module 6 - ecosystems, population and stability Flashcards
define biotic conditions
give examples
living conditions in the habitat for a species.
e.g. predation, interspecific competition
define abiotic conditions
give examples
non-living conditions in the habitat of a species
climate, sunlight water availability
why are plants central to all ecosystems
because they produce biomass through photosynthesis.
how are organic molecules produced in plants, (biomass) used
organic molecules are used as respiratory substances and to make other biological molecules (carbs, proteins and lipids)
define biomass
the chemical energy store for an organism
energy stored within biomass can be passed along the food chain to different trophic levels
how can you measure biomass
in terms of per unit area or the mass of carbon in an organism - use calorimeter
define gross primary production
the chemical energy stored in a plant, in a given area or volume. during respiration, almost half of GPP is lost as heat - respiratory loss (R)
define net primary production
the chemical energy stored in a plant biomass after respiratory losses (R)
to the environment have been taken into account.
NPP= GPP-R
define consumer production
net production of consumers, refers to the production of new biomass by the consumer. consumers cannot convert all the energy available from the previous trophic level due to energy loss. e.g. respiration, excretion,
how do you calculate consumer production
N= I - (F+R)
N = net production of new biomass by consumers,
I= chemical energy stored in ingested food.
F= chemical energy lost to the environment in faeces and urine.
R = chemical energy used in respiration
define respiratory loss
the energy lost as heat during respiration
what are saprobionts
microorganisms that feed on dead or decaying matter.
play an important role in decomposition and recycling nutrients
why is nutrient recycling important
nutrient recycling is important in ecosystems because it allows the nutrients to be continually recused
how do saprobionts digest the decaying/ dead matter
secrete enzymes onto dead organic matter - extracellular digestion
they then absorb the digested molecules for storage or use in respiration
what stage of the nitrogen cycle are saprobionts important in
ammonification stage - ammonium ions are released as a result of extracellular digestion
what are the stages of the nitrogen cycle
- nitrogen fixation - atmospheric nitrogen (N2) is converted to ammonia (NH3) by nitrogen-fixing bacteria in the soil.
- ammonification - decomposition of a dead organism releases ammonium ions
- nitrification - ammonium ions are converted into nitrates by bacteria in the soil
- denitrification - denitrifying bacteria converts nitrates in the soil back into atmospheric nitrogen (N2)
at what stage in the nitrogen cycle is atmospheric nitrogen converted into ammonia
nitrogen-fixation
what are the types of biochemical carbon stores
terrestrial - decay conversion into other carbon stores in soil
roles of organisms - photosynthesis etc.
oceans - compression and cementation of organic matter forming sedimentary rock
atmosphere - carbon dioxide
what are the geological carbon stores
formation of natural gas - methane
formation of limestone - compacted phytoplankton organisms
formation of coal - land based plants
formation of crude oil
what are terrestrial primary producers
(usually plants) are the first organisms in the food chain.
make their own energy from sunlight and CO2 through photosynthesis
through what process do land-based plants sequester carbon?
photosynthesis
what processes are involved in the formation of crude oil
settling of fine-grained sediments
anaerobic reactions
impermeable rock will result in crude oil being trapped
what type of relationship is formed between mycorrhizae and the roots in the plants
symbiotic - close or intimate relationship between members of two different species
what is leaching
when water soluble plant nutrients are lost from the soil
what is the name given to the chemical store of an organism
biomass
what term describes the rate of production of new biomass
productivity
what are some ways to reduce energy loss in secondary productivity?
limit movement of animals
antibiotics
heating in barns
what confidence level are statistically significant biological results given to?
p<0.05
define succession in ecosystems
the changes in an ecosystem over time - due to complex interactions between organisms and their environment
define primary succession in ecosystems
changes that take place on newly exposed or newly formed land. - colonised by living things
describe the process of secondary succession
- pioneer species colonise damaged land.
- colonisation by new species
- increased complexity
- climax community - ecosystem reaches an equilibrium point
describe the process of primary succession
- pioneer species - colonise newly exposed land
- soil formation - pioneer species break down substances on exposed land
- colonisation by new species - less hostile now
- altering abiotic conditions - composition of soil changes
define deflected succession
ecosystems are disturbed by humans, succession cannot take place.
what conditions do new species alter when they colonise an area
abiotic - non-living
what is the equilibrium state in an ecosystem called
climax community
what is the Mark-Release-Recapture process
used to investigate population size of mobile organisms
1. capture - (small) Sherman trap, (large) Pitfall trap
2. mark - using tags, bands or paint etc
3. release - marked animals released back into environment
4. recapture - new sample collected from trapped and process is repeated
what is the maximum size a population can maintain called?
carrying capacity
when can exponential (continuous) growth occur?
when there is an infinite supply of resources (not in real ecosystems)
how do abiotic factors (non-living) influence carrying capacity of a species
promote growth - favourable for species to reproduce
slowing growth - conditions unfavourable for the species so fewer reproductions
define interspecific competition
competition between individuals in different species
define intraspecific competition
competition between individuals in the same species
define predation
one species is killed and eaten by another species (predators and prey)
how is succession managed?
grazing - animals graze to prevent growth of vegetation
burning - kills vegetation and encourages secondary succession
what are the two main human threats on biodiversity
population growth and resource exploitation
define “seral stages”
when succession after succession continues
what makes a climax community
large range of biodiversity
dominant species
environment becomes stable and reaches an equilibrium
why does secondary succession take less time than primary?
because there is already a base, some soil, left so it takes less work for the pioneer species to change/ alter and produce more soil
what is “plagioclimax”
plagio - relates to humans
natural succession changed due to humans
describe the process of coppicing
- trunk cut close to base
- several new shoots grow from surface
–> protect young shoots from grazers - process repeated indefinitely after a certain time
what are the benefits of coppicing
new stems grow more rapidly than
saplings
lifespan of tree extended
provides variety of light levels
fewer large trees means more light for
smaller plants
provides a variety of habitats
roots prevent soil erosion
maintains soil quality
prevents succession
large machinery not needed
how can we measure biomass transferred?
measured in terms of Carbon or dry mass of tissue
formula for efficiency of biomass transferred
efficiency=biomass transferred / biomass intake x 100
what are the nitrogen-fixing bacteria and where are they found?
Rhizobium in the root nodules of leguminous plants
Azotobacter in the soil
what are the nitrifying bacteria and what do they do
Nitrosomonas convert ammonium into nitrites
Nitrobacter converts nitrites into nitrates
what is deflected succession
where succession is interrupted, usually by human interference
Define carrying capacity
the maximum population size that a habitat can support, defined by the presence of limiting factors
Describe the difference between conservation and preservation
Conservation allows sustainable use of resources there
Preservation maintains an ecosystem/habitats present state
Give social, economic and ethical reasons as to why we conserve and preserve habitats
economic - food source, natural pest control, boosts tourism
social - many organisms can be used in medicine, aesthetics
ethical - we have responsibility to maintain habitats for future generations
define sustainability
using resources in a way that maintains them for future generations
what methods allow sustainable use of an ecosystem’s resources
timber production = coppicing, replacing felled trees, selective cutting
fishing = stocks not depleted, no overfishing, continue indefinitely
define net primary productivity
the rate at which energy is transferred into the organic molecules that make up new plant biomass, after respiratory losses
abundance of organisms can be measured with the use of:
belt transect - 2 tape measures, measure at intervals down the line
quadrat - random sampling in a square frame
line transect - line placed across a habitat - species in contact with line are recorded
what are ways ecosystems can be managed to protect the species and habitats
- controlling number of visitors/ tourists
- involvement of local communities
- education of local communities
- active management of vegetation
- control of the introduction of species
Explain the term succession
Directional changes in composition of species over a period of time. Seral stages (seres), one stage changes conditions for the next. Add examples: e.g. soil becomes more stabilised leading to a climax community
Explain the difference in protein yield in leguminous plants compared to other plants
Rhizobium bacteria in root nodules - nitrogen-fixing bacteria that convert nitrogen into nitrate ions/ ammonium ions for plants to absorb. Plants use nitrates to make amino acids for protein synthesis
What does the graph look like for predator prey population correlation
Predator is always slightly to the right and lower peaks than prey
Explain biotic factors that lead to population explosion of prey
- Fewer predators
- High abundance of alternative prey for predators
- Increased food availability
State ways which managing woodland as a mix of standard and coppiced trees would be of economic benefit to the land owner
Coppicing can increase ecotourism by increasing biodiversity
Coppicing is continual
Different variety of wood products can be sold
Larger pieces of wood can be produced from standard which are more valuable
Describe the Masai Mara national reserve -
Suffered from deforestation of acacia bushes, causing increased soil erosion
Define detritivore
give an example
An organism that breaks down large pieces of dead material into smaller pieces - heteroytic e.g. earthworms
