Chapter 2 Flashcards
Species
Group of organisms (living things) sharing common characteristics that interbreed and produce fertile offspring
Population
Group of organisms of the same species living in the same area at the same time, and which are capable of interbreeding
Habitat
Environment in which a species normally lives
Population density
Average number of individuals in a stated area
Abiotic factors
Non-living, physical factors that influence the organisms and ecosystem, eg temperature, sunlight
Biotic factors
Living components of an ecosystem - organisms, their interactions or their waste - that directly or indirectly affect an organism
Niche
Describes the particular set of abiotic and biotic conditions and resources to which an organism or population responds
Fundamental niche
Describes the full range of conditions and resources in which a species could reproduce and survive
Realised niche
Describes the actual conditions and resources in which a species exists due to biotic interactions
Limiting factors
Factors which slow down the growth of a population as it reaches its carrying capacity
Carrying capacity
The maximum number of a species or ‘load’ that can be sustainably supported by a given area
Population dynamics
The study of the factors that cause changes to population sizes
Butterfly effect
Refers to small changes that happen in a complex system that lead to seemingly unrelated results that are impossible to predict
Intraspecific competition
Individuals of the same species competing for the same resources
Interspecific competition
Individuals of different species competing for the same resources
Predation
When one animal (predator) eats another animal (prey)
Herbivory
An animal (herbivore) eating a green plant
Parasitism
A relationship between two species in which one species (parasite) lives in or on another (host), thus harming the host
Mutualism
A relation between two or more species in which all benefit and none suffer
S and J population curves
Describe a generalized response of populations to a particular set of conditions (biotic and abiotic factors)
S curve
Also known as a logistic growth curve, which begins with an exponential growth and then slows down as it reaches its carrying capacity
J curve
Also known as an exponential growth curve, in which the population fluctuates at a rapid rate
Carrying capacity
The maximum population size of the ecosystem
Environmental resistance
The area between the exponential growth curve and the S-curve
Diebacks
Collapse in a population after an exponential growth
Overschoot
When the population exceeds the carrying capacity on a long-term or continuing basis before the collapse occurs
Community
A group of populations living and interacting with each other in a common habitat (the same place)
Ecosystem
Community and the physical environment it interacts with
Photosynthesis
The process by which green plants make their own food from water and carbon dioxide using energy from sunlight
Photosynthesis equation
Carbon dioxide + water = glucose + oxygen
Respiration
The conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy
Respiration equation
Glucose + oxygen = energy + water + carbon dioxide
Compensation point
When carbon dioxide that plants produce in respiration is used up, the rates of the 2 processes are equal and there is no net release of either oxygen or carbon dioxide
Food chain
Flow of energy from one trophic level to the next. It shows the feeding relationships between species in an ecosystem
Trophic level
The position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in a food chain
Top carnivore
The carnivore at the top of the food chain
Producers/autotrophs
Green plants which make their own food from carbon dioxide and water using energy from sunlight
Chemosynthetic organisms
Organisms that make their own food from other simple compounds instead of using sunlight
Consumers/heterotrophs
Organisms which feed on autotrophs or other heterotrophs to obtain energy
Detritivores
Organisms that derive their energy from detritus or decomposing organic material
Decomposers
Organisms that obtain their energy from dead organisms by secreting enzymes that break down the organic matter
Omnivores
Organisms that eat autotrophs and heterotrophs
Bioaccumulation
The build-up of persistent/non-biodegradable pollutants within an organism or trophic level because they cannot be broken down
Food web
Complex network of interrelated food chains which create a food web
Biomagnification
The increase in concentration of persistent or non-biodegradable pollutants along a food chain
Ecological pyramids
Include pyramids of numbers, biomass, and productivity and are quantitative models and are usually measured for a given area and time
Pyramid of numbers
A pyramid that shows the number of organisms at each trophic level in a food chain at one time
Standing crop
The number of organisms at each trophic level in a food chain at one time
Pyramid of biomass
A pyramid that contains the biomass (mass of each individual x number of individuals) at each trophic level
Pyramid of productivity
A pyramid that shows the rate of flow of energy or biomass through each trophic level
Trophic efficiency
The percentage of energy that moves from one trophic level to the next
Solar radiation
Energy emitted by the sun and is made up of visible and invisible wavelengths
Solar constant
The solar energy reaching the top of Earth’s atmosphere per second
Productivity
The conversion of energy into biomass per unit area per unit time over a given period of time. It is the rate of growth or biomass increase in plants and animals
Gross
Refers to the total amount of something made as a result of an activity, e.g. profit from a business or salary from a job
Net
The amount left after deductions are made. (e.g. costs of production or deductions or tax and insurance from a salary.) It is what you have left and is always lower than the gross amount
Primary
Means to do with plants
Secondary
Is to do with animals
Biomass
The living mass of an organism or organisms but sometimes refers to dry mass
Gross productivity (GP)
The total gain in energy or biomass per unit area per unit time. It is the biomass that could be gained by an organism before any deductions
Net productivity (NP)
The gain in energy or biomass per unit area per unit time that remains after deductions due to respiration
Gross primary productivity (GPP)
The total gain in energy or biomass per unit area per unit time by green plants. It is the energy fixed (or converted from light to chemical energy) by green plants by photosynthesis.
Net primary productivity (NPP)
The total gain in energy or biomass per unit area per unit time by green plants after allowing for losses to respiration. This is the increase in biomass of the plant - how much it grows - and is the biomass that is potentially available to consumers (animals) that eat the plant
Net primary productivity (NPP) formula
NPP = GPP - R, where R = respiratory loss
Gross secondary productivity (GSP)
The total energy or biomass assimilated (taken up) by consumers
Gross secondary productivity (GSP) formula
GSP = mass of food eaten - mass of fecal loss
Net secondary productivity (NSP)
The total gain in energy or biomass per unit area per unit time by consumers after allowing for losses to respiration. There are other losses in animals as well as to respiration but respiration is the main one
Net secondary productivity (NSP) formula
NSP = GSP - R, where R = respiratory loss
Biogeochemical cycles
When nutrients are absorbed by organisms from the soil and atmosphere and circulate through the trophic levels and are finally released back to the ecocystem
Carbon fixation
When carbon dioxide, water vapour and heat are recaptured by photosynthesis in green plants and locked up in their bodies for a time as glucose or other large molecules
Haber process
Nitrogen-fixing process used to make fertilizers. Nitrogen and hydrogen gases are comined under pressure to form ammonia
Nitrification
- Nitrifying bacteria convert ammonium to nitrites
- Nitrifying bacteria convert nitrites to nitrates
Denitrification
- Denitrifying bacteria convert ammonium, nitrate and nitrite ions to nitrogen gas, which then goes into the atmosphere
Decomposition
- Decomposition of dead organisms provides nitrogen for uptake by plants
- Supplies the soil with a lot of nitrogen
Assimilation
- Absorb into
- When living organisms take in nitrogen and build it into more complex molecules
Energy budget
The quantities of energy entering, staying within and leaving the animal or population
Anthropogenic
A process, effect or activity derived from humans is known as anthropogenic
Energy subsidy
The additional energy that humans have to put into the system which comes from the Sun’s energy
Maximum sustainable yield (MSY)
The largest crop or catch that can be taken from the stock of a species without depleting the stock. Taken away is the increase in production of the stock while leaving the stock to reproduce again.
MSY = NPP/NSP of a system
Biome
A collection of ecosystems sharing similar climatic conditions
Biosphere
That part of the Earth inhabited by organisms. It extends from the upper part of the atmosphere down to the deepest parts of the oceans which support life
Latitude
The distance north or south from the equator
Wind
Air moving horizontally at the surface of the Earth. Winds blow from high to low pressure areas
Ocean currents
Distribute surplus heat energy at the equator towards the poles
Latent heat
When water changes from state to state and either gives out or takes in heat
P/E ratio
The ratio of precipitation to evaporation
Productivity
The conversion of energy into biomass over a given period of time. It is the rate of growth or biomass increase in plants or animals. It is measured per unit area per unit time
Tropical rainforest
- Hot and wet
- High rainfall 2000-5000 mm yr-1
- NPP 2200
- No seasonal variation
Desert
- Dry, hot areas
- Evaporation > precipitation
- Very low NPP as water is a limiting factor
Temperate grassland
- P slightly > E
- NPP 600, not very high
- Low rainfall, threat of drought
Temperate forests
- Mild climate
- P > E
- Rainfall 500-1500
- Seasonal variations
- Second highest NPP, but still low because of low photosynthesis (leaves falling)
- NPP 1200
Arctic tundra
- NPP 140, very low
- Cold, low precipitation
Deep ocean
- NPP low, around 20-300
Zonation
The change in community along an environmental gradient due to factors such as changes in altitude, latitude, tidal level or distance from shore/coverage by water
Succession
The process of change over time in an ecosystem involving pioneer, intermediate and climax communities
primary succession
A type of succession that occurs on a bare inorganic surface
pioneers
First species to colonize an area; can adapt to extreme conditions; are usually r-selected species
R-selected species
Small size, short life cycles, rapid growth and production of many offspring or seeds
K-selected species
Small number of offspring, parental care, most offspring survive, good competitors (out-compete r-strategists in a stable and climax ecosystem)
Climax community
- Maximum possible development that a community can reach under the environmental conditions of temperature, light and rainfall
- The final stage of succession when species composition stops changing
- Is stable and self-perpetuating
- Exists in a steady-state dynamic equilibrium
Secondary succession
Type of succession where soil is already developed and ready to accept seeds carried in by the wind
Gross primary productivity
- Initially: low due to the initial conditions and low density of producers
- Increases through the pioneer and early stages
- Decreases as the climax community reaches maturity
productivity: respiration ratio = 1
Net productivity
- Initially: high, the proportion of energy lost through community respiration is low
- NPP as a % of GPP can fall, as respiration rates increase with more biomass
productivity: respiration ratio = 1
Sub-climax community
When succession is stopped by an abiotic or biotic factor. This can only continue its development if the limiting factor is removed
Plagioclimax community
When a climax community is affected by a natural disturbance or human activity. eg pastures or farmlands. This can only continue its development if the human activity stops.
Biodiversity
- Increases during succession
- Decreases slightly if a stable climax community is reached
Mineral cycling
- Slow at the early stages
- Increases strongly during the succession process
