Abstract:

Biomass of understory vegetation in Chinese fir(Cunninghamia lanceolata) forests in successive rotation was investigated for 14 years in the sixth watershed of National Field Station for Scientific Observation and Experiment in Huitong, Hunan Province to study dynamics of understory vegetation species and biomass at different growth stages. The results showed that with the 14-year growth and development of Chinese fir forests in successive rotation, biomass of understory vegetation descended from 10.02 t ·hm^-2 at young (3-year-old) forest stage to 1.60 t ·hm^-2 at pole stage of 14-year-old Chinese fir forests, decreased by 84.0%. At the young forest stage, biomass of trees and small trees (470.74-885.68 kg ·hm^-2) was dominant in understory shrub layer, accounted for 58.3%-78.3%;biomass of Miscanthus sinensis (342.67-6 853.23 kg ·hm^-2) was the most in herb layer, which accounted for 50.2%-80.7%. At fast growing stage, biomass of small trees e.g. Aralia chinensis (1 068.37-2 886.01 kg ·hm^-2) was highest in understory shrub layer, which accounted for 41.2%-69.6%;biomass of ferns(1 187.67-1 856.51 kg ·hm^-2) is highest in herb layer, which accounted for 44.7%-74.3%. At pole stage, biomass of Rhus chinensis and Maesa japonica (439.63-1 133.7 kg ·hm^-2) was dominant in understory shrub layer, which accounted for 65.2%-89.4%; biomass of Dicranopteris linearis (236.67 kg ·hm^-2) and ferns(874.40 kg ·hm^-2) was highest in herb layer, which accounted for 33.4% and 94.3%, respectively. The results provided scientific basis for maintaining nutrient cycling and carbon balance, conserving and increasing forestland capability and sustainable management.

Key words: Chinese fir(Cunninghamia lanceolata) forests of successive rotation, understory vegetation, biomass, dynamics, Huitong in Hunan Province