OUR Ecological Footprint 1. Live near work; ride bike; minimize car use.2. Buy energy-efficient furnace.3. Programmable thermostat: 50 winter/ 80 summer4. Turn off lights when leave room; unplug appliance5. Eat low on food chain.6. Buy food locally; eliminate transportation energy.7. Buy hybrid car - reduce gas consumption by 1/28. Get ‘on demand’ water heater.9. Winterize house.10. Recycle; pay tax for it.11. Reduce paper/plastic (and ALL) consumption.12. Reuse (and repair) items; don’t use ‘throw- aways’13. Restore: Buy C offset for travel--> plant trees.

…For Tuesday

•Go to website for Lecture Outline

•Read 10 sections in text about

‘Global Change Biology’

•Pay particular attention to Figures

•Be ready to explain topic/figures to

group/class

Our ‘stuff’… or“how humansalter nutrientcycles and deplete naturalresources…”

OBJECTIVES

Human Activities Alter Nutrient Cycles Relates to Intersystem Cycles:

Pools/Fluxes altered

Inputs/Outputs disrupted-->consequences

• Water

• Carbon

• Nitrogen

• Phosphorus

• Sulfur

• Ozone

Intersystem cycling: Nutrients gained (input) and lost (output) by an ecosystem

Ecosystem 12

Input output

Ecosystem 2

Input

Output

Ecosystem 1

Ecosystems modeled as linked compartments (box = pool; arrow = flux).

Figure 2

Nutrient inputs on land from:

• Lithosphere (weathering of bedrock and

soil)

• Atmosphere

– Wetfall (in precipitation)

– Dryfall (particles)

• Hydrosphere

• Human Activities

Nutrient losses (output) on land to:

• Atmosphere

• Streams and groundwater

• Human activities

• How do human activities alter output?

Plowing of prairies contributed to the creation of the Midwest’s Dust Bowl (1930s).

Soil erosion on plowed farmland…about 1% of topsoil is lost each year.

Over-grazing leads to loss of vegetation and leads to soil erosion.

WATER

*

Water use greatly exceeds water supplies in many parts of our West.

Irrigation can turn desert into productive farmland…

But…accumulation of salts in soil that accompanies irrigation can damage crops.

Clear-cutting affects hydrology, erosion, nutrient-off…

50% of water in the Amazon Basin is internally recycled. Predict how deforestation there might be affecting the local hydrologic (water) cycle and the forest.

How are humans altering water cycle?

• Depletion from overuse• Fossilized vs. re-chargeable aquifers• Overpopulation--> insufficient local water• Used to produce crops to produce meat• Irrigation --> salt problems • Land-use changes lower local cycling-> drought• Links to other cycles:• Water carries solutes (e.g. N,P,K, H+)• C cycle - link to global warming -->• precipitation changes worldwide• glacial melt --> loss of water source

CARBON --> Global warming

Human production of CO2 by burning of fossil fuels has increased greatly.

Greenhouse gases and other human inputs add to the heat budget of the atmosphere =(radiative forcing)

snow intact

snow removed

intactremoved

WILDFIRES: accelerate several cycles

Forest fires increase CO2 emissions. Fires are increasing in frequency/severity.

NH4 1 3b2a

2b

3a

4

5

-3

+3

i

NITROGEN

How are humans altering the N cycle?• Nitrogen-fixing crops

• Invasive species fix N2

• Fossil fuel burning--> nitrous oxide (N2O)

• Nitrogen fertilizer

• Animal feed lots + manure

Inputs of N into rivers (and then oceans) has increased greatly since 1960.

• Consequences:• produce greenhouse gas (N2O)• N2O + O2 --> NO3

- + H2O --> nitric acid (rain)• increase nitrogen saturation of soils/forests --> change soil chemistry --> leach nitrates• increase runoff into aquatic systems + water supply; causes eutrophication• alter biodiversity and species mix

PHOSPHORUS

How are humans altering P cycle?• Mining for P to add to fertilizer for crops

• Consequences: • Run-off into aquatic communities -->

increases algal abundance--> eutrophication • Lowers water quality• Moves P to water sediments --> moves to

geological time scale; not available

Phosphorus concentration controls the

trophic structure and productivity of lakes.

CNP

CN

• How do human activities affect input from

land to water?

• runoff/seepage

• agriculture land, especially NPK

• animal feedlots, especially N

• sewage input, C, N

• -->into groundwater/aquifers/streams/oceans

Nutrient-rich fresh water floats over salt water.

Oyxgen depletion by great bacterial response to input of organic waste--> anoxic conditions for fish that die

Large ‘dead zones’ with hypoxic bottom waters.

• Correlate with human footprint

• Exponential increase since 1960s

‘Dead zones’ from eutrophication

Human eutrophication (overproduction of organic matter in aquatic systems) is harmful.

• Added nutrients stimulate algal GPP, BUT• • Too much overwhelms intrasystem regeneration• • Increase in dead organic matter• • Energy flows to bacteria, not higher trophic level• • Increase in decomposition + respiration • ---> depletes oxygen (hypoxia + anoxia)• ---> kills aerobes, including fish

Consequences for aquatic systems

• create ‘dead zones’ in oceans

• nitrates lower quality of drinking water

• “blue baby” alert

• change freshwater aquatic communities

SULFUR

1

2 345

-2

+6

SO4 emissions from copper smelter

(Sulfuric) acid drainage from coal mines.

pH profoundly affects ecosystems, especially aquatic systems.

****

Acid rain from coal-burning industries affects forest growth.Slow recovery from its effects…

Effects of acid rain on a forest.Why is damage greater on 1 side of mt.?Why haven’t forests recovered when acid rain was lessened?

Lessons from acid rain research

How do humans affect S cycle?• Burning of fossil fuels containing H2S puts S into the atmosphere-->• SO4 reacts with H20 to form sulfuric acid --> acid rain.

• How did S get incorporated into coal? Non-decomposed plants got buried in swamps, allowing

anaerobic processes to proceed --> H2S in coal.

• Consequences of S presence in coal? Strip-mine - sulfuric acid directly into streams--> lowers pH-->disrupts aquatic community Acid rain Lowers Ca++ in soils-->lowers forest productivity. Lowers pH in lakes--> disrupts aquatic community.

Ozone (O3) + UV radiation

1. at surface

• N2O from burning gas in cars (GH gas)

• O2 with N2O with light --> O3

Consequences:

• Smog + health problems

• Ozone = oxidant of organic molecules

• SOYFACE: elevated O3 lowers crop

productivity

2.In upper atmosphere O3 blocks UV radiation CFCs destroy ozone -->creates ‘black hole’-->increase damage to DNA from UV --> skin cancer

Treatiesban CFCs, but slowrepair of hole…

How do our choices leave a FOOTPRINT at higher levels of ecological organization?

Our Ecological Footprint• How does a single choice impact

energy flow and cycling of matter?

H2O C N P S ozone

•1 Drive car w gasoline Buy sandwich with

•2 Take bus with biodiesel 5. Lettuce from CA

or ethanol 6. Meat from feedlot• 3 Work out at ARC 7. Take out in plastic bag

+ take + styrofoam cup• 4 Long shower + 8. Print lecture outline

hair spray