 They can even survive being covered by snow and ice for over a year.Arctic vegetation is largely controlled by temperature.Woody plants first occur in Subzone B (meaning July temperature about 3–5 °C) as prostrate (creeping) dwarf shrubs, and increasing in height up to 15 cm in Subzone C (about 5–7 °C), to erect dwarf shrubs (up to 40 cm tall) in Subzone D (mean July temperature about 7–9 °C), and low shrubs (40 cm to 2 m tall) in Sub zone E (mean July temperature about 9–12 °C).