Climate and Vegetation

what are the four levels of ecological organization?

1. Individual

2. Population

3. Community

4. Ecosystem


* looking @ one organism

* generalize to include entire species

* how do the get what they need?

* where do they get what they need?


* groups of individuals of the same species

*where are the?

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

*reproduction rate, age structure


*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


* 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
*inherited (genetic) trait that allows organism to function
* a population with a given adaptation

* 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


* 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


* 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


* # 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

* how many births at a given 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

* “holistic” “closed communities”

* strong species associations and interactions

* composition changes abruptly

*relationships between species determine composition


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

* the environment determines composition


* 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



*winds, tornadoes, hurricanes





*change in composition over time after a disturbance
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)


following a minor disturbance


(10s of years)

* pioneer species improve conditions for later plant
*one species keeps another out
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



B Climate Vegetation

warm/hot, dry


more scrub




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
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


Disease (beetles and budworms)