Structural characteristics of natural spruce-fir forest in Wangqing Forestry Bureau of Jilin Province, northeastern China.

This study focused on the 0.2 hm2 plot of natural sprucefir forest in Wangqing Forestry Bureau of Jilin Province, northeastern China, and the investigation data from 1986 to 2011 were used to analyze the forest structural characteristics by composition of species, diameter structure, age structure, spatial structure and natural regeneration. Results showed that the species composition of conifer and broadleaf with the proportion of 5∶5 was stable. The diameter grade and number distribution were expressed in a reverse letter “J” and the forest was mature and overmature. The forest community structure was complex with different species mixed strongly, and its mingling degree was 0.83. The tree storey was divided into upper storey (tree height≥17 m), middle storey (12 mtree height17 m) and understorey(tree height≤12 m) based on the dividing standards. The average number of seedlings was 4 328 trees/hm2, which can meet the needs of regeneration thought it was reducing from 1988 to 2011. The regeneration species were mainly composed of Abies nephrolepis, Pinus koraiensis and Picea koraiensis.