Ecological Energetics Flashcards
What are producers
Producers are organisms that manufacture organic substances from inorganic substances using energy (from the sun)
-use light energy to produce compounds by photosynthesis
-Trophic level 1
What are chemoautotrophs
-use chemical energy to produce organic substances
-found in ecosystems where there is no light available
-have developed n energy source other that light
What are consumers
-organisms that obtain their energy by feeding on other organisms
-eg animals
What are primary Consumer
eg herbivores- feed on producers (plants)
-trophic level 2
What are Secondary Consumers
-eg carnivores (meat) or omnivores (meat and plants), feed on primary consumers
-trophic level 3
What are tertiary consumers
-feed on secondary consumers
-trophic level 4
What is the purpose of decomposers and detritivores
-involved in the decay and decomposition
-flow of energy through the detritus pathway is important
Decomposers- bacteria and fungi
Detritivores- earthworms, millipedes and woodlice
What is a food chain
-shows the link between a producer, primary consumer, secondary consumer and a possible tertiary consumer
-each stage is referred to as a trophic level (1-5)
-energy is lost at each stage- why the chain is short
What is a grazing food chain
-grazing food chains cycle energy from living plants
What are detritus food chains
-cycles energy from the non-living remains (detritus) of both plants and animals
What is a food web
-The pattern of interrelated food chains that operate in a ecosystem
What is an advantage of food webs
-a more realistic representation of the feeding relationships between organisms that food chains as most animals do not rely on a single food source
-In a Climax Community, food webs are very complex involving many different species
How do food chains display quantitative relationships between trophic levels
-food chains and food webs display the path of energy flow but they do not provide information on the number or biomass of each trophic level, ie the quantitative relationships
-the relative number, biomass or energy of the organisms involved can be represented by ecological pyramids
What is a pyramid of numbers
-Represents the total number of organisms at each trophic level in food chain or food web.
-The length of the bars is proportional to the number found at each level
-Typically there are more organisms at the producer level and successively less numbers of organisms at each consumer level- results in a pyramid shape
What is a disadvantage of the pyramid of numbers
-they are a simplified and inaccurate representation of the energy flow between trophic levels as they do not take into account the size of the organism- just the numbers
What is the pyramid of Biomass
-represent the biomass of the organisms at each trophic level
-can be measured as fresh mass or dry mass
-fresh mass is more variable but may still give an accurate representation
-Dry mass (drying the organism until constant mass is achieved)- more accurate but is time consuming and organisms are killed in the process
-Inverted pyramids of biomass are less likely
What are the advantages of Pyramid of numbers
-Data is easily acquired
-not time consuming
-organisms not harmed in process
What are the disadvantages of pyramid of numbers
-more representative and accurate representation of the energy flow
-inverted pyramids are less common
What are the advantages of pyramid of biomass
-simplified and inaccurate picture of the energy flow
-greater chance of an inverted pyramid
-do not take into account the size of the organism
What are the disadvantages of pyramid of biomass
-fresh mass can give variable results
-difficulty in obtaining the fresh mass- how to get fresh mass of an oak tree?
-dry mass is more accurate but time consuming
-organism is killed in the process
-can give false indication of energy available
