Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
137 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
List the components of an ecosystem. |
|
|
|
|
Define population. |
All of the organisms of one species that live in the same place at the same time and that can breed together. |
|
|
|
Define the term ecosystem.
|
All the living organism and all the non-living components in a specific habitat and their interactions.
|
|
|
|
Define habitat.
|
The place where an organism lives |
|
|
|
What is the name given to the role that each species plays in an ecosystem?
|
Niche |
|
|
|
Explain why it is difficult to define the niche of an organism precisely.
|
Organisms interact with both living (biotic) and no living (abiotic) things so it’s difficult to know exactly what service it is providing for what. |
|
|
|
Define community.
|
All the populations of different species who live in the same place at the same time and can interact with each other |
|
|
|
Define biotic factor using named examples. |
Living component (plant/animal) that affects an ecosystem.
|
|
|
|
Define abiotic factor using named examples. |
The non-living components of an ecosystem
|
|
|
|
Explain why ecosystems are described as being dynamic. |
Changes (rise and fall in population sizes) are occurring all the time because the community of living things are interacting with each other in the ecosystem. |
|
|
|
Matter and energy are continually being recycled in an ecosystem. True of false.
|
False
|
|
|
|
Define producers.
|
Autotrophic organism (make their own food) that convert light energy to chemical energy which they then supply to consumers.
|
|
|
|
Give examples of autotrophic organisms.
|
|
|
|
|
Define consumers.
|
Living organisms that feed on other living organisms. |
|
|
|
Explain the difference between primary secondary and tertiary consumers. |
|
|
|
|
Define decomposer.
|
Organisms that feed on dead organic matter-->releasing molecules,minerals and energy that then become available to other living organisms in that ecosystem. |
|
|
|
Define trophic level.
|
The level at which an organisms feeds in a food chain.
|
|
|
|
Describe the niche of a rabbit that lives in a field.
|
|
|
|
|
Suggest why two species never occupy exactly the same niche in an ecosystem.
|
If they did then they’d compete as one will be better than other and will survive to reproduce whilst other fails to reproduce and dies out. |
|
|
|
What do food chains and foods webs show?
|
The transfer of energy from one organisms to another (that’s what arrows represent).
|
|
|
|
How is a food web different to a food chain?
|
Food web is a collection of food chains that show how energy’s transferred from lots of different organisms in a community.
|
|
|
|
Why is a food web more useful than a food chain?
|
Organisms are members of more than one food chain and food web show the interconnected feeding relationships of many organisms in an ecosystem.
|
|
|
|
Describe how energy is transferred through ecosystems.
|
Energy is transferred from one living organism to another through feeding.
|
|
|
|
Discuss the efficiency of energy transfers between trophic levels.
|
Some energy is lost at each trophic level and is therefore unavailable for organism in next trophic level because:
|
|
|
|
Recall 3 methods of measuring energy transfers between trophic levels.
|
|
|
|
|
Describe how pyramids of numbers work.
|
|
|
|
|
Describe how a pyramid of biomass works.
|
|
|
|
|
When drawing a pyramid of biomass how do ecologists find the dry mass of the organisms?
|
All organisms collected and put in oven at 80°C until all water in them has been evaporated. |
|
|
|
Why do ecologists prefer not to measure the dry mass of organisms for pyramid of biomass?
|
|
|
|
|
Why is a pyramid of biomass preferable to a pyramid of numbers?
|
Pyramid of numbers just shows the numbers of individuals at each trophic level and not how much living tissue there is so is not useful measure of energy transfer ( as not all of organisms can be eaten) |
|
|
|
Describe how a pyramid of energy works.
|
Measures energy released by unit mass of each organism at trophic level and bar is proportional to this.
|
|
|
|
Describe how the information for pyramid of energy is obtained.
|
Organisms burnt in a bomb calorimeter and energy is worked out by measuring temperature rise of a known mass of water (E=MCΔT)
|
|
|
|
What are the disadvantages to a pyramid of energy?
|
Destructive:involves burning organisms in calorimeter.Time consuming.Doesn’t take into account population fluctuations-so gives distorted idea of energy transfers*so pyramid of biomass used instead)
|
|
|
|
What information do you need to construct a pyramid of Numbers/Biomass/energy
|
Number of organisms at each trophic level.Dry mass of organisms at trophic level.Energy released by unit mass of organisms at each trophic level
|
|
|
|
What does a pyramid of energy flow measure and what is this called?
|
The rate at which energy passes through each trophic level (rate of energy flowcalled productivity)
|
|
|
|
What does productivity show?
|
The amount of energy available to an organisms at specific trophic level per unit area (1 sq metre) in a given amount of time (1 year).Measured in KJ/m2/year Or MJ m-2yr-1
|
|
|
|
What is primary productivity and give two examples of it.
|
Primary productivity:rate of energy transfer at producer level.Gross primary productivity:rate at which plants convert light energy into chemical energy.Net primary productivity:rate of production of new biomass available for consumption by heterotrophs
|
|
|
|
Explain why the NPP is less than the GPP?
|
Plants respire and heat energy is lost to this so less energy is available so NPP is smaller than GPP because of this this loss.
|
|
|
|
Explain why ecologists may prefer to draw a pyramid of energy instead of a pyramid of biomass.
|
Pyramid of energy provides a more accurate picture of energy at each trophic level because dry mass in different organisms releases different amounts of energy so pyramid of energy looks at energy PER unit mass which is more accurate.
|
|
|
|
Suggest why there are fewer individuals at higher trophic levels in a food chain.
|
Energy leaves the food chain at each trophic level (through metabolic losses/inedible parts etc.) so there is less energy available at each successive trophic level meaning fewer and fewer organisms can survive at higher trophic levels.
|
|
|
|
Suggest why most food chains have no more than 5 stages.
|
Energy leaves the food chain at each trophic level and eventually there is not enough energy to sustain any individuals at highest trophic level.
|
|
|
|
Suggest why PP is higher in tropical regions (closer to the equator) than in more temperate regions (closer to the poles).
|
There are higher temperatures and greater light intensity near the equator which increases rate of photosynthesis.
|
|
|
|
Explain why NPP is usually very low (1-3%).
|
The environmental conditions aren’t right E.g. Less than 1% of sunlight energy is actually used for photosynthesis (thus in production of new biomass) as its reflected by clouds not of correct wavelength so not captured by chlorophyll.
|
|
|
|
What is the formula for NPP?
|
NPP= GPP-R.Where R is equal to respiratory heat loss.
|
|
|
|
How can humans increase NPP?
|
Manipulating environmental factors (e.g. light intensity/water levels) to increase rate of photosynthesis and therefore rate of production of new biomass (so more biomass formation) which available to heterotrophs.
|
|
|
|
Outline the ways in which human activities can make NPP more efficient.
|
Manipulating:Light levels.Lack of water.Temperature.Availability of nutrients.Pest resistance.Fungal resistance.competition
|
|
|
|
Explain how manipulating pest resistance can improve NPP.
|
Pests eat crop plants (thus remove biomass-living tissue) and stored energy from food chain and lower yield so crops sprayed with pesticides or been bred to be pest resistant.
|
|
|
|
Explain how manipulating light levels can improve NPP.
|
Light levels can limit rate of photosynthesis and hence NPP-->so some crops planted early to provide to longer growing season to harvest more light or grown under light banks so more photosynthesis =more biomass
|
|
|
|
Explain how manipulating resistance to fungi can improve NPP.
|
Fungi can reduce biomass by causing disease and reducing yield--> reducing NPP so farmers spray fungicide or genetically modify or selectively breed crops to be resistant.
|
|
|
|
Explain how manipulating competition can improve NPP.
|
Competition from weeds for light/water and nutrients can reduce NPP by reducing photosynthesis (thus formation of biomass) so farmers use herbicides to kill weeds.
|
|
|
|
Explain why energy transfer from producers to consumers is inefficient.
|
Some plants die Consumers don’t eat every part of plant-don’t digest everything they eat-egesting it in their faeces and even when food is digested they use most of it in staying alive(e.g. staying warm+ metabolic reactions) so only small amount stored for growth which is available for next consumer (secondary consumer-usually humans)
|
|
|
|
Explain how manipulating nutrient availability can improve NPP.
|
Lack of nutrients can slow growth and photosynthesis--> crop rotation (growing different crop in each field on a rotational cycle) allows soil to replenish nutrients (nitrates) + including nitrogen fixing crop (peas or beans) in cycle
|
|
|
|
Explain how manipulating resistance to fungi can improve NPP.
|
Fungi can reduce biomass by causing disease and reducing yield reducing NPP so farmers spray fungicide or genetically modify or selectively breed crops to be resistant
|
|
|
|
Explain how manipulating water levels can improve NPP.
|
Water needed for photosynthesis crops irrigated/drought resistant strains bred in places with low water availability so water levels not an issue + more biomass produced
|
|
|
|
Explain how manipulating temperature can improve NPP.
|
Temperature can limit speed of chemical reactions in plant (because of enzyme activity) so greenhouses used to provide warmer temps + crops planted early provide longer growing season (so winter doesn’t affect yield)
|
|
|
|
Outline how secondary productivity (energy transfer from primary consumers to secondary consumers) can be improved.
|
Younger animals harvested because they invest more energy into growth (new biomass) than adult ones which minimises energy losses from food chain.Steroids used to increase rate of growth-increase proportion of energy allocated to growth-more biomass.Selective breeding used to produce breeds with faster growth rates
|
increased egg and milk production.Antibiotics used to prevent unnecessary energy loss to fighting pathogens +parasites.Movement restricted to reduce energy losses and maximise energy allocated to muscle (meat) production.Environmental conditions kept constant and optimum so no energy lost to staying warm
|
|
|
Energy transfer from producers to consumers and from primary consumers to secondary consumers (humans) is inefficient the why don’t secondary consumers just eat producers directly?
|
Although it’d be more efficient for humans to eat produces like grain as opposed to feeding it cattle and then eating
|
there are some places where such producers can’t grow and instead vegetation that only cattle can eat grow so there’s no other choice but to grow cattle and then eat them.
|
|
|
Would it be more efficient to farms endotherms like birds and mammals (with constant body temperature) or ectotherms like worms/fish and reptiles (with varying body temperature)?
|
Ectotherms as they would not need to invest energy in maintain constant body temperature like endotherms and hence more energy can be used for growth and contribute to yield.
|
|
|
|
Explain why a vegetarian diet is good idea in terms of maintain biodiversity and energy loss from food chains.
|
A lot of land is allocated to producing meat worldwide through rearing cows/sheep/pigs etc.This land could be used for arable crop production which involves shorter food chain (wheathuman) and less energy is wasted than in longer food chains (grass/cow/humans).If less people at meat then more land would be used for arable crop production and less rainforest would need to be felled which maintains the biodiversity of the rainforest.
|
|
|
|
Define succession.
|
A directional change in a community over time.Primary succession: development of a community from bare previously not colonised ground. |
|
|
|
Describe primary succession on a sand dune.
|
Pioneer plants like sea rocker and prickly sandwort colonise sand just above the high water mark-these can tolerate the harsh conditions e.g. salt water spray+lack of fresh water and unstable sand .Windblown sand builds up around base of these plats forming mini sand dune--> as they die and decay nutrients accumulate in this mini dune-->as dune gets bigger plants like sea sandwort and sea couch grass colonise it-->this is useful as sea couch grass has underground stems which helps to stabilise the sand.With more stability and accumulation of more nutrients plants like sea spurge and marram grass start to grow-->marram grass has shoots which trap windblown sand and as sand accumulates in its shoots the shoots grow taller to stay above growing dune which traps more sand.As sand dune and nutrients build up other plants colonise the sand such as members of bean family
|
hare’s foot clover and bird’s foot trefoil.They have bacteria In their root nodules which convert nitrogen into nitrates--> with nitrates available more species like sand fescue and vipers bugloss colonise the dunes. |
|
|
What role do the following plants have on succession in a sand dune? Sea rocket/prickly sandwort.Sea couch grass.Hare’s foot clover/bird’s foot trefoil
|
Sea rocket/prickly sandwort: pioneer communities which provide nutrients for successors when they die and decay.Sea couch grass: has underground stems so it stabilises sand (similar to providing foliage in soil).Hare’s foot clover/ bird’s foot trefoil: have nitrogen fixing bacteria so provide nitrates for more species
|
|
|
|
Describe primary succession on a rock resulting in a climax community
|
Algae and lichens begin to live on the bare rock-these called pioneer communities.Erosion of rock (by weathering) and build-up of dead and rotting organisms (algae or lichens) produce enough soil for larger plants like mosses and ferns to grownthese replace or succeed the lichens/algae.Larger plants then succeed these smaller plants after they’ve decomposed and nitrified soil-->these contains until a final and stable community is reachedthis is the climax community |
|
|
|
Why are sand dunes useful in understanding about succession.
|
They show all the stages of succession in the same place and at the same time. |
|
|
|
Explain why all the stages of succession are visible on a sand dune. |
The sea deposits sand on the beach so sand nearest to the sea and just above the high water mark is deposited more recently and is at the start of succession whereas sand much further away was deposited long ago and already hosts its climax community so by walking up the beach and through the dunes it is possible to see each stage in the process of succession. |
|
|
|
Explain the meaning of the following terms.Primary succession.Secondary succession.Pioneer community.Climax community
|
A directional change in a community of organism beginning from bare ground.Succession on previously colonised but disturbed or damaged habitat.Living organisms which first begin to colonise land.The stable community that emerges at the end of a process of succession |
|
|
|
Compare and contrast the process of succession on bare rock and on a sand dune.
|
Similarities:Dead and decaying organisms provide minerals for successors.Climax community is woodland Difference:Pioneer community is lichens and algae on bare rock but plants on sand dunes.Windblown sand provides shelter in sand dunes but there is no windblown sand on bare rock
|
|
|
|
Describe the role of decomposers in the decomposition of organic material.
|
Bacteria and fungi involved in decomposition feed saprotrohically:They secrete enzymes onto dead and waste organic material.These enzymes digest the material into small organic molecules which are then absorbed into the microorganism body.Molecules are then stored or respired to release energy after abortion.
|
|
|
|
How do saprotrophs feed differently to animals?
|
They feed saprotrohically which means they secrete enzymes outside to digest organic materials into smaller molecules and then absorb these smaller molecules into their body.
|
|
|
|
Why are decomposers important in the recycling of carbon and nutrient and efficiency of energy in food chains?
|
Energy and materials lost from food chains when living things die or excrete waste.If decomposers did not break these down then energy and valuable nutrients would remain trapped in dead organisms -->decomposers convert these nitrogenous compounds in dead or waste into organic nitrogen in soil which can be used by plants for growth
|
|
|
|
How do decomposers contribute to the nitrogen cycle?
|
Organic nitrogen in decaying plans and animals is converted into organic nitrogen in soil .Organic nitrogen in animals waste by excretion is converted into urea.Both are converted into ammonium (NH4+) which can be converted into nitrates and nitrites in cycle.
|
|
|
|
Outline the 4 ways that microorganisms recycle nitrogen within ecosystems.
|
1. decomposition.Nitrogen fixation.Nitrification.Denitrification
|
|
|
|
Explain why nitrogen fixation is and why it needs to happen.
|
Conversion of nitrogen in air to ammonium ions (NH4+) or nitrate ions (NO3-).Although nitrogen is abundant in air (79%) plants cant used it directly because it’s very unreactive so it needs to be fixed into nitrogenous compounds that plants can use.
|
|
|
|
Recall the ways in which nitrogen in air can be fixed.
|
Lightning strikes.Haber process.Nitrogen fixing bacteria .lightening and Haber process only account for 10% of nitrogen fixation whilst nitrogen fixing bacteria is rest*
|
|
|
|
Describe the role of nitrogen fixing bacteria in the recycling of nitrogen within ecosystems.
|
Nitrogen fixing bacteria found either living freely in the soil or inside root nodules of leguminous plants (ones living in root nodules have mutualistic/symbiotic relationship with host plant as provides carbon compounds e.g. glucose and bacteria provide fixed nitrogen).These bacteria fix nitrogen gas in the air within soil into useable nitrogenous compounds such as NH4+ or nitrate ions.
|
|
|
|
How do plants help nitrogen fixing bacteria in their nodules to carry out nitrogen fixation?
|
Oxygen reduces activity of nitrogen reductase (enzyme involved in nitrogen fixation ) so plants produce protein leghaemoglobin which has high affinity for oxygen which binds to oxygen and maintains low O2 concentration-essentially anaerobic condition which allowing nitrogen reduce to reduce nitrogen gas to ammonium ions that can be used by host plant.
|
|
|
|
Give an example of a nitrogen fixing bacteria and the type of plant it might be found in.
|
Rhizobium.Beans.Peas.Clover.Alfalfa.all are members of bean family*
|
|
|
|
Describe how microorganisms involved in nitrification.
|
Nitrification happens when chemoautrohic bacteria absorb NH4+ ions produced by decomposition of proteins (putrefaction) by decomposers and oxidise it into nitrites (nitrosomonas bacteria) or oxidise nitrites into nitrates (nitrobacter bacteria).
|
|
|
|
Why do chemoautrohic bacteria oxidise ammonium ions or nitrites?
|
As chemoautotrophs they gain their energy by oxidising ammonium ions into nitrites or oxidising nitrites into nitrates.This is unlike photoautotrophs which gain their energy from sunlight.
|
|
|
|
What are the conditions necessary for chemoautrohic bacteria to oxidise NH4+ ions into nitrites and nitrites into nitrates?
|
Well aerated soils with sufficient oxygen needed as this oxidation requires oxygen.
|
|
|
|
Give examples of chemoautotrophic bacteria.
|
Nitrosomanass.Nitrobacter
|
|
|
|
How can the nitrates (NO3-) produced by nitrification be recycled?
|
Absorbed by plant roots to produce organic nitrogen in leguminous plants for amino acids this can then continue in cycle by decomposition to provide NH4+ ions.Denitrification to produce N2 gas in air.
|
|
|
|
Describe how microorganisms involved in denitrification.
|
Bacteria growing in anaerobic conditions (waterlogged soils) use nitrates as a source of oxygen for respiration and convert nitrates (NO3-) back into nitrogen gas.
|
|
|
|
What is the product of denitrification?N2 (nitrogen gas)
|
Nitrous oxide N2O.2N03--> N2O +2.5O2
|
|
|
|
Explain the difference between nitrogen fixation and nitrification.
|
Nitrogen fixation is converting nitrogen in air intro nitrates whereas nitrification is oxidising ammonium ions into nitrites and then into nitrates.
|
|
|
|
Explain the significance of limiting factors in determining the final size of a population.
|
Size of a population depends upon the balance between the mortality and reproduction rate.Limiting factors affect either of these two by reducing the size of the population (through predation/parasites) or reduce growth of the population by limiting availability of resources e.g. oxygen/light/nesting sites.
|
|
|
|
Outline the stages of the growth of a population.
|
Lag phase.Log phase.Stationary phase
|
|
|
|
Describe what happens in the lag phase of population growth.
|
There’s only a few individuals who are still acclimatising to their habitat.Rate or reproduction is slow and growth in population size if slow.Resources are plentiful and conditions are good
|
|
|
|
Describe what is happening in the log phase of population growth.
|
Rate of reproduction is fast and exceeds mortality --> population size increase rapidly.Population size has levelled out at the carrying capacity of the habitat and habitat cannot support a larger population.Rate of reproduction and mortality equal
|
|
|
|
Describe what is happening in the stationary phase of population growth.
|
Population size remains stable or fluctuates slightly up or down in response to small variations in environmental conditions every year.
|
|
|
|
Define carrying capacity.
|
The maximum population size that can be maintained over a period of time in a particular habitat.
|
|
|
|
Recall factors which determine final population size.
|
Availability of resources:Food.Water.Light.Oxygen.Nesting sites/shelter.Biotic factors:Parasites.Predators.competition
|
|
|
|
Describe K strategists.
|
Species whose population size is determined by carrying capacity.Limiting factors exert more and more significant effect as population size gets closer to carrying capacity (e.g. less food might mean less energy to reproduce) so rate of reproduction decreases to meet mortality rate and population size to gradually level out.
|
|
|
|
Describe r strategists.
|
Population increases so quickly (because of rapid reproductive rate) that it can exceed carrying capacity of the habitat before limiting factors start to have an effect.Once CC has been exceeded there are no longer enough resources to allow individuals to reproduce or even survive + excessive build-up of waste products may start to poison population so they begin to die entering a death phase where they all die.
|
|
|
|
What is the name given to the type of population growth that r strategists go through?
|
Boom and bust
|
|
|
|
What is the single most influential factor on population growth in r strategists?
|
Rate at which individuals can reproduce.
|
|
|
|
Recall examples of r strategists.
|
Bacteria.Pioneer species.species with short generation times
|
|
|
|
Why are r strategists good at colonising disturbed habitats?
|
R strategists like pioneer species have rapid reproductive rate which is much faster than k strategists so it possible for a lot more of them (colony) to be present than with k strategists.
|
|
|
|
Are k-strategists or r-strategist more likely to be members of a climax community?
|
K-strategists.Climax community is a stable population and population of strategists stabilizes once carrying capacity has been reached unlike r-strategists.
|
|
|
|
Describe predator-prey relationships and their possible effects on the population sizes of both the predator and the prey.
|
Predators are animals that eat other animals.When predator population gets bigger more prey are eatenthis reduces population of prey-->this leaves less food for predators and with less food fewer predators can survive so population of predators decreases as well --> with fewer predators less prey are eaten and their population size increases with more prey the predator population gets bigger again and cycle continues.
|
|
|
|
Why are studies of predator-prey relationships so complex?
|
Predators usually eat more than one prey and there are number of limiting factors on prey population.Difficult to all these factors in the population of predator and prey.
|
|
|
|
Define competition.
|
Happens when resources like food or water are not present in adequate amounts to satisfy the needs of all the individuals who depend on those resources so organisms compete for this limited amount.
|
|
|
|
What is the effect of competition on population size?
|
Increased competition (fighting over limited resources) reduces population size.Rate of reproduction decreases as fewer organisms have enough resources to reproduce (as there’s not enough resources for all individuals so many of those who lose in competition do not reproduce).Death rate increases (fewer organisms-those who lost- have enough resources to survive) and die.
|
|
|
|
Describe intraspecific competition.
|
Occurs between individuals of the same species as food such as food and space become limiting the members have to compete for them.Those individuals best adapted to obtaining limited resource will survive and reproduce whilst those not so well adapted will die or fail to reproduce--> this slows down population growth and population size enters stationary phase.
|
|
|
|
Describe the role of intraspecific competition on population size.
|
Keeps population size fairly stable.If population size drops -->competition reduces and population size increases again.If population size increases competition increases and population size drops (as growth drops) |
|
|
|
Explain interspecific competition.
|
Is competition between individuals of different species and affects the population size and distribution of a species in an ecosystem.If species occupy similar niches (i.e. eat the same food) then competition is intense and one species will be more effective than another and the weaker will die or be excluded.
|
|
|
|
How can different species avoid niche overlap to avoid interspecific competition?
|
By niche specialisation.They can use different sources (i.e. different food or location).Or use the resources differently (i.e. change the time of day they go to feed).
|
|
|
|
Describe the experiment done on interspecific competition carried out by Georgyi Gause.
|
He grew 2 species of paramecium both separately and together.When together there was competition for food with paramecium Aurelia obtaining food more effectively than paramecium caudatum.Over 20 days the population of paramecium caudatum reduced and died out whereas population of paramecium Aurelia increases eventually being the only species remaining. Gause concluded that niche overlap would result in more competition and weakest would be outcompeted and die out or become extinct-->this idea became known as competitive exclusion principle.
|
|
|
|
How is the competitive exclusion principle useful?
|
It can be used to explain why particular species only grow in particular spaces (as competition in other areas would cause them to die out).
|
|
|
|
What are some flaws in the competitive exclusion principle?
|
Interspecific competition does not inevitably lead to extinction--> sometimes both species exist at stable population size but one species is just significantly smaller than the other).Unlike in the laboratory in the wild there are other limiting factors which might change the outcome and the values of these factors may change over time.
|
|
|
|
Explain why is meant by sustainable management.
|
Maintaining biodiversity whilst ensuring that wood and timber companies have a financially secure and sustainable supply of wood.
|
|
|
|
Explain how the management of an ecosystem can provide resources in a sustainable way with reference to timber production in a temperate climate on a small scale.
|
Coppicing: involves harvest wood whilst keeping the tree alive (sustainable as you can get more wood in the future).Wood is cut at the trunk of a decided tree close to ground and once cut several new shoots grow from the cut surface and eventually mature into stems of narrow diameter which can be cut to use for fencing/firewood +furniture.New shoots grow after cutting and process continues.Pollarding: similar to copping except trunk is cut higher up to stop deer from eating the emerging shoots from a coppiced stem.Rotational coppicing: woodland divided into sections and one section is cut each year and by the time they finish all the division in the woodland the stems in the first sections would have matured and be ready to be coppiced again.
|
|
|
|
Why some trees are left uncoppiced in rotational coppicing?
|
They are left to grow so that they eventually can provide larger pieces of timber (as opposed to the narrow stems of regularly coppiced trees) .These trees are called standards.
|
|
|
|
Why is rotational coppicing good for biodiversity?
|
Without it woodland goes through succession and larger trees would block out sunlight to the floor of the woodland and reduce the number of species that can grow there but by using rotational coppicing different areas of woodland can provide different types of habitat letting more light in and increase number and diversity of species on floor.
|
|
|
|
Explain how the management of an ecosystem can provide resources in a sustainable way with reference to timber production in a temperate climate on a large scale.
|
Coppicing +rotational coppicing + pollarding.Selective cutting: only cutting largest/most valuable tree so that habitat is broadly unaffected and can serve its ecological functions.Strip felling: cut patches of woodland completely leaving other patches untouched so that they can be cut many years later after first patch has regrown-->ensures large areas not all cut at same time loss of species and soil erosion avoided.Increase growth and quality of wood so that each tree provides more wood so that less trees needed to be cut by (controlling pest and pathogens/planting native trees where they will grow well/position trees optimum distance apart so that there is less competition for light/space etc. or they will grow tall and thin and produce bad quality timber if too close.Replace any tree harvested by planting new one.Allow local people to derive benefit from forest.
|
|
|
|
Explain what coppicing is.
|
Involves cutting a tree trunk close to ground to encourage new growth.
|
|
|
|
Explain why it is important to that large scale clear felling of trees in an area does not occur.
|
Trees are important as they provide ecological services like:Remove water from soil and stops soil being washed by rain.Maintain soil nutrient levels through their role in carbon +nitrogen cycle.Can destroy habitat by reducing soil mineral levels and leave soil susceptible to erosion and soil may run off into waterways-polling them.
|
|
|
|
Explain the nature of conservation.
|
Conservation is not about keeping things natural but instead maintaining biodiversity-->it is a dynamic (active) process which involves management of ecosystem through management strategies and reclamation.
|
|
|
|
Recall some management strategies for maintaining an ecosystem.
|
Raise carrying capacity by providing extra food (so there’s less competition and more species can survive).Move individuals or encourage natural dispersion of individuals between damaged habitats by developing dispersal corridors to allow populations to enlarge.Restrict dispersal of individuals by fencing.Control predators and poachers.Vaccinate individuals against disease (to stop species from dying out).Preserve habitats by preventing pollution or intervene to restrict the progress of succession by coppicing/mowing or grazing.
|
|
|
|
Why might reclamation of an ecosystem be chosen sometimes instead of management?
|
Disruption of ecosystem have gone too far so different strategy will be adopted to reverse the effects of human activity and try to return it into previous/better state as opposed to maintaining it the way it is.
|
|
|
|
Describe conservation of an ecosystem by reclamation.
|
Cleaning up the pollution/removing unwanted species and recolonizing with the original species from captive breeding programmes.*requires detailed knowledge of all species involved*
|
|
|
|
Why is reclamation of an ecosystem difficult?.
|
Understanding which species were part of original community is difficult + not always clear.Succession is likely to take a long time before it allows a stable community like the previous to exist again.
|
|
|
|
As well a management strategies what else does successful conservation require?
|
Consideration of social and economic costs to local community:Effective education liaison with community.Establishing:National parks.Green belt land.Sites of special scientific interest.Legal protection to endangered species.Conserving ex-situ:zoo.botanic gardens.
|
|
|
|
Describe how humans have threatened biodiversity.
|
Overexploitation of wild populations for food (e.g. cod in North Sea) sharks for sport and pears for commerce-->these species are harvested faster than they can replenish themselves and their populations decrease significantly or become extinct.Habitat disruption as a result of intensive agricultural practices + increases pollution or widespread building.Foreign species introduced into ecosystems deliberately or accidently which may outcompete native species who may then become extinct.
|
|
|
|
Distinguish between preservation and conservation.
|
Preservation is about protecting areas of land unused by humans and in their untouched form and is passive whereas conservation is active and aims to maintain biodiversity in an area.
|
|
|
|
What are the types of biodiversity that conservation aims to maintain?
|
Diversity:Between species.Within species.Of a range of Habitats and ecosystems
|
|
|
|
Explain the ethical argument for conservation of biological resources.
|
Every species has an inherent value in its own right irrespective of whether it has financial value to humans so every living thing has a right to survive and humans have an ethical responsibility to look after them.
|
|
|
|
Explain the economic arguments for conservation of biological resources.
|
Many species provide valuable food source.Genetic diversity in wild strains may be needed in the future to breed for disease resistance/drought tolerance and improved yield.New species may be domestic for food use.Natural environments are a valuable source for potentially beneficial resource (medicine).Natural predators of pests can act as biological agents (so insecticide may not be needed).Insect species pollinate crops plants which we need to eat (indirect).Other species maintain water quality/protect soil (trees) and breakdown waste.
|
|
|
|
Explain the social arguments for conservation of biological resources.
|
Ecotourism and recreation rely on biodiversity.Living things are aesthetically pleasing and therapeutic.
|
|
|
|
Explain the difference between the direct and indirect financial values of a species.
|
A species has direct financial value if it can be harvested or otherwise exploited directly for money.It has indirect value if its activities (natural pest control) provide a function that would otherwise cost money.
|
|
|
|
Explain why it is impossible to conserve an ecosystem by simply putting a fence around it.
|
Succession will take place and reduce biodiversity and conservation is about maintain biodiversity so active actions must be taken to stop succession.
|
|
|
|
Explain the main reason for the problems in the Galapagos.
|
Famous as Darwin’s site for his theory of natural selection and has attracted a lot of tourism with a rapid increase in human population to service this tourism trade + as well as demand for marine products like sea cucumbers +lobsters
|
|
|
|
List the ways that humans have negatively affected the animal and plant populations in the Galapagos Islands.
|
Habitat disturbance.Over-exploitation of resources.Introduction of foreign species.
|
|
|
|
Explain how human have causes habitat disturbance in the Galapagos Islands.
|
Population has increased from 5000 (1980) to 28000 (2005).This dramatic rise in population has placed huge demands on water/energy and sanitation services.Demand for oil has increased.More waste and pollution produced.Conversion of habitats for building and agriculture has destructed and fragmented these habitats.Forests of scalesia trees have been almost eradicated to produce timber for building + construction.
|
|
|
|
Explain how humans have over-exploited resource in the Galapagos Islands.
|
Whales and seals were harvested faster than they could replenish themselves to sell internationally.Giant tortoises taken as they could survive on little food in the hold of a ship for long time before being killed and eaten-->this damaged tortoise populations which decreased by 2000000 in ½ a century-->last surviving tortoise is lonesome George.International market for shark fins had led to deaths of 150000 sharks each year around the island.Sea cucumber populations depleted which had had damaging effect on under-water ecology.
|
|
|
|
Explain how humans have introduced species into the Galapagos and its effect on animal and plant populations.
|
Foreign spaces have been brought which can eat native species/destroy native species habitats+ bring diseases (avian malaria).Red quinine tree is an aggressive invasive species on Santa Cruz Island which occupies and spreads rapidly (has wind dispersed seeds) and has changed ecosystem in highlands from low shrub+ grassland to closed forest -native cactotillo shrub has been almost eradicated from Santa Cruz + Galapagos petrel has lost its nesting site + has outcompeted native scalesia trees.Goats have been introduced:Which eat Galapagos rock purslane-a species unique to island+ Outcompetes giant tortoise for grazing/trampling and feeding on its food supply +Changes habitat to reduce number of tortoise nesting sites.Has transformed forests to grassland leading to soil erosion. |
|
|
|
What action has been taken on the Galapagos islands to reduce the effect that foreign species have had on the ecosystem.
|
Quarantine system to search arriving boats and tourists for foreign species.Natural predators have been used to reduce damage caused by pest populations e.g. ladybirds released to wipe out a foreign insect specie.Culling has been used against feral goats on Isabella Island and pigs on Santiago Island |
|
