Introductions of the two study forests
Field work were conducetd mainly in the two types of forests at Qingyuan Forest (CERN) in Northeastern China, the larch forest and the mixed broad-leaved forest. Qingyuan has a continental temperate monsoon climate with annual precipitation 811 mm (more than 80% falling during June-August) and annual average temperature of 4.7℃. The soil is typical brown soil and the rock is composed of granite and granite-gneiss. The larch forest (41°50'58"N, 124°56'18"E, 625 m above the sea level) is dominated by Larix olgensis, while the mix forest (41°50'48"N, 124°56'01"E, 640 m above the sea level) is mainly composed of Quercus mongolica, Juglans mandshurica, Phellodendron amurense, including a small abundance of Larix olgensis and Fraxinus mandschurica.
Long-term N addition experiments were established in both forests from 2004 to study the characteristics of retention and cycling of N within these two types of temperate forests. The infrared warming system were only established in the mixed forest to study the effects of global warming (2℃) on C and N cycling in temperate forests.