Biodiversity & Populations (4) + (6) Flashcards
as seral stages increases, what happens
Numbers increase more
During primary succession, at each stage until climax populations alter their environment enabling larger organisms to thrive.
Most rapid change at stages 3 + 4:sub-climax community
AT seral stage 5, climax community, most biodiversity, highest # of plant species, most niches, longest food chains, high biomass, high PP. Soil: low pH, large q of humus, deep with topsoil/subsoil, high q of N2
describe 5 factors that depict LOW biodiversity in a habitat
- Relatively few successful species
- The nature of the environment is stressful/extreme with few ecological niches
- Relatively few species live in the habitat, often with very specific adaptations for the environment.
- Simple food webs
- A change to the environment will have a major effect on the ecosystem
describe the steps in population size fluctuating due to intraspecific competition
- when resources are plentiful, population increases
- tf there will be more organisms competing for the same q of food/space
- these resources become scarce, the population decreases
- a smaller population means there’s less competition for food/space, which is better for growth/reproduction- pop. grows again
describe the trend of a predator-prey graph
+ however?
- Prey population increases = there’s more food for predators, so their pop. increases
<em>Predator pop. increases AFTER prey pop.</em>
- <em></em>As predator pop. increases, greater numbers of predators consume prey, so more prey is eaten, so their pop. decreases.
- There’s tf less food for predators, so their pop. decreases after prey pop. decreases.
However, they are usually more complicated eg. due to availability of food for prey. The prey pop. size might dec. because there are too many, then predation amplifies this. -intraspecific competition + pred-prey. There may be other predators/prey too.
explain the pitfall traps and Tullgren funnel ways of sampling animals
> creating a pit in the ground, with waterproof cover to prevent rainwater from filling the traps. Alcohol can be placed in the bottom to prevent invertebrates leaving.
> Soil/leaf litter placed in funnel on a sieve, with a light bulb above and a jar of alcohol below. Small organisms are collected from the jar.
Light bulb dries out soil, organisms move away from heat + light. They fall through the sieve.
explain what happens in these stages of the carbon cycle
- CARBON into PLANTS
- CARBON into ANIMALS/CONSUMERS
- CARBON out of PLANTS/ANIMALS
- BREAK DOWN
- RELEASE
- Atmospheric CO2 diffuses into mesophyll cells + photosynthesis converts it to carbs/organic compounds
- Primary/secondary consumers move C to the next trophic level, (herbivores, then carnivores/omnivores) C-containing organic compounds are hydrolysed and they become part of the organism eg. lipids, proteins, carbs.
- Any organism in the food chain dies, undigested food contains C compounds & passes out of animal/plant bodies. Now part of dead remains/excretory products.
- Saprotrophic decomposers, mainly bacteria but also fungi, secrete enzymes hydrolysing the large organic molecules. C-containing compounds now in decomposers eg. lipids, protein, carbs. Some products used in respiration by bacteria.
- ALL ORGANISMS IN THE FOOD CHAIN RESPIRE, releasing CO2 into the atmosphere
give 5 factors that depict high biodiversity
- Large number of successful species
- The nature of the environment is relatively benign/not stressful, with more ecological niches
- Many species live in the habitat, often with few specific adaptations to the environment
- Complex food webs
- The effect of a change to the environment is often relatively small for the whole ecosystem
give examples of cooperation at inter and intra specific levels
- Intraspecific- social insects eg. ants, termites, honey bees*
- Interspecific- mutualism eg. coral + algae*
Give the first three factors that affect genetic biodiversity (MICAIN) + one line how they affect it
MUTATIONS- new alleles produced increase
INBREEDING/ SELECTIVE BREEDING- only a few individuals selected for breeding decrease
CAPTIVE BREEDING PROGRAMMES- endangered species are low in number decrease
Give the second set of three factors that affect genetic biodiversity (MICAIN) + brief description
ARTIFICIAL CLONING- genetically identical offspring are produced decrease
INTERBREEDING/ GENE FLOW- between 2 populations increase
NATURAL SELECTION- alleles for disadvantageous characteristics are lost decrease
how are conservation/preservation needs balanced with human needs in the UK peat bogs
Areas of wet peat store water + CO2, and are home to many plants & animals eg. moss
Farmers use peat bogs to graze sheep/deer- overgrazing = loss of moss species, soil compaction (increasing water runoff, taking sediment with it), and peat bog erosion.
Govt. has given farmers £ to use peat in a sustainable way- to reduce water runoff, lower the number of livestock or remove them over winter. eg. Environmental Stewardship Scheme
how are the following edaphic factors measured
- soil texture
- soil moisture content
- mineral ion content
- humus content
- mineral matter content
- soil pH
- temperature of soil
- air content
- depth of soil
- Pass dry soil through sieves of different mesh to find composition of gravel, sand, clay
- Drying soil to constant mass
- Conductivity of a soil solution
- Mass lost by heating dry soil to burn off organic matter
- Mass left after organic matter is burnt off dry soil
- pH of soil water, using pH meter, universal indicator paper or solution
- Temperature probe
- Add known volume of soil to water, stirring to drive off air. The expected volume of soil + water = actual volume of soil + water = AC
- Soil auger or cut a soil profile with a spade
how can one calculate the energy in:
- secondary production*
- consumption*
- food absorbed*
E <em>biomass</em> = E consumed - E respired - E excreta - E egesta
the length of the food chain is limited by these losses, energy converted to biomass in consumer = secondary production. Energy is lost in metabolism, mainly in respiration.
E consumed = E biomass + E respired + E excreta + E egesta
E <em>food absorbed in alimentary canal </em>= E consumed - E egesta
how can ABIOTIC FACTORS be divided
climatic eg. temperature range, precipitation
edaphic eg. features of the soil
topographic eg. altitude, aspect, gradient, shape of the land
how can one sample using a belt transect
Place a quadrat along the transect, count the species inside the quadrat, giving a frequency.
(A qualititative ACFOR scale: abundant, common, frequent, occasionally, rare, N for none)
Use an identification key
how can one study succession most easily
Usually difficult bc it happens over time, however
SAND DUNES
because they constantly shift, tf those nearest the shore are youngest. As one moves away from sea, the dunes are older.
how can the proportion of polymorphic gene loci be measured
+ what does the result infer
number of polymorphic genes / total number of loci
eg. 2 / 8 = 0.25, tf a quarter of the gene loci are polymorphic
* The greater the proportion of polymorphic gene loci, the greater the genetic biodiversity within the population because there are greater differences in the alleles among individuals in the population.*
what does a pyramid of numbers and a pyramid of biomass
Numbers: shows the relative numbers of individuals at each trophic level eg. by length of bar
whereas, Biomass shows relative amount of biomass at each trophic level eg. by length of bar
how can population growth be summarised
It changes in a population over a period of time.
The population will grow exponentially if:
> the species enters an unoccupied area
> there is no food shortage
> there are no predators
The population will then always reach an equilibrium
how do farmers ensure plants can uptake more N2
PLOUGHING; increases drainage + aeration,
reducing anaerobic conditions, reducing their growth on farmland
how do farmers control disease/predation in their artificial ecosystems
PLANTS: fungicides, disease-resistant GM crops
fencing to exclude grazers such as rabbits/deer, using pesticides to kill insect pests/slugs etc. pest-resistant GM crops
ANIMALS: antibiotics/vaccines
ranching control predators eg. wolves + are extensive systems
intensive systems- eg. keeping animals in sheds
how do farmers maximise energy input for maximising secondary production
plant - Optimum planting distances between crop plants, light in greenhouses on overcast days, early seeding
animal - providing good-quality feed, high in energy so not wasted in excretion
how do farmers maximise growth of livestock and crop plants
Livestock (primary consumers)
Provide food supplements eg. vitamins/minerals, selective breeding for fast growth (kill just before adulthood)
Crop plants (producers)
Provide water (irrigation), fertilisers (containing NPK + other elements eg. S), selective breeding for fast growth, CO2 pumped into greenhouses, crop rotation
how do farmers reduce competition + energy loss in their agriculture
CROP PLANTS/PRODUCERS
Ploughing + herbicides for weeds
Selectively breeding plants that maximise energy storage in edible products eg. seeds, fruits, tubers
LIVESTOCK/PRIMARY CONSUMERS
Control competitors eg. rabbits, deer
Animals kept in thermostatically-controlled sheds, less energy lost in movement/maintaining body temp.
how do humans affect biodiversity
Deforestation, agriculture + climate change due to human population growth requiring housing, industry and farming.
how do the words habitat, niche, population, species & community interact
SPECIES is a group of organisms interbreeding to produce fertile offspring. A group of the same species in a give space is a POPULATION, and they inhabit a HABITAT, a place within the ecosystem. NICHE is where they live and how they live i.e. which specific factors influence it; only one SPECIES inhabits a niche, often the role of the organism within an ecosystem.
A COMMUNITY is a group of POPULATIONS interacting in a habitat/ecosystem.
how does succession progress
Succession begins with low mineral ions due to farming/new land/no soil profile, then seeds/roots grow from previous crops etc., followed by herbaceous shrubs/plants (high leaf area = increasing NPP) then trees (large tress = decrease in NPP due to more dead parts/non-photosynthetic tissue = less photosynthesis compared to rate of respiration)
Increased plant biodiversity = more niches for animals, increasing index of diversity, then stabilises and decreases as trees shade areas, decreasing herbaceous abundance. Mineral ion content increases as humus/decaying matter increases and microorganisms release minerals from it. SUBCLIMAX COMMUNITY HAS HIGHEST PRODUCTIVITY.
Will also reduce mineral ion content due to large trees shedding fewer leaves for decay/humus/microorganisms.
how does agriculture affect the environment and what is its effect on biodiversity
To feed growing populations, monocultures are established.
- DEC. as only a few species are farmed
- Deforestation + removal of hedgerows to allow for large farming machinery- loss of habitats/plant species eg. for mice, hedgehogs, birds, invertebrates etc.
- Herbicides/pesticides dec. species diversity
- M supports v few species
how does <strong>intraspecific competition </strong>affect population size
Organisms of the same species competing for the same resources. Population ‘booms and busts’ as it moves towards and away from/fluctuates around the CARRYING CAPACITY; the maximum stable population size of a species that an ecosystem can support
how is genetic biodiversity measured
By measuring polymorphism; polymorphic genes have more than one allele at a locus.
The greater the proportion of polymorphic gene loci, the greater the genetic biodiversity within the pop.
eg. Multiple alleles; blood groups IA IB IO
* Dominant/recessive A, a*
how is genetic biodiversity reduced, and what occurs if it is
In isolated populations, GB is often decreased eg. in captive breeding programmes, leading to problems from in-breeding.
In Ecology, what is reclamation
restoring ecosystems that have been damaged/destroyed
In the Carbon cycle, what is the unnatural route?
What do Saprotrophs do to decaying matter.dead organisms?
Dead matter forms sediment and under special geological conditions becomes fossil fuels. These are mined by humans and combustion returns large quantites of CO2 to the atmosphere.
Convert it to humus in the soil (dead organic material, formed from leaves, plant & animal material by soil microorganisms)
name a Seed Bank & its aim/uses
Kew Millenium Seed Bank Project
-aims to store a representative sample of seeds from every known species of plant
- AIMS: to maintain viability of seeds, tf kept in cold/dry conditions. Samples are periodically germinated to test viability.*
- USES:*
- Provide food crops + building materials
- Maintain genetic biodiversity in wild species of crop
- For habitat reclamation/repopulation of endangered habitats
name the 3 factors limiting PG that are density independent or both
Independent- climate
both- shortage of food, water, oxygen
lack of light
name the 5 limiting factors for PG that are density dependent
- Predators- critical to carrying capacity
- Lack of shelter
- disease
- Accumulation of toxic waste
- Psychological factors eg. overcrowding. reluctance to breed
name the 5 phases of the population growth curve
LAG
LOG
PG DECELERATES
STATIONARY
DECLINE
name the 8 methods of regulating sustainable fisheries
- exclusion zones
- limiting boats
- banning in season
- nets/hook rules
- quotas
- inspection of catches
- restocking
- ecosystem approach: no trawlers, no-catch zones, leave oldest fish + youngest fish
name the BIOTIC factors in an ecosystem
- Members of a food chain- producers, consumers (10, 20, 30), decomposers
- Competition- intraspecific, interspecific
- Cooperation- intraspecific, interspecific
- Parasitism
- Predator-Prey
name ways of catching insects for sampling from long grass, trees and river beds
long grass; sweep net, used to catch insects from long grass + crops
trees; tree beating or bushes, a large white cloth is placed under the tree
river beds; kick sampling- net is placed downstream, current carries material into the net, including organisms living in river bed
On a xerosere eg. bare rock, name the seral stages, the plants that grow at that time + the abiotic changes incurred
Abiotic factors dominate.
- PIONEER SPECIES eg. lichen. Simple soil forms
- eg. dominance by moss/small hardy plants an increase in organic matter + mineral particles, increase in moisture retained, shading = lichen outcompeted
- MID-SUCCESSION eg. dominance by herbaceous plants/shrubs soil build up, pH decreases as humic acid increases from humus in soil
- SUB-CLIMAX COMMUNITY eg. dominance by tree seedlings. increase in soil profile, increase in moisture, rate of change of species is rapid
- CLIMAX COMMUNITY eg. mature woodland. increase in shade, smaller trees/shrubs outcompeted
Biotic factors dominate.
STAGE 4 for nitrogen-fixing bacteria in the Nitrogen cycle
Nitrogen-fixing bacteria reduce atmospheric N2 to NH3, using nitrogenase enzyme.
Two types of N-F B:
- Free-living bacteria; bacteria living soil, 90% of N2-fixing eg. Azobacter
- Bacteria in root nodules of leguminous plants eg. Rhizobium
STAGE 1 for nitrifying bacteria in the Nitrogen cycle
ammonification & putrifaction
The nitrogen in plants and animals re-enters by -death -excretion + egestion and is broken down by decomposers/bacteria which carry out “ to form NH3 (usually proteins & aas released into soil which are broken down).
STAGE 2 for nitrifying bacteria in the Nitrogen cycle
Nitrification = oxidation of ammonia to nitrite NO2-by Nitrosomonas. then oxidation of nitrite to nitrate NO3-by Nitrobacter.
Nitrates are very soluble and are easily taken up by plants- soil fertility INCREASES
STAGE 3 for denitrifying bacteria in the Nitrogen cycle
- denitrifying bacteria remove the nitrates from the soil by converting it into atmospheric nitrogen NO3- → N2*
- these bacteria are facultative anaerobes; they can use NO3- instead of O2 to carry out the equivalent of resp. on an ETC*
- tf they thrive in anaerobic conditions/water-logged soil*
what are the aims of CITES
Convention on International Trade in Endangered Species
- Regulate/stop trade in endangered species
- Make killing of endangered species illegal
- Limit trade in less endangered species i.e. only w/ a permit/licence
- Trade in products** of endangered species **illegal
- Stop trade in wild plants for commercial purposes
what are the axes for a population growth curve and what is the maximum called
x axis = time
y axis = population size
The carrying capacity is the maximum the population grows to
what are the effects of the following abiotic factors on adundance and distribution
- Temperature
- pH
- Depth of water
- Flow rate
- O2 conc.
- Turbidity
- Dissolved solid eg. conc. of ion
- Light intensity
- Type of subtrate
- Temp. range determines the species which can survive
- Many species cannot survive in waters of low pH
- Determines size of fish that can survive
- Some species prefer high flow rates, others cannot survive
- Few species survive low O2 conc.
- Makes vision difficult for predators
- Ions provided for physiological processes
- Influences rate of photosynthesis of submerged plants
- eg. species burrows in mud, woodlice survive under stone
what are the two types of food chainnn
Grazing chain- based on living plants
Decomposer or detrital chain- based on dead plant material
what are the two levels of primary productivity
gross primary productivity (GPP)
The rate at which the solar energy absorbed by the plant is converted to chemical energy. Normally 1%
net primary production (NPP)
NPP = GPP - respiration
Some of GPP is lost in respiration, leaving energy stored in the biomass of producers (NPP), which is the energy available to the next trophic level
what are the types of non-random/selective sampling
- opportunistic*
- systematic*
- stratified*
what are the two types of belt transect
continuous belt transect
-place the quadrat all the way along the tape measure
interrupted line transect
-place the quadrat at fixed intervals along the tape measure
what are density dependent and density independent factors
Factors that limit population growth.
Density dependent depend on the number of individuals present in the population.
Some factors can be both, depending on the species and its environment.
what are producer+consumers and predators+prey
Producer: green plants that produce organic material by the process of photosynthesis
Consumer: animals feeding on plants or other animals- they can be Predators: an animal that lives by killing and eating other animals or Prey: an animal hunted or seized for food, especially by a carnivorous animal
what happens to the net primary productivity
Energy + biomass are transferred along the food chain as carnivores consume food. The energy that remains is incorporated into the biomass of the consumer = secondary production/productivity.
eg. if net primary production of grass = 21,135, food eaten is 3,153, and heat loss in respiration = 1,020 faeces = 1,970 urine would be 38 kJm-2yr-1 and energy efficiency = 3.964%
Energy + biomass are lost at every trophic level by:
Egestion, excretion, respiration, death.
what happens when abiotic factors are optimum and when they are not ideal
WHEN OPTIMUM FOR THAT SPECIES: organisms can grow fast/rate of reproduction increase/is more successful.
eg. when temp. of organism’s surroundings is ideal, does not use energy to maintain core temp. but for growth/reproduction/seeds- pop. size increases
CONDITIONS NOT IDEAL- organisms grow more slow/reproduction is less successful.
eg. is temp. of surroundings sig. higher or lower than their optimum body temp., they use a lot of energy to maintain core temp, less for growth/repro., pop. size decreases
what is a keystone species
A species that has a disproportionate effect on its environment relative to its adundance (often a top predator). If this species is removed, the ecosystem changes dramatically and may cause other species numbers to change. eg. wolves in yellowstone park.
what is an abiotic factor
A non-living condition/thing, as climate or habitat, that influences or affects an ecosystem and the organisms in it.
what is an ecosystem
The sum total of biological life + non-biological components within an area i.e. biotic + abiotic components, which are interacting and where energy flows in food chains/webs and nutrients cycle eg. C, N, minerals, water.
what is a decomposer
A heterotrophic microorganism that breaks down dead organic matter to simpler organic/inorganic matter.
what is a detritivore
Organisms that break down/feed on detritus i.e. Dead organic matter. into simpler molecules for decomposers. They preceed decomposers in the process of decomposition.
what is a pooter (2)
A sampling technique: one tube pointed at invertebrate, the other one inhales with, invertebrate enters jar
what is a transect, from which you can sample
how do you sample
A line across a habitat made by a long tape measure.
Species which touch the transect/tape are counted.
what is dry biomass + how is measured
Dry biomass is an accurate measure of the organic material in organisms/living things.
Dry the organisms in an oven at 80’C. Weigh sample until mass remains constant
(not practical for higher trophic levels)
what is rAnDoM SaMpLiNg and what are the adv/dis of it
- Random coordinates are generated to choose which sampling sites to use, and a portable global-positioning satellite to find exact positions of #s.
- Random number tables for where to place quadrat within specified area.
- Data are not biased by selective sampling, but it may not cover the habitat equally, leading to under/overestimation of biodiversity because a high presence/low presence is missed.
- Each individual has the same probability of being selected.
what is the definition for conservation
Maintenance of biodiversity through human action + active management.
eg. Forests managed as a sustainable source of timber; controlled grazing.
what is the definition for preservation
Protection of an area by restricting/banning human interference. Visitation is not allowed except for those who monitor the area.
eg. Galapagos islands, Virgin caves, marine conservation zones
what is the difference between a herbivore, a carnivore and an omnivore
An animal feeding only on plants only compared to one that feeds on other animals, and one that eats both animals and plants.
They create a food chain, i.e. a linear sequence of eating and being eating. Interacting chains = food web.
what is the difference between a sustainable resource, sustainability & sustainable management
what is the difference between bacteria cultured separately and cultured together
Cultured separately = they have normal growth curves. One grows more rapidly than the other.
Cultured together = One experiences a high rate of growth, whilst the other has an initial increase followed by negative growth- they have similar niches and the ‘competitive exclusion principle applies- abiotic factors favour one species over the other.
what is the difference between in-situ and ex-situ conservation
& examples
IN-SITU: active management to maintain biodiversity in the natural environment
- eg. wildlife reserves, marine conservation zones*
- nature reserves, natural parks*
EX-SITU: conservation outside the normal environment of the species
(plants are easier to conserve e-s because as part of their life cycle, they have a dormant stage/seeds)
eg. captive breeding programmes, zoos
botanical gardens, seed banks
what is the difference between species diversity, habitat diversity + genetic diversity
- Habitat diversity:* number of different habitats in an area
- Species diversity:* number of different species and relative abundance in an area
- Genetic* diversity: variety of alles within a species (or pop. of species) in an area
what is the Simpson’s Index of Biodiversity
A measure of species biodiversity - (including evenness+richness), carried out by taking a sample and/or animals in an area.
what is the biosphere & biome
Biosphere; inhabited part of the Earth
Biome; life-zone determined by temperature & rainfall, characterised by the dominant plant species present (plant species may determine animal life present in biome because the producer starts the food chain, all other energy is gathered from it)
what is the difference between conservation & preservation
CONSERVATION: recognises that humans need to live within ecosystems + interact with other species
PRESERVATION: recognises that nature has intrinsic values which are diminished by the presence of humans. All species should be conserved regardless of whether they are of value or harmful to humans. Protection of ecosystems = protection from encroachment by humans.
what is the Maasai Mara and how does it work?
The Maasai Mara is a national reserve in Kenya, supporting a large area of grassland/savannah, for populations of cheetah, wildebeest, zebra, lions.
Traditionally Maasai people raised livestock, such as cattle, for a living. This led to overgrazing, destroying grassland for wildlife.
Conservation trusts work with Maasai people to make money through conservation/ecotourism projects to meet their economic needs, and teach sustainable farming for ecological needs.
what is the result of the burning of fossil fuels and what is the effect on biodiversity
- An increase in global temperature, acid rain destroying forests, sea levels causing loss of land/habitats*
- Loss of ice caps/habitat*
- # of Non-drought species decrease, animals feeding/dependent on them decrease
- Salt water moves upstream in rivers, decrease habitats for freshwater species
- Extinction of polar species
what is the result of deforestation
what is its effect on biodiversity
Deforestation leads to loss of forests/habitats to provide wood for fuel/construction + create space for construction/agriculture.
- decrease in # of trees, habitats, food sources, potential medicines
- #s of animals dependent on trees decreases
- animals migrate to nearby ecosystems
what is the Terai Arc and how has management led to a balance between conservation/preservation & human needs
An area of forest/grassland on the border of India/Nepal.Endangered species inhabit it eg. Bengal tiger, Asian elephant. 7 million people inhabit it too.
Areas of the forest are destroyed for housing/development + humans uses forest resources to survive. This leads to destruction of habitat, and brings animals/humans into closer contact eg. elephants tramping crop fields/tigers killing livestock and being shot.
WWF conservation charity work with locals to bring them solar cookers/biogas generators to reduce usage of wood from the forest. They encourage farmers to plant mint hedges around crops to keep animals away bc they dislike the taste of mint!
what is autotrophism + heterotrophism
A process of obtaining carbon from CO2 using energy from light or chemical reactions.
Heterotrophs obtain carbon from the breakdown of organic compounds.
what is BIODIVERSITY
The variety of different organisms in an area.
Levels: species diversity, habitat diversity, genetic diversity
what is biomass
Total quantity of dry mass in organisms, commonly measured for a trophic level, a population or a community inhabiting a certain region.
what is deflected succession
Succession deflected/arrested directly or indirectly due to human activity.
eg. agriculture, grazing, burning, conservation management, mowing. Acidic conditions (climate change) can deflect communities- acid soil/peat results in moorland.
leading to a sub-climax community called a plagio climax.
how does interspecific competition affect population sizes/growth
Organisms of different species compete for limited resources eg. red/grey squirrels for food sources/habitats in the UK.
This reduced the resources available to both pops., leading to population sizes reducing because there is less energy for growth/reproduction.
It also affects distribution of species, i.e. if one species is better adapted to its surroundings than the other, it will out-compete the less well adapted species- cannot exist alongside it because it has a lower chance of survival.
what is opportunistic sampling and give its advs/disadvs.
A type of selective/non-random sampling, Choice of sampling sites is based on prior knowledge/research eg. deliberately sampling an area with species X, or because subjects are easily accessible eg. questioning passing people in a pilot study.
Placing the quadrat where you feel/know is best/easiest.
- It is quicker/easier/cheaper
- Can lead to over/underestimation due to small sample size, bias. A large proportion of the population is excluded.
What is predation and what effect does it have population size
= where an organism/the predator kills and eats another organism/ the prey
eg. lions killing and predating on buffalo
The population sizes of predators and prey are interlinked- as the pop. of one changes, it causes the other to change.
what is primary succession
+ types: xerosere, hydrosere, psammosere, halosere
Succession that occurs on bare rock (newly formed land). eg. due to cooled volcanic lava, a sand dune, river delta/retreating lake.
Initially there is no soil profile.
Sere = where succession occurs.
- Xerosere =* succession on dry land (pioneer species is xerophytes)
- Hydrosere =* succession originating on water (“ hydrophytes)
- Psammosere* = sand dunesHalosere = salt marshes
what is secondary succession
Succession on soils that have already been formed but have suddenly lost their community.
eg. due to fire, harvesting/fallow fields
Secondary S is much quicker than 10 because soil is already present.
what is stratified sampling and give advs./disadvs.
A type of non-random/selective sampling. Dividing a habitat into areas that seem different, sample each separately. Strata should be mutually exclusive, individuals should be assigned to one stratum only. Individuals are then randomly sampled from the strata.
<strong>Sample in the different area/vegetation of a habitat.</strong>
> All areas sampled- species not under-represented
> possible over-representation i.e. disproportionate #s because small areas look different
what is succession
The progressive change, over time, in the composition of a community of organisms from initial colonisation by a pioneer species towards a largely stable climax community.
what is <strong>systemic sampling</strong> and give its advs./disadvs.
A type of non-random/selective sampling.
Samples are taken at fixed intervals across a habitat- line/belt transects.
<strong>Sample every <em>n </em>metres along a line/belt transect.</strong>
> Useful in showing a gradient across a habitat of an environmental factor eg. drier further away from a pond/the sea.
> Only the species on the line is recorded, and species may be missed leading to an underestimation of biodiversity
what is trophic level
A stage in a food chain at which organisms obtain their food in the same general manner.
what occurs during the deceleration, stationary & decline phases
3.POPULATION GROWTH DECELERATES
Environmental resistance increases i.e. limiting factor increases, increasing death rate or inhibiting birth rate.
4.STATIONARY PHASE
birth rate = death rate
(if applicable, immigration rate = emigration rate, i.e. equilibrium reached) = carrying capacity, the maximum pop. size that can be maintained in a habitat
5.DECLINE PHASE
If/Due to limiting factor eg. new predator, unfavourable climate, natural disaster, accumulation of toxic waste eg. in yeast in closed system
what occurs in the LAG + LOG phases
Lag: reproduction begins. Slow because few individualsare present and may be widely spaced and acclimatising to the environment, leading to a decreased rate of reproduction. Some components required for growth may not yet be at optimum conc. eg. primary metabolites.
Log: rapid/maximum growth rate under optimum conditions. i.e. There is no environmental resistance. Birth rate > death rate. Struggle for existence is low, survival is high. The species realises its full reproductive potential.
what were the aims of the Countryside/Environmental Stewardship Scheme
- Sustain the beauty/diversity of the countryside
- Improve, extend + create wildlife habitats
- Restore neglected land + conserve archaeological & historical features
- Improve countryside enjoyment by public eg. creating footpaths
- Giving money to farmers to manage their land with biodiversity in mind
what were the aims of the Rio Convention for Biodiversity
- Provide guidance to governments on how to conserve biodiversity
- Promote sustainability
- International sharing of/access to genetic resources/benefits from them
- Sharing of scientific knowledge/discoveries
what apparatus is used to sample plants
QUADRAT: ‘frame’ or ‘point’
- frame is 0.5m, split into smaller squares. Each square/25 is worth 4%.*
- point has two vertical legs, pin inserted to find smaller areas*
where in a food chain is energy transfer least efficient
SUN → PRODUCER
where is nitrogen found in the ecosystem, and how is it obtained by animals and plants
Proteins & nucleic acids contain N, which are found abundantly in living organisms.
Animals consume plants/animals, whilst plants obtain it from the soil. The availability is highly dependent on the action of bacteria in the soil.
which characteristics show continuous & discontinuous variation
SINGLE GENE/ monogenic = dis__continuous variation due to very limited number of variants
MANY GENES/ very polygenic = continuous variation because large number of phenotypes
Environmental influences may also affect phenotype
which terms are used to discuss energy transfer through a food chain
The rate at which energy flows through the food chain = productivity
Energy enters the food chain through the producers
The rate at which energy is stored by producer in the form of their biomass = primary productivity
why do ecosystems have the potential to be self-supporting
The interrelationship between producers, consumers + decomposers eg. producers/green plants need the Sun for energy, all other organisms need the producers, who also depend on decomposers + weathering of rocks for their supply of inorganic nutrients.
All ecosystems influences by nearby ecosystems.
why does population size vary 1
Due to abiotic factors i.e. non-living features of the ecosystem.
- light intensity
- water/shelter availability
- temperature
- chemical composition of surroundings eg. soil pH
eg. because there’s only enough shelter for a certain # of individuals
why does population size vary 2
Due to BIOTIC FACTORS
- interspecific competition- reduces q of resources available to species
- intraspecific competition
- predation (predator and prey population sizes are linked)
why is the Simpson Index effective
because it takes into account the species richness and species evenness, i.e. the number of different species and their relative numbers
- IMAGE: A : high evenness, high richness- higher biodiversity*
- B : high richness, low evenness*
why is genetic biodiversity necessary (5)
Genetic biodiversity will lead to survival of the species; Individuals have little variation in their DNA. A population has different versions of a gene; alleles; creating diversity within the pop. The more alleles present, the more genetically diverse.
These pops. can adapt to changes in their environment, tf less likely to become extinct bc some organisms will likely carry an advantageous allele, enabling them to survive eg. a fatal disease, and reproduce.
