| Date | May 2021 | Marks available | 3 | Reference code | 21M.1.SL.TZ0.6 |
| Level | Standard Level | Paper | Paper 1 | Time zone | Time zone 0 |
| Command term | Explain | Question number | 6 | Adapted from | N/A |
Question
Figure 7(a): Fact file on taiga
- Taiga is the world’s largest terrestrial biome.
- The Siberian taiga contains about 20 % of the world’s forested areas.
- The taiga includes evergreen trees such as pine, spruce, fir, and some deciduous trees such as birch and poplar.
- Nutrient-poor soil and the climatic conditions contribute to slow rate of tree growth.
- Threats to taiga include forest fires, clearance for agriculture land, logging for timber, mining, road building and climate change.
- The region suffers deforestation rates of 20000km2 annually.
- Conservation measures include restoration of forests through replanting and designating protected areas such as National Parks and selective logging policies.
- There is high global demand for timber with markets throughout Asia, Europe and the USA. Economic incentives to increase exports have increased timber production, destroying more of the forest ecosystems.
Figure 7(b): Total exports of timber (in units of thousand cubic metres) from Russia between 2012 and 2014
[Source: With permission from GRID-Arendal. Source adapted.]
Outline one ecological service provided by the Siberian taiga.
With reference to Figure 7(b), calculate the percentage of timber exports to China between the years 2012–2014.
Explain how deforestation in the taiga may impact the world’s oceans.
State one natural limiting factor to the successful restoration of taiga through replanting.
Markscheme
provides habitat for animals/birds;
(photosynthesis) acts as a carbon sink/absorbs CO2 reducing greenhouse emissions;
(photosynthesis) releases O2 necessary for living organisms;
filters water / maintains water table;
cools/moistens climate through evapotranspiration / source of moisture for precipitation;
vegetation prevents soil erosion;
increases/maintains biodiversity (increasing/maintaining resilience of biosphere);
pollination of plants/crops;
Do not accept only ‘photosynthesis.
Do not accept provision of goods e.g. timber/food.
Do not accept cultural, intrinsic or aesthetical benefits e.g. spiritual/tourism/recreation.
For credit response must focus on ecological service/function.
Note: Units are not required for credit.
removing vegetation increases CO2 levels in atmosphere which promotes global warming / deforestation increases melting of permafrost which releases CO2 and CH4 which promotes global warming;
increased CO2 levels lead to ocean acidification (reduction in ocean pH) / carbon stores within oceans increase;
ocean acidification causes the bleaching of corals/corrosion of shells/loss of marine species/diversity;
global warming/higher temperatures cause thermal expansion which raises sea levels;
global warming/higher temperatures cause the melting of glaciers which raises sea levels;
higher sea water temperature causes bleaching of corals/loss of breeding grounds for marine organisms/loss of marine species;
deforestation leads to an increase in surface runoff which raises sea levels;
increase in freshwater input results in a reduction in seawater salinity;
reduction in forest cover so more soil erosion (by rain), leading to sediment input to the ocean / roots no longer hold soil in place which results in soil erosion, leading to sediment input into the ocean;
warmer waters can lead to a reduction in oxygen levels within the oceans;
lower oxygen levels within the oceans can reduce biodiversity;
Do not accept ‘the transport/exportation of timber causes ocean pollution’.
Do not accept only ‘global warming causes sea-level rise’.
Do not accept that deforestation causes an increase in nutrient run-off that causes eutrophication (taiga soils are nutrient poor).
Do not accept ‘climate change’ instead of the term ‘global warming’.
Accept other reasonable responses.
nutrient poor soils / low temperature / low rainfall / limited growing season / limited amount of sunlight / slow growth rates / permafrost inhibits plant growth;
Do not accept ‘wildfires / grazers/animals eat the plants/seedlings’.
Do not accept just ‘temperature/rainfall/soil fertility/time it takes for trees to grow/long mature time for trees’.
Examiners report
Many candidates correctly answered this question with popular responses including the taiga acts as a carbon sink, absorbs carbon dioxide or produces oxygen (via photosynthesis). However, a significant number of responses did not focus on an ecological service or function but instead included provision of goods e.g. timber.
The majority of candidates successfully performed this calculation. Incorrect rounding, i.e. 60 %, was the most common source of error.
Responses varied widely for this question. Good responses gave detailed answers that linked deforestation to impacts in the ocean, ranging from ocean acidification to sea-level rise. A common error was to assume that eutrophication would occur as a consequence of deforestation despite the taiga soils being nutrient poor.
This question was generally answered well by most students. Common errors included stating "time it takes for trees to grow" or stating only "temperature" or "rainfall" rather than "low temperature" or "low rainfall".
