Final Flashcards
What is absolute abundance?
the number of individuals of a given species
What is relative abundance?
the proportion of all individuals
What does evenness mean?
how similar abundances
are among the species of the
community
What is a diversity index?
a single number that
summarizes the species richness (S)
and the variation in species’ relative abundances of a community
What is the Simpson’s diversity index?
Measures the “effective” number of species, Denominator is the probability that two individuals drawn randomly from the population will be of the same species
What is the Simpson’s diversity index equation?
Simpson index = 1/ Σ(Pi)^2
(the sum of the squared proportions of individuals belonging to each species).
What is the Shannon(-Wiener) diversity index?
Imagines sampling an individual at random from the community, measuring how hard it is to predict which species that individual will belong to
What is the Shannon(-Wiener) diversity index equation?
Shannon index = -Σ(Pi)(ln(Pi))
How does nutrients effect species richness?
-More nutrient additions (= high productivity) reduced richness (park grass experiment)
What is a keystone species?
a species that strongly and disproportionately affects the structure of communities compared to its abundance
what is a trophic level?
a level in a set of feeding relationships measured as the number of energy-transfer steps to reach that level
What characteristics effect species diversity?
Resources, habitat diversity, keystone species, disturbance, area
What is a guild?
a group of species that feed on similar resources within a trophic level
What is a Density-mediated indirect effect?
Changes in the abundance (or density) of one species can ripple through a food web, changing the abundances of other species
(Ex: Fish eating the eggs of dragonflies that feed on pollinators, Less fish means more dragonflies and therefore less pollinators)
What is a trait-mediated indirect effect?
Changes in the traits or behaviors of one species can ripple through a food web, changing the abundances of other species
(Ex: Predators can reduce herbivory without needing to eat the herbivore)
What is a seral stage (sere)?
the stages communities go through in the process of succession
What is an example of primary succession?
The natural
revegetation of Krakatau (Island with a very strong volcano)
What is primary succession?
the development of communities on habitats without any existing plant life or organic soil
What is secondary succession?
the development of communities on habitats without any existing plant life, but where there is still organic soil
(Think development after fire, storms, or plowing fields)
How does succession impact species richness?
Species richness increases as species change the environment and enable even more species to establish
What is Facilitation?
The presence of one species aids the establishment of another
What is inhibition?
the presence of one species hinders the establishment of another
What is Tolerance?
the probability of a species establishing depends on its ability to persist under the physical conditions of the environment
What mechanisms underlie the timing of species establishment & replacement during succession
Facilitation, Inhibition, and Tolerance
What is resistance in context of community stability?
the ability of a community to remain unchanged after a disturbance
What is resilience in context of community stability?
the ability of a community to return to its previous state after a disturbance
What is a legacy effect?
A long-lasting influence of a
historical process on the current ecology of an area
(Ex: the connection of north and south America lead to biotic exchanges over land but stop marine species from crossing over the continents)
What is habitat fragmentation?
the process of breaking contiguous patches of habitat into smaller, disconnected pieces
What is a fragment?
a patch of the previous
habitat
What is a matrix?
the area in between fragments (often not suitable habitat for species found in fragments)
What is alpha diversity?
Local diversity, the number of species found in a specific, relatively homogenous location
What is beta diversity?
species turnover between locations
What is gamma diversity?
regional diversity, which can be at broad scales encompassing several adjacent communities to whole biomes and continents
What is instrumental value?
The economic value that a species or ecosystem can provide
What is Intangible & intrinsic value?
the value that a species or ecosystem can provide outside of economic exchange
What is mass extinction?
a rapid, world-wide event causing >70% of species to go extinct within 2 million years
What is the current extinction rate?
- 100-1,000× higher than historic average
- 10-100× higher than during any of the previous mass extinction events
What human activities are causing the loss of biodiversity
Habitat destruction, overharvesting, Introduced species, pollution, global climate change
What conservation efforts are happening in the world?
Habitat protection, reducing harvesting, preventing species invasions, climate change policy
What is a pool in context of the nutrient cycle?
a stock of the nutrient contained in biological or abiotic material
What is flux in context of the nutrient cycle?
a movement between pools; happen at a rate (amount / year)
What is residence time in context of the nutrient cycle?
how long a typical nutrient spends in a pool
What is Assimilation?
Transfer of nutrients from a non-biological pool into a biological pool (e.g., photosynthesis capturing atmospheric carbon)
What is Dissimilation?
Transfer of nutrient from a biological pool into a non-biological pool (e.g., respiration releasing carbon from
organism into atmosphere)
What is the largest pool of carbon?
The earths crust mainly in limestone and dolomite
What is primary production?
The rate at which solar or chemical energy is captured & converted into chemical bonds
What is Gross Primary Productivity (GPP)?
The rate at which energy is captured and assimilated by producers in a given area
What is Net Primary Productivity (NPP)?
The rate at which energy is assimilated by producers and converted into producer biomass in a given area
What is Terrestrial NPP limited by?
Temperature and Precipitation limit their NPP
What is Aquatic NPP limited by?
Nutrients (nitrogen and Phosphorus) & light scarcity
What is consumption efficiency?
Thee percentage of energy at a lower trophic level that is consumed by the next higher level
What is Assimilation efficiency?
The percentage of consumed energy that is taken up by the
consumer
What is Net production efficiency?
The percentage of assimilated energy that is used for growth and reproduction
What is ecological efficiency?
he percentage of net production from one trophic level compared to the next lower trophic level (a.k.a. food chain efciency) (ranges from 5-20% but 10% is used as an estimate)
What are the steps in the nitrogen cycle? (In order)
1.Nitrogen fixation
2.Nitrification
3. Mineralization
4. Denitrification
5. Assimilation
What is the Haber Process?
Converts N2 + 3H2 → NH3 at high heat (350– 550ºC) and pressure (150-300 atmospheres) (very importance source of nitrogen for farming)
What are the consequences of elevated nitrogen in ecosystems?
Acid precipitation by NOx & Eutrophication
