U3 T2 - Ecosystem Dynamics Flashcards
Define Biomass
the total amount (dry weight) of biologicial matter of a group of organisms in a given area
Define Autotrophs.
The main producers who use energy (sun) and inorganic molecules to produce organic molecules, which is the main energy source for all ecosystmes and organisms. (photosynthesis)
Explain the transfer of energy between Photoautotrophs and heterotrophs
- Solar energy transformed into chemical energy (glucose) by the autotrophs.
- Glucose is then consumed by the heterotrophs and transform it into ATP for use by the cells. (Or consumed and left as biomass)
Define Trophic level. Name the four main trophic levels.
An organisms level in the food chain of an ecosystem based on feeding relationships.
1st - autotrophs.
2nd - Primary consumer
3rd - Secondary consumer
4th - Tertiary consumer
Describe the loss of energy from the sun to the autotrophs
Energy is lost through radiation, absorption, and reflection.
55% of light energy is refleccted by Earth’s atmosphere
95-99% of light reachin plants is relfected or absorbed by the plants
1-5% of light is used for photosynthesis
Describe GPP and NPP
GPP - the rate at which solar energy is used to fix carbon into organic molecules
NPP - subtract the energy used in metabolism from the GPP
Describe trophic level energy transfer efficiency
Only about 10% of the previos trophic level energy is transferred into the next levels biomass. Most energy is lost through:
-transformed to heat energy (80%)
-chemical energy of uneaten portion (10%)
Describe the water cycle
-Evaporation from oceans and fresh water
-Condensation in clouds
-Precipitation as rain or snow
-Release from organisms through transpiration and respiration
-Run off from land into waterways
Describe how carbon enters the ecosystem
-Combustion of fossil fuels
-Respiration of dead animals/plants
-Death and decay of living organisms
-Coming out of solution into water
-Volcanic activity
Describe how carbon is taken up in the ecosystem
-Photosynthesis by plants
-Dissovling in water and forming carbonates
-Formation of fossil fuels
-Incorporation as biomass
Describe how nitrogen enters the ecosystem (5 ways)
Dentrification
Ammonification
Nitrification
Lightning
Fertilizers
Describe dentrification
decomposers break down faeces and dead organisms and return nitrogen to soil as ammonia
Descibe Ammonification
bacteria in the soil of legumes fix nitrogen into ammonia
Describe Nitrification
bacteria in soil converts ammonia into nitrite/nitrate ions
Describe Lightning
making nitrogen and oxyegn react to form nitrogen dioxide which dissolves in the rain to form nitrate ions
Describe how nitrogen is taken up in the ecosystem
Plants take up nitrogen through the soil to produce proteins
Animals consume plants and animals and obtain nitrogen compounds
Define Ecological Niche
a role or space that an organism fills in an eocsystem, including all its interactions with the biotic and abiotic factors in an environment
Describe Ecological Niche in termrs of habitat, feeding relationships and interactions with other species.
Habitat - how the organism uses the available resources in the habitat
Interactions - symbiotic relationships, competition
Feeding Relationships - Predation
Describe the competitive exclusion principle.
Two species that require the same resources can live in the same environment together but cannot coexist in the same niche
Define keystone species.
a species that plays a critical role in maintaining the structure and functioning of their ecosystem
Name exapmles of Keystone species
Sharks, Bees, Wolf
Define Carrying Capacity
the size of the population that can be supported indefinitely on the available resources and services of the ecosystem
define limiting factor
any factor that limits the size of a population
Give examples of both biotic and abiotic limiting factors.
Biotic - presence of predators, competition for resources, disease/parasite
Abiotic - space, natural dissasters, water availability
Name the four processes that affects a population’s size
-Natality (birth)
-Mortality (Death)
-Immigration (moving in from another popualtion)
-Emigration (moving out to another population)
What is the formula for population grwoth rate
PGR = (birth rate + immigration rate) - (death rate + emigration rate)
Recall the Lincoln index formula
N = (Mn)/m
N=size of target population
M=no. caught, tagged and released in first sample
n=no. caught in second sample
m=no. tagged previously in second sample
Name the two patterns of poulation growth
-Exponential
-Logistic (flattens out)
Define Ecological Succession
the sequences of change in an ecosystem, where one kind of community is replaced by another moe complex one
Describe seres, pioneer, and climax communities.
Sere - the successive community to the one before
Pioneer communities - the first/orginal sere
Climax Community - the final stable community which has no seres after it
Describe Features of Pioneer Species.
-Ability to perform nitrogen fixation
-Ability to photosythesise efficiently
-Rapid seed or spore germination
Describe the differences between Primary and Secondary succession.
Primary is the conolonization of a previously uncolonised area.
Secondary is the recolonization of a previously colinzed area that has been disturbed.
Describe spatial and temporal changes.
Spatial - changes in the area
Temporal - changes over time
Name the 3 considerations when making predictions based on human impact.
-Magnitude
-Duration
-Speed
