Unit 1 - MSH - Complexity & Gap Dynamics Flashcards
definition: the process of development that over time, gradually and predictably changes the biological community
succession
What drives succession forward? What replaces one community with another over time?
facilitation
What is the broad framework of succession?
bare rock–> lichens–> small annual plants/ moss–> perennial herbs/grasses–> shrubs/shade-intolerant trees–> shade-tolerant trees
What makes up the climax community in succession?
shade-tolerant trees
What makes up the pioneer stages in succession?
bare rock, lichens, & small annual plants/moss
What makes up the intermediate stages in succession?
perennial herbs/grasses & shrubs/shade-intolerant trees
Where do we find primary succession?
mountain tops, glacial retreat, parking lots, granite outcrops
Does the pumice plain experience primary or secondary succession? Why?
secondary; tephra, although nutrient poor, is still soil, things can put down roots, not solid bare rock but rock dust
What was the succession process like on MSH?
lupine–> fireweed, pearly everlasting–> willows/red alder–> noble fir/Douglas fir/red cedar
What makes up the pioneer stages in succession on MSH?
lupine & fireweed/pearly everlasting
What makes up the intermediate stages in succession in MSH?
willows, red alder
What makes up the climax community in succession in MSH?
noble fir/Douglas fir/red cedar
Are all successional pathways the same? why?
no, random variation can lead to different outcomes
definition: the “final” stage that will persist as a static ecosystem and will continuously regenerate itself
climax community
Why are shade-tolerant trees often a part of the climax community?
they are able to grow underneath the shade that their parents are providing; the last stage is self-perpetuating; shade tolerant trees are able to regenerate themselves
How does soil development change with succession?
soil accumulates in volume, depth, and nutrients over time
What particular part of the soil changes with a good amount of time?
stratification - the development of layers
With succession: over time, what increases?
complexity
What does the succession progression look like in the Midwest/Northeast?
exposed rocks–> lichens and mosses–> annual weeds–> perennial weeds & grasses–>shrubs–>aspen, cherry & young pine forest–>beech and maple broadleaf forest
What are 3 types of complexity we observe?
(1) structural - horizontal vs vertical
(2) soil complexity
(3) biodiversity - species richness
What does vertical complexity mainly look at?
the layers of a forest
What are the different layers of a forest with regards to vertical complexity?
soil–> forest floor–> understory/shrub layer–> sub canopy–> canopy
Did the old growth forest on MSH have vertical complexity pre-eruption?
yes, almost every inch was full of life
Did the blowdown zone have much vertical complexity post-eruption?
no, only a few plants on the forest floor and then really tall trees w/no leaves (not much in the middle)
What does horizontal complexity mainly look at?
patchiness - how many different kinds of communities exist right next to each other
Is complexity just based on time since eruption? What else is it based on?
distance from eruption:
closer to greater: least vertically complex
further away forest: more vertically complex
Which type of farming, traditional or permaculture, has more vertical complexity? Why?
permaculture; traditional ag is very low to the ground while permaculture contains all different levels
Which type of farming, traditional or permaculture, has more horizontal complexity? Why?
permaculture; permaculture has more patchwork in a small space while traditional ag just has a few species grown in longs rows
Do ecosystems only change in one direction with succession?
no
What can push change in the other direction with regards to succession?
a disturbance
What acts in opposition to succession?
disturbance
How does disturbance lead to horizontal complexity?
disturbance allows succession to be constantly occurring at different stages and scales, forming more patches
What type of complexity does a disturbance cause more of?
horizontal - forms patches
definition: when little disturbances happen gradually and accumulate over time this will lead to more patches that exist in different successional stages
dynamic equilibrium
What two things together over a period of time create an ecosystem in dynamic equilibrium?
succession & disturbance
What is the early-successional forest of MSH?
willows/red alder
What is the late-successional forest of MSH?
noble fir/Douglas fir/red cedar
What is the term for an ecosystem that is in a constant state of flux/change due to disturbance and succession?
dynamic equilibrium
What are two important characteristics of dynamic equilibrium?
(1) develops over time
(2) contains patches in DIFFERENT successional stages
What type of complexity increases with small-scale disturbances?
horizontal
A forest in ________ might have a patch of climax community (red cedar trees) next to a patch of grass.
dynamic equilibrium
In dynamic equilibrium:
overall high ______ complexity
some patches with high _____ complexity and some with low _____ complexity depending on successional stage
horizontal; vertical
What happens to biodiversity over time with succession?
increases - more species in different layers
What happens to biodiversity when we add disturbance (dynamic equilibrium)?
increases - many different biological communities right next to each other in equilibrium
What is the first species that secondary succession starts with?
small annual plants (completely skips bare rock and lichen stage)
Why are some places more biodiverse than others?
(1) time - succession and dynamic equilibrium develop over time
(2) ecosystem complexity - horizontal and vertical; topographic
(3) more energy in the system
Where does energy in an ecosystem come from? In what locations is this energy most abundant?
sun/solar energy - most abundant in places near the equator
Why do mountains have such high biodiversity?
dynamic equilibrium at different elevations & contains different biomes in a condensed fashion
How does species richness at the equator compare to that at the poles?
equator: very high
poles: extremely low
More energy in the system = more _____
biodiversity
What is the relationship between number of plant species and degrees Latitude increasing from 0 out N or S?
negative - further from equator, less plant species present
What are two main reasons that biodiversity is advantageous to a place?
higher resistance & resilience
What is the main ecological reason for why biodiversity is important?
the more biomass in an ecosystem, then less likely to be impacted as heavily by disturbances
What is the relationship between the number of plant species before a drought and change in biomass?
negative; more plant species = lower change in biomass
As the number of species increases, the amount of biomass lost in a disturbance _____.
decreases
definition: total weight of all the LIVING things in an area
biomass
definition: ability to prevent impacts from disturbances
resistance
Do ecosystems with high biodiversity change drastically with a minor disturbance? Why?
no because of more species leading to redundancy; if one species is lost, another can fill in its position
If there is 0 change in biomass, then an ecosystem is completely ______ to disturbance (impossible).
resistant
definition: ability to recover after a disturbance
resilience
Ecosystems with ___ biodiversity recover faster from disturbances.
high
Why are ecosystems with high biodiversity more resilient to disturbances?
as a community accumulates species, there is a higher chance of any one of them having traits that enable them to adapt to a changing environment
definition: ecosystems are more CONSISTENT over long periods of time
stability
higher biodiversity = more ______
stability
Why is high biodiversity important to the stability of an ecosystem?
species with high genetic diversity and many populations adapted to a wide variety of conditions are more likely to be able to withstand weather disturbances, disease, and climate change
What is the term that refers to the capability of a natural system to apply self-regulating mechanisms so as to return to a steady state after a disturbance?
stability
Under what conditions is an ecosystem said to possess ecological stability?
if its capable of returning to its equilibrium state after a disturbance or does not experience unexpected large changes in its characteristics over time
If an ecosystem is stable for a long period of time, what will happen to complexity and biodiversity?
increase
Why are stable ecosystems not characterized as static?
they still experience changes and add complexity with minor disturbances
Increased biodiversity, increased _______, increased ______ (positive feedback loop).
complexity, stability
What is an example how organisms in an ecosystem with great biodiversity have higher stability>
organisms rely on more than one type of food, so if a food source gets wiped out by a disturbance, they have others to rely on
What are 2 major advantages to a population?
(1) genetic diversity
(2) ecosystem complexity
What are some other disciplines that the ideas of resilience and stability span across?
ecological and social
definition: openings in a forest canopy (due to a disturbance) where new trees can grow
forest gaps
What is the advantage of a forest gap?
increased sunlight reaches the forest floor for plants to take advantage of
What is the goal when trying to fill the gap?
to reach the canopy
Why do trees want to reach the canopy?
increased fitness - more energy
Is there an evolutionary trade off with short vs long-term strategies?
yes
definition: a situation in which evolution cannot advance one part of a biological ecosystem without distressing another part of it
evolutionary trade off
Explain how colored feathers are an evolutionary tradeoff?
pro: they help attract mates
con: they are more easily spotted by predators
What type of trees are the first species to come in and establish in a gap that forms?
early successional trees (hares)
What type of trees can establish underneath an existing canopy and slowly make their way to the canopy themselves?
late successional trees (tortoises)
What are 4 traits involved with trees?
(1) maximum growth rate
(2) persistence
(3) shade tolerance
(4) longevity
definition: how fast a tree is able to grow given ideal conditions (some trees are better at growing faster than others)
maximum growth rate
definition: how little growth a tree can sustain without dying (all about height of a tree)
persistence
definition: how much light a tree requires in order to live (maintain a positive carbon balance)
shade tolerance
definition: max life-span of a tree
longevity
What is the trade off between maximum growth rate and persistence?
an early successional tree that can grow at fast speeds also can be likely to die very quickly
Early successional trees (high/low):
max GR:
persistence:
shade tolerance:
longevity:
high
low
low
low
Late successional trees (high/low):
max GR:
persistence:
shade tolerance:
longevity:
low
high
high
high
What is the relationship between shade tolerance & max growth rate?
negative
Do shade tolerant trees grow fast?
no - they are slow steady growers
example of evolutionary tradeoff:
although late successional trees can live longer, they can’t grow very _____
fast
What is the relationship between shade tolerance and lifespan?
positive
Over very long periods of time, which kinds of trees will accumulate in the canopy? Why?
shade tolerant trees because they can live a long time (high longevity) and can regenerate themselves
example of evolutionary tradeoff:
although early successional trees have a high growth rate, they can’t _____ for very long (low _____)
survive; longevity
What is the order of tree species on MSH from early successional (1) to late successional (4)?
(1) red alder
(2) noble fir
(3) Douglas fir
(4) red cedar
