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176 Cards in this Set
- Front
- Back
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Define species richness
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Number of species in a community
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What are the two components of species diversity?
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Species Richness and Evenness
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Define evenness
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Abundance of species (# of individuals)
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What is the lognormal distribution a consequence of?
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Species within a community subdividing niche space
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If community A has
2 different species with one species more abundant then the other and Community B has 2 species both having the same abundance in the community Which community would be more diverse? Why? |
Community B, equal proportional abundance between the two species gives in greater species evenness.
Greater species evenness= greater species diversity |
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When analyzing an abundance curve, what would be the result of a lower slope?
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A lower slope means that the species has greater evenness
or higher species richness and diversity |
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What is a
Rank Abundance Curve? |
Relative abundance of species
vs Their rank in abundance |
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When comparing species diversity and complexity, what trend is observed?
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Positive trend
Diversity increases with environmental complexity or heterogeneity |
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Phytoplankton reside in simple environments but compete for the same nutrients
Even still, many species compete without competitive exclusion What is the explanation for this phenomenon? |
Environmental complexity may account for a significant portion of the diversity
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Algal niches appear to be defined by their ____________ __________
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nutrient requirements
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Tilman found coexistence of freshwater diatoms depended upon ratio of __________ and _______.
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silicate and phosphate
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Tilman found coexistence of freshwater diatoms depended upon ratio of silicate and phosphate.
This allowed for coexistence. Why? |
Diatoms held different trophic niches
Different diatoms would dominate different areas |
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Describe the two ways that tropical forests are organized
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Large # of species in most tropical forest communities
Large # of plant communities in a given area, each with a distinctive species composition |
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These two characteristics:
Large # of species in most tropical forest communities Large # of plant communities in a given area, each with a distinctive species composition Are typical of what community? |
Tropical Forest
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Tropical forests are organized in two ways:
They have a large number of _________ in most tropical forest communities and a large number of _________ communities in a given area, each with a distinctive __________ composition |
Species; plant; species
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What occurs as a result of changes in soil type depth to ground water?
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Differences in vegetation over short distances
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What happens to plants and algal species diversity when nutrients become more available?
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As nutrients become more available a negative relationship is observed and there is less species diversity
Adding nutrients to water or soil generally reduces diversity of plants and algae |
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What is the explanation for the negative relationship observed between nutrient availability and and algal and plant species
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Reduces the number of limiting nutrients
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Discrete, punctuated, killing, displacement or damaging of one or more individuals that directly or indirectly creates an opportunity for new individuals to be established
This defines |
Disturbance
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Any relatively discrete event in time that disrupts ecosystem, community or population structure and changes resources, substrate availability or physical environment
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Disturbance
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Two major characteristics of disturbance
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Frequency and Intensity
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High and low levels of disturbance _________ disturbance
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Reduce
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What would one expect if sufficient time between disturbances was observed?
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Sufficient time between disturbances allows wide variety of species to colonize, but not long enough to allow competitive exclusion
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Disturbance Vs Diversity in the intertidal zone
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Disturbance depends on boulder size
Large boulders = more force required to move |
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Boulder supporting the greatest diversity of species were those subject to which level of disturbance
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intermediate level of disturbance
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Paine suggested that what had the dominant influence on community?
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That feeding activities of a few species may have a dominant influence on community structure
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Pain suggested that feeding activities of a few species may have a dominant influence on community structure
What did he suggest was the criteria for strong interaction? |
Criteria for strong interaction is the degree of influence on community structure
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Tscharntke studied
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food webs associated with wetland reeds (Phragmites australis).
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What type of species reduce the likelihood of competitive exclusion?
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Keystone species
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If keystone species reduce likelihood of competitive exclusion, their activities would increase the number of species that could ___________ _____ ____________.
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coexist in communities
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Paine found as number of species in intertidal food webs increased,
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proportion of the web represented by predators also increased.
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Paine found as number of species in intertidal food webs increased, proportion of the web represented by predators also increased.
According to his hypothesis, higher proportion of predators produces |
higher predation pressure on prey populations, in turn promoting higher diversity.
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If starfish were a keystone species and were removed from the environment, what would happen to species diversity?
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Species diversity would decline
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Lubchenko studied
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influence of intertidal snail (Littorina littorea) on structure of an algal community.
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Snails fed on green (Enteromorpha spp.) and red (Chondrus crispus) algae.
Under normal conditions, Enteromorpha out-competes Chondrus in tide pools, and Littornia prefers Enteromorpha. In the absence of snails, what would happen between the two species of algae |
Chondrus is
competitively displaced. |
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At low snail density, what would happen between Enteromorpha and Chondrus?
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Enteromorpha dominates tide pool.
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At medium snail density what would happen between Enteromorpha and Chondrus?
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Competitive exclusion eliminated, and algal diversity increased.
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As high snail density what would happen between Enteromorpha and Chondrus?
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Feeding requirements are high enough that snails eat preferred algae and less-preferred algae.
Algal diversity decreased. |
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Power investigated whether
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California roach Hsperoleucas symmetricus and steelhead trout Oncorhhyncus mykiss significantly influence food web structure.
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Keystone species effect on community vs biomass
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Keystone species exert strong effects on their community structure, despite low biomass.
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Define dominant species
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Have influence on community structures by virtue of high biomass
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Why do exotic species have dramatic impact on their community
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Exotic species have dramatic impacts on communities because they were outside the evolutionary experience of local prey populations.
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Christian observed
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native ants disperse 30% of shrubland seeds in fynbos of South Africa.
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Primary production
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Fixation of energy by autotrophs in an ecosystem.
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Rate of primary production
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Amount of energy fixed over a given period of time
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Gross primary production
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Total amount of energy fixed by autotrophs
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Net primary production
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Amount of energy left over after autotrophs have met their metabolic needs
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Trophic Level
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Position in a food web determined by number of energy transfers from primary producers to current level
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Primary producers
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occupy first level
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Primary consumers
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occupy second level
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Secondary consumers
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occupy third level
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Tertiary consumers
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occupy fourth level
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This guy estimated influence of moisture and temperature on rates of primary production by plotting relationship between annual net primary production and annual actual evapotranspiration (AET).
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Rosenzweig
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Annual Evapotranspiration
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Annual amount of water that evaporates and transpires off a landscape
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Low Annual Evapotranspiration (AET) is commonly seen where?
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Cold dry ecosystems
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A __________ relationship is observed between net primary production and AET
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positive
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Sala found that east-west variation in primary production correlated with
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rainfall
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What happens to terrestrial primary production as AET is increased?
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Terrestrial primary production will increase
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AET increases with increased _____________ and __________
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precipitation and temperature
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Shaver and Chapin found arctic net primary production was twice as high on ________ plots as ________ plots
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fertilized; unfertilized
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Who found that arctic net primary production was twice as high on fertilized plots rather as unfertilized plots
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Shaver and Chapin
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Bowman suggested that ____ is the main nutrient limiting NPP in a dry tundra and
___ and ____ jointly limit production in a wet meadow |
N
and N and P |
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Who suggested that N is the main nutrient limiting NPP in a dry tundra and N and P jointly limit production in a wet meadow?
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Bowman
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__________ availability control the rate of primary production in freshwater ecosystems
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Nutrient
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What would increase primary production in both wet and dry meadows?
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Adding nutrients
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The highest rates of primary production by marine phytoplankton are generally concentrated with higher levels of nutrient availability
What are the two reasons that higher rates are found along continental margins? |
Nutrient run-off from land
Sediment disturbance |
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Open ocean tends to be nutrient poor, why?
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Because vertical mixing is the main nutrient source
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Who gathered results suggesting rate of primary production is nutrient limited?
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Graneli
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Graneli found that increased nutrients lead to increased __________ concentrations
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chlorophyll
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Increased nutrients led to increased chlorophyll concentrations.
What appears to be limiting nutrient |
N
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Define Residual Variation
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Proportion of variation not explained by the independent variable
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Who suggested environmental factors besides nutrient availability significantly influence phytoplankton biomass
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Dillon and Rigler
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Influences of physical and chemical factors of an ecosystem
This statement defines: |
Bottom-up controls
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What controls influence consumers
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Top-down
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Carpenter proposed __________ and __________ fish can cause significant deviations in primary productivity.
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piscivores and planktivorous
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Carpenter and Kitchell proposed the influence of consumers on lake primary productivity propagate through _______ ______.
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food webs
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Carpenter and Kitchell proposed the influence of consumers on lake primary productivity propagate through food webs
This is also known as the |
Trophic Cascade Hypothesis
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Primary Production on the Serengeti
Rate of primary production in the Serengeti is |
positively correlated with rainfall quantity
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Grazer have what effect on primary production
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increase primary production
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Who found compensatory growth highest at intermediate grazing intensities.
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McNaughton
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Where is compensatory growth highest when looking at grazing intensities?
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Intermediate
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Heavy grazing reduces plant’s capacity to
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recover
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Light grazing insufficient to produce
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compensatory growth
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As energy is transferred from one trophic level to another, what happens?
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energy is degraded
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concluded the ecosystem concept is fundamental to the study of energy transfer within an ecosystem.
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Lindeman
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As energy is transferred from one trophic level to another, energy is degraded
What three factors are responsible for this phenomenon |
Limited assimilation
Consumer respiration Heat production – Energy quality decreases with each successive trophic level. » Pyramid-shaped energy distribution. |
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Who studied energy flow in a temperate deciduous forest
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Gosz
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When studying the energy flow in a temperate deciduous forest
What percent is reflected? |
15
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When studying the energy flow in a temperate deciduous forest
What percent is converted to heat? |
41
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When studying the energy flow in a temperate deciduous forest
What percent is absorbed during evapotranspiration? |
42
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When studying the energy flow in a temperate deciduous forest
What percent is fixed by plants as gross PP? |
2.2
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When studying the energy flow in a temperate deciduous forest
What percent is used in plant respiration? |
1.2
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When studying the energy flow in a temperate deciduous forest
What percent is left for PP? |
1
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What % of solar energy unavailable for use by second trophic level
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99
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As energy losses between trophic levels accumulate, eventually there is insufficient energy
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left to support a viable population at a higher trophic level
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Most of the energy traveling thrugh a temperate deciduous forest is either
or |
Lost as heat
or absorbed through evapotranspiration |
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NPP is only about ____% of total input of solar energy
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1
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Nearly 90% of energy input to a stream is released during _______
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respiration
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Where are quantities of phosphorous most likely found?
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Deposits
Marine sediments |
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What takes place that releases phosphorous into the environment?
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weathering of rocks
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What can return phosphorous to terrestrial ecosystems?
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Uplift of marine sedimentary rocks
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How much of phosphorous is dissolved in in oceans then in organisms?
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Amount of phosphorous dissolved in oceans is 1000x the amount in organisms
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Where is the largest amount of P found?
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Marine sediments
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Atmospheric supply of N2 can be used by
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Nitrogen fixers only
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The process of fixing nitrogen demands a lot of energy, what occurs?
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N2 is reduced to ammonia
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Nitrogen is only available to organisms after this process
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Nitrogen fixation
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Upon death of an organism, nitrogen is released during decomposition by what two things?
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Bacteria and fungi
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Annual nitrogen fixation by ________ is about 1/7 of biological fixation
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lightning
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Amount of nitrogen cycling in which ecosystem is about 10x that of annual fixation?
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Terrestrial ecosystems
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What is the largest actively cycles pool of nitrogen?
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Ocean
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Carbon moves between organisms and the atmosphere as a consequence of _________ and _________
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photosynthesis and respiration
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In aquatic ecosystems, CO2 must first be
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dissolved into water before it can be used by primary producers
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Carbon coming from what process is approximately 40% of fossil fuel burning?
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destruction of vegetation
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What amount of carbon is contained in soils vs the atmosphere?
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twice as much carbon
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What contains the largest pool of carbon on the planet?
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Carbonate rocks
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This contains carbon fixed by primary producers millions of years ago
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Fossil fuels
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The rate at which nutrients are made available to primary producers is determined largely by what process?
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Mineralization
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Mineralization occurs primarily through
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decomposition
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The rate of decomposition in terrestrial systems is determined by which three things?
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Temperature
Moisture Chemical compositions |
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founddifferencesinmass loss by the target species reflected differences in the physical and chemical characteristics of their leaves.
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Gallardo and Merino
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Gallardo and Merino found differences in mass loss by the target species reflected differences in the
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differences in the physical and chemical characteristics of their leaves
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Soft leaves with higher nitrogen content
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lost more mass
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Tough leaves with lower nitrogen content
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lost less mass
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used litter bags to study decomposition in temperate forests.
Found leaves with higher lignin:nitrogen ratios lost less mass. |
Melillo et. al.
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Leaves with higher ___:____ ratios lost less mass
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lignin:nitrogen
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found leaves with a higher lignin content decomposed at a slower rate.
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Gessner and Chauvet
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Gessner and Chauvet found that leaves with higher lignin content decompose at a
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slower rate
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leaves with a higher lignin content decomposed at a slower rate.
Why? |
Higher lignin inhibits fungi colonization of leaves.
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found leaves degraded faster in streams with higher nitrate concentrations.
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Suberkropp and Chauvet
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Leaves degraded faster in streams with higher _______ concentrations
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Nitrate
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While leaves with higher ______ content decompose at a slower rate
Leaves with higher ________ content decompose at a faster rate |
Lignin; Nitrate
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Who pointed out nutrients in streams are subject to downstream transport.
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Webster
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Nutrient Spiraling
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Little nutrient cycling in one place
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Define
Spiral length |
the length of a stream required for a nutrient atom to complete a cycle
Related to rate of nutrient cycling and velocity of downstream nutrient movement |
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Spiral length is the length of a stream required for a nutrient atom to complete a cycle.
It is related to rate of |
nutrient cycling and velocity of downstream nutrient movement
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What slows transport of nutrients by streams?
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Nutrient uptake by the benthic ecosystem
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Nutrient release from the benthos transport by water and downstream uptake by the benthos produce what
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nutrient spiraling
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Spiraling Length: S =
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VT
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S = Spiraling Length
V = T = |
Average velocity of a nutrient atom.
Average time to complete a cycle. |
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showed aquatic invertebrates significantly increase rate of N cycling.
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Grimm
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Grimm showed aquatic invertebrates significantly increased rate of
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N cycling
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Grimm showed aquatic invertebrates significantly increase rate of N cycling.
Suggested rapid recycling of N by _____________ may increase primary production. Excreted and recycled 15-70% of nitrogen pool as ammonia. |
macroinvertebrates
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found pocket gophers altered N cycle by bringing N-poor subsoil to the surface.
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Huntley and Inouye
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Huntley and Inouye found pocket gophers altered N cycle
How |
By bringing N-poor subsoil to the surface
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found a positive relationship between grazing intensity and rate of turnover in plant biomass in Serengeti Plain.
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MacNaughton
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MacNaughton found a ________ relationship between grazing intensity and rate of turnover in plant biomass in Serengeti Plain.
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positive
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Without grazing, nutrient cycling occurs more slowly through _________ and __________
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decomposition and feeding of small herbivores
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Plot A
20 species Each species contains 5-7 individuals Plot B 5 species One species has 80 individuals Other 4 have only 1 individuals Concerning species richness, which plot is higher? Concerning species diversity, which plot is higher? |
Plot A
Plot A |
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As environmental complexity increases, species diversity usually
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increases
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Prestons concept of distribution of commonness and rarity states that there are relatively few species that occur at ____ densities or levels of abundance
low moderate high low or high |
low or high
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What does "lognormal distribution" mean?
The graph will normally show a logistic pattern as density increases the graph will show a normal distribution when the horizontal axis is plotted on a log scale |
The graph will show a normal distribution when the horizontal axis is plotted on a log scale
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You place two similar species of microbes in a petri dish and find that after 24 hours, there is only one species remaining
This is an example of bottom-up control the trophic dynamic concept the trophic cascade hypothesis the competitive exclusion principle |
the competitive exclusion principle
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What effect does disturbance have on the plant species diversity of a community?
Diversity is highest at low levels of disturbance Highest at intermediate levels of disturbance Highest at high levels of disturbance Usually not effected by disturbance |
Diversity is highest at intermediate levels of disturbance
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Species that make up a large proportion of the biomass in a community are
dominant species competitive species keystone species exotic species all of the above |
dominant species
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Species that have a disproportionately large influence (for their biomass) on the structure of a community are
dominant species competitive species keystone species exotic species all of the above |
keystone species
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Tidal pool communities in which a relatively high proportion of the animal species are predators (rather than primary consumers) tend to have:
low animal species richness and diversity high animal species richness and diversity |
high animal species richness and diversity
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A herbivore species has been found to exert a strong influence on the makeup of its plant community. The herbivore prefers to eat a plant species that is competitively superior to the other plant species
As the density and grazing intensity of the herbivore increases from low to high, the species richness of plants would most likely decline as herbivore density increased increase as herbivore density increased increase as herbivore density reached moderate levels, and then decrease at higher herbivore density |
A herbivore species has been found to exert a strong influence on the makeup of its plant community. The herbivore prefers to eat a plant species that is competitively superior to the other plant species
As the density and grazing intensity of the herbivore increases from low to high, the species richness of plants would most likely decline as herbivore density increased increase as herbivore density increased increase as herbivore density reached moderate levels, and then decrease at higher herbivore density |
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Mary Power studied the influence of the predatory fish steelhead trout in a California river. She found that at high densities of steelhead trout, algal biomass and primary production were relatively
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low
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Primary production can be assed by measuring the
carbon uptake of photoautotrophs biomass produced by photoautotrophs oxygen produced by photoautotrophs energy fixed by photoautotrophs all of the above |
all of the above
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You measure all of the water vapor lost by your lawn and express it in units of water vapor lost per area of your lawn per time. This is an example of
net primary production gross primary production actual evapotranspiration potential evapotranspiration |
AET
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You dry the clippings of grass over a year and weigh them. This is an example of
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Net primary production
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An infrared gas analyzer (IRGA) can be used to measure net primary production by measuring:
oxygen produced by plants biomass produced by plants carbon dioxide uptake by plants energy fixed by plants |
Carbon dioxide uptake by plants
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If you placed the IRGA chamber over your lawn during the nighttime and made a measurement, it would be an estimate of
net primary production gross primary production potential evapotranspiration respiration |
respiraton
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A red-tailed hawk which feed primarily on herbivorous rodents would be an example of a
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secondary consumer
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Net primary productivity (examined across a diverse set of biomes) is positively correlated with:
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Annual actual evapotranspiration
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Sala et al found that primary NPP was positively correlated with annual precipitation. However, an example where this is not the case would be in such a biome would be
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tundra
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Above average precipitation for 2 years is responsible for an increase in the NPP of a ponderosa pine forest. This would be an example of a ______ of NPP
top down control bottom up control |
bottom up control
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A wolf population in this ponderosa pine increases for several years and this results in a decline in populations of several herbivore species. This in turn leads to an increase in the NPP of this forest. This would be an example of a _______ of NPP
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top down control
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You find that the energy contained in all the primary producers in Lake A is ten times greater than the energy contained in all the primary producers in Lake B. Which would likely be true?
NPP would be greater in Lake A There would be more trophic levels in Lake A ET would be greater from Lake A All of the above A and B |
A and B
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In a natural, undisturbed hectare of grassland or prairie, C (carbon) goes from the terrestrial pool to the atmospheric pool through:
photosynthesis respiration |
respiration
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In a natural, undisturbed hectare of grassland or prairie, C (carbon) goes from the terrestrial pool to the atmospheric pool through:
photosynthesis respiration |
photosynthesis
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When comparing two seasons, one in early july and one in late june, when it has not rained and the soils are unusually dry and most of the vegetation in the forest is experiencing water limitations. How would the percentages of energy going into heating objects and ET differ in late July from the values you found in early June?
Heating objects would be higher (in late July) ET would be higher ET would be lower A and B A and C |
A and C
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Which global pool of C has increased dramatically in size over the past 100 years?
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atmospheric
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This nutrient or elemental cycle has the smallest atmospheric pool
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P
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Nitrogen (N) in the biotic pool can be lost from an ecosystem to the atmospheric pool through:
a) N fixation b) denitrification c) ammonification |
denitrification
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Which factor or variable is positively correlated with terrestrial NPP across different ecosystems?
a) actual ET b) potential ET c) grazing intensity d) a and c |
Actual ET
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