Chapter 3 - Ecoystems

Systems

Systems

A set of components that function and interact in some regular and theoretically predictable manner and can be isolated for purposes of observation and study

Input

• matter

• energy

• informative flowing into system

Flow/Throughputs

• matter

• energy

• information flowing at a certain rate within a system

• stores/storage area

  • area of accumulation for various lengths of time before being released

Outputs

• matter

• energy

• information that flows out of a system into sinks in the environment

3 Components of a system summary

Matter is a circular system

Energy is linear

Feedback Loops

A runaway cycle in which a change in a certain direction provides further information that causes a system to change further in the same direction

• can destabilize a system

  • Ex: climate change, Hubbard brook experiment

Negative Feedback Loop

One change leads to a lessening of that change

• desirable

• stabilizes a system

  • Ex: homeostasis, thermostats, recycling

3 Factors of Life

1. One way flow of high quality energy from the sun

   • governed by 1st and 2nd Laws of Thermodynamics

2. Cycling of matter and nutrients

   • fixed supply of nutrients needs to constantly be recycled

3. Gravity

   • allows the planet to keep the atmosphere

Population

a group of organisms of one type

• same species

• living in the same area

Community

all populations that live together in a defined location

Ecosystem

communities and abiotic factors

Biosphere

the part of earth that contains all ecosystems

Abiotic factors

• soil type

• temperature

• precipitation

• water availability

• sunlight

• wind

• pH

Cell theory

1. all things are made of one or more cells

2. cells only come from existing cells

3. all of an organisms life functions occur within cells

4. cells contain DNA

   • needed for regulating all functions

   • passing hereditary informaion

Biotic Components

• living components of an ecosystem

  • bacteria

  • protists

  • fungus

  • plants

  • animals

Abiotic components

• nonliving components of an ecosystem

• determines which organisms can live there

  • sunlight

  • temperature

  • precipitation

  • pH

  • soil

  • nutrient availability

Effects of abiotic factors on biotic factors

• each population in an ecosystem has a range of tolerance

  • range of physical and chemical conditions that must be maintained for a population to stay alive, grow, and function normally

Biomes

terrestrial regions inhabited by certain types of life, especially vegetation

Trophic levels

Levels in the feeding structure of organisms

• higher trophic levels consume organisms from lower levels

Trophic pyramid

Represents the distribution of biomass among trophic levels in an ecosystem

Trophic cascade

Ecological phenomenon that occurs when the addition or removal of a top predator affects the population of predators and prey throughout a food web

• may lead to significant changes in the structure of an ecosystem and how nutrients cycle

Autotrophs

Plants, algae, and other organisms that use the sun’s energy to produce usable forms of energy

Photosynthesis

Process by which autotrophs trap energy from the sunlight with chlorophyll and use energy to convert carbon dioxide and water into simple sugars

• waste product is oxygen

Chemical equation for photosynthesis

6CO₂+6H₂O → C₆H₁₂O₆+6O₂

Heterotrophs

must obtain their energy from consuming other organisms

Primary consumers

heterotrophs (herbivores) that consume producers

Carnivores

heterotrophs that obtain energy by eating other consumers

Tertiary consumers

carnivores/omnivores that eat primary consumers

Scavengers

carnivores that consume dead animals

• vultures

Detritivores

organisms that specialize in breaking down dead tissues and waste products into smaller particles

• dung beetles

• earthworms

Decomposers

organisms that complete the breakdown process by recycling the nutrients from dead tissues and wastes into the ecosystem

• fungi

• bacteria

Food chain

the sequence of consumption from producers through all levels of consumers

Food web

a complex model of how energy and matter move between trophic levels

• more accurate

Ecological efficiency

useable energy that is passed along from one trophic level to the next

Biomass

the energy in an ecosystem can be measured in biomass which is the total mass of all living matter in a specific area

• NPP establishes the rate at which biomass is produced over a given amount of time

Gross Primary Productivity (GPP)

the measure of the total amount of solar energy that the producers in an ecosystem capture via photosynthesis over a given amount of time

Net Primary Productivity (NPP)

the energy captured by producers minus the energy that producers respire

• allows us to compare the productivity of different ecosystems

NPP equation

GPP - respiration by producers = NPP

Biosphere

the region of our planet where life resides

• matter does not enter or leave the biosphere

  • Earth is a closed system with respect to matter

Biogeochemical cycles

the movement of matter within and between ecosystems involving biological, geological, and chemical processes

Pools/reservoirs

components that contain matter

• air

• water

• organisms

Flows

processes that move matter between pools

The Hydrology Cycle

1. Solar energy heats Earth and causes evaporation

   • evaporation from ocean

   • evaporation from soil

   • evapotranspiration from plants

2. Evaporated water condenses into clouds

3. Water returns to Earth as precipitation

   • rain

   • snow

   • hail

4. Precipitation falling on land is taken up by plants, run off along the land surface, and enters groundwater

   • surface water

   • surface runoff

   • groundwater

The Carbon Cycle

1. Producers convert CO₂ into sugars

2. Sugars are converted back into CO₂

3. Some carbon is buried

4. Human extraction of fossil fuels brings carbon to Earth’s surface, where it can be combusted

5. CO₂ in the atmosphere and CO₂ dissolved in water are constantly exchanged

6. Combustion converts fossil fuels and plant material into CO₂

The Nitrogen Cycle

1. Nitrogen fixation

   • nitrogen fixation converts N₂ from the atmosphere

   • Biotic processes convert N₂ to ammonia (NH₃)

   • Abiotic processes convert N₂ to nitrate (NO_3- )

2. Assimilation

   • producers either take up ammonium (NH₄₊ ) or nitrate (NH_3-)

   • consumers assimilate nitrogen by eating producers

3. Ammonification

   • decomposers in soil and water break down biological nitrogen compounds into ammonium (NH₄₊)

4. Nitrification

   • nitrifying bacteria convert ammonium (NH₄₊) into nitrate (NO_2-) and then into nitrate (NO_3-)

5. Denitrification

   • denitrifying bacteria in oxygen poor soil and stagnant water (NO_2-) into nitrous oxide (N₂O)

   • eventually becomes nitrogen gas (N₂)

The Phosphorus Cycle

1. Weathering of uplifted rocks contribute phosphates to the land. Some phosphates make their way back to the ocean

2. Phosphate fertilizer applied to fields can run off directly into streams, become part of a soil pool or absorbed by plants

3. Excretion by animals and decomposition of both animals and plants release phosphates on land or in water

4. Dissolved phosphates precipitate out of solution and contribute to the ocean sediments

   • conversion of sediments into phosphate rocks is a very slow process

5. Geologic forces slowly lift up phosphate rocks from the ocean floor to form mountains.