APES Chapter 3

Ecosystem

A particular location on Earth with interacting biotic and abiotic components

What are the characteristics of ecosystems dependent on?

Climate

Why is a cave a well defined ecosystem?

contains identifiable biotic components, such as animals and microorganisms that are specifically adapted to live in cave environments as well as distinctive abiotic components ex: water, temp, salinity

Regions with greater quantities of water in the soil can support trees whereas regions with less water

can only support grasses

Why are cave ecosystems easy to study?

Boundaries are clear, easily defined

Why are aquatic ecosystems easy to study?

Ecosystem boundaries correspond to boundaries between land and water

Why is knowing the boundaries of an ecosystem important?

Makes it easier to identify systems biotic and abiotic components and to trace the cycling energy and matter through the system.

Biosphere

The region of our planet where life resides, the combination of all ecosystems on Earth.

Why do we study processes that move energy and matter?

To understand how ecosystems function and how best to protect and manage them

How do we understand energy relationships?

Look at the way energy flows across an ecosystems

Producer

An organism that uses the energy of the Sun to produce usable forms of energy (also known as autotroph)

Photosynthesis

The process by which producers use solar energy to convert carbon dioxide and water into glucose

What does photosynthesis produce as a waste product?

Oxygen

Who is photosynthesis performed by?

autotrophs (plants, algae, and some bacteria)

Respiration

The process by which organisms convert glucose and oxygen into water and carbon dioxide, releasing the energy needed to live, grow, and reproduce.

Who is respiration performed by?

All organisms

Why are plants beneficial to our atmosphere?

They produce the oxygen we need to breath.

cellular respiration

The process by which cells unlock the energy of chemical compounds

aerobic respiration

opposite of photosynthesis converts glucose and oxygen into energy, carbon dioxide and water

anaerobic respiration

The process by which cells convert glucose into energy in the absence of oxygen

What provides more energy anaerobic or aerobic respiration?

Aerobic

Consumer

An organism that is incapable of photosynthesis and must obtain its energy by consuming other organisms (also known as heterotroph)

Herbivore

A consumer that eats producers (also known as Primary consumer) ex: zebra, zooplankton

Carnivore

A consumer that eats other consumers

secondary consumer

An organism that eats primary consumers ex: lions, snakes, hawks

tertiary consumer

A carnivore that eats secondary consumers

Trophic levels

The successive levels of organisms consuming one another

Food chain

the sequence of consumption from producers through tertiary consumers

Food web

A complex more realistic model of how energy and matter move between trophic levels

Omnivores

eat both plants and animals

scavenger

A carnivore that feeds on the bodies of dead organisms

Detritivore

An organism that specializes in breaking down dead tissues and waste products into smaller particles

Decomposers

fungi and bacteria that convert organic matter into small elements and molecules that can be recycled back into the ecosystem

3 types of organisms that feed on dead organic matter

Scavengers, Detritivores, Decomposers

What would happen without scavengers, detritivores, decomposers?

there would be no way of recycling organic matter and energy, and the world would rapidly fill up with dead plants and animals.

detritus

dead tissues and waste products

How many interconnected food chains does a food web have?

At least 2

trophic cascade

removal or addition of a top predator has a ripple effect down through lower trophic levels

Gross Primary Productivity (GPP)

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

Net primary production

the gross primary production of an ecosystem minus the energy used by the producers for respiration.

Why is determining GPP a challenge for scientists?

plants usually simultaneously respire and do photosynthesis at the same time, but both rates have to be calculated separately

How much solar energy is captured by photosynthesis?

1%

how much GPP is lost at respiration?

60%

how much GPP supports the growth and reproduction of producers?

40%

Where is productivity the highest?

where temperatures are warm and water and solar energy are abundant

primary productivity

rate that solar energy is converted into organic compounds via photosynthesis over a unit of time

Primary productivity unit

kcal/m^2/yr (energy/area/time)

Biomass

the total mass of all living matter in a specific area

What does higher primary productivity mean for an ecosystem?

Higher plant growth which equals more shelter for animals

What ecosystems are the more diverse?

Ones with higher primary productivity

standing crop

the amount of biomass present in an ecosystem at a particular time

Difference between standing crop and productivity

standing crop measures the amount of energy in a system at a given time, productivity measures the rate of energy production over a span of time

ecological efficiency

the proportion of consumed energy that can be passed from one trophic level to another

What do ecological efficiencies range from?

5-20%

Average ecological efficiency

10%

trophic pyramid

A representation of the distribution of biomass, numbers, or energy among trophic levels

Respiration loss

plants use up some of the energy they generate via photosynthesis by doing cell. respiration (movement, internal transportation, etc.)

The more productive the biome is

higher biodiversity

What leads to high NPP?

Water availability, higher temperature, nutrient availability

Why does a desert have low NPP?

low water availability and nutrients

Why does tundra have a low level of net primary productivity?

lower temperature and water availability

Why does an open ocean have low NPP?

low nutrients

What is the hydrologic cycle powered by?

sun

biogeochemical cycles

the movements of matter within and between ecosystems

types of biogeochemical cycles

water cycle, carbon cycle, nitrogen cycle, phosphorus cycle

What do biogeochemical often exist in the form of?

Water, Air, Land

What happens when water vapor enters the atmosphere?

Cools and forms clouds, which in turn produce precipitation in the form of rain, snow and hail. Some precipitation falls back into the ocean some falls on land

What can happen when water falls on land?

Evapotranspiration and runoff

How can humans alter hydrologic cycles?

Harvesting trees to reduce evapotranspiration reducing plant biomass.

Evapotranspiration

The combined amount of evaporation and transpiration

Pools

components that contain matter such as air, water, and organisms

Flows

processes that move matter between pools

Runoff

Water that moves across the land surface and into streams and rivers

Transpiration

Evaporation of water from the leaves of a plant

What happens majority of the time when precipitation occurs?

runoff

Largest water reservoir

ocean

What contains the most freshwater usable for humans?

Ice caps and groundwater?

2 main sources of water

evaporation, evapotranspiration

Why is water important to molecules?

Allows essential molecules to move between cells, draws nutrients into leaves of trees dissolves and removes toxic materials, and performs many other critical biological functions.

Infiltration

the process by which water on the ground surface enters the soil

Percent of freshwater in the world

2.5%

Percolation

The downward movement of water through soil and rocks

Which macronutrient is required by humans in the largest amounts?

nitrogen

7 processes that drive the carbon cycle

1. photosynthesis 2. respiration 3. exchange 4. sedimentation 5. burial 6. extraction 7. combustion

How much percent of our body does carbon make up?

20%

carbon cycle

The movement of carbon around the biosphere

What are the carbon cycle processes categorized as?

Fast or slow

Fast parts of carbon cycle

Processes associated with living organisms

slow part of carbon cycle

the part of the carbon cycle that involves carbon that is held in rocks, in soils, or as petroleum hydrocarbons

carbon sink

a natural or artificial reservoir that accumulates and stores some carbon-containing chemical compound for an indefinite period

Does extraction alter the carbon cycle by itself?

No it is a subsequent step of combustion

Differences between respiration decomposition and combustion.

Respiration and decomposition are biotic processes whereas combustion is an abiotic process.

Similarities between combustion, respiration, decomposition

they all cause organic molecules to be broken down to produce CO2, water and energy.

Macronutrients

The six key elements that organisms need in relatively large amounts: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.

limiting nutrient

a nutrient required for the growth of an organism but available in a lower quantity than other nutrients

Examples of carbon sinks

Ocean (algae & sediments), plants, soil

carbon source

Releases more carbon into the atmosphere than it takes in

examples of carbon source

fossil fuels, deforestation (releases CO2 from trees)

Movement in atmosphere

atmospheric carbon as CO2 (0.04% of troposphere)

Movement through food web

carbon moves in organic form from organism to organism