Climate and Vegetation
what are the four levels of ecological organization?

1. Individual

2. Population

3. Community

4. Ecosystem

Individual

* looking @ one organism

* generalize to include entire species

* how do the get what they need?

* where do they get what they need?

Population

* groups of individuals of the same species

*where are the?

*how many are there – past, present, future?

*reproduction rate, age structure

Community

*interrelated populations

*ex: plants & animals combined = community

* which species are there? which species are together?

* ex: ponderosa pine and douglas firs

* how do they interact

*ex: ponderosa creates shade for doug firs

Ecosystem

* community and abiotic factors (energy, nutrients, etc)

* flows and cycles of abiotic factors

* plant and environment interactions

What do plants do?
* use water, ligt, CO2, nutrients to grow/reproduce
Adaptation
*inherited (genetic) trait that allows organism to function
Ecotype
* a population with a given adaptation
Acclimate

* individual develpmental change that enhances physiological function

* ability to acclimate = an adaptation

tolerance curve

* curve which shows how well a plant does with varying temp, water etc

* varies between species and indiv

tolerance

* can function under adverse conditions (w/in plant)

ex: needle-leaf evergreens tolerate cold weather -> not a lot of surface area on needles, tough, don’t freeze

avoidance

* action to prevent adverse conditions

ex: deciduous trees drop leaves to avoid damaged leaf tissue in cold weather

water: tolerance
* chapparal shrubs can dehydrate and still function
water: avoidance

* prevent dehydration

* closing stomata

* biomass allocation (keep below ground, rooty)

* rapid life cycle

temperature: tolerance
* most plants
temperature: avoidance

* dormancy (trees and shrubs)

* face toward or away from the sun

* change in reflectance (albedo)

* heat generation (skunk cabbage)

spatial population structure

* where individuals within the population are located

*depends on habitat availabilty

random spatial population structure
* independent of other individuals (unlikely)
uniform spatial population structure
* evenly distributed -; indicates competitors
clumped spatial population structure

* resource concentration

* proximity to parents

mortality

* # of individuals that die at a given age

* survivorship curve = a graph of mortality

* type I – most survive

*type II

* type III – live fast, die young

natality
* how many births at a given age
age

* how many of each age in the population?

* can infer history of mortality and natality

*easy for trees vea dendrochronology

Geometric Growth

* births ; deaths

* some fraction of population = born in given time period

* as pop increases so do # of births

* starts slowly and increases rapidly to infinity

* r=(births/carrying capacity) – (deaths/carrying capacity)

*P =Poe^(r*t)

*Po = starting pop, t = time, r=above rate, e = 2.71828

Logistic Growth

* starts out like geometric growth

* slows as it approaches a limit

* limit = carrying capacity = maximum stable population for a given environment (K)

*either birth rate goes down or death rate goes up until they are equal

*density dependent birth/death rate

Overshoot and Collapse

* exponential growth until a key resource is depleted (like food) then die off

*can lead to extinction of the population

*deer example

Damped Oscillation

*initial rapid growth

*population goes above K but density-dependet factors bring it back down (like logistic growth)

* delay between population increase and effet of limiting factors -; oscillation

* approaches K

Stable Limit Cycle

* sustained oscillation

* delay between population increase and density-dependent factors influence

ex: predator and prey relationships

Abiotic Factors

* sunlight heat water (climate)

* nutrients (soils)

Biotic Factors

* competition – limits resources

* stress – lower birth rates, raises death rates

*predation – increases with density

* parasites – lower BR, raise DR

Reproductive Costs

how much energy, nutrients etc used to produce and raise offspring

;

includes nutrients provided to young/time to care for young etc

Timing and Amount of Reproduction

* type III (high mortality) reproduces early and often

;

* type I (low mortality) reproduces later and less often

Environmental Influences
* stressful and variable climate have higher reproductive output
r selection

* repeated disturbance keeps pop low (below k)

;

* early reproductive maturity

;

* high reproductive investment

;

*type III

k selection

* stable climate allows pop to grow to k

* r reduced as density increases

late reproductive maturity

* low reproductive investment

* high competition

*type I

fundamental niche
* all environments where a species could live
realized niche
* the environment in which a species actually does live
Organismic

* “holistic” “closed communities”

* strong species associations and interactions

* composition changes abruptly

*relationships between species determine composition

Individualistic

* “open communities”
* community composition changes gradually as environment changes (soils, moisture, temp etc)

* the environment determines composition

Disturbance

* too low = good for competitors

* too high = good for colonizers

* medium = both do ok

;

Resource Availability

*medium resource availability = highest diversity

* too low = few species can tolerate

* high = favors competitors

what causes disturbances?

* floods/tidal waves

* lava/ volcanic ash

* avalance

*rockslide

*glaciers

*winds, tornadoes, hurricanes

*fire

*drought

*disease

*humans

succession
*change in composition over time after a disturbance
sere
an individual community at one successional stage
primarey succession
succession from bare mineral soil (1000s of years)
secondary succession

following a disturbance

;

parts of previous community are still there (100s of years)

recovery

following a minor disturbance

;

(10s of years)

facilitation
* pioneer species improve conditions for later plant
inhibition
*one species keeps another out
tolerance
no interaction
nitrogen cycle

N2 in atmosphere -; nitrates and ammonium in soil -;water and plants -;animals -; detritus -;n2 in atmosphere

;

water-; lakes and algae -; eutraphication = overgrowth of algae due to excess nitrogen runoff

;

n2 in atmosphere -; chemical fertilizers -; soil -; water and plants -; excess runs off into lakes

Carbon Cycle

CO2 in Atmosphere -; plants -; animals -; detritus -; CO2 in Atmosphere and Fossil fuels

;

combustion of fossil fuels -; CO2 in atmosphere

Gross Primary Production (GPP)
total energy assimilated by photosynthesis for an ecosystem community
Primary Production
* rate at which energy is stored by organisms
net primary production (npp)

the accumulation of energy in plant biomass

;

GPP – Respiration

spatial primary production

climatic constraints

soil type

soil texture

specific plant specis

temporal primary production
disturbance and succession
secondary production

NPP -;growth incriment -; detritus and detrivores -; other detrivores and detritus

;

npp -; herbivores -; detritus and carnivors -; other carnivores, detritus, and detrivores -; other detrivores and detritus

A Climate Vegetation

warm, wet, tropical rain forest

;

tropical seasonal forests

;

scrub

B Climate Vegetation

warm/hot, dry

;

more scrub

;

desert

;

tropical savanna

B/C vegetation
midlatitude grasslands
C vegetation

midlatitude broadleaf/mixed forest

;

temperate rainforest

;

mediterranean shrubland

D/H vegetation
needle leaf forest (high latitude) and montane forest (high altitude)
E/H vegetation
arctic (high latitude) and alpine (high altitude) tundra
Boreal forest
high latitude
Montane forest
high elevation
Temperate rain forest
costal
Boreal – high lattitude

Climate = continental, dramatic seasonal change in daylenth, cP airmasses and midlatitude cyclones, p=pet, low temps, short growing season, Dfb, Dwb, Dwc, Dfd, Dwd

;

Soils = thin, acidic, few nutrients

;

Compositon = spruce-fir dominant canopy, some paper birch, aspen, esp after fire, grades into tundra

;

Disturbance = moderate fire frequency

;

Ecosystem = Npp @ 800g/m^2/year

Montane: high altitude

Climate =; high altitude, cold temps, short growing season, orographic precip and cyclonic storms, “highland climates”

;

Soils = thin

;

Composition = varies w/ elevation -; different zones varying temp and moisture

;

Disturbance = *Fire*

Histonic Fire regime by zone, lower montane: high frequency low severity, upper montane: variable frequency/variable severity, subalpine: low frequency, high severity

Avalanches

Disease (beetles and budworms)

Logging

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