ecosystems

ecosystem

all the organims living in a certain arae and all the non-living factors found there

biotic factors

the living features of an ecosytem

abiotic factors

non-living factors of an ecosytem

food chain order

producer-primary-secondary-tertiary consumer

how does energy eneter an ecosytem

mainly through sunlight

producers

store energy as biomass

biomass

mass of living materials

trophiv level

a stage in a food chain that’s occupied by a particular group of organisms

why is 60% of energy not taken in

plants can’t use all the light energy that reaches their leaves, some sunlight hits parts of plants that can’t photosyntheise, some parts of the food not eaten e.g. bones and some parts of the food are indigestible so pass through organisms and come out as waste

how much energy is taken in by next trophic level

10% of the 40% gross product

net productivity

amount of energy available to the next trophic level

net prodcutivity calculation

gross productivity-energy not taken in

%efficancy of energy transfer

net productivity of trophic level/net productivity of previous trophic level x 100

trend in efficancy transfer

tends to increase as you move up a food chain

how to clculate efficancy of energy levels between trophic levels

dry the organism (heat it up to 80 degrees so all the H20 has evaporated) and weigh the organism then multiply the results from the sample to get an estimate of the energy in one trophic leve. The difference in energy between trophic levels is the amount of energy transferred

herbacides

kill weeds that compete with agricultaral crops for energy reducing competition so the agricultaral crops recieve more enrgy so grow larger and faster

fungicides

kill fungal infections that damage crops so that the crops can use more energy for growth not fighting infections

insecticides

kill insects and pests that eat and damage crops so that less biomass is lost from the crops

natural predators

introduced to ecosystems to eat the pest species so crops loose less biomass and energy

fertilisers

chemicals that provide crops with the minerals needed for growth so more energy from one ecoytem can be used for growth

rearing live stock intesley

controlling livestock living conditions and when theyre slaughtred so more of their energy is used for growth to generate more biomass e.g. restrciting their movement

decomposition

a chemical process in which a compound is broken down into its constituent elements

decomposer

an organism that feeds on and breaks down dead plant or animal matter

detritivores

speed up the decay process by feeding on detrivitites breaking it down into smaller pieces

what is nitrogen essential for

making amino acids and nucleic acids.

nitrogen cycle

First, nitrogen fixation occurs where nitrogen fixing bacteria that contain the enzyme nitrogenase like Azotobacter and Rhizobium combine N2 and H2 to form ammonia- which can be taken in by plants. Rhizobium live inside of root nodules on legumes where the legumes take up the ammonia they produce and the rhizobium gets the carbohydrates produced by the plant during photosyntheisis to use as energy (simbiotic releationship). The nitrification occurs the processes by which ammonium compounds in the soil are converted to nitrogen-containing compounds. Nitrification is an oxidation reaction so only occurs in well areated soil. Nitrosomonas oxidise ammonium compounds into nitrites (NO2-). Nitrobacter then oxidises nitrites into nitrates (NO3-). In the absencen of O2 denitrification occurs where denitrifying bacteria convert nitrates in the soil back to nitrogen gas to use as a source of energy for respiration. Decomposers can alos convert nitrogen-containing molecules in dead organisms, feeces and uringe into ammonium compounds via ammonification.

carbon cycle

fossil fuels undergo combustion releasing CO2 into the atmosphere some of which dissolves in the sea. This CO2 can be used by producers for photosnyntheisis and can also release more CO2 in to the atmosphere via respiration. Feeding can pass carbon molecules from producers to the primary consumers when they eat producers and so on. The organisms can die and have their carbon compunds released via decomposition. That carbon is then released into the atmosphere when the decomposers respirate. The dead material can also fossiliez into fossil fuels storing the carbon.

succesion

a process by which ecosystems change overtime occuring as a result of changes to the enviroment

primary succesion

occurs on an area of land that has been newly formed or exposed so has no soil or organic material to begin with e.g. volcanoes erupt depositing lava which cools and forms rocks or sand is blown by wind or deposited by the sea creating a new sand dune or glaciers retreat exposing rock.

secondary succesion

occurs on land where soil is present but there are no plant or animal species

climatic climax

the climax community for a particular climate

seral stages

each stage of succesion

stages of primary succesion

Begins when a new species colonise a new land surface e.g. seeds/spores are blown in and being to grow. The first species to colonise the area is known as the pioneere species and they’re specialised to cope with the harsh abiotic conditions e.g. can fix nitrogen. As the speces dies and microorganisms decompose the humus a basic soil is formed making thr abiotic factors less harsh so new organisms can move in and grow. These new organisms also die and decompose adding more nutrients to the soil e.g nitrates which can be turned into ammonia by nitrogen fixing bacteria to be used by plants so larger plants like shrubs can grow. At each stage new species move in increasing biomass and making abiotic conditions less harsh eventually resutling in a climax community.

climax community

when the ecosystem is supporting the largest and most compllex community of plants and animals it can and is in a steady state

secondary succesion stages

the same as primary succesion but begins at a latyer stage and the pioneer species are larger

pioneere speicies

the first species to colonise an area

deflected succesion

when succesion is prevented via human activity so the plagioclimax that develops is one that is diffrent to any of the natural stages of the ecosystem

plagiclimax

the climax community formed when succesion is stopped artificially