Topic 2: Ecosystem Dynamics Flashcards
what are autotrophs
an organism that can feed itself – able to convert inorganic carbon-containing compounds into organic compounds – e.g. plants - done thru photosynthesis
what are the two stages of photosynthesis
light dependent and light independent
define biomass
the total amount of living tissue in a defined volume or area – often defined as the “dry weight”
what is gross primary productivity - explain
the total biomass that autotrophs create through photosynthesis.
what is net primary productivity
the biomass left over after the autotroph has used what it needs itself
define heterotoph
organism that cannot manufacture its own food - eats plants/ animals
what are trophic levels
feeding levels!! - a group of organisms within an ecosystem which share the same relationship to the producers in the ecosystem
list a few different trophic levels
producers, primary consumers, secondary consumers (first level that feed on animals rather than producers), tertiary consumers
what is a food chain
diagram that shows the linear flow of energy thru an ecosystem
what is a food web
similar to a food chain, but includes many interconnected ones
define what a biomass pyramid is
shows the total biomass of the organisms at each trophic level
what is an ecological niche
the role a species plays in the ecosystem
define carrying capacity
the pop. size that the environment is able to support - given the availability of food, water, shelter, etc
define limiting factor
prevents something from increasing
what are the factors that affect population size
immigration, emigration, births, deaths
how to calculate population change
(births + immigration) - (deaths + emigration)
what is succession
a change in the species structure of an ecological community over time
what is a pioneer species
hardy species which are the first to colonise barren environments
what is a sere
an intermediate stage found in an ecological succession - each stage of succession
what is “the final sere” in ecosystem succession
the end result of succession is called a climax community
(stable, reaching equilibrium). They take a long time to become established and damage cannot be restored quickly (other terms: mature/ old growth)
what is primary succession
succession that begins on lifeless ground where there is no soil, or the soil is incapable of supporting life – begins on newly exposed or created ground
what are the features of a pioneer species
- able to fixate nitrogen (or a symbiotic association with something that can)
- tolerance to extreme conditions
- rapid germination of seeds
- ability to photosynthesise
what is secondary succession
begins in an area where a disrupted community already exists (eg. after a fire)
what are methods for estimating CO2 concentration in past ecosystems
- stomatal density in plants - as CO2 level increases, density decreases
- ice cores - one layer of ice per year - when the layers form, the ice traps samples of the atmosphere in tiny bubbles
what are the methods for estimating temperatures in past ecosystems
- ice cores - looking at the proportion of different oxygen or hydrogen molecules
- diatoms (tiny algae) - found to be directly linked to ocean temperatures - the warmer the sea temp., the lower the diatom biodiversity
what are methods for estimating the types of past ecosystems
- pollen - shows the ecosystems of the past - like the diatoms of the land
- other fossils (eg. trees)
list the different ways in which humans impact biodiversity
- habitat destruction
- land and soil degradation (loss of quality)
- creation of monocultures (uniform quality produce - demand from food industry - favours genetic uniformity)
- selective breeding
- biotechnology (cross species genetic modification - superior to natural species - so used less and less for farming)
