Contain up to one-half of the world's known terrestrial plant and animal species
Disruption of tropical rain forests
Reduces biodiversity
Accelerates climate change
Changes regional weather patterns
Major components of the earth's life-support system
Atmosphere (air)
Hydrosphere (water)
Geosphere (rocks, minerals, and soil)
Biosphere (living things)
Troposphere
Innermost layer of the atmosphere, contains the air we breathe
Stratosphere
Contains the ozone layer, filters sun's harmful UV radiation
Hydrosphere
All water vapor, liquid water, and ice
Oceans contain 97% of the planet's water
Geosphere
Upper portion of crust contains nutrients organisms need to live, grow, and reproduce
Biosphere
Parts of atmosphere, hydrosphere, and geosphere where life is found
Factors that sustain the Earth's life
One-way flow of high-quality energy from the sun
Cycling of nutrients through parts of the biosphere
Gravity holds the earth's atmosphere
Levels of matter studied by ecologists
Biosphere
Ecosystems
Communities
Populations
Organisms
Producers (autotrophs)
Organisms that make needed nutrients from their environment through photosynthesis
Consumers (heterotrophs)
Organisms that cannot produce the nutrients they need
Types of consumers
Primary consumers (herbivores)
Carnivores
Omnivores
Decomposers
Consumers that release nutrients from wastes or remains of plants or animals
Aerobic respiration
Using oxygen to turn glucose back to carbon dioxide and water, releases energy
Anaerobic respiration and fermentation
Used by some decomposers in the absence of oxygen, releases methane gas, ethyl alcohol, acetic acid, and hydrogen sulfide
Soil
Complex mixture of rock, particles, mineral nutrients, organic matter, water, air, and living organisms
Soil formation begins with weathering of bedrock into small pieces
Mature soils contain several layers (horizons) that differ in texture, composition, and thickness
Formation of 1 inch of topsoil can take hundreds to thousands of years
Soil becomes nonrenewable if we deplete faster than it can be replenished
Food chain
Movement of energy and nutrients from one trophic level to the next
Food web
Network of interconnected food chains
Every use and transfer of energy involves energy loss as heat
Pyramid of energy flow
90% of energy lost with each transfer, less chemical energy for higher trophic levels
Biomass
Total mass of organisms in a given trophic level
Gross primary productivity (GPP) is the rate at which an ecosystem's producers convert solar energy to stored chemical energy, measured in units such as kcal/m2/year
Netprimaryproductivity (NPP)
The rate at which an ecosystem's producers convert solar energy to chemical energy, minus the rate at which they use the stored energy for aerobic respiration
Terrestrialecosystems and aquatic life zones differ in their NPP
The planet's NPP ultimately limits the number of consumers (including humans) that can survive on the earth
Nutrientscycle within and among ecosystems, driven by incoming solar energy and gravity, and can be altered by human activity
Nutrient cycles
Water
Carbon
Nitrogen
Phosphorus
The water cycle
1. Evaporation
2. Precipitation
3. Surface runoff
4. Groundwater storage
Ways humans alter the water cycle
Withdrawing large amounts of freshwater at rates faster than nature can replace it
Clearing vegetation, increasing runoff and decreasing infiltration
Draining and filling wetlands for farming and urban development, reducing flood control and water absorption
Properties of water include being a liquid over a large temperature range, storing a large amount of heat, taking lots of energy to evaporate, dissolving a variety of compounds, filtering out UV radiation, and expanding when it freezes
The carbon cycle
1. Photosynthesis removes CO2 from atmosphere
2. Aerobic respiration adds CO2 to atmosphere
3. Carbon in dead plant matter and algae converted to fossil fuels over millions of years
4. Some CO2 dissolves in the ocean and is stored in marine sediments
Humans have added large quantities of CO2 to the atmosphere at a faster rate than natural processes can remove, resulting in a warming atmosphere and changing climate
Clearing vegetation reduces the ability to remove excess CO2 from the atmosphere
The nitrogen cycle
1. Lightning and specialized bacteria convert atmospheric nitrogen to useful forms
2. Plants use nitrogen compounds to produce proteins, nucleic acids, and vitamins
3. Bacteria convert nitrogen compounds back into nitrogen gas
Human alteration of the nitrogen cycle includes burning fuels creating nitric oxide, removing large amounts of nitrogen from the atmosphere to make fertilizers, and adding excess nitrates to aquatic ecosystems
Human nitrogen inputs to the environment have risen sharply and are expected to continue rising