*2.1. Study Area*

The study was conducted in the Natural Reserve, Changbai Mountain (41◦59 N, 127◦59–128◦ E) in northeastern China. The area was not disturbed because of its remoteness and high elevation. The area has a temperate continental climate [23] with mean growing season (late May to late September) temperature of 5.87 ◦C (ranging from 3.37 to 8.82 ◦C) [24]. The annual precipitation ranges from 700 to 1400 mm (data from Tian-Chi Meteorological Station located at 2623 m a.s.l.) [25] and the annual

frost-free period is about 65 to 70 days [26]. Soils on the Changbai Mountain are classified as mountain soddy forest soil [25]. The Changbai Mountain has vertical spectra with four vegetation belts [27]: mixed coniferous broad leaved forests distributed from 740 to 1100 m a.s.l., coniferous forests from 1100 to 1700 m a.s.l., birches (*Betula ermanii*) distributed from 1700 to 2200 m a.s.l., with the birch alpine treeline at 2030 m a.s.l., and tundra above 2000 m a.s.l. [22,26].
