Exam QS Flashcards
Examine the significance of vegitation in linking the carbon and water cycle (10) - AO1
- Vegetation stores both water and carbon
- Changes in vegetation cover affect both cycles
- water availability affects the rate of photo synthesis, NPP, transpiration, inputs of organic matter into soils.
-Water storage in soils increases with organic content.
Examine the significance of vegetation in linking the carbon and water cycle (10) - AO2
the significance in terms of temporal and spatial
scales e.g. vegetation interacts with other parts of the carbon and water cycles in different time scales from days to decades and how this short term cycling is significant to the continual functioning of the cycles
the disturbance of systems in equilibrium and the resultant positive or negative feedback e.g. reduced water input into the biosphere means that plants cannot exchange carbon with water through N
photosynthesis and so the plants cannot absorb carbon and grow, as decomposition is extremely slow when water is limited
to what extent interdependence is a two-way relationship e.g. if carbon cycle processes linked with vegetation, like photosynthesis and decay,
stopped then the water cycle would still continue, though its balance might be upset. But if the water ceased to evaporate off of the oceans and rain down on the land, the carbon cycle would not be able to function.
consideration of whether the significance varies with different types of vegetation e.g. rates of exchange through photosynthesis varying in different types of vegetation
the extent to which the role of vegetation in linking the cycles is significant when compared to other links e.g. discussion of smaller stores (for example
oceans contain 38,000 billion tonnes of carbon compared to around 2000 billion tonnes combined in living plants and animals, and plant remains and organic matter) but vital in keeping the two cycles functioning.
Calculate the standard deviation of the following:
4 4 5 4 4 7 8 10 9 9 6 2
What is the formula for standard deviation
Standard deviation=(square root of) all numbers squared divided by amount of items minus mean squared
= √(∑(x−¯x) ( x − x ¯ ) 2 /n)
Examine how water abstraction influences flows and stores in the water cycle. AO1 (6)
- Water extraction
o Extractionfromsurfaceandgroundwater
sources to meet public, industrial and
agricultural demand
o Groundwaterextractedforpublicsupply
from aquifers by wells and boreholes e.g. River Kennet supplying Swindon’s population. Focus near urban centres and is spatially uneven.
o Removalofwaterforindustrialpurposes e.g. from groundwater sources beneath London under artesian pressure
o Around 300million m3yr-1 is used for agricultural use in the UK, around half for irrigation and all extracted from surface or ground sources. This removes ~1.5% of fresh water in the UK. This varies spatially across the country
o Somecountriese.g.Cyprusremove significant amounts of fresh water from limited sources to facilitate tourism - Flows and stores in the water cycle
o Fall/riseofwatertable
o Flowratesinchannels,soil,bedrock
o Storesofwateronthesurface,inthesoil
and aquifers
Examine how water abstraction influences flows and stores in the water cycle. AO2 (4)
- Comments may relate to spatial and/or temporal variation in scale of change
- Range of changes may also be commented on, including, perhaps, both positive and negative changes
- Locational contexts may be provided, and although these are not required by the question, they may help the answer
- Rates of extraction exceeding recharge creating a falling water table and lower river flows e.g. River Kennet decreased by 10-14%
- Lower flows reducing flooding and wetland areas within catchment basins
- Springs and seepages dry up reducing incidence of saturated overland flow on chalk in Kennet’s drainage basin
- In central London overexploitation of groundwater led to 90m fall in water table in 1900-1950, reducing store under artesian pressure and springs on North Downs and Chilterns
- Colorado River, USA stopped flowing into the sea due to increased abstraction for urban centres, reducing channel storage and flow
Examine the extent to which an individual tree can influence the water and carbon cycles within a tropical rainforest.(AO1-6 MARKS)
Emergents in particular can be 40m in height providing a large store of carbon (around 180 tonnes C/ha above ground and 40 tonnes C/ha below ground)
* Each leaf affects the water cycle by releasing water through the stomata into the atmosphere as well as fixating carbon through photosynthesis in the leaves
* Roots will absorb water from the soil which affectsorganiccontentandcarbonstore
* Discussion of the influence of a tree on transpiration, interception, photosynthesis and so on are all relevant
Examine the extent to which an individual tree can influence the water and carbon cycles within a tropical rainforest. (AO2 4 MARKS)
Individual trees will have a significantly lower impact than the entire forest, however each tree has a small and vital role
* Level of influence relates to the size of the tree, the larger the tree, the larger the carbon store, the more leaf litter is produced which would have a larger influence on organic content of soil
* Seasonal changes in influence are limited as seasonal variations are small, however prolonger drier seasons would limit growth and cycling rates
* Rates of flow between stores of carbon is rapid due to the high average temperatures and high annual precipitation, so decomposition of leaf litter is fast and minerals quickly absorbed into the soil
Rates of transpiration high for trees, higher for emergents as leaves exposed to sunlight and able to heat quickly and transpire water effectively, although wind chill may small effect
* Temporal changes in influence significant as influence of the tree much more during sunlight hours as photosynthesis, transpiration and evaporation occurring at rapid rates. During the night these rates slow although transpiration is likely to continue as stomata close
