Ecosystems 10 Flashcards
What is an ecosystem?
An environment that includes all of the organisms living in a particular area
What is a community?
All the populations of all the different species of organisms living in a habitat at any one time
What are the four sizes of ecosystems?
-Biosphere
-Biome
-Habitat
-Microhabitat
What is meant by an animals trophic level?
An animals feeding relationship with other organisms or its position in a food chain
What are the five trophic levels?
-Producers
-Primary consumers
-Secondary consumers
-Teritary consumers
-Decomposers
What is a pyramid of numbers?
Shows the number of organisms at each trophic level
What is one advantage of using pyramid of numbers?
Easiest to measure
What is one disadvantage of using pyramids of numbers?
Can be distorted by large organisms
What does a pyramid of biomass show?
The combined mass of all the organisms in a particular habitat
What is an advantage of using a pyramid of biomass?
More accurate and realistic model of trophic levels
What is a disadvantage of using pyramid of biomass?
Dry mass has to be used and this involves destroying the material
Why can’t we use wet mass to measure biomass?
Wet mass is inaccurate as it is affected by water uptake, drinking and defaecating
What does a pyramid of energy show?
Represents the total energy store of the organisms at each level
What is an advantage of using pyramids of energy?
It is the most accurate way to represent a food chain
What is a disadvantage of using pyramids of energy?
It is extremely difficult to measure and uses an outdated model of energy
How can we quantify how productive an ecosystem is?
By using Net primary productivity and Gross primary productivity
What does productivity of an ecosystem depend on?
How favourable abiotic and biotic factors are
What is Gross primary productivity (GPP)?
Total energy resulting from photosynthesis or rate at which light from the sun catalyses production of new plant material
What is the formula for Net primary productivity (NPP)?
GPP - R (respiration)
What does NPP take into account?
The energy lost during respiration
What is one limitation of efficiency calculations?
You have to measure: number of abundant species, amount of organisms and body mass
Making it difficult to measure
What is the definition of succession?
The change in an ecological community over time
What is a plagioclimax community?
A final community due to human intervention
What is a climatic climax community?
The only climax community possible in a given climax
When does secondary succession occur?
After succession has been disrupted eg, a fire or flood
What does succession result in?
-Increased species richness
-Increased biodiversity
-Food webs becoming more complex
What is a climax community?
The most productive, stable community of organisms the environment can support
What is the first species in primary succession?
Pioneer species
How is soil formed in primary succession?
-Pioneer species penetrates bare rock
-Humus is created
-Leading to the formation of soil
When is a quadrat used?
When measuring abundance of non-motile organisms
What are individual counts?
Measure of the number of organisms in the area being sampled
What is one limitation of using quadrants?
Limitations to how much area you can sample
What is the ACFOR scale used for?
To measure abundance by describing abundance by 5 key terms
What is one limitation of the ACFOR scale?
It is subjective and everyones definitions of the terms may be different
What is a permanent quadrat?
A quadrat left there all the time to collect data over a long time
What is a point quadrat?
Species that touch a pin put into the group are recorded to record percentage cover
How are transects better than quadrats?
They are not random so data is systematic
What is a line transect?
A tape is placed on the group and every organism that touches the line is recorded to measure abundance
What is a belt transect?
Two tapes are lined opposite and the organisms on the ground between the lines are recorded
When are transects used?
-Investigate link between distribution and abiotic factors
-Find correlations between abundance and abiotic factors
