Unit 1 - Mount St Helens Background Info Flashcards
What defines an ecosystem?
pre & post eruption
What defines a species as members of populations that actually or potentially interbreed in nature, NOT according to similarity of appearance?
biological species concept
What defines all of the individuals of a SINGLE species that interact?
population
What defines all of the populations of LIVING things that interact in a place?
community
What defines a biological community of interacting organisms and their physical environment (biotic and abiotic components)?
ecosystem
How does a community differ from an ecosystem?
community is based solely on organisms and within an ecosystem the physical environment is included
What are some ways that ecosystems are defined by organisms (biotic)?
(1) Biodiversity
(2) Biomass (NPP - net primary productivity)
(3) Species interactions
(4) Invasive or keystone species
What are some ways that ecosystems are defined by their environment (abiotic)?
(1) Climate - averages & seasonality
(2) geology - bedrock, water, soils, topography
(3) disturbance - natural, human & scale, frequency
What are some components of soil that we can study?
(1) pH levels
(2) nutrients
(3) composition (sand, silt, clay, organic matter)
(4) depth
What are some common examples of landforms?
mountains, cliffs, valleys, plains
Scales and frequency levels of the following:
(1) tornadoes
(2) hurricanes
(3) thunderstorms
(1) large scale / low frequency
(2) large scale / low frequency
(3) small scale / high frequency
Definition: how much land is covered in a natural disaster
scale
definition: how often a natural disaster occurs
frequency
Is there a defined size of an “ecosystem”?
no
Are there boundaries dividing ecosystems?
no
Why are there no boundaries in an ecosystem?
because of migration - animals can continuously fly in & out
Where is the location of MSH?
Washington state
What mountain range is MSH also a part of?
cascade mountains
How would you described the biome of MSH?
temperate rainforest
What do biomes classify ecosystems by?
primarily their vegetation type
What biome is the temperate rainforest fairly similar to? And in what way are they similar?
tropical rainforest & they both have annual precipitation
How does the temperate rainforest mainly differ from the tropical rainforest?
cooler temperatures
Describe common characteristics of the Pacific NW Climate?
(1) mild & wet year round
(2) lots of snow in the mountains
(3) infrequent fire
(4) VERY infrequent volcanic events
What region of the US is MSH located in?
Pacific NW
What changes as you go up in elevation?
(1) temperature
(2) animals
(3) biomass and soil nutrient levels
(4) precipitation
Is there more rain at the bottom or tops of mountains?
top
What impact does changing elevation have on biological communities?
(1) changes in biomes / ecosystems in a condensed fashion (tropical RF, temperate RF, taiga, tundra, polar ice)
(2) relationship between latitude and altitude
What is the biodiversity of mountains like?
very HIGH - all different kinds of ecosystems represented
definition: the variety of different kinds of life you will find in one area–the variety of animals, plants, fungi, and even microorganisms
biodiversity
What was the “old growth” forest of MSH like pre-eruption?
had never been logged, very diverse, includes lots of wildlife, but NOT necessarily undisturbed
What was the soil of MSH like pre-eruption?
“rich” with lots of available nutrients suitable for plant life
Was MSH a homogeneous ecosystem pre- eruption?
NO - Mountains have lots of different ecosystems that change with elevation
definition: an ecosystem that has indistinguishable features and looks exactly the same all over
homgeneous
How does the top of a mountain compare to the bottom?
top: colder, more rain, thinner air, poor soil, less / smaller plants, fewer animals
bottom: mild/warmer, less rain, richer soil, more large and small plants, more animals
When was the date and time of the MSH eruption?
May 18th, 1980 at 8:32 AM
The MSH eruption went directly up what side of the mountain?
North side
What was unique about the southern slopes of the mountain?
they experienced so little damage that they looked almost identical to pre-eruption
What were the 3 main areas of disruption on MSH?
(1) Pyroclastic flow / pumice plain
(2) Blow down zone / lateral blast
(3) Scorch zone
What main area of MSH is being described here:
-most damaged area
-pumice covering all the ground
-NOTHING in this area survived
-covered up with 6’ of tephra/ash
pumice plain
Describe the destruction of MSH.
230 square miles of forest were blown done & scorched up to 17 miles away from MSH
What is tephra/ash?
rock dust
Was tephra very suitable for plants after the eruption?
no, its different from normal volcanic ash in that it does not contain many nutrients in it
What made MSH different from a normal volcano?
lateral explosion - directed sideways rather than upward and NO magma was involved, it was tephra
What main area of MSH is being described here:
-shattered trees - big wave of heat killed all trees
-wasn’t much ABOVE ground that survived
blowdone zone / lateral blast
What main area of MSH is being described here:
-outermost reach of impact
-some trees managed to stay up but all of their leaves were blown off
-plants among the forest floor survived in this area
scorch zone
Why did some plants survive in the scorch zone?
the timing of the eruption left a layer of snow over the slopes still & this snow pact protected everything a certain level above ground
What two things will affect the order of reestablishment on MSH?
(1) what can reach the area first
(2) what can survive there
The first to reestablish in the pumice plain will need to be the first that can _____ & ______.
reach; survive
What are some example of organisms that will reestablish in the MSH pumice plain first?
insects - live low to ground; feed off dead plant matter
birds - they can fly, migrate into pumice plain
small rodents - feed on insects
smaller plants / shrubbery
bacteria
How are plants able to move/migrate?
seed dispersal
definition: how seeds/spores are spread from the parent plant
dispersal
What is a negative consequence of seed dispersal?
plants spend a lot of time & energy making/dispersing their seeds
What is the purpose of parents taking a lot of time & energy to disperse seeds?
to reduce competition for resources among parents & offspring
How is pollen dispersal different from seed dispersal?
pollen is used for fertilization - combines genes of separate plants & is sexual reproduction
What are the 4 main ways that plants disperse seeds?
(1) wind
(2) water
(3) animal
(4) gravity
What is the main benefit of wind dispersed seeds?
very long dispersal distance
What is the main benefit of animal dispersed seeds?
the digestion of the fruit leads to fertilized soil
What is a negative of animal dispersed seeds?
(1) takes a lot of energy to create desirable fruit
(2) dispersion distance varies
What is a specific form of gravity dispersal that includes pods that shoot out seeds from them?
ballistic dispersal
How is the dispersal distance for water dispersed seeds?
variable (can be a splash or long-distance)
What is a negative of gravity dispersed seeds?
short dispersal distance (seeds roll down a hill)
What is a pro of seeds dispersing close to their parents?
probability of survival is higher (environments already suitable for that species)
What is the purpose of a seed coat?
to protect seed from environment
definition: embryo sack wall surrounding a seed
seed coat
definition: food storage area of a seed (largest part)
cotyledon
What are the benefits of a thick seed coat?
(1) protects seeds from getting eaten by an animal/insect
(2) protects from temperature / atmospheric conditions - prevents inside from drying out / becoming to waterlogged or wet
What are the negatives of a thick seed coat?
(1) take a lot of energy to create
(2) may have shorter dispersal distance
What are the benefits of a thin seed coat?
(1) disperses easily
What are the negatives of a thin seed coat?
(1) not as much protection from outside environment
What is the purpose of the cotyledon of a seed?
to store food as fats and oils (think peanuts)
What are the advantages of having a large cotyledon?
(1) can store more energy
(2) seed can last longer before sprouting (germination)
(3) more likely to survive
(4) can grow quickly to overtop competitors
(5) can’t disperse far - suitable environment (adv?)
What are the advantages of having a small cotyledon and seed coat?
(1) can produce MANY more seeds
(2) longer dispersal distance
What does the concept of evolutionary trade-offs explain?
(1) a pool of energy can be allocated in different ways
(2) there are advantages and disadvantages of each selection
(3) its impossible to have the best of both worlds
How do we see evolutionary trade-offs with regards to large seeds?
can’t have a massive amount of large seeds
What type of relationship occurs between seed size and seed number (fecundity)?
inverse
What type of relationship occurs between per capita seedling survivorship and seed size?
direct
Per capita = per _______
individual
per capita survivorship = probability of survival for _____ seed
one
Is there one best strategy for small vs large seeds?
No, both can have = fitness levels (total survivorship
definition: the ability to pass on genes to subsequent generations (amount surviving to reproduce)
fitness
