Global Ecology Exam 1

Study Guide

Standing stocks

• how much is sitting around

• how much of something exists at a given moment

• ex: carbon stock - total carbon stored in all the trees and soils of Amazon rainforest

Flux

• how much is moving in or out over time

• ex: carbon being absorbed by a forest or released from soil

Size variation in ecosystems

• Human gut: bacterial community interacting with physical environment of your intestines

• Pond: food web of microbes, plants, and animals in the water

• Catchment: forest/grassland + streams/lakes

• Earth

Primary production

• GPP

• NPP

• Autotrophic respiration (Ra)

• Heterotrophic respiration (Rh)

• Respiration (R)

• NEP

GPP

Gross primary production

• total rate of photosynthesis

NPP

Net primary production

• NPP = GPP - Ra

Respiration

R = Ra + Rh

NEP

Net ecosystem production

• NEP = GPP - R

Terrestrial NPP

Main controls are temperature and precipitation

Marine NPP

Nutrients and light are the main controls

Freshwater NPP

Nutrients, light, temperature, water flow are the main controls

Why study NPP?

• NPP sucks up CO2

• NPP changes with a changing climate

Positive coupling (1 way)

• something increases (decreases) causing something else to increase (decrease)

Negative coupling (1 way)

• something increases (decreases) causing something else to decrease (increase)

Negative feedback

• stabilizing

• reduce the original force

Positive feedback

• destabilizing

• reinforce the original force

Daisyworld

• understand systems and feedbacks

• realize that life can regulate planet (Gaia hypothesis)

Gaia hypothesis

• James Lovelock

• Life doesn’t adapt to Earth — it helps control Earth’s environment

• Self-regulation of Earth

Average albedo of Earth

0.30

• 30% of the sunlight that hits the Earth is reflected back into space

• 70% is absorbed by the planet, warming the surface

Daisyworld

• White daisies that reflect sunlight

• Black daisies that absorb sunlight

Sun heats up and the white daisies reflect more light cooling the planet while the black daisies absorb more light warming the planet

If the planet gets too hot more black daisies thrive, if it gets too cold more white daisies thrive

Daisies adjust their population based on the temperature, and self-regulate the climate

Radiative balance

Incoming solar radiation = outgoing IR radiation

Natural “Greenhouse Effect”

• the envelope of atmospheric gases that absorb and re-emit radiation at specific wavelengths

Main greenhouse gases

• CO2

• CH4

• N2O

• CFC

Role of Aerosols in planet temperature

• reflect sunlight which can cool the surface

• seeds for cloud formation

• some aerosols can absorb sunlight like black soot

Role of clouds in planet temperature

• cooling effect — reflect sunlight back into space (low clouds like cumulus/stratus)

• warming effect — trap heat by absorbing and re-emitting infrared radiation (high clouds like cirrus)

Stratospheric ozone

• 90% of ozone

• major UV shield

• greenhouse gas

Tropospheric ozone

• 10% of ozone

• greenhouse gas

• forms from nitrogen oxides and VOCs

• key component for smog

insolation

• higher at the equator and lower at the pole with seasonal variations

Monsoon

• strong seasonal change in wind direction

• generally requires heating of a large landmass near the ocean

• connected with ITCZ

Coriolis Effect

the way Earth’s rotation makes moving air or water curve instead of traveling in a straight line

IPCC predictions for temperature

• Low emission

  • peak at 1.5 then decline to 1.4

• Intermediate

  • 2.0-2.7

• High

  • 4.4

IPCC predictions based on latitude

• Equator: continue to heat up

• Mid-Latitude: Warm more than average with hot summers and mild winters

• Polar regions: warm fastest with dramatic changes

IPCC Missouri Outlook

• increase in hot days

• Increased precipitation

• flood risks

• droughts

Water distribution

• 97.6% oceans and saline lakes

• 2.4% freshwater

  • 87% ice and snow

  • 13% liquid water

    • 95% groundwater

    • 3% lakes, streams, rivers

    • 2% soil moisture

Hydrologic terms

• Evaporation

• Transpiration

• Sublimation

• Condensation

• Precipitation

• Interception

• Infiltration

• Recharge

• Overland flow/runoff

Runoff

P - ET

Water scarcity index

measure to assess the availability of fresh water in a region relative to its population and demand

• annual water demand/annual renewable water supply

WSI values

WSI < 0.2 = abundant

0.2 < WSI < 0.4 = moderate

WSI > 0.4 = high scarcity risk

Areas with high scarcity

• parts of the Middle East

  • Saudi Arabia

  • Iraq

  • Iran

Precipitation by region

• more in northern latitudes

• less in subtropics

• more floods with river discharge

• Snowpack/glacial water storage declines = reduced water flow

GRACE

Gravity Recovery and Climate Experiment

• measures tiny changes in Earth’s gravity by tracking the distance between two satellites in orbit

• creates maps of earth’s mass changing

• measures water storage, ice sheets and glaciers, earth’s mass changes

Sea level rise

• Greenland ice sheet mass loss

• Antarctic ice sheet mass loss

• Glacier mass loss

• thermal expansion

Arctic Sea ice patterns

• average annual discharge of fresh water increased by 7%