Answer to Question 1
Answer: Taiga. It has a tree cover, long, cold winters, low energy conditions, poor soil, and found only in the Northern Hemisphere.
Answer to Question 2
Answer: It is continentality which produces wide seasonal swings in weather because of the relatively wide swings in temperature and humidity which occur in places not strongly affected by oceans. The cause is the rapid heating and cooling of land with respect to ocean water.