Ecosystems and succession Flashcards
why the biomass of phytoplankton less than zoo plankton
phytoplankton reproduce at a rate which is greater than their consumption
advantages of using an organic fertilizer
greater range of nutrients
nutrients released slowly
improves soil quality adds humus adds microbes and improved the soil structure
improves water holding capacity of soil reducing leaching
improves soil aeration
already available
advantages of using inorganic fertilizer
known nutrient content fast acting nutrients distributed evenly no pests contained better to handle store and transport concentrated in nutrients applied using light machinery avoids soil compaction
how deforestation leads to a decrease in diversity of organisms
removal forest removes habitats ecological niches shelter
reducing the number of species that can exist in that area
how deforestation changes levels of CO2
increases
reduced amount of CO2 used in photosynthesis
increase CO2 produced in combustion and decomposition
decreases
less respiration
by plants animals decomposers
units for energy transferred bet trophic levels
KJm-2 year-1
difference in the amount of solar energy reaching the primary producer and the energy in the biomass of primary producers
light reflected light misses a chlorophyl wrong wavelength respiration inefficiency of photosynthesis
explain the affect of sodium nitrate on the growth of the plant
the nitrate places the nutrients already removed
nitrate needed for protein AA production
more fertiliser more growth more yield
why a large volume of insecticide was found in ladybirds
greenflies take in insecticide from plant
ladybirds eat many greenflies
bioaccumulation
insecticide cannot be excreted remains in body stored as fat not broken down
factors which make effective pesticides
SPECIFIC- only toxic to organisms its directed harmless humans nat predators earthworms pollinating bees
BIODEGRADE - once applied breakdown harmless substances in soil and chemically stable - long shelf life
COST EFFECTIVE -dev costs high new pesticides only useful short time - genetic resistance
NOT ACCUMULATE -not build up specific parts organism or passes along food chain (BIOACCUMULATION)
integrated control
choosing variety suit local area and pest resistant as poss
suitable habitats close crops for nat predators
reg monitoring crops- signs of pests early action can be taken
remove pests mechanically if exceed the level
using biological agents if necc and available
why are integrated pest control systems good
effective
min impact on enviroment
equation for net productivity
net = gross - respiratory losses
what is net productivity
chemical energy stored in the plant from sunlight
what is gross productivity
the rate at which plants assimilate chemical energy from photosynthesis
monoculture
large area of land where only 1 type of crop is grown
how does factory farming increase energy conversion rate
movement restricted- less E used muscle contraction
environment kept warm- reduce heat loss
controlled feeding -opt food max growth no wastage
excluded predators- no loss other organisms in food web
other means of improving E conversion rate
selective breeding-more eff converting food into body mass
hormones to increase growth rate
why the biomass of primary consumers is less than the biomass of producers
loss of energy and heat -
respiration and movement
loss of mass -excretion
less energy left to sustain a higher level
more inedible parts
biomass
total mass of living material in a specific area at the same time -usually measured as dry mass - amount of water in an organism very variable
Farming practices which reduce species diversity
(direct) Removal of hedgerows and woodland monocultures-grass cereal crops filling in ponds and draining wetlands over grazing of land - sheep--> preventing regeneration of woodland
(indirect)
pesticides inorganic fertilisers- reduce diversity, polluting water courses
escape of farm waste into water courses
absence of crop rotation- poor soil structure
species diversity
the number of different species and the number of individuals of each species within one community
conservation
methods of painting a ecosystem and the living organisms which occupy them. Best use of resources while preserving natural landscape and wildlife.
conservation techniques
Maintaining existing hedgerows ( height and shape)
planting hedges not hedges
maintaining existing ponds
leaving wet corners of fields
planting native trees on land with a low species diversity
use biological control
organic fertilisers
crop rotation using a nitrogen fixing crop not fertilisers to improve soil fertility
natural meadows
leaving cutting of field edges until after flowering and seeds dispersed
nitrogen fixing
incorporating atm nitrogen gas into organic nitrogen containing compounds
lightning
industrial processess
free living and mutualistic bacteria
efficiency of energy transfer equation
energy transfer = energy after transfer/ energy before *100
nutrient cycle simple sequence
Nutrient taken up producers as simple inorganic molecules
producer incorporates the nutrient into complex organic molecules
producer eaten nutrient passes to consumers
producers and consumers die- complex molecules broken down by saprobiotic microorganisms release nutrient in its original simple form
factors which increase global levels of CO2
Combustion of fossil fuels - coal oil peat releases CO2 locked up within theses fuels
Deforestation (esp rainforests) removed photosynthesising biomass –> less CO2 removed from atm
How saprobiotic organisms break down animals and plants
secrete enzymes onto dead organisms– enzymes break down complex molecules into SMALLER SOLUBLE molecules absorbed by diffusion + carbon released as CO2 respiration of sapmic
climate community
stable state
balanced equilibrium of species few new species replacing the ones which have been established
why is biodiversity at its peak mid succession
decreases as climax community is reached
dominant species outcompete pioneer and other species
eliminated from community
features of succession
non living environment less hostile -nutrients shelter
greater number and variety of habitats
increased biodiversity - peaks mid succession
complex food webs
increased biomass
“Succession occurs in natural ecosystems. Describe and explain how succession
occurs.”
- Colonisation by pioneer (species);
- Change in environment enables other species to colonise/survive;
- Change in diversity/biodiversity;
- Stability increases / less hostile environment;
- Climax community is reached.
“Mowing was also found to affect the number of insect species found on a roundabout.
Use your knowledge of succession to explain how.”
1 Mowing prevents growth of woody plants by cutting off growing point.
2 The longer the interval between mowing, the further succession can
progress.
3 With frequent mowing diversity of plants will be less and so fewer insect inhabitants/niches are available;
Disadvantages with using protected areas to conserve habitats?
National parks are also used as tourist destinations (so theyre funded by the revenue from the tourists that visit).
How can habitats in protected areas be managed to conserve them.
Coppicing/cutting down trees in a way that allows them to grow back so they do not need to be replanted.
What is habitat conservation and how do you do it.
Protected areas like national parks protect habitats and the species in them.
By restricting urban and industrial development and farming.
conservation of organisms by relocation…
- Relocating a species involves moving a population of a species to a new location because they are under threat.
- the species is moved to an area where they are not at risk but with a similar environment to the one it came from so that it can survive.
Disadvantages of relocation
Native species in the new area may be out competed by the new species that are moved in and so the native species then become endangered.
How animals can be conserved using captive breeding programmes
Captive breeding programmes involve breeding animals in controlled environments.
Disadvantages of captive breeding programmes?
Animals can have problems breeding outside their natural habitat.
When the animals are reintrodiced into the wild they could bring new diseases to habitats; harming the other species living there.
How fish species can be conserved using fish quotas
Fishing quotas are limits to the amount of certain fish species that fisherman are allowed to catch.
Disadvantages of fishing quotas?
Many fisherman do not agree with the scientists who say that fish numbers are low.
Some think introducing quotas will result in job losses.
How plants can be conserved using seed banks
A seedbank is a store of lots of seeds from lots of different plant species.
-So if plants become extinct in the wild, the stored seeds can be used to grow new plants.
Disadvantages of seedbanks?
The Seeds have to be regularly tested to see if they are still viable/whether they can grow into a plant. This can be expensive and time consuming.
What is conservation?
The protection and management of ecosystems involving preventing succession in order to preserve an ecosystem in its current stage.
What are some factors limiting the size of the climax community?
- The numbers of producers providing energy for the food chain.
- The light intensity as it affects the right of photosynthesis.
- Competition for habitat/food
What are the farming effects on succession?
- Crops that are not native plants are planted.
- These compete with native plants
- Ploughing returns the land to bare soil, herbaceous plants are destroyed.
- Grazing by farm animals destroys herbaceous plants too.
What is primary succession?
This happens on land that has been newly formed or exposed. Just bare rock, no soil or organic material.
What is secondary succession?
This happens on land that has been cleared of all plants, but soil REMAINS.
Environmental issues raised by fertilisers
Fertilisers can be washed into rivers and ponds, killing fish and plant life because of eutrophication.
-Using fertilisers changes the balance of nutrients in the soil- too much of a particular nutrient can cause crops & other plants to die.
Economic issues raised by fertilisers
Farmers need to get the amount of fertiliser they apply JUST RIGHT. If they apply too much. money is wasted and excess fertiliser is washed away - eutrophication.
- Too little and productivity wont be increased so less money can be made form selling the crop.
“Explain how the use of pesticides can result in resistant strains of insect pests.”
- Variation exists in pest
population due to mutation; - Allele for resistance is passed on via selection;
- Pests with the resistant allele survive and reproduce
4.Increase in frequency of allele in the population.
“Explain how farming practices increase the productivity of agricultural crops.”
-Fertilisers are added to the soil.
-Pesticides used to prevent damage to the crop.
-Herbicides used to kill weeds to compete with the crops and so reduce competition.
-Ploughing to aerate soil/improve drainage and to allow nitrification to occur.
“Managed ecosystems such as wheat fields are prone to pest infestations. Describe the advantages and disadvantages of using biological agents to control pests.”
Advantages: 1. Specific to one pest 2. Only needs one application. 3. Keeps/maintains low population; 4. Pests do not develop resistance; 5. Does not leave chemical in environment or on the crop. (so no bioaccumulation) Disadvantages: 1. Does not get rid of pest completely; 2. May become a pest itself; 3. Slow acting - takes time to reduce pest population.
“Explain how the intensive rearing of domestic livestock INCREASES net productivity.”
animals are slaughtered whilst growing so more energy is transferred to biomass
-their movement is restricted so less respiratory loss.
-Animals are fed a controlled diet, so a higher proportion of digested food is absorbed.
-They are kept inside so less heat loss.
-They are genetically selected for high productivity.
Rearing Livestock intensively
.
It involves controlling conditions the animals live in and so more of their energy is used for growth and less is used for other activities.
Advantages of intensive rearing
the efficiency of energy conversion is increased so more biomass is produced and productivity therefore increased.
Ethical issues of intensive rearing
some people think the conditions that intensively reared animals are kept in cause the animals pain and distress/ restricts the natural behaviour
advantages of using a pest as control
specific
can reproduce - only 1 application
DOES NOT BECOME A PEST
