Ecosystem, Populations and sustainability Flashcards
what are abiotic factors ?
non living features of an ecosystem
define population size
total number of organisms of one species in a habitat
what causes population size to vary ?
abiotic factors
what is inter specific competition ?
competition between different species for the same resources (food / territory)
what are biotic factors ?
living features of an ecosystem
intraspecific competition …
competition between same species for the same resources (food / territory)
what is carrying capacity ?
the maximum stable population size of a species that an ecosystem can support
give some examples of limiting factors of population size
abiotic - shelter
biotic - interspecific competition (limits resources)
what determines the carrying capacity of an ecosystem ?
the limiting factors
define conservation of ecosystems
protection and management of ecosystems so that the natural resources can be used without them running out
what is reclamation ?
restoring ecosystems that have been damaged / destroyed
how is conservation important for economic ?
- ecosystems provide many resources used to trade on local + global scale
- less trade without ecosystems
how is conservation important for social ?
ecosystems bring joy (attractive + activities)
how is conservation important for ethical ?
- moral responsibility to conserve ecosystems for future generations
define producer
organism that produces organic molecules using light energy
what does it mean that ecosystems are a dynamic system ?
constantly changing
what is biomass ?
mass of living material
what do food chains show ?
simple lines of energy transfer
what do food webs show ?
multiple food chains and how they overlap
state the reasons why not all the energy is taken in by organisms
- plants can’t absorb all wavelengths of light
- some parts of food are not eaten (roots/bones)
- some parts are indigestible like cellulose (passed onto decomposers)
what is gross productivity ?
% of energy taken in
what happens to energy that is taken in ?
- most is lost to environment when respiring (respiratory loss)
- some goes to biomass
what is net productivity ?
the amount of energy available to next trophic level (biomass)
net productivity =
gross productivity - respiratory loss
% efficiency of energy transfer =
gross productivity / net productivity
how do you measure energy transfer ? (trophic levels)
- measure dry mass (biomass) of one organism
- multiply by size of population to get total energy in that population
- energy transfer is difference in energy between trophic levels
what is the problem with the method for measuring energy transfer ?
consumers take in energy from multiple diff. producers/prey
how does human activity increase energy transfer ?
- herbicides (kills weeds that compete)
- fungicides (kills fungal infections so less energy on fighting infections)
- insecticides (kills pests that eat - less biomass lost)
- natural predators (eat pests)
- fertilisers
- rearing livestock
give two examples of rearing livestock to increase energy transfer
- kept in warm pens where movement is restricted
- given feed high in energy
how is limestone/chalk involved in the Carbon cycle ?
- drawn deep into Earth’s crust (movement of tectonic plates)
- undergo chemical changes and release CO2
- released out of volcanoes
how is rock involved in Carbon cycle ?
- weathered chemically (rain)
- mineral ions and bicarbonate ions are released and enter ground water to rivers/oceans
- combine to form carbon compounds (CaCO3)
how much nitrogen in the air ?
78%
nitrogen fixation is when …
atm nitrogen is turned to ammonia
what causes nitrogen fixation ?
bacteria like Rhizobium and Azotobacter
lightning
where do the nitrogen fixing bacteria live ?
Azotobacter - soil
Rhizobium - root nodules of leguminous plants
what is the mutualistic relationship between Rhibozium and plants ?
plant is provided with nitrogen compounds
bacteria provided with carbohydrates
what is ammonification ?
nitrogen compounds from dead organisms are turned into ammonia by decomposers (which goes to form ammonium ions)
what is nitrification ?
ammonium ions changed into nitrogen compounds
what is the 1st nitrifying bacteria and what does it do ?
Nitrosomonas - ammonium ions to nitrites
what is the 2nd nitrifying bacteria and what does it do ?
Nitrobacter - nitrites to nitrates
what is denitrification ?
nitrates converted into atm nitrogen by denitrifying bacteria
what causes denitrification ?
bacteria using nitrates for anaerobic respiration and producing atm nitrogen
give an example of where denitrification may occur ?
waterlogged soil - anaerobic condition
give formula for nitrite
NO2-
what is succession ?
progressive change in the composition of a community, from the initial colonisation by a pioneer species to a stable climax community
what is primary succession ?
succession that occurs on newly formed land (with no organic material/soil)
give 2 examples of newly formed land
rock from volcanoes
sand dunes
what is secondary succession ?
succession on land that has been cleared of land, but soil remains
give 2 examples of pioneer species
marram grass
lichen
how does the pioneer species start succession ?
- breaks down rocks and releases minerals
- die and decompose to form thin soil which builds up more organic material
- soil means moisture can be retained, so other species grow
what is the difference between pioneer species of primary / secondary succession ?
secondary ones are larger (e.g. shrubs)
what is climatic climax ?
climax community for a particular climate
what do peat bogs store ?
water and carbon dioxide
how does moss help a peat bog form ?
retains water
why do conservationists have a problem with farmers overgrazing on peat bogs ?
- loss of moss species
- soil compaction
- peat bog erosion
what government funded program is paying farmers to use peat bogs in a sustainable way ?
Environmental Stewardship Scheme
how can farmers use peat bogs in a sustainable way ?
- carry out measures to reduce water run off
- lower no. of livestock on peat bogs
- remove livestock in winter
what is coppicing ?
cutting trees in a way that lets them grow back so new ones don’t have to be planted
what is pollarding ?
similar to coppicing but cut at main stem or trunk to control height
name some sustainable ways of managing timber
- coppicing / pollarding
- attaching post and tubes to support and protect
- trees not too close so less competition
state the reaction of nitrosomonas
2 NH3 + 3 O2 — 2 NO2- + 2 H+ + 2 H2O
state the reaction of nitrobacter
2 NO2- + O2 — 2 NO3-
state the reaction of denitrifying bacteria
NO3- — N2 atm
how do you use a point quadrat ?
- bar w/ legs and holes to put pins in
- point quadrat randomly placed in area
- pins dropped through holes
- every plant that the pin touches is recorded
- repeat …
what are transects used to measure ?
distribution of populations
for plant populations, how do you use line transect ?
- tape measure placed along transect
- any plant that touches is recorded
for plant populations, how do you use belt transect ?
- data collected along transect using frame quadrats
for plant populations, how do you use interrupted transect ?
measurements are taken at intervals
what are the two main ways of controlling over fishing
- fishing quotas
- controlling mesh size of nets
how do fishing quotas control over fishing ?
- limit amount of certain fish species fishermen are allowed to catch
- reduces no. fish caught and killed
what are the problems with fishing quotas ?
- wrong species still caught and usually die
how does controlling mesh size of nets control over fishing ?
- reduces no. of unwanted fish accidentally caught
- allows younger fish to escape net and reach breeding age
what is the Terai Arc ?
- area of forest and grassland in Nepal
- home to variety of plants and animals, including endangered species (Bengal Tiger)
what problem is there in the Terai Arc ?
- destruction of habitat to make housing spacing for ppl living there
- closer contact increases conflict (tigers killed for killing livestock)
how is the problem in the Terai Arc being overcome ?
WWF works w/ local ppl to help balance their needs w/ conservation (e.g. supplying with solar cookers so don’t need so much wood)
what is the Maasai Mara ?
- national grassland reserve in Kenya
- home to huge populations of wildebeest/zebra/lions/cheetahs
what problem is there in the Maasai Mara ?
- ppl there make money by raising livestock
- overgrazing by livestock can destroy grassland for wildlife
how is the problem in the Maasai Mara being overcome ?
conservation trusts help Maasai ppl make money through conservation and ecotourism projects and how to farm in sustainable way
state the effects of human activities on Galapagos islands
- non native animals introduced, reducing native populations
- non-native plants introduced, decreases native populations
state the methods of control at Galapagos islands
- eradication programmes remove non native animals and plants
- visitors must follow rules, including bringing no non native species
state the effects of human activities on Antarctica
- visitors have caused pollution (sewage, rubbish, oil spills)
- hunting and fishing have reduced wildlife populations
state the methods of control at Antarctica
- waste taken away by ship
- ships must use lighter fuels
- tourist restrictions
- hunting and whaling have been banned
state the effects of human activities on Lake district / snowdonia
- erosion of footpaths and loss of soil from hillsides
2. walkers often trample on surrounding vegetation
state the methods of control at Lake district / snowdonia
- regular repair on paths
2. walkers educated on importance of sticking to footpaths
what is a density dependent factor and give an example
factor whose effect on population size varies w/ population density (e.g. food availability)
define preservation
protection of an ecosystem so its kept exactly the same
