exam 1 global change

global change biology

any consistent trend in the environment past, present or projected, that affects a substantial part of the globe

examples of global change

• acid rain formation

• land use change

• ozone hole

• climate change

drivers of global change

human activities

• agriculture

• industry

• recreation

• intl commerce

impacts of global change

• land use change

• global biogeochemistry

• biotic additions and losses

• climate change

• change in biodiversity

all related

levels of ecological organization - organismal ecology

organisms and how they intrxt with their environment

levels of ecological organization - population ecology

individuals of the same species living together

levels of ecological organization - community ecology

populations of different species living together

levels of ecological organization - ecosystem ecology

intrxns among organisms and their physical environment as an integrated system

levels of ecological organization - biosphere approach

the movement of air, water, nutrients, energy and organisms around the earth

meeting the needs of the present without compromising the ability of future generations to meet their needs depends on

sound science - understanding how the world works and how humans interact with it

stewardship - managing natural resources and human well-being for the common good

structure

“things you can observe with a camera”

one time - how many trees in a given environment, how much of whatever element

function

things that happen over time

ultimate factors

mechanism for why an ecosystem does/doesn’t exist over LONG TIME PERIODS

• something that COULD happen

• time since last volcanic eruption/ice age

proximate factor

mechanism for why an ecosystem does/doesnt exist RIGHT NOW

• what DOES live somewhere

• building of housing development removes mangrove forest

state factor model

• climate - precipitation and temperature

• geology - what rocks/how did they form/what soils form

• past disturbance - volcanic eruptions, forest fires, deglaciation

• topography - flat/slope/what direction/how steep

  • + human activities

controls (in the ultimate sense) the characteristics and properties of ecosystems AKA controls what an ecosystem could be like

ecosystem structure examples

species diversity (# bugs or trees etc)

standing crop biomass (how much biomass is present now

trophic categories of organisms

living organisms are ecologically categorized based on how they get their energy

• autotrophs

  • producers

• heterotrophs

  • consumers

  • decomposers

autotrophs

make their own energy from inorganic nutrients

• producers - generate energy from sunlight and CO2

  • photosynthetic green plants - use chlorophyll to absorb light

  • photosynthetic bacteria - use purple pigment to absorb light

  • chemosynthetic bacteria - use high energy inorganic chemicals such as hydrogen sulfide (H2S)

heterotrophs

feed on organic matter for energy

• consumers

  • first order consumers/herbivores - animals that feed exclusively on plants

  • omnivores - animals that feed on both plants on animals

  • second order consumers - animals that feed on primary consumers

  • higher orders of consumers/carnivores - animals that feed on other carnivores

  • parasites - plants or animals that become associated with another plant or animal and feed on it over an extended period of time

• decomposers

  • scavengers - eat larger dead things, may also eat living things some of the time

  • detritus feeders - organisms that feed directly on detritus

  • chemical decomposers - fungi and bacteria that cause rotting

examples of human activity on proximate structure and function in MA

introduced bobolink and meadowlark (grassland loving birds) into an environment that wasnt supposed to have them, then phased back out cause they werent supposed to be there anyways

ultimately - forest loving birds prevail because climate state factor would predict that forests dominate the landscape

proximately - grassland loving birds dominated in the 1850s since we cut down most of the forests and created open grasslands

investigate impact of one state factor

keep everything else constant

for example if youre looking at climate in hawai’i you want to keep geology, topography and past disturbances constant

state factor investigation - influence of climate on plant productivity and decomposition

kept other state factors constant (topology, past disturbance, geology)

conclusion:

• warmer temps makes forest grow more and decomp goes up

what causes spatial variation in climate?

circulation

• differential heating of tropics vs the poles

  • solar radiation reaching earth most direct at equator, travels farther distance to reach the poles

• circulation of temps results in three wind cells across the globe

prevailing winds

source to sink (easterlies come from the east and go to the west)

convection cells

0-30 HADLEY

30-60 FERREL

60-90 POLAR

high/low pressure systems

high - air sinks → contracts → no space for precipitation → warm. high pressure of air on your head

low - air rises → expands → gathers space for precipitation → cools. low pressure of air on your head. rainy

global circulation driven by

latent heat flux (evaporation) and coriolis effect

latent heat flux

how precipitation relates to air temp

solar radiation at equator heats up air, air rises and cools

movement of water - water evaporates at surface and condenses in troposphere

coriolis effect

takes into account the earths spin

air deflected about 45* (CW NH, CCW SH)

trade winds

EWE

• polar easterlies

• westerlies

• easterlies

ITCZ btwn easterlies

thermohaline etymology

thermo- - temperature

-haline - salinity

drivers of surface water currents

prevailing winds

gyres

circulation deflected by the coriolis effect

drivers of deep water currents

temperature and salinity (thermohaline)

ocean water circulation

winds at surface cause evaporative cooling → evaporates out the water so that the molarity of salt increases → makes water denser → cold water sinks to the bottom in antarctica and greenland (1) → reaches the bearing strait (2) and current slows and warms → becomes less dense → flows to surface → repeats

predicted global climate modified by

• landmasses (heat faster than oceans)

  • monsoons

  • land-sea breeze

• ocean (moderates land temperature)

  • mediterranean climate

• mountain ranges (stick out physically and break winds)

  • deflect trade winds

  • produce rainfall gradients

mountains effects

orographic (mountainous) lifting of air - mountain is physically in the way, so the wind climbs the mountain then falls on the other side

rain shadow effect - rain hits one side of the mountain and cant get past the peak, so the side facing the rain is forest while the side away from it is desert

microclimate - north vs south facing slopes

northern hemisphere

• south facing slopes get more direct sun → dries out more quickly → dry soil so end up with grass instead of trees (FACES THE EQUATOR)

• north facing slopes get less sun → soil stays moist → large trees

la nina

strong easterly winds at the equator → pushes the warm surface of the ocean from south america to indonesia → upwelled cold ocean water replaces it in south america

el nino

trade winds at equator get paused/weakened → lack of trade winds means warm water stays at south america → ocean temps at west south america stays warm

greenhouse effect

atmosphere is transparent to visible light → warms the earths surface → warm surface emits infrared radiation → IR light emitted by earth is absorbed in part by the atmosphere which is only partially transparent to IR → gases like CO2, N2O and CH4 increase the absorptive capacity of the atmosphere to IR → more IR trapped in the atmosphere warms earths surface and lower atmosphere

eunice newton foote

• discovered greenhouse effect, claimed CO2 in atmosphere is heat trapping and leads to earths climate

• compared temps of glass jars filled with dry air/moist air/CO2 all impacted by sunlight

• CO2 warmed more and stayed warm for longer

albedo

reflection of IR back into the atmosphere

convergence/convergent evolution

similar dominant traits (or in this case plants/organisms) occur under similar conditions but through an unrelated lineage

biomes

categories that group communities by the dominant plant forms

• similar dominant plant forms occur under similar climactic conditions (moisture and temperature)

dictated by climate, topography and soil

why do biomes occur

no single type of plant can endure all climactic conditions

convergence example

same type of plant found both in california and in south africa cape

plant survival curve

optimal range - ideal condition range for a plant to grow

range of tolerance - range of conditions that a plant Can grow in

stress increases on either side of the optimal range

soil horizons/vertical profile of a soil

O - organic horizon

• everything that is organic that is now dead (includes animals, plants, roots, fungi, etc)

A - mineral horizon

• humus, roots, living creatures, inorganic minerals

B - depositional horizon

• iron, aluminum, accumulated compounds, clay leached down from above horizons

C - weathered parent material

• partially weathered rock

whittaker’s biome concept

x axis is flipped (high → low temps)
forms a triangle with corners being:

• warm and wet

• warm and dry

• cold and dry

NO cold and wet

whats missing from whittakers biome concept

cold and wet - why?

• cant have a wet cold region because itll freeze over

biome cutoffs whittakers biome concept

>30cm rain - forest

what determines type of forest? - temperature (deciduous vs rainforest vs boreal etc)

why no forests at lowest temps like tundra? - permafrost (the soils at the depths end up frozen year round so no roots can properly take hold)

mountain gradient

analogous to biome map AKA increasing latitude from the equator and increasing altitude from sea level

tropical rainforest → temperate deciduous forest → boreal forest → tundra → ice and snow

climate zones

heinrich walter - climactic classification system

• focused on temp and precip

• 9 zones from equatorial (tropical rainforest) to polar (tundra)

walters climate diagrams

temperature in red, precipitation in blue

temperature line above precipitation line → drought conditions

walter main three climates

tropical (seasonal forests)

mediterranean (woodland/shrubland)

boreal (taiga)

walter tropical climate

tropical seasonal forest

• year round warm temp

• summer rainfall

SOUTHERN HEMISPHERE

walter mediterranean climate

woodland/shrubland

• warm, dry summers

• cool, wet winters

walter boreal climate

taiga

• year round cold

• wet summer

tundra biome

• very cold temps

• relatively little precip

• short wet summer

• low decomposition

• permafrost

• treeless, many dwarf/woody shrubs

• intense growing season during 24-hour summer days

taiga/boreal forest

• 11% of earths land area

• low temps → slow decomposition → accumulation of organic matter

• evergreen conifers (spruce and fir)

• frost-tolerant vegetation → low plant diversity

TRADE-OFFS - carbon sequestration (trapped in the soil under dead organic matter) and biodiversity

woodlands/shrublands

• mediterranean

• relatively dry in the summer, wet in the winter

• all continents except antarctica

• ~30-30* latitude

• cool and moist winter → hot and dry summer

• trees and shrubs typically evergreen

• fire-resistant plants due to frequent fires

why do mediterranean climates have hot dry summers

30-40* N/S latitude

subtropical high pressure systems maintain dry conditions in the summer

cold ocean currents along western coasts help to stabilize summer climate aka ocean currents keep the air dry

WINTER - subtropical high pressure system shrinks and moves towards subpolar regions → low pressure system takes over and rains

LONG STORY SHORT - high pressure summer, low pressure winter

temperate grasslands

• annual rainfall 300-1000mm, but mostly <500mm

• hot wet summers, cold winters

• periodic droughts and fires

• soils extremely nutrient rich and deep (fires feed organic matter)

• dominated by herbaceous vegetation

• large roaming ungulates (bison, cattle)

• many converted to deserts

why do grasslands not have trees

recall whittaker triangle corners (hot-wet, hot-dry, cold-dry)

>30cm rain is forest → grasslands usually get under 50cm

also recall roaming grazers → chew and eat saplings before they can establish as trees

desertification of grasslands

<1800s large grazers were brought in - pronghorn antelope, tule elk, mule deer

within 10-15yrs of overgrazing by cattle + sheep - most grasslands were converted into deserts

• now dominated by species like cheatgrass which outcompetes native plant species (cheatgrass increases fires and are also more fire resistant than native plants)

desert

• high temps low precip

• 20-30 N and S latitude

• 20% of earths land area

• soil usually extremely low in organic matter - what organic matter there is just decomposes due to the heat

• plant cover - sparse to none

• animal abundance low, but biodiversity may be high

convergent evolution in desert plants

cacti vs euphorbs

NA vs africa - evolved without each other but into very similar organisms

a - temperate deciduous forest

• boston

• moderate climates with winter freezing

• dominated by deciduous trees with understory of small trees and shrubs, often abundant herbs

• warmer and drier parts dominated by needle-leaves trees, typically pines

  • fires may be frequent in the desert and species can resist fire damage

b - temperate rainforest

• sitka, alaska

• mild winters, heavy winter rains, summer fogs

• dominated by tall evergreens (douglas fir, coastal redwood)

  • not as diverse as tropical rainforests

• PNW

tropical seasonal forest + savanna

• relatively warm throughout the year

• huge seasonality irt precip (climate alternates between wet/dry seasons)

• dry season gets so dry that lightning can cause wildfires

• low water permeability soils

• grassland with scattered trees

• controlled fires lead to conversion into dry forest

why do tropics have wet/dry seasons

ITCZ - intertropical convergence zone

• sun rays hit equator most directly

• earths tilt - most direct rays vary in summer/winter months

ITCZ moves throughout the year

NH dry season - dec-jan

NH wet season - may-aug

warmest months are the wettest

tropical rainforest

• within ITCZ year round (10* lat of equator)

• little temp/precip variation between months

• very diverse plant communities

• mychorrizal fungi

symbiosis

“the living together of unlike organisms” - anton de bary

• long term

• positive/negative/neutral effects

mychorrizae

nutrient exchange symbiosis

• essential for plant growth and survival

• assist in uptake of nutrients from soil

• 10-100s of species on a single plant

mykes - fungus

rhiza - root

some plants need mycorrhizal fungi to grow

essential but overlooked component of global diversity

movement of nutrients in mycorrhizae

fungus uses its hyphae (roots-ish) to go out into the soil and scavenge for NPK → transfers it to the plant → in return plant provides it with sugars via photosynthesis

ectomycorrhizal morphology

root colonizers

relationship between a fungal symbiont and the roots of various plant species

SPUN

society for the protection of underground networks

a global effort to map the planets fungi and advocate for their protection

biodiversity response to climate change

negative effects of climate change on biodiversity have been well documented in plants/animals

irt mycorrhizal symbiosis?

• pines as mycorrhizal models - improves soil aeration and protects against pathogens

• ectomycorrhizal fungal diversity predicted to substantially decline due to climate change

invasion biology

study of the introduction of non-native species into ecosystems

invasion biology - pines in australia

pines wouldnt grow no matter how they planted them - dominant plant in AUS is eukalyptus

introduced mycorrhizal fungi to make them grow (invasive)

worked

then pines AND FUNGI escaped the plantations

takeaways mycorrhizal fungi

• affected by global changes

• exacerbate/increase severity of existing global changes (via invasion)

• determine the effects of global change on plants

natural variability in climate

geographically vs temporally

OR:

• spatially vs day-and-night/seasonally/annually/over millenium

• space vs time

spatial variability examples

climate + biome

temporal variability examples

el nino/la nina, milankovitch cycles, glacial cycles

glacial cycles

every 100,000 years

milankovitch cycles

collective effects of earths movement on its climate

determined by:

• eccentricity - how much the earths orbit deviates from a circle, resets 100,000 years

• axial tilt - angle of earths rotational axis, 41,000 years

• precession - amount of wobble the tilt has, 26,000 years

results in variation in amt of solar radiation reaching the earths surface/how far the earth is from the sun

predicts global heating/cooling cycles

eccentricity

earths orbit around the sun is an ellipse - eccentricity is the departure of this ellipse from being a perfect circle

perfect circle = 0

strong ellipse = 1

no units because its a ratio of distances !!!

• earths mean eccentricity = 0.028

• earths CURRENT eccentricity = 0.017 and decreasing

higher eccentricity = higher likelihood to enter glacial period

why does eccentricity vary

earth isnt the only planet orbiting the sun

• if it was, eccentricity wouldnt vary

earth is also in the gravitational fields of jupiter and saturn as well

eccentricity calculation

distance between two focal points of an ellipse / length of the major axis

axial tilt

cause of seasons

22.1 - 24.5 degree variation

currently 22.4 and decreasing

greater tilt → greater change in seasons

summer vs winter for determining ice ages?

summer

• winter can be as cold as it wants, we look at the hottest temperature to determine the maximum

what causes axial tilt to change over time

large land masses/ice sheets make earth top heavy

shifts in these land masses/ice sheets cause variation in tilt (like sticking something on a spinning top)

why doesnt axial tilt change biomes

its hard to move biomes around in the time period of axial tilt change

if earth had no axial tilt - very little seasonal variation across earth

precession

wobble around the axis

what causes precession to change over time

gravitational forces of sun/moon

milankovitch cycle adding everything together

eccentricity + axial tilt + precession → ~100,000 year cycles of ice ages

• eccentricity smallest - seasonality most mild

• axial tilt smallest - smallest difference btwn winter and summer

• precession smallest - summers too cool to melt all accumulated snow from prev winter

recent temperature changes

general increase in global temps since 1880

what caused variability - temp cooling?

• 1940-1980 - particulates and aerosol pollution counter-acted effects of elevated co2 → industrial revolution into clean air act

• 1990 - mount pinatubo → high SO2 concentrations

why such focus on CO2 irt greenhouse gases

most of greenhouse gas emissions is CO2

how do we know atmospheric CO2 is rising?

• keeling curve

charles keeling

• funded to develop analytical equipment to measure atmospheric CO2

• mauna loa, hawai’i → very little CO2 due to human activityy

• only asked to measure a couple of years to determine global concentration

  • decided to measure multiple times within first year

  • discovered within year 1 that CO2 concentration was rising