Abstract:

Studies on biomass, net productivity and annual turnover rate of fine roots in mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum and in pure stand of Cunninghamia lanceolata at 27 years old were carried out. The existing amount of living fine roots in both stands were up to 3.872 and 3.315 t·hm^-2, and their seasonal changes showed two peaks in March and September, and those of dead fine roots amounted to 1.509 and 1.269 t·hm^-2, being lowest in May or March. The net productivity of fine roots in both stands totaled to 4.124 and 3 528 t·hm^-2a^-1, accounted for 22.9% and 20.9% of total net primary productivity of community, respectively. In both stands, annual mortality of fine roots were 2.119 and 1.894 t·hm^-2, respectively, amounted 31.4% and 27.8% of annual aboveground litterfall. Annual turnover rate of fine roots was 1.07 in mixed stand and 1.06 in pure stand, which decreased successively from Tsoongiodendron odorum, Cunninghamia lanceolata in mixed forest to the pure stand, and that of undergrowth were higher than that of tree stralum in both stands. It was concluded that annual turnover of fine roots was an important way for organic matter in communities returning to forest floor.

Key words: Fine roots, Biomass, Net productivity, Turnover rate, Tsoongiodendron odorum, Cunninghamia lanceolata