Secondary Production Flashcards
Why are big fierce predatory animals rare
As you go up the trophic levels only 10% of energy is passed on, therefore there’s not a lot of energy for large predators at the top of the food chain
This limits their numbers because of this energy loss and because they cannot eat the base of the food web and there for limits their potential numbers
Define and contrast ingestion, assimilation, and production efficiency
- ingestion efficiency: calories ingested/cals available
- assimilation: cals assimilated/ cals ingested
- production: cals produced/ cals assimilated
From One step to the next the energy decreases because of this and other losses only 10% of energy can be passed along
Explain how iron has been demonstrated to be a limiting factor off the coast of Africa
The wind blows the iron rich dust into the ocean and the primary productivity increases in these areas
This shows how iron has a bottom up effect on marine systems
What yields a eltonian pyramid. Measuring energy or numbers of individuals at each tropic level
- measuring energy creates a proper pyramid shape opposed to numbers which can be all over the place
- And example is when comparing the shape of the pyramids for temperate forest and for grasslands using numbers of individuals yield different results but for energy they are similar
Why is the shape always a pyramid
Because energy is always lost as you go through the trophic levels so the bottom levels will always have the most energy and then as you go through the levels energy is always lost and therefore become smaller and smaller like a pyramid
Define and describe Lindeman Efficiency. What is its typical value in wild systems
The proportion of energy transferred from a lower trophic level to a higher one usually around 10%
How many trophic levels are in a typical ecosystem
Usually around four or five because there’s only enough energy for that money
What are three reasons that make it difficult to measure secondary production
- Animals don’t fit neatly into their trophic levels example fox may eat plants if need be
- What to do with the detritivores because they are very complex and important parts of secondary production
- Choosing adequate sampling and choosing appropriate scale for the complex diverse systems can’t sample an entire food web
Explain bottom up and top down pressures as discussed in lecture
Bottom up: Limited production from the lower primary producers affects all the organisms up the food chain. In marine systems with less nutrients there are less phytoplankton in there for less of all other species
Top down: is where terrestrial systems consumers are removing biomass at the same rate or faster than it can be produced. This causes issues all down the trophic levels
Define emergent property and cite an example
Any property or phenomenon in a state that is not the sum of its components. The response of the prairie grass to both nitrogen and water together was far greater than each of them some together individually
Life itself is an emergent property as are the defining properties of an ecosystem
Secondary production
Rate of accumulation of biomass by heterotrophs
Trophic levels
Solar radiation - primary producers - primary consumers - secondary consumers - tertiary consumers
How do graphs show evolution
Only the most efficient survive or else there would be much more variation in the lines
Reproductive rates based on mass
The larger the mass the less the rate of reproduction
-this is because it takes more energy and they spend less energy making but more energy caring for it
Production efficiency
Net productivity/ total assimilated
