Q44 - Vegetation Removal and Permafrost Dynamics in Siberian Tundra

Theoretical A Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Arctic tundras are warming faster than the global average. This influences their soil carbon reservoirs. The permafrost layer in the tundra is covered by an active layer, which has an annual thaw/refreeze dynamic. The influence of tundra vegetation as a driver of this dynamics was studied in Siberia from 2006 to 2012. Four parameters were measured in plots, where the woody vegetation was removed (blue bars in the figure), and in undisturbed control plots (black bars). A, Surface elevation relative to ground surface level; B, spring snow depth; C, summer ground water level compared to soil surface level; D, August CH4 emission (+ value, emission).

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. Soil subsides when its woody vegetation is removed

B. Undisturbed tundra woody vegetation functions as a source of global methane emission

C. Removal of woody vegetation initiates a cycle, leading to more dominance of water-tolerant plants

D. After removal of woody vegetation, the chain of events will be: Fig. B --> Fig. C --> Fig. A --> Fig. D

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Question reproduced from IBO 2015, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)