C Communities and ecosystem

Question 1

what are trophic levels

Answer 1

an animals feeding position in a food chain

can be deduced form content in the stomach or adaptation fo an animal

food webs show all possible food chians in as community

Question 2

what are food conversion ratios

Question 3

what is the impact of the climate on ecosystem type

Answer 3

climate emergs from teh interaction of a number of variables including temp and precipitation

temp inlfuces organism distribution as influences rate of cellular respiration, photosynthesis, decomposition and transpiration and hence productivity

precipitation influences prodcutivity as affects photosynthesis, decompositio

see whittaker climograph

Question 4

what are gersmehl nutrient cycle diagrams

Answer 4

show the inter relationships between nutrient stores nad flows

has three compartments - biomass litter and soil

thickness of arrows is flow rate

Question 5

what is successsion

Answer 5

succession refers to changes to the environment (abiotic factors) , e.g environment becomes less hostile over time so larger more complex animals can grow and survive

two types primary and secondary

primary occurs in newly exposed area where initally there was no soil or organic matter there - first bacteria and lichen land and grow on rock, weathering of rock creates soil so moss grows, then grass, then trees, then animals

secondary

soil is present but not plant or animals eg. after a forest fire

Question 6

how can productivity be measured

Answer 6

production in plants is when organic matter is synthesizes through photosynthesis

in animals it is when organic matter is synthesized ater food is ingested, digested and absorbed

net production = gross prodcution - respiration

gross = total amount of organic matterr synthesizes ber unit area per unit time by a single trophic level

net = total amount of gross production after respiration has occured to break down some of this matter

Question 7

how does productivity link to succession

Answer 7

at very start of succession there is little respiration

during succession there is high iintensity sun light so the gross production is high , a lot of light used to syntheisie organic matter

as succession continues more plnants grow and respriation by these plants increase

at the end of succession when a stable woodland is created the amount of gross production decreases as most available spaces are filled up with trees

an equilibrium is reached where totaly productions : total respiration rate P/R equals 1 - stable ecosystem as rate s are equal

Question 8

how to measure succession

Answer 8

1. leaf area index
2. stem density
3. diversity
4. above ground biomass
5. light levels
6. volume of leaf litter
7. bulk soil denstiy
8. soil variable ( nutrient level, moisture, …)

Question 9

what are the 3 types of ecosystems

Answer 9

1. open - exchange both matter and energy with surroundings though cycles, if disturbed by humans this exchange of matter increases from eg. humans harvesting crops
2. closed systems exchange energy but not matter - mecocosms , biosphere 2
3. isolated systems exchange neither - thoeretical

Question 10

how do disruptions affect the nutrient cycling?

Answer 10

humans can accelerate flow into and out of ecosystems - e.g. in agriculture teh harvesting of crops and transport out of area where grown depeletes the area of teh nutrients thatt are locked in to the biomass fof the crop

–> regular inputs of nutrients must be added to teh soil so that agriculture can continue - phosphate and nitrogen are key

phosphate is mined, nitrogen is produced from gaseous N2 in the haber process –> run off from agriculture can lead to eutrophication