ES 60 Flashcards
ecosystem
Biological communities of interacting organisms and their physical (abiotic) environment
* Biotic and abiotic pieces linked through nutrient cycles and energy flows
Ways we test hypotheses
- Observations
- Experiments (lab or field)
- Models
- All must be repeated with replication
Rigor
- Replication within the study
- Random assignment of samples
Evolution by natural selection
- variation in traits
- differential reproduction
- heredity
More advantageous trait (-> more offspring) will become more common in pop. Eventually everyone will have it
variation in traits
Individuals within populations are not identical (Ex: black and tan mice on dark rock -> black mice live)
differential reproduction
Not all individuals reproduce - do not contribute equally to the next generation. Some have more offspring than others aka great fitness (Ex: tan mice eaten, black mice reproduce next gen)
heredity
Some variation between individuals in a species is genetic , meaning it is heritable (Ex: black mice gave next gen the trait of having black fur)
adaptions
- Trait that increases fitness in a given environment
- (evolution) Change in a species over time from one generation to the next
- One individual does not evolve (e.g. “adapting” to climate change…)
- Note: natural selection can select for or against
Why is evolution an important
backdrop for Applied Ecology?
- Evolution of pesticide & disease resistance
- Understanding local impacts of “selective
pressures” - Climate change, air pollution, harvesting
- Conservation genetics
scale dependent relationships
- Spatial dimensions
- Temporal dimensions
- Diurnal vs nocturnal
- Seasonal
- Annual vs perennial
density independent pop growth
Not linked to pop density and can result in pop crashes- Seasonal weather changes, Temp, Drought, Large disturbancesEx: exxonmobil oil spill effect on killer whales
density dependent pop growth
Intraspecific competition,
- Between same species for limited resources, Decreased reproduction rates, Increased death rates, Lower birth rates, More emigration
ex: lynx and hares
Keystone species
- Some species have disproportionate effects
on biodiversity - Impact greater than predicted by mass or
abundance - If keystone species removed community
collapses – often due to indirect effects
Cultural keystone indicator
species
- Both ecological keystone & cultural keystone
- Changes in pops indicates environmental
change
Ecological succession
continual, non-seasonal process where mix of species in an area changes over time following disturbance*
primary succession
Disturbance removes all organisms & exposes baresediment/rock
Ex: lava flows. Glacier forelands (edge of a glacier)
secondary succession
Follows disturbances when some organisms survive
Ex: wildfire (often still things that live, seeds germinate by fire), occasionally floods (not severe), refuge of beavers
Succession causes
1) Facilitation
2) Inhibition
3) Tolerance
(ex: right after fire need resources but later species can tolerate fewer secondary)
facilitation
- Early spp improve (or facilitate, improve the soil) for later spp
inhibition
- First spp prevent others, once first spp die then other come
tolerance
- Later spp tolerate low resources better than first spp
Why does primary succession
matter for env management?
- Important to know timelines so you know what you’re doing
- Knowing factors -> increase recovery
- Acknowledge stage for restoration
- More glacial forelands being exposed
See what is to come
Why does secondary succession
matter for env management?
- Used for management! What will actually happen?
- Human activity can cause - how can communities bounce back
- Increased frequency of disturbance events - fires & floods
- Weeds coming in to areas more disturbed than ever
- Should we intervene?
causes of biodiversity loss
H:habitat destruction, loss, fragmentation, disturbance
I: invasive species (widely spreading and sharing native ecosystems/humans)
P: pollution (air, water, etc)
P: population (human population growth- exponential)
O: overexploitation (harvest or use > productive capacity of a species)
why does urban ecology matter?
- 83% pop lives in urban areas
- Hotspots of HIPPO
- Ecological footprint (Not only the space it takes up but also the use of resources of other parts of the world)
biogeography
geographical distribution of organisms
island biogeography
- Islands isolated from
mainland - Diversity ↑ by
immigrations - ↓ by extinctions
- Limited # of niches
island diversity (high vs low)
island diversity (high vs low)
Island Size & distance
- Distance from mainland
- Fewer immigrants
- Lower diversity
- Size of island
- More niches in large
- Higher diversity
When is island diversity
highest?
Near mainland AND large island size
Ecosystem ecology
All spp in the community + abiotic factors (energy, Temperature, Water, Soil)
biosphere
the big ecosystem
inputs- solar radiation
outputs- heat, space junk 🙁
energy flow
Movement of energy through systems, Food chain/food webs
Chemical cycling
Use and reuse of elements in system (Carbon (C), Phosphorus (P), Nitrogen (N))
- Life depends on
recycling of
chemicals—
abiotic & biotic
processes
gross primary productivity VS net primary productiviety
GPP- how much an organism photosynthesizes, total amount of pp (before cell respiration)
NPP- What is remaining in plant tissue (bc some lost as heat in cell respiration)
GPP variation
Abundant water, moderate temperatures, aseasonal climate, high solar input
Ecosystem Resistance vs. Resilience
● Resistance: When an ecosystem can maintain its normal functioning after or during a disturbance
● Resilience: When an ecosystem can return to its normal functioning after or during a disturbance
groundwater recharge
● Groundwater can recharge from precipitation infiltrating soil
● Not all rain recharges groundwater:
○ Runoff, Plant uptake + release (transpiration), Evaporation
● The recharge ratio is the % of precipitation that becomes groundwater.
Why do we care for
endemics?
● Biodiversity
● Genetic diversity
● Ecosystem balance
○ Niche, keystone species
● Cultural value
○ Chumash
● Economic benefit
○ Tourism
Energy flow: primary
Conversion of energy (solar) to organic compounds (also using CO2), Plants create sugars via photosynthesis
- sugars -> biomass
- Some energy loss via
respiration (Net Primary
Production (NPP))
- Primary production
varies widely by biome
Energy flow: secondary
Herbivores only consume a fraction of primary
~50% as waste (Indigestible, Toxins)
~35% of energy lost in respiration
~15% becomes biomass (Secondary (2°) production)
Pyramid of production
Energy that passes through trophic levels ranges from 5-20% and averages at 10% (rule of tens)
Biogeochemical cycle
- Weathering of rocks & erosion contribute chems
- Detritivores break down complex chem compounds
- Abiotic chems -> producers
- Producers -> consumers
- Producers & consumers release chemical waste
C cycle
- C sequestered by photosynthesis
- Passed along food chain
- Respiration returns C to atmosphere
- Return of C was similar to C sequestration in past
Traditional Ecological Knowledge (TEK)
the collective and cumulative knowledge that a group of people has gained over many generations living in their particular ecosystem
Local Ecological Knowledge (LEK)
Knowledge about nature, organisms , ecosystems and ecological interactions, held by local people who interact with and use natural resources.
Western Science
Science that is based on the physical realm of the world. Facts and theories. When things can be physically measured, observed, documented and tested.
Wildfire effects depend on
Seasonality
Intensity
Return interval
Size
Historic fire regime
Fuel continuity
Culture and fire
Culture -> perceptions -> actions
- Pyrophobia: Fire is a threat to infrastructure, revenues (logging), control
- fire suppression era: Resource-based capitalism in the west “unauthorized disturbances” seen has threats to revenues
Indigenous burning
Prescribed and cultural burns
Challenges
- Indigenous sovereignty and autonomy
- Degraded novel landscapes
- Flammable, invasive plants
- Development
How does fire suppression affect forests? How can cultural burning change this?
With suppression vegetation accumulates in a forest, which serves as fuel — when a fire comes through.
Cultural burning burns the understory and prevents it from getting overgrown & reduces fuel, as well as forefronting human connections to fire as a powerful & ceremonial tool
Flammability
- live fuel moisture
- flammable compounds
- Structure (of plant & plant community)
-> Ladder fuels (low to high tree heights) and continuity (high continuity = more flammable)
Serotiny
needs fire to germinate (ex: kills old pine cones allows new ones to germinate)
Fire & N cycle
N Cycle
During fire, organic nitrogen (C-N and other elements) in plants turns into NH4 (ammonium)
Microorganisms convert NH4 to NO3 (nitrate)
How much NO3 runs off?
- Seasonality (when fire vs when rain)
- How much rainfall
- Soil type
- Plants/plant growth (take up N)
- How patchy plants post-fire
Fire retardant effect on ecosystems
85% water, 10% nitrogen & phosphorous, thickeners, coloring
If it lands in waterways, kills fish
High nutrients promote weedy grasses
Reduces mycorrhizal fungi
wildfire effect on weeds
Weeds often increase wildfire risk
Fire can remove weedy grasses… but can also quickly come into burned areas
High resource availability (N- weeds tend to love)
Permafrost & grazing animals
- Snow insulates frozen soil like a blanket, keeping warmth in
- Animals move snow & expose soil to frigid temps, further freezing soil. More frozen soil in winter means more stays permanently frozen (during warm
months)
Range & restoration
- assisted population migration-new locations in historic range
2.Assisted range expansion- facilitating/mimicking natural dispersal to new areas - Assisted species migration- far outside historic range; impossible to happen naturally (on short time scale)
population
interacting individuals of same species living in the same place at the same time
- size, structure, growth rate, dispersion patterns
annual VS perennial
- annual: One generation (whole life cycle) in one year
- perennial: lives more than one year (biennial = lives 2 years)
edge effects
Changes in population/community structures that occur at the boundary of 2+ habitats
life history traits
Traits that affect schedule of reproduction & survival
* First reproduction
* Frequency of reproduction
* Number of offspring
* Amount of parental care
opportunistic VS equiibrial populations
- opportunistic: Take advantage of favorable conditions
- Type III (live fast die young) survivorship curve .EX: Wildflowers - equilibrial: Type I curve. EX: Elephants, Coconut trees
biocontrol
The use of a species to control the population growth or spread of an undesirable species
ex: mongoose mistake
Generalist vs specialist
A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (for example, a heterotroph with a varied diet).
A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet. (better for biocontrol bc less risk of becomign invasive)
soil carbon arctic vs tropics
arctic: soil carbon is high
tropics: soil carbon is low bc the plants are carbon sinks
