Abstract:

The net primary productivities of a mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum and a pure stand of C. lanceolata were measured. Annual net biomass increment was up to 9.899 t·hm^-2a^-1 in mixed stand, amounts 1.15 times higher than that in the pure stand. Annual litterfall production was 6.759 t·hm^-2 in mixed stand and 6.804 t·hm^-2 in pure stand, and the amount of litterfall from tree stratum in mixed forest was 1.05 times as compared with pure forest but from undergrowth in pure stand was 1.39 times as compared to the mixed forest. Annual return from fine roots litter was 35.66% and 33.42% of aboveground litterfall in mixed stand and pure stand, respectively, of which fine roots of trees accounted for over 80%. Of annual litterfall from <2 mm fine roots associated with C.lanceolata and T.odorum, <0.5 mm roots occupied over 60%. The net primary productivity of mixed stand totaled to 18.003 t·hm^-2a^-1, which was 1.09 times as much as that of pure stand, of which the net primary productivity of tree stratum was 1. 19 times as much as that in pure stand, but of undergrowth was 1.44 times in pure stand compared with mixed forest. In pure stand, the loss of net production in tree stratum cannot be compensated for by the increase in undergrowth. It was concluded that a more reasonable community structure was related to a higher net productivity.

Key words: Cunninghamia lanceolata, Tsoongiodendron odorum, Mixed forest, Litterfall, Fine roots, Net primary productivity