Exam Four: Learning Objectives Flashcards
What is a tropic cascade?
An effect of a predator that extends beyond one link in a food web
Why would a shallow marine ecosystem become a kelp forest or an urchin barren?
Kelp are eaten by urchin, which are eaten by otters
Fish are eaten by seals which are eaten by orcas
If commercial fisheries take out fish, seals die off, orcas are forced to eat otters, which increased sea urchin, decreasing kelp forest
Why is apparent competition considered an indirect interaction?
Consider two species on the same trophic level, when species A is present, population density of species B declines because species A attracts predators and they consume both A and B
When would two species exhibit apparent competition?
they should share predators/ consumers
mustard and bunchgrass
T/F: There is a difference between apparent competition and competition for resources
True
Identify two species with the potential to exhibit resource competition?
they should share a resource
How do fish enclosure and exclosure experiments in streams demonstrate trophic cascades?
Largemouth bass indirectly benefited zooplankton and indirectly reduced algae density due to their direct interaction (consumption) of minnows
Define feeding guild
A group of species exploiting a common resource base in a similar fashion
What is an example of a feeding guild
Filter feeders, insectivores
Define a keystone species
low abundance, but big impact because they play a special role
Define a foundation species
define the ecosystem; abundant, provide structure, habitat, and mutualistic support to most other species; regulate flows of energy, nutrients, water (mangrove trees in a mangrove forest, coral in a coral reef)
Identify ecological impacts of starfish, as keystone predators
predatory sea stars were removed, which resulted in the loss of species and a decline in species richness
Identify the ecological impacts of cleaner wrasses and some native ant species, as keystone mutualists
removal of cleaner wrasse resulted in a decline in fish species richness, addition of cleaner wrasse to coral reefs increased fish species richness; exclusion of seed dispersing ants decreases recruitment of large-seeded plants
Why will predation increase in diversity in a community if the main prey species are strong competitiors?
Snails were added to this tide pool and the tasty algae population declined, snails were removed and the tasty algae increased while the crusty algae population declined
Define a trophic level
each feeding level in a food chain
Define a food web
shows feeding relationships in a community; can be used to document main energy flows or aggregate species into groups
T/F: Snail density increases will increase algae species richness
True - up to a point, at very high densities, herbivory is so intense algae diversity declines
How does energy flow food webs?
Sunlight to primary producers to herbivores and detritus
deritius goes to detrivores and eat dead predators/ carnivores
herbivores go to predators/ carnivores
Heat is lost in each step
Define a primary producer
photosynthesizers (plants, algea); chemoautotrophs and their detritus
Define an autotroph
aka primary producers
synthesize organic molecules from inorganic carbon (CO2)
Define primary production
production of new organic matter, or biomass, by autotrophs
Define a heterotroph
aka consumers, secondary producers
consume organic matter synthesized by other organisms
Photosynthesis transforms __ energy into sugars (__ __) that provide energy to the rest of the food web. Autotrophic chemosynthesis transforms __ energy of reduced mineral compounds into organic __
solar; organic matter
potential; energy
What is the equation for respiration?
6O2 + C6H12O6 –(ATP)-> 6CO2 + 6H2O
Breakdown (__) of sugar molecules drives production of usable cellular __ (__), releasing __ in the process. Both _- and __ perform respiration
catabolism; energy; ATP; CO2
photoautotrophs, heterotrophs
Define respiration
converts energy stored in sugar into ATP; reverse of primary production
Write the equation for primary production, balancing both __ and __
matter; energy
6CO2 + 6 H2O –(solar energy)–> C6H12O6 + 6O2
Define GPP
gross primary production
all the carbon fixed by autotrophs (primary producers) in an ecosystem; all of the photosynthesis (and chemoautotrophy) occuring in an ecosystem
Define NPP
Net primary production
organic carbon remaining after autotrophs meet their own energy needs (after accounting for primary-producer respiration, Rp); energy and biomass available for plants to add biomass and to supply food and energy for the rest of the food web
GPP - Rp = NPP
If an ecosystem is adding biomass, GPP _ Re, so NEP is __
> ,positive
Define Rp, Rh, and Re
Rp - respiration done by plants
Rh - respiration by all heterotrophs
Re - respiration of everyone (Re = Rh + Rp)
Define NEP
Net ecosystem production
organic matter left after all organisms have met energy needs
NPP - Rh = NEP
What percentage of GPP is allocated to Rp, and what percentage is left over for NPP?
Rp consumes about half of the GPP generated by plants
NPP is approx. half of GPP
GPP is partitioned into __ and __?
Rp and NPP
Describe evidence showing the influence of climate on primary production
productivity is greater in wetter and warmer biomes
grassland productivity is influenced by precipitation, more precip = more NPP
Describe evidence of the influence of plant growth form (leaf area) on primary production
Productivity is greater where there is more leaf area
Define the term limiting nutrient
nutrient that is least available relative to demand; nutrient is in limited supply
Describe research evidence you would use to identify which nutrient is limiting
addition of a limiting nutrient increases productivity
Identify the nutrient that typically limits primary production in various types of in various types of aquatic ecosystems
lakes - phosphorus
streams, rivers, estuaries, and oceans - Nitrogen
Sketch a 2x2 factorial design in which N and P fertilizers are experimentally added to ecosystems
Ambient N - Ambient P and +P
+N - Ambient P and +P
Describe the effect of moderate grazing on plant productivity, and explain why this effect happens in reference to compensatory growth
Compensatory growth: greater primary production at moderate grazing
moderate grazing results in lower plant respiration, lower water loss, and less shading, thereby promoting a faster rate of leaf growth
Provide evidence which demonstrates that species richness of the primary producers (plants, algae) influences primary production, and explain why this effect occurs
trophic cascades, high zooplankton density results in low algae growth (and vice versa)
Define ecologyical efficiency
the percent of energy in biomass at one trophic level that is transferred to biomass at the next level
Why is ecological efficiency only about 5-20%?
limited consumption, poor assimilation, respiration and heat
Define secondary production
production of biomass by heterotrophic consumer organisms
Describe evidence from research demonstrating bottom-up control of secondary production
If precipitation influences primary production, and if primary production regulates secondary production, does precipitation influence secondary productions???
YES - secondary production in savannah ecosystems is higher where there is more precipitation; precipitation fosters more primary production, which enriches secondary production
Explain how the roles of the atmosphere and sedimentary rock are different in the global cycle of phosphorus than in the global cycles of nitrogen and carbon
Identify the biggest human impacts on the global cycles of phosphorus, nitrogen, and carbon
Identify the roles of nitrogen fixation and denitrification in the exchange of nitrogen to and from the atmosphere
Describe the role oceans play in the global carbon cycle
Identify the sources of nutrient input to ecosystems, and the mechanisms for nutrient export from ecosystems
Create a graphic ‘box-and-arrow’ model of an ecosystems nutrient budget, showing ecosystem boundaries, reservoirs or pools within the ecosystem, fluxes in and out of the ecosystem, and fluxes among reservoirs within the ecosystem
Create a box and arrow model depicting an ecosystem with positive nutrient retention and one that shows net nutrient loss by the ecosystem
input and output fluxes should be different sizes
How are decomposition and mineralization related and separate?
__ is a process that occurs during __
mineralization; decomposition
Define organic nitrogen and organic phosphorus
Identify inorganic (__) chemical compounds that carbon, nitrogen, and phosphorus are transformed into when they are mineralized
mineral
!!
Describe how rates of decomposition are affected by temperature, soil moisture, litter tissue properties, and nutrient supply
Explain how the invasion of certain areas in Hawaii by Myrica faya has altered nitrogen cycling in those locations
Explain how grazing of vegetation can accelerate nutrient cycling
Describe how pocket gophers influence the spatial heterogeneity of soil nitrogen and light across a grassland landscape
Explain the concept of nutrient spiraling, and identify the type of ecosystem in which nutrient spiraling is a particualry useful concept
Define spiraling length
What factors result in longer nutrient spiraling lengths
Identify how nitrogen storage in organism tissues, and rapid cycling of nitrogen among organisms and detritus, help to shorten spiraling lengths and improve nitrogen retention in streams
Explain how nitrogen isotopes were used to discover the role of salmon migration in transporting marine-derived nitrogen to inland streams and riparian forests
Describe the typical effect of disturbance on an ecosystem;s nutrient budget. Support your description with evidence about nitrogen export from forested watersheds and phosphorus export from stream sediments
Provide evidence from watershed studies demonstrating that human activities tend to accelerate nutrient cycling
