Ecosystems Flashcards
What is an ecosystem
All the interacting living organisms & non-living factors in a particular in a particular area - this is a dynamic system, & varies in size too e.g. a rock field, a playing pool, a large tree
What’s a community
All populations of all species in a particular habitat
What is a population
All the individuals of one slices in a particular habitat
What is a ‘species’
Can reproduce to produce fertile offspring
Biotic vs Abiotic factors
Biotic = living factors that affect it e.g. competition, predation, disease
Abiotic = non-living factors that affect it e.g. light, pH on soil, temp, water & O2 availability
What is a niche
The role of a species in an ecosystem
Types of changes in ecosystems
Cyclical (repeat in rhythm e.g. tides)
Directional (e.g. go in 1 direction, lasting life, like erosion)
Erratic/ Unpredictable = no rhythm / direction (natural disasters)
What is a tropic level
The stage in food chain
Order = producers -> primary consumers -> secondary consumers -> tertiary consumers -> apex predator
What is biomass
The dry mass (without water) of living material in an area / organism
-> we consider this: > mass as water levels can fluctuate within the organism, depending on time of day / year / area
How is biomass measured
Using calorimeters:
- collect the sample, kill the organism, put it in the over @ 80° to remove the water by evaporation & stop once a constant mass has been reached
What are the limitations of calorimeters
- can take a long time to fully dehydrate sample
- precise equipment needed
- heat energy lost by calorimeter & not efficiently transferred
Land animals vs marine animals unit
G/m^2 vs G/m^3
Ecological efficiency formula
(The efficiency with which biomass is transferred between consecutive tropic levels)
How can energy be lost in a food chain
- sunlight reflected so not all used in photosynthesis
- other factors affect photosynthesis rate
- hear energy from respiration
- process of excretion & production of waste materials
- some parts of food not eaten / digested
What is ‘useful energy’
Used to build biomass / body growth
How can we make biomass transfer efficiency of consumers
- Vaccinate animals / provide antibiotic (less energy loss to pathogens)
- Restrict animal movement - less e loss via respiration
- Harvest @ peak times (animals can’t grow anymore as adults so don’t waste e on them)
- Plants planted earlier (longer growing seasons, more light etc)
- Maintain nutrient rich soil (crop rotation)
Decomposers vs detrivores
Decomposers feed on dead organic matter (secrete enzymes, digest externally, absorb matter)
Detrivores different as they digest internally & increase the SA of the matter to inc rate of decomposition
Steps in nitrogen cycl
- Nitrification
- Ammonification
- Denitrification
- Nitrogen fixation
What happens in stage 1 (Nitrification)
ammonium ions -> nitrite ions -> nitrate ions
(Oxidation, therefore requires oxygen (well aerated soils))
Nitrifying bacteria in Nitrification
Nitrosomonas
Nitrobacter
Nitrosomonas action
Ammonium -> nitrite
Nitrobacter action
Nitrite -> nitrate
What happens in Ammonification (stage 2)
Carried out by decomposers
Nitrite / nitrate -> ammonium ions -> ammonia
Denitrification (stage 3) - what happens
Nitrate ions -> nitrogen gas
Anaerobic conditions (as there are water logged soils, so low O2 levels)
Denitrifying bacteria = Pseudomonas
What happens in stage 4 nitrogen fixation
Atmospheric nitrogen gas + 3H2 (g) -> 2Ammonia
- nitrogen fixing bacteria (Azotobacter & Rhizobium)
Nitrogen needed to make amino acids & nucleic acids
Where are azotobacters found
Free living
Where are rhizobiums found
in root nodules
Nitrogen cycle diagram
What is primary succession
A newly formed / exposed land with no species present is gradually colonised by an increasing number of species
This causes the biotic components of the eco system to change over time
What is a pioneer species
The 1st species to colonise the land
-> autotrophic + able to survive harsh environmental conditions
What is a climax community
When the final species colonises land
-> becomes a dominant species in an ecosystem
- most complex & diverse community the ecosystem can sustain
Succession process
1) pioneer species begins to grow
2) this species changes abiotic conditions, therefore less hostile
3) pioneer species die and decompose
4) dead organic matter forms deeper & more nutrient rich soil
5) new species able to grow in less harsh conditions
6) new species outcompetes the pioneer species & previous species
7) changes the abiotic conditions so less hostile to next new colonising species, & less suitable for older ones
8) previous species die, soil deeper & more nutrient rich as a result
9) cycle repeats
10) eventually, climax community reached
What is deflected succession
When human activities prevents /interrupt the process, resulting in a different climax community than what would be from natural succession
How can human activities prevent succession & why is this good
E.g.
- managed burning, mowing lawns, introducing grazing animals
This can be good as it maintains high plant & animal diversity, which won’t exist if the climax community is reached
What is a sere
Each level of succession
Details about the Masai marai
- savannah in Africa
- people raise livestock
- ecotourism projects, where people employ locals to monitor lions, as conservation trusts help locals make money
Details about the terai region in Nepal
Grassland, & forest, & variety of plants & animals
-> densely populated region therefore highly dependent on natural resources
E.g. fuel, animal feed, human food, medicines
-> conservation chattiest have worked to conserve the forest e.g. protecting against poaches teaching locals forestry skills
Peat bogs details
Areas of water logged land (incomplete decomposition)
Anaerobic & acidic conditions = decomposed plant matter accumulates and becomes compacted & = PEAT, which builds up to form carbon store
-> this carbon store is exploited & burns as fossil fuels, even tho the peat supports lots of plant species & those in turn support intervertebrae
