and animal species
ancient DNa reveal late survival of mammoth and horse in interior Alaska: what kind of DNa used?
sedaDNA - DNA from securely dated sediments
explain the mammoth study:
found that mammoths lived until 10,500 BP, several thousand years later than indicated from macrofossil surveys.
- mammoth and horse survival overlap with humans
- contradicts the findings that extinction was due to extraterrestrial impact in late pleistocene
put these in the correct order: bare ground, climax, pioneer seral stage, primary succession, serial stage, secondary succession
bare ground, primary succession, pioneer seral stage, serial stages, secondary succession, climax
T/F: disturbance resets ecological succession back to the bare-ground stages
false, sets it back to any stage
what are examples of disturbances that would set ecological succession back?
fires, melting glaciers, etc
what is allogenic succession?
abiotic disturbances, such as fire, earthquakes, volcano (pushes back to earlier state)
what is autogenic succession?
biotic disturbances such as deaver ben
why is old growth important?
more biodiversity
in the summer after clear cutting, diversity is very _____, it then _____ before _______
high, plummets, increasing
immediately after clear-cutting, there are many _____, which means _____ is very _____. this is followed by a long period of _____
small shrubs (and small animals), diveristy, high, low diversity
in the winter after clearcutting, species ____ is very _____ for a long time. there is no _____ to _____ a winter _____
diveristy, low, old growth, support, habitat
diversity after clear-cutting is _______ dependent
season
after cleatcutting, biomass _____ immediately, then ____ to _____
drops, increases, aggradtation
aggradation
accumulation of sediment
total biomass peaks at _____, then ____ during the _____, before reaching a ready state
aggradation, decreases, transition
what causes total biomass to decrease during transition?
soil community
the soil community ____ after cleatcutting, then gradually ____ during aggradation. it is ____ once the community _____ because there is _____
dies, accumulates, lessened, stabilizes, less decomposition
soil is built by…
decomposition
how long to tropical regions such as Krakatau take to recover from primary succession to tropic forest?
100 years
how long would it take coastal bc rainforest to recover
- 1000 yrs for insect community
- 100 yrs for trees
how long would it take the arctic to reach late seral stages?
~10,000 yrs bcuz it is still changing
rate of succession is correlated to ____
temp and rainful
-> warm, wet habitat succession is fast
-> cool ,dry habitat succession is slow
what are the 4 ecological mechanisms for succession?
- stochastic events
- facilitation
- inhibition
- tolerance
stochastic events
largely unpredictable
- who gets there first can become established (by chance), major process in early seral stages
which ecological mechanism is most important in early seral stages?
stochastic events
facilitation
a species creates conditions favorable for a succeeding species but not itself
- eg. clover facilitates colonization of another species at the expense of itself (trees cover)
- leads to regular, sequential shift in species (assembly rules)
- major process in early seral stages
facilitation example
- predators cannot colonize successfully unless prey are already present
- pollinators cannot colonize successfully unless flowering plants are present
facilitation is ____, while stochastic events are ____
regular, unpredictable
facilitation events lead to reguar and sequential shifts in species, “______”
assembly rules
assembly rules example
predators cannot colonize successfully until prey are already present
inhibition
a species inhibits the colonization of subsequent colonists
- eg allelopathy: chemical inhibition (coral reefs), competitive exclusion
in inhibition, a species slows ____ and prolongs the ______
succession, seral stage
allelopathy
the production of chemicals by plants that inhibit the growth of neighboring plants
allelopathy is an example of____, it is common in ______
inhibition, plant communities (or coral reefs)
competitive exlcusion is an example of _____, it is common in _____
inhibition, intertidal communities
tolerance
members of a seral stage are those that co-exist due to the use of different resources
- combines facilitation and inhibition into a co-evolutionary view of succession
tolerance combines ____ and ____ into a _____ view of succession
facilitation, inhibition, co-evolutionary
‘the ghost of competition past’ refers to present _____
tolerance of species
species ____ among seral stages
change
in early seral stages:
_____ seed dispersal
_____ plant efficiency at low light
_____resource (nutrient) acquisition
good, low, fast
in late seral stages:
_____ seed dispersal
_____ plant efficiency at low light
_____resource (nutrient) acquisition
poor, high, slow
in early seral stages:
_____ biomass
_____ stability
_____ diversity
small, low, low
in late seral stages:
_____ biomass
_____ stability
_____ diversity
large, high, high
in early seral stages:
_____ species life history
_____ seed dispersal vector
_____ seed longevity
_____ shoot to root ratio
r, wind, long, high
in late seral stages:
_____ species life history
_____ seed dispersal vector
_____ seed longevity
_____ shoot to root ratio
k, animals, short, low
shoot to root ratio high vs. low seral stage
high in early, low in late stages
trophic levels
the sequence of steps in a food chain or pyramid
what are the 4 trophic levels?
- primary producer
- primary consumer
- secondary consumer
- tertiary consumer
what is the problem w trophic chain?
over simplified
a food web has many “_____’
chains
a food web has numerous ‘_______”
connections between chains
mean chain length
mean number of links running from a primary producer to each of the top predators
connectance
actual number of links in a food web divided by the total number of possible links
if a community has n species, then the total number of possible links (N) is:
N= n(n-1)/2
connectance equation
C=L/N
what is L?
actual number of links
linkage diversity
the average number of links per species
- total number of links divided by the total number of species
equation for linkage diversity
LD = L/n
how many types of trophic pyramids are there?
3
what kinds of trophic pyramids are theree
numbers, biomass, energy
umbrella (indicator) species
a species used for conservation decisions (grizzly bear, panada, spotted owl)
dominant species
a common species with an effect proportional to its biomass
zooplankton is a ____ species, while grizzly bears are a ____ species.
dominant, umbrella
keystone species
a species with an effect on the community that is disproportional to its biomass
examples of keystone species
sea otter, starfish
T/F: dominant, umbrella and keystone species never overlap
false, sometimes they do
where would 1. keystones and 2. dominants be located (below line/above line, top/bottom)
above line top, below line top
marine and terrestrial ecosystems: what is it called when nutrients move from terrestrial ecosystems to marine ecosystems?
downloading
marine and terrestrial ecosystems: what is it called when nutrients are moved from marine to terrestrial ecosystems?
uploading
how are nutrients downloaded to marine ecosystems?
rivers
how are nutrients uploaded to terrestrial ecosystems?
seabird guano
downloading leads to increased _____ in estuaries and _____ marine waters
primary productivity, adjacent
rivers discharge _____ to marine waters via downloading
sediment, trace elements, organic matter, nitrogen, phosphates
oligotrophic means
low productivity
clear and deep mountain lakes:
- oligotrophic
- N and P limited
- low plankton abundance
- usually few fish
migration of salmon greatly ____ of lakes and streams
increase primary productivity
why do clear/deep mountain lakes have few living things in them?
no trace elements
productivity of lakes are proportional to amount of…..
dead salmon that drift back
increase in _____ to abundance of salmon carcasses
productivity proportional
riparian zone
forest habitat adjacent to stream that is influenced by stream parameters
what are stream parameters?
flooding, nutrients
roughly what percent of salmon carcasses transferred by black bears into riparian zone at Bay Harbour were male?
33%
roughly what percent of salmon carcasses transferred by black bears into riparian zone at Bay Harbour were female?
66%
what part of the female salmon do bears like best?
eggs
what part of male salmon do bears dislike?
testes
during the day, bears mostly eat
females
at night, bears eat mostly
whatever sex they can catch
how do bears discriminate between salmon?
smell
productive condition of salmon captured by bears: average male salmon….
spawned 5-8 times before capture
productive condition of salmon captured by bears: female salmon…
70% were spawned out
most of the predation is on _____ salmon. therefore bear predation has a ____ on the reproduction of salmon
post-reproductive, minor effects
flow of salmon biomass: birds, sea lions, and seal eat salmon in _____
estuaries
flow of salmon biomass: bears, eagles, crows and insects eat salmon in _____
streams
flow of salmon biomass: marine invertebrates scavengers eat salmon that have
floated downstream
flow of salmon biomass: bears, small carnivores such as mink and insects eat salmon on the
forest floor
explain how salmon feed spring birds
insects lay eggs in salmon, hatch in spring, eaten by songbirds
nitrogen is a limiting resource for ____ in ____
vegetation, coastal forests
3& of total mass of salmon tissue is
nitrogen
salmon carcasses
in riparian zones contribute 120kg nitrogen per hectare
nitrogen
- 78% of earths atmosphere
- exists as 2 stable isotopes
14N
light isotope, 99.3% of total nitrogen (7 protons, 7 neutons)
15N
heavy isotope, 0.7% total nitrogen, 7 parts per thousand (7 protons, 8 neutrons)
- relative amount in biological systems varies
how are isotope ratios measured after the tissues have been collected?
washed, dried, and ground into a fine powder for combustion in a mass spectrometer
to determine how much of nitrogen is NOT from the atmospheres, we compare _____ _____ of tissues relative to _____ _____
isotope values, atmospheric standard
list in order of increasing d¹⁵N levels (lowest at top, highest at bottom):
bear
deer
phytoplankton/algae
salmon
small fish
trees/shrubs
wolves
zooplankton
trees/shrubs
deer
wolves
phytoplankton/algae
zooplankton
small fish
salmon
bear
15N values are higher in ____ waterfalls than ____ water falls
plants below, above
explain: what do waterfalls have to do with salmon?
salmon can’t climb steep waterfalls
therefore salmon are below falls, not above them
nitrogen levels can affect
community structure
certain plants are found in nitrogen-rich soil and others are found in nitrogen-poor soil. what do we call these species?
indicator species
if salmon can’t get over a waterfall, what kind of plant indicator species would you expect to find above the falls?
nitrogen-poor soil indicator plant species
if salmon can’t get over a waterfall, what kind of plant indicator species would you expect to find below the falls?
nitrogen-rich indicator species
up to ____% of nitrogen in riparian plants is derived from salmon nutrients
80%
T/F: core samples show that the growth rate. of trees is due to the abundance of salmon
false
T/F: ¹⁵N levels for yearly growth rings show that the growth rate of trees is due to the abundance of salmon
true
if abundance of salmon affects tree growth, we will see _____ in the δ¹⁵N of trees ____ the spikes in salmon
lag, alter
how much nitrogen in feathers of songbirds is from salmon?
30-95%
30-95% of insect diet of winter wren is
salmon derived
salmon constitute about ___ of ____ diet of wolves
20%, fall
____ of bears 40x greater on ___ watersheds than on watersheds without ____
population density, salmon, salmon
___ are the major species that transfer salmon into ___ around the north pacific
bears, forests
each bear can transfer up to ___ salmon into the forest over a 6 week ____
500, spawning period
average transfer of ____ carcasses per km per year along ___ of river
1000, spawning reaches
up to 80% of the ____ in riparian plants come from salmon. this is an example of ____
nitrogen, marine-terrestrial ecosystem linkages
there is increased primary productivity and species diversity in watersheds with ___ and___
salmon, bears
salmon are a ____ species
dominant
bears are a ___ species
keystone
