5B ecosystems

What is Gross primary productivity, or GPP?

the rate at which chemical energy is converted into carbohydrates during photosynthesis

What is Net primary productivity, or NPP

rate at which energy is stored in plant biomass

NPP = GPP - R

• Using area: J m^–2 yr^-1

• Using volume: J m^–3 yr^-1

what is the process of energy transfer?

• Only around 10 % of the energy is available to the consumer to store in their tissues

• This is because around 90 % of the energy is lost to the environment

How is 90% of energy lost to the environment?

• Not every part of the food organism is eaten

• Consumers are not able to digest all of the food they ingest

• in the form of heat when consumers respire

• when organisms excrete the waste products of metabolism

Why is a large proportion of the sun's energy is not available to producers for building biomass?

• Light passes through leaves or is reflected away

• Light hits non-photosynthetic parts of the plant

• Light is a mixture of wavelengths and only certain wavelengths are absorbed in photosynthesis

• Plants release energy during respiration, some of which is lost to the environment in the form of heat

How to calculate the efficiency of energy transfer

Energy efficiency = (net productivity ÷ energy received) x 100

How to calculate the efficiency of biomass transfer

Efficiency of biomass transfer = (biomass transferred ÷ biomass intake) x 100

Habitat

the place where an organism lives

Population

all of the individuals of one species living in a habitat

Community

a group of organisms of different species interacting in a particular area

Ecosystem

a community and its interactions with the non-living parts of its habitat

Biotic factors

living factors that influence populations within their community; can about as a result of the activity of other organisms

Abiotic factors

non-living factors that influence populations within their community

Niche definition

the role of a species within its habitat

The role of a species includes…

• What it eats

• Which other species depend on it for food

• What time of day a species is active

• Exactly where in a habitat a species lives

• Exactly where in a habitat a species feeds

Can species have the same niche?

No two species can fill the same niche within a habitat; if this ever happens the two species will be in direct competition with each other for resources and one of the species will die

Primary succession

the process that occurs when newly formed or newly exposed land is inhabited by an increasing number of species

Process of primary succession

• Seeds and spores that are carried by the wind land on exposed rock and begin to grow

• The first species to colonise the new land, often mosses and lichens, are known as pioneer species which can germinate easily and withstand harsh conditions such as low nutrient and water availability 

• As pioneer species die and decompose, the dead organic matter forms soil

• Seeds of small plants and grasses land on this soil and begin to grow

• As these small plants die and decompose, the soil becomes deeper and more nutrient-rich 

• Larger plants and shrubs, as well as small trees can now begin to grow

• Over time the soil becomes sufficiently deep, contains enough nutrients, and can hold enough water to support the growth of large trees

• The final species to colonise the new land become the dominant species

• The final community formed is known as the climax community

Secondary succession

• takes place on previously occupied land e.g. after a wild fire or deforestation

• soil is already present

Plagioclimax

Climax communities that develop as a result of human intervention

Difference between abundance and distribution

Abundance - the no. of a particular organism

Distribution - where the organism is found