BIOL 230 - FINAL Flashcards
What constrains net primary production?
Physical and biotic factors
Ecosystem definition
Refers to all the components of an ecological system, biotic and abiotic, that influence the flow of energy and elements.
Primary production
Chemical energy generated by autotrophs during photosynthesis and chemosynthesis.
Source of energy for all organisms.
How is energy assimilated by autotrophs stored? How is it measured?
Carbon compounds in plant tissues.
Amount of carbon produced.
What accounts for the largest movement of CO2 between earth and atmosphere?
Primary production
What is gross primary production and what is it controlled by?
Total amount of carbon fixed b y autotrophs and is controlled by climate due its influence on photosynthetic rate and leaf area per unit of ground area.
Why does the respiratory costs of adding leaves eventually start to outweigh the photosynthetic benefits?
Due to shading, each added layer of leaves decreases the amount of photosynthesis that occurs?
Which type of plant would have high respiratory carbon losses? Why?
Trees, plants with a lot of non-photosynthetic tissues have higher losses.
What increases respiration rate?
Higher temperatures so tropical forests have higher respiratory losses.
How much carbon that is fixed is used for cellular respiration?
~50%
What is NPP and what is it equal to?
The amount of energy captured by autotrophs that results in an increase in biomass.
NPP = GPP - Respiration
What conditions lead to a plant allocating more NPP to its roots?
Places where soil nutrients and water are scarce
E.g. Grasslands, deserts, tundras
Where on earth is their the highest NPP?
The equator
0 degrees
How come at a certain point NPP no longer increases with more precipitation?
At a certain point, heavy cloud cover reduces the amount of light. Nutrients can also be leeched from soils.
Secondary production
The energy that is derived from the consumption of organic compounds produced by other organisms.
Net secondary production equals?
Ingestion - respiration - egestion(pooping)
Allochthonous inputs
Detritus derived from terrestrial organic matter
Why is the biomass pyramid of aquatic ecosystems inverted?
The primary produces are phytoplankton with short life spans and high turnover.
What factors affect energy flow?
NPP at the base of the food web
Proportion of each trophic level consumed by the one above it
Nutritional content of autotrophs, detritus and prey
Efficiency of energy transfers
Which herbivores consume a lower proportion of autotroph biomass?
Herbivores (13%)
Aquatic (35%)
Trophic efficiency and it’s three components:
Amount of energy at one trophic level divided by amount of energy at the next lowest trophic level.
Consumption efficiency, assimilation efficiency, and product efficiency
Consumption efficiency:
The proportion of available biomass that is ingested by consumers
Assimilation efficiency
The proportion of ingested biomass that consumers assimilate by digestion
Production efficiency
The proportion of assimilated biomass used to produce the new consumer biomass.
Bioaccumulation
Chemicals that aren’t metabolized or excreted, become more concentrated over an organism’s lifetime.
Biomagnification
Concentration increases in animals at higher trophic levels, as they consume prey with higher concentrations.
Where are nutrients ultimately derived from?
Abiotic sources.
Elements are released from rock minerals by weathering.
Which have Lower C:N ratios, animals or plants?
Animals
Nutrient cycling
Movement of nutrients in ecosystems as they undergo biological, physical and chemical transformations.
Mineralization
The process of transforming organic material into ammonium and nitrate.
Where is the largest pool of nitrogen in an alpine example?
Detritus
Cross -system subsidies
Transforme of materials across ecosystem boundaries.
E.g. salmon being eaten by bears.
Eutrophication
Too many nutrients
Ecosystem function
The physical, chemical and biological processes that transform and translocate energy or materials in an ecosystem.
OR
The capacity of natural processes and components to provide goods and services that satisfy human needs, either directly or indirectly.
Ecosystem services
Benefits that people obtain from ecosystems,s
Functional redundancy
The degree to which the loss of a species affects the overall structure and function of an ecosystem.
What are the four stages of species invasion?
Arrival (Introduction)
Establishment
Ecological integration with negative impact
Spread
Invasive vs introduced species
Invasive species are introduced species whose introduction negatively impacts the environment.
Introduced species are species that have been introduced into areas beyond their native range.
Propagule pressure
The number of individuals arriving per unit of time.
Effect of invasive species on small vs large areas?
Why?
The effect of invasive species in large areas is only weakly negative. At large spatial scaled vulnerable species are more likely to have a refuge somewhere.
The effect of invasive species in small areas is strongly negative.
For a species to respond positively in terms of species richness but negatively in terms of Shannon diversity, what must be true?
The species evenness decreased after invasion.
