GEOG 1001 Lecture Notes

 

Objectives:

Understand what where and why of climate and weather

Know the fundamentals of plant requirements, individually and in larger groups

Combine climate and vegetation knowledge to explain global patterns of climate and vegetation

Have a basic understanding of the science behind current issues connected to climate and veg

 

Introduction to Earth

Earth-not quite a sphere but close enough

Rotates around axis->north and south poles

 

Describe location using latitude and longitude

Latitude (changes in attitude, changes in latitude): angular distance north or south of equator

Equator = 0 degress

Points

North Pole = 90 degrees north

South Pole = 90 degrees south

Parallels = lines of equal latitude

Tropic of Cancer          = 23.5 degrees north

Tropic of Capricorn      = 23.5 degrees south

Arctic Circle                 = 66.5 degrees north

Antarctic Circle            = 66.5 degrees south

 

Longitude: angular distance east or west of meridian which passes through Greenwich, England

Meridian-line which is perpendicular to all parallels

 

Earth-Sun Relationships

Tilt of axis=23.5 degrees

 

Revolution around sun--shape of orbit: perihelion and aphelion distances and difference

p=147,255,000 km  a=152,083,000

 

Revolution around sun + tilt -> sometimes of year n.h. gets more sun, sometimes s.h. gets more

 

Circle of illumination-line separating illuminated half of earth from darkened half

 

Subsolar point-latitude at which sun is directly overhead at 12:00 noon-receives greatest amount of incoming sun--all others receive less because radiation is spread out over greater distance

 

June 20-21: Northern Hemisphere’s summer solstice

24 hrs daylight north of arctic circle+24 hrs darkness south of antarctic circle

longest day of year in northern hemisphere+shortest day of year in southern hemisphere

northern hemisphere pointed towards sun, southern hemisphere pointed away

 

September 23: Northern Hemisphere’s fall or autumnal equinox

12 hr light/12 hr dark everywhere

 

December 22  Northern Hemisphere’s winter solstice

24 hrs darkness north of arctic circle+24 hrs daylight south of antarctic circle

shortest day of year in northern hemisphere+longest day of year in southern hemisphere

southern hemisphere pointed towards sun, northern hemisphere pointed away

 

March 21 Northern Hemisphere’s spring equinox

12 hr light/12 hr dark everywhere

 

Recap: Revolution, Rotation, and Tilt

Revolution

seasons and climate variability

 

Rotation

wind patterns

day and night pattern

ocean currents

 

Tilt

variation in day length

tropical and arctic boundaries

 

Why Seasons?

Revolution and Tilt->variation in amount of incoming energy

 

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Radiant Energy Between The Sun and Top of Atmosphere

 

Energy from sun comes in the form of electromagnetic waves

            solar constant = amount of energy (insolation) that arrives at top of atmosphere

            all energy absorbed by earth is reradiated

 

Waves have wavelength and amplitude

 

Short wavelength = high energy

 

short                                         wavelength                                           long

gamma             xrays    uv         visible   IR        microwave        radiowaves

 

Electromagnetic spectrum

-visible is only a small part of the spectrum

-sun emits mainly visible  

-earth reradiates mostly IR (longer wavelength because temperature is lower)

 

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The Atmosphere

4 Temperature layers w/boundaries

Thermopause=top of troposphere where solar constant is measured 480 km/ 300 mi above surface

Thermosphere=80-480 km abover surface temp increases from -90 degrees C with elevation

 

Mesopause=80km (50mi) above surface coldest point in atmosphere:  temp averages -90C

Mesosphere=50-80km above surface (almost the same composition as atmosphere near surface) temperature decreases with elevation

 

Stratopause=50km (31 mi) above surface average temperature 0C

Stratosphere=10/20-50km above surface-contains concentrated ozone which shields earth from UV radiation, temperature increases with elevation

 

Tropopause=10/20km above surface depending on latitude (lower over poles)

Troposphere=0-10/20km above surface temperature decreases with elevation (on average at 6.4C/1000m)

 

 

Stable components of troposphere, stratosphere, mesosphere (by volume)  --> they are relatively well mixed and unifromly distrubuted

Nitrogen                       78.084

Oxygen                        20.946

Argon                           00.934

Carbon Dioxide            00.036

Neon                            00.001818

Helium                          00.000525

Methane                       00.00014

Krypton                       00.0001

Ozone                          variable

Nitrous Oxide               trace

Hydrogen                     trace

Xenon                          trace

 

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Radiation and the Earth’s Heat Budget

 

What can happen to incoming radiation

 

Reflection

Albedo=how much of radiation is reflected as a fraction no heating

albedo = 1 -> all is reflected

albedo = 0 -> none is reflected

 

High                             Low

light colors                    dark colors

smooth                         rough

water-low angle            water-high angle

snow                            vegetation, asphalt, concrete

 

change in snow cover-> huge change in albedo

dirty snow melts faster

 

Scattering

changing direction of incoming radiation without changing its wavelength no heating

 

Absorbtion

assimilation of energy with conversion of one form of energy to another

(like radiation into thermal or chemical)

leads to heating

energy is reradiated, wavelength depends on temperature

 

Transmission

passes through unaltered no heating

 

Heat Transfer  (how does energy get around?)

Radiation

-electromagnetic energy emitted by all objects (sun, earth, chair, desk)

-(reminder) can be transmitted, reflected, scattered, or absorbed--how much of each depends on wavelength of radiation and property of transmitting material

-ex: glass transmits more visible, less infrared

 

Conduction

-adjacent molecles heat each other (can’t get energy from sun this way--no molecules between here and there)

-ex: holding a warm coffee cup

-rate depends on temperature difference: greater difference = greater heating or cooling and conductivity of material

 

Evaporation-molecules absorb (heat) energy (sensible heat) when changing from liquid to gas (latent heat) they can also move from one area to another

 

Convection and Advection

-increase conduction by moving warm gas or liquid away from source (ex: wind chill)

-increase evaporation by moving moist air away from source (ex: biking vs running in heat)

 

Greenhouse Effect

Shortwave radiation (from sun) passes through atmosphere; longwave radiation from earth is absorbed by greenhouse gasses in atmosphere  => keeps surface warmer

shortwave passes through easily, longwave absorbed

 

Heat Budget

For earth: combination of reflection and absorbtion + reradiation

 

100 units incoming

 

 

3 absorbed and reradiated by ozone

 

 

28 reflected above surface        21 absorbed by atm, clouds (and reradiated)

(clouds and atm)

 

3 reflected at surface     45 transmitted to surface [19 latent (evap) 4 convection 110-96 IR via greenhouse 8 direct heat loss to space]

 

 

This is the energy budget for the whole earth on average--it varies spatially and temporally

 

Global Net Radiation

Radiation balance also depends on latitude

reflection exceeds absorbtion at poles

absorbtion exceeds reflection at equator/tropics: tendency of warm/cold to seek equilibrium   => movement of energy surplus toward poles

 

Daily Radiation Patterns and Temperature

(Idealized situation-uniform cloud cover, etc)

Radiation balance varies over the course of the day

Difference between insolation (just incoming) and net radiation (incoming-outgoing)

As long as more comes in than goes out, temperatures increase (except...)

As long as more goes out than comes in, temperatures decrease

Temperature response to changes is fast--even when the sun is relatively weak

 

Global Temperature Controls

Differential Heating and Cooling of Land and Water

Water heats and cools more slowly than land (why does the lake stay nice and cool in the summer? Why doesn’t it seem so cold first thing in the am?)         

continental” and “maritime” climates

Holds true at varying spatial and temporal scales

-global and local patterns 

-day/night and seasonally

 

            Summer            Winter

Land    warmer colder

Water   cooler               warmer

 

            Day                  Night

Land    warmer colder

Water   cooler               warmer

 

 

Latitude

Remember that the equator gets the most incoming solar radiation; insolation decreases toward the poles

 

Altitude

Temps are generally colder at high altitude (lapse rate)

Air is thinner so it can’t insulate as well

ex: Bolivia

 

Cloud Cover

Generally reduce variation in temperature:

reflect incoming radiation so earth heats up less

traps heat so earth cools off more slowly

 

Thermal equator=line of highest average temperatures

Isolines generally run from east to west

Colder toward poles, warmer toward equators

effect of continents: lines bend up in July, down in January

effect of mountains: notice andes--lines bend up since it’s always colder at higher elevations

 

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Atmospheric Pressure and Circulation:

From the Global to the Local

 

Basics

Atmospheric Pressure=weight of the air above us--it is pulled down due to earth’s gravitational pull

average value=760 mmHg=29.92 in Hg=101.32kPa=1013.2mb

 

Pressure Gradients

Air tends to move from high to low pressure, just like heat tends to move from high to low temperatures

 

The Coriolis Force

Because the earth is rotating underneath it, flowing air is deflected from its path from the perspective of an observer on the surface

Deflected to the right in the n. hem

Deflected to the left in the s. hem

 

Friction-earth surface exerts drag on air

            -effect extends up to about 500 m

            -magnitude depends on surface texture, among other factors

 

Global Circulation Patterns: distributing energy across the globe

 

If the earth did not rotate

The air along the equator would warm and rise, creating a low pressure area, while the air at the poles would cool and sink, creating a high pressure area.  Since air flows from areas of high to areas of low pressure, surface winds would flow from the poles to the equator.  The air would warm as it approached the equator where it would rise and be pulled toward the poles by the sinking air ahead of it.

 

The rotating earth and the Hadley Cells

Because of the Coriolis force this circulation cell only reaches to 20-30 deg N/S latitude.

The air rises out of the ITCZ and descends into the STH

The surface winds curve to the west (again due to Coriolis force) to become the Northeast and Southeast trades

 

The winds flowing out of the STH to the North and South are curved to the east by the Coriolis Force and become westerlies

 

The Polar High and Subpolar Low

Forms because cooling of air causes it to descend at poles. 

Air flows toward equator (with Coriolis Curvature, of course).  Polar Easterlies

The edge of this cold air is called the polar front.

Notice that the polar easterlies and the westerlies are on a collision course.  They meet at the subpolar low where the westerlies are forced up over the colder polar front

 

The Polar Front, Rossby Waves, and the Jet Stream

The polar front is not always smooth--it can be wavy. 

The waves are known as Rossby Waves. 

The waves bring cold air to the south and create low pressure systems which lead to frontal precipitation.

The polar jet strem forms in the upper atmosphere along the polar front because there is a steep atmospheric pressure gradient along the tropopause here.

 

Cyclones and Anticyclones

 Three factors determine wind pattern: pressure, coriolis, and friction

 

Cyclones

Low pressure areas

air flows into low pressure area

coriolis force bends air flow to the right in northern hemisphere & to the left in southern hemisphere

pressure+coriolis=circular flow--actually exists in upper atmosphere (geostrophic winds)

at surface, ground exerts friction so cyclones converge

Northern Hemisphere: counter clockwise and converging

Southern Hemisphere: clockwise and converging

 

Anti Cyclones

High pressure areas

air flows out of high pressure areas

pressure+coriolis=circular flow--actually exists in upper atmosphere (geostrophic winds)

at surface, ground exerts friction so anticyclones diverge

 

Local Winds

Land and Sea Breezes

Land heats faster during the day->warm air rises->localized low pressure->sea breeze

Land cools faster at night->cool air sinks->localized high pressure->land breeze

 

Mountain and Valley Breezes

Hillsides heat faster during the day->warm air rises->localized low pressure->valley breeze

Hillsides cool faster at night->cool air sinks->localized high pressure->mountain breeze

 

Ocean Circulation Patterns

Most ocean circulation is driven by air circulating around high pressure cells

Currents bring cold water from poles toward equator along west coasts

bring warm water from tropics along east coasts

Ocean circulation cell called a “gyre”

 

 

Atmospheric Moisture

 

State Changes for Water

 

latent heat = amount of energy stored or released as phase changes (it’s always the same for any given substance)--can’t be felt

phase = solid, liquid, gas

sensible heat = heat that can be measured via temperature

ex: 100 degree steam and 100 degree water are at the same temperature, but the steam has more energy.  If the steam condenses on your skin, the latent heat is released=>burns.

 

For water:

latent heat of vaporization = 540 cal/cc (from liquid to gas)

latent heat of fusion = 80 cal/cc (from solid to liquid)

so how much energy required to go from solid to gas (“sublimation”) without changing temperature? 620 cal/cc

 

Measures of Humidity

 

Absolute Humidity = amount of water vapor in a given volume of air

            --grams of vapor/ cc of air

 

Water Vapor Capacity = amount of water vapor that could be held in a given volume of air

            --dependent on temperature

            --warm air can hold more moisture than cold air can

            --also g/cc

 

Relative Humidity = ratio of how much water the air has to the amount that it could have

            -expressed as a percent

            -RH = AH/WVCx100

 

Saturation = point at which evaporation<condensation

            -RH = 100%

            -AH = WVC

 

Dew Point = temperature at which a given air mass reaches saturation--depends only on absolute humidity

 

Measured using a psychrometer + psychrometric tables (more about this in lab)

 

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Adiabatic Processes

 

Cooling/Warming Rates

Environmental Lapse Rate = rate at which still air cools with increased altitude

            -variable

            -average value = 6.4C/1000m or 3.5F/1000ft

 

Dry Adiabatic Rate

            -cooling due to the expansion of rising air or warming due to compression of falling air

            -adiabatic => no heat exchange with surrounding air

            -dry => no condensation

            -average value = 10C/1000m

 

Wet/Saturated/Moist Adiabatic Rate

            -cooling due to expansion of rising air

            -wet => air cools enough that WVC = AH => condensation

            -condensation releases latent heat, slowing rate of cooling

            -average value = 6C/1000m

 

Stable and Unstable Atmospheric Conditions

-> Depends on environmental lapse rate

 

Stable: ELR < SAR  warm air cools as it rises.  it cools faster than the air around it until it reaches the same temp as the air around it, then stops rising

 

Conditionally Unstable  DAR>ELR>SAR

            warm air cools as it rises.  it cools faster than the air around it as long as it remains unsaturated.  if it reaches the same temp as the air around it before it becomes saturated, it will stop.  otherwise, if it reaches saturation before it cools to the same temperature as the air around it, it will start to cool more slowly than the air around it.  it will always be warmer than the air around it and will continue to rise

 

Unstable  ELR > DAR

            even dry air will never cool off as much as the air around it and continues to rise until clouds form, etc.

 

Precipitation Formation

 

Air Masses, Front and Storms

 

Clouds

            - made up of tiny water droplets and ice crystals

            - when air cools to the dew point, condensation outweighs evaporation

            - requires condensation nuclei-the atmosphere has plenty

 

Cloud Classification

            -altitude and form

            -cloud forms

                        stratiform: flat and layered

                        cumuliform: puffy/globular

                        cirriform: wispy

 

Class                Name                           Description

Low                 Stratus                          Low, flat

water                Stratocumulus               Low, globular, overcast

                        Nimbostratus                Gray, low, rain (light)

 

Middle             Altostratus                    Flat, overcast but not as low as stratus, etc

water/ice          Altocumulus                  puffy, middle level, lenticular clouds

 

High                 Cirrus                           Mare’s tails

ice                    Cirrostratus                  thin, high, flat => halo around the sun

                        Cirrocumulus                high, puffy

 

Vertical                        Cumulus                       Puffy

water lower      Cumulonimbus  thunderheads (cumulus gone bad)

ice higher

 

Lifting Mechanisms

 

Convergent Lifting

            -air coming into low pressure area then rising

            -regional/global scale ex: ITCZ

            -extended time -doesn’t stop at night

 

Convectional Lifting

            -Local heating, warm air rising

            -shorter period of time--stops at night

 

Orographic Lifting

            -winds push air over mountains

            -more precip on windward side

            -warm dry air on leeward side “Chinook” winds

            -important in Colorado--why does Winter Park get more snow than Nederland?

            -what about “upslopes” when it dumps in Boulder and nothing in Summit County?

 

Cold Fronts

Where faster moving cold air runs into warm air mass

warm air is forced upward rapidly b/c cold air is denser

cooling, condensation, precipitation (heavy)

 

Warm Fronts

faster moving warm air overruns cold air

warm air is forced upward but more slowly

cooling, condensation, widespread clouds, precipitation

 

Occuluded Fronts

when a cold front runs into a warm front

warm air is lifted totally off ground

combines clouds and precip of both fronts

little temperature change

dissipate rapidly

 

Wave Cyclones=Mid Latitude Cyclones

Warm Front + Cold Front revolving around a low pressure cell

Forms at polar front (remember how it undulates)

Moves across continent from west to east (Westerlies)

Four stages

            -early-just starting to form

            -open-two separate fronts

            -occluded-the cold front catches up with the warm front

            -dissolving-the warm air is completely above the cold air, everything settles down

Temperate Zone Phenomenon

 

Air Masses

Homogeneity-body of air with uniform upward gradients of temperature and moisture

Properties derived from region of origin cold vs warm, moist vs dry

Naming: latitude (capital letter)

                        Arctic/Antarctic

                        Polar

                        Tropical

                        Equatorial

            surface (small letter)

                        maritime

                        continental

 

Climate Classification

 

Water Balance

ET=evaporation from surface +transpiration from plants

Ocean water balance => P + R = E

Land water balance => P = ET + R

Global => P = E

 

Soil Water Budget

Potential ET-how much water a plant could use if it had unlimited supply-depends on temp

Actual ET-how much water plants actually used

 

P=PET medium climate ex:Ontario

P<PET dry climate ex:Sudan

P>PET wet climate ex:tropical rainforest

 

The Koeppen System of Climate Classification

 

Classification Criteria

1. Precip

2. Temp

3. Soil Water Balance

4. Air Masses

5. Geographic Distribution

 

The 5 climates of the Koeppen System

B Climates-Dry

            due to descending limb of Hadley Cell or rainshadow

            P<PET

            some frontal precipitation

 

E Climates-Very Cold 

            warmest month <10 C

 

D Climates-Cool/Cold

            warmest month > 10C

            high/mid latitudes

            cyclonic frontal precipitation

            variable year round precipitation

            P~ET

 

C Climates Hot-Warm/Cool

            grab bag for climates that don’t fit elsewhere

            often hot summer

            seasonally variable precip

            cyclonic frontal precip

 

A Climates Warm and Wet

            little seasonality

            ITCZ-convective precipitaiton

            P>PET

 

 

Introduction to Ecology

 

Definition and 4 levels of ecological organization

What is ecology?  Study of relationships between organisms (living) and their environment (non living)--they affect each other, not just one way or another

 

Four levels of ecological organization-

Individual-one organism--generalize to include entire species-how do they make a living?  where do they live? 

 

Population-groups of individuals of the same species-where are they?  how many are there?  how many will there be later?  how many were there before?

 

Community-interrelated plant populations--what plants are there?  how do they interact?

 

Ecosystem-larger scale communities and including abiotic environmental factors such as nutrients and energy “self sustaining association of living plants and animals and their physical environment

 

Physiological Ecology

 

What do plants do?  Use water, light, CO2, and nutrients to grow and reproduce

 

Photsynthesis:

 

CO2 + H2O    ----->             Carbohydrates

                        (light)

 

Plant Strategies: what if there are not optimal amounts of what they need?

            Adaptation-inherited trait allows organism to live in an environment

            Ecotype-recognizes that adaptation operates at population level

            Acclimation-at level of individual, developmental rather than genetic

 

Tolerance Curves

            Plants do best at certain temperatures--varies with species, acclimation, adaptation

            ex: plants and temperature:  too cold and membranes freeze, too hot and enzymes break

                        down

 

Tolerance and Avoidance: Water and Temperature

            Water: Tolerance

                        Chapparal Shrubs can dehydrate with minimal metabolic inhibition

            Water: Avoidance

                        close stomata--reduce ET

                        CAM-allows plants to take in CO2 at night and store it until daylight

                        Biomass Allocation-more biomass underground to protect it from heat

                        Rapid Life Cycle-germinate, grow, flower, seed before conditions deteriorate

            Temp: Tolerance

                        many plants, esp trees

            Temp: Avoidance

                        dormancy-annual plants, leaf deciduousness

                        orientation-face toward or away from sun

                        change in reflective properties-growing tiny hairs to increase reflectance in heat

                        heat generation-skunk cabbage

           

 

Population Ecology

 

Natural Selection and Evolution

evolution-change in genetic characteristics of population over time

 

natural selection

-more offspring produced than can survive (competition for survival among many offspring)

-heritable variation members of poulation vary-variation can be passed to next generation

-adaptive traits some variation are more adaptive than others (improves chances of surviving and reproducing under prevailing env conds)

-differential reproduction

-natural selection is the result of differential reproduction

 

speciation-when two different populations evolve in different directions such that they can no longer interbreed

 

Structure

            Spatial locations of individuals

                        depends on locations of suitable habitat

                        Random-not dependent on location of other individuals

                        Uniform-competition

                        Clumped-resource concentration, proximity to parents

            Density-number of individuals/unit area

            Mortality-how many die at a given age->survivorship curves

                        Type I-slow and steady (trees)

                        Type II-average (perennials)

                        Type III-live fast, die young (desert annuals)

            Natality-how many births at a given age--related to survivorship curve

            Age-how many of each age in a population-can tell pretty well with trees via dendrochronology

 

Dynamics

Geometric Growth

            the same fraction of the population is born each year

            as population increases, births increase as well

            starts slowly and increases rapidly, approaches infinity eventually

            births exceed deaths

            r = births/capita - deaths/capita

            can’t go on forever--the population would run out of room->what actually happens?

Logistic Growth

            starts out like geometric growth

            begins to slow down and eventually approaches a limit

            limit=Carrying Capacity=maximum stable population for a given population

            either birth rate slows down or death rate increases until they are equal

            density dependent birth and death rates

Overshoot and Collapse

            exponential growth until a key resource is totally depleted, then massive dieoff

            can lead to extinction if area of population is small enough

Damped Oscillation

            initial oscillation that approaches K over time

            delay between population increase and effect of population dependent factors

                        (always a little bit behind the times)

Stable Limit Cycle

            sustained oscillation

            a delay between population increase and density dependent factors which limit population

            ex: predator-prey relationships

 

Constraints on population growth

Physical Environment-climate, soils, etc

Biotic Factors-

            competition-limits resource availability

            stress response-reducing birth rates, increasing death rates

            predation-increases with density

            parasites-consume but don’t necessarily kill-can reduce birth rates and increase death rates

 

Life History Traits

reproductive costs can vary (it takes energy to reproduce)

            nutrients provided for young + time for their care

 

timing and amount of reproduction

            type III reproduces early

            type I reproduces later

            high mortality->high reproduction

            low mortality->low reproduction

 

environmental influences

            stressful and variable climates have higher reproductive output

 

r and K selection

r-repeated disturbance keeps N below K early reproductive maturity, high reproductive investment, type III

K-stable, density control of r, density near K, late reproductive maturity, low reproductive investment, type I

 

 

Community Ecology

 

Community-naturally occuring and interacting assemblage of organisms living in same habitat

Niches-ecological role of species within community

includes: temperatures, what they eat, when they do what, where they live, etc

species occypying the same niche compete for the resources within that niche

 

Organismic vs Individualistic Theories

organismic=holistic (closed communities)

-strong species associations and interactions

-community composition changes abruptly

-biotic interrelationships determine composition

 

individualistic (open communities)

-community composition changes gradually as environmental conditions change

-environmental conditions determine vegetation composition

 

Succession

Concepts

            -directional change in species composition following a disturbance

            -seres-sequence of communities that occur in transition

            -primary succession-beginning from bare mineral soil (glacial retreat, lava flow, etc)

            -secondary succession-following a disturbance-parts of previous community still there

 

Mechanisms that affect species composition during succession

Colonization-immigrants from surrounding areas

Previous Vegetation-seed banks in the soil etc.

Competition-species with competetive advantage dominate in late stages

Life History-some plants just don’t live as long

Species Interactions

            -facilitation-pioneer species change environmental conditions so that other species can survive

            -inhibition-species prevent other species from colonizing

            -tolerance

-these factors plus variations in intensity of disturbance (size of disturbed area, amount of vegetation remaining) affect the exact sequence of community composition

-climax is not always stable, especially in fire-adapted ecosystem

 

Disturbance

            Agents of Disturbance

                        Wind

                        Floods

                        Drought

                        Fire

                        Herbivory

                        Volcanoes

                        Glaciation

                        Erosion

                        Avalanches

            Spatial Scale

                        Larger area-greater impact

                        small scale disturbances are most important--more frequent, more area

            Frequency

                        Floods and Fires-fairly regular

                        Droughts less predictable

            Adaptations

                        Serotinous Cones

                        Thick bark

                        rapid resprouting after disturbance, etc

 

Landscape Mosaic-a collection of patches of different ages/successional development: spatial series of small scale disturbance/recovery

 

Community Structure

Physical Descriptors

            Vegetation type

                        Growth Forms ex: Evergreen coniferous trees

            Vertical Stratification: canopy, understory

            Edges=ecotones--sharp or gradual

Biological Descriptors

            Niches

            Species Abundance (a measure of success for that species)

                        dominant species

                                    based on abundance, size or area covered, or use of resources

            Diversity

 

Diversity-

definitions

species richness-number of species in community

species evenness-distribution of number of individuals of each species

biodiversity indices consider both factors

variations

disturbance-high favors colonizers, low favors competitors, medium greatest diversity

environmental heterogeneity-variety of niches available

resource availablity-intermediate->greatest diversity

                        -low, few species can tolerate/high, competetive exclusion

evolutionary time-older communities have more speciation, niche partitioning

disequilibrium-temperate and arctic zones are increasing their biodiversity

climatic stability-tropics’ stable climate allows narrower niche partitioning

islands-diversity is determined by immigration and extinction rate

            near better than far

            large better than small

 

Ecosystem Ecology

 

Differences from Community Ecology

-includes abiotic factors as well as biotic factors

-process oriented

-less concern with actual organisms

 

Ecosystem Components

 

Energy Flows

 

Nutrient Cycles