Topic 2 - Ecosystem Dynamics Flashcards
What is a biomass?
Total dry mass of all living matter in a certain area
What is the gross productivity of a trophic level?
Amount of energy obtained from the previous trophic level
What is the net productivity of a trophic level
The amount of energy available for the next trophic level
What is the approximate efficiency of each trophic level?
10%
What are primary producers?
The autotrophs at the bottom of a food chain/web which provide food for all other trophic levels
What is an ecological niche?
The role and space that an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment
What is the competitive exclusion principle?
Two species cannot stably coexist while competing for the same resources
Niche Differentiation
When two competing species use the environment differently so they can co-exist
What is a fundamental niche?
The total potential resources a species could use
What is a realised niche?
The actual resources used by a species after accounting for all factors
What is a keystone species?
A plant or animal that plays a unique and crucial role in the way an ecosystem functions
What are the 5 processes in the nitrogen cycle?
Nitrogen Fixation, Ammonification, Assmilation, Nitrification, Denitrification
What 2 processes return water to the atmosphere?
Percipitation, Evaporation
What is carrying capacity?
The size of the population that can be supported indefinitely on the available resources and services of that ecosystem
What is a density dependent limiting factor?
A factor that is dependent on population size
What is a J-curve
An exponential curve that continues upwards in a ‘J’ shape that represents population numbers over time
What is an S-curve?
A curve in the shape of an ‘S’ that represents population numbers over time including the carrying capacity of a population
How do you determine population change?
Population change = (births - deaths) + (immigration - emigration)
What is primary succession?
Ecological changes happening in an entirely new habitat (no soil)
What is secondary succession?
Ecological changes happening in a damaged ecosystem that was previously functioning
What is a pioneer species?
The first colonies in an ecosystem
What defines a pioneer species?
They can photosynthesise, fix nitrogen, rapidly reproduce, and tolerate extreme conditions
What is a seral stage?
The intermediate stages before an ecosystem reaches a climax community
What is a climax community?
When an ecosystem reaches a stable, balanced point and is self-perpetuating
