Ecosystems Flashcards
what is an ecosystem
- all organisms living in a certain area
- dynamic system
- self-contained community of interacting organisms and the environment they live/interact in
- flow of energy + nutrients
- abiotic and biotic factors
what are biotic factors
- living features of the environment
- predators, competition, disease, mankind
what are abiotic factors
- non living features
- water, light, temperature, humidity
what are the impact of factors on rock pools
Biotic
- seaweed acts as a food source for consumers
- intense competition for food can limit no. organisms present
Abiotic
- influenced by tides
- hight tide = submerged by ocean
- low tide = extreme conditions
what are the impact of factors on a playing field
Biotic
- producers attract organisms to use them as a food source
Abiotic
- rainfall / sunlight affect growth
- very wet = waterlogged soil
- poor plant growth = decrease number of consumers the ecosystem can support
what are edaphic factors
- soil factors
- provides minerals for growth
- water for photosynthesis
- anchorage for roots
what is biomass
- mass living material of the organism or tissue
- chemical energy stored within
how to measure biomass
- dry mass
- mass of carbon it contains
- chemical energy content of the organism when burned in pure energy
what is dry mass
- mass of an organism/ tissue after all water had been removed
- used to calculate the total biomass of a total population of organisms
what is calorimetry
- estimate chemical energy stored in biomass
- burning sample of dry biomass in a piece of equipment
- burning sample heats a known volume of water
- change in temperature of water provides an estimate of chemical energy
how is energy transferred through an ecosystem
- energy enters through photosynthesis
- primary producers convert light energy to chemical energy
- storing the chemical energy as plant biomass makes a certain amount of energy available to the next trophic level
- energy transfers through trophic levels
where does the energy go
- 60% of available energy not taken in
- plants cannot use all light energy that reaches the leaves
- some light hits bark
40% absorbed
- 30% lost to the environment
- 10% becomes biomass
how do human activities increase the transfer of energy
- herbicides kill weeds - reduce competition means crops receive more energy
- fungicides kill fungal infections that damage agriculture - crops use more energy for growth
- fertilisers provide crops with minerals needed for growth
what are saprobionts
- decompose waste and dead matter via extracellular digestion
- inorganic ions available to other organisms
- ammonification
what is nitrogen fixing bacteria
- convert atmospheric nitrogen gas into nitrogen containing compounds
- forms ammounium ions in soil
what is nitrifying bacteria
- convert ammonium ions in the soil to nitrogen compounds that can be used by plants
- convert ammonium ions into nitrites
what is denitrifying bacteria
- uses nitrates during respiration
- release nitrogen gas
what is mycorrhizal fungi
- increase surface area of root systems
- help plats absorb water and scarce mineral ions from soil
what are the stages of the nitrogen cycle
- nitrogen fixation
- ammonification
- nitrification
- denitrification
what is the process of nitrogen fixation
- nitrogen gas in the atmosphre is turned into ammonia by bacteria
- ammonia used by plants
- Rhizobium found inside root nodules and form a mutualistic relationship with plants - provide plant with nitrogen compounds
what is the process of ammonification
- nitrogen compounds from dead organisms are turned into ammonia by decomposers to form ammonium ions
- animal waste contains nitrogen compounds
what is the process of nitrification
- ammonium ions in the soil are changed into nitrogen compounds then used by plants (nitrates)
- nitrifying bacteria (Nitrosomonas) change ammonium ions into nitrites
- Nitrobacter change nitrites into nitrates
what is the process of denitrification
- nitrates in soil converted into nitrogen gas by denitrifying bacteria
- use nitrates in the soil to carry out respiration and produce nitrogen gas
what is the process of the carbon cycle
- carbon is absorbed by plants when they carry out photosynthesis
- carbon passed on to primary consumers
- eat plants and passed to secondary
- carbon compounds in dead organisms are digested by microorganisms called decomposers
- carbon is returned to the air for respiration
what is succession
- process by which an ecosystem changes over time
Primary = happens on newly exposed land
Secondary = happens on land cleared of all plants
what are the stages of succession
- pioneer species colonise a new land surface
- harsh abiotic conditions
- pioneer species change abiotic conditions - die and microorganisms decompose the dead organic material
- basic soil formed
- conditions less hostile
- as succession goes on the ecosystem becomes more complex
- new species move alongside existing species
- biomass increases
what is a climax community
- ecosystem supports the largest and most complex community of plants and animals
example of primary succession
- pioneer species colonise rocks
- lichens grow and break down the rocks releasing minerals
- lichens die and decompose to form a new soil
- soil thickens as organic material grows
- larger plants that need more water can move in as soil deepens
- soil deepens as larger plants die and decompose
- shrubs and trees grow
how can succession be managed
- human activities can prevent effects
- regularly mown lawn won’t develop woody plants
how to manage succession - conservation
- protecting an area from reaching a climax community
- ecosystems at an intermediate succession stage
- hold distinct diversity
how to prevent succession
- grazing animals introduced temporarily
- managed burning - controlled fires burn away shrubs and trees to reset succession process
