通过对27a生杉木观光木混交林群落净生产力的研究,结果表明:混交林群落的总年净增量达9.899t·hm-2a-1,是纯林的1 15倍,其中乔木层的是纯林的1.30倍,而纯林灌木层和草本层的则分别是混交林的1.06倍和1.93倍。混交林和纯林群落总凋落物分别为6.759t·hm-2和6.804t·hm-2,其中混交林乔木层的是纯林的1.05倍,而纯林林下植被层的则是混交林的1.39倍;混交林和纯林细根枯死物年归还量分别占相应地上年凋落物量的35.66%和33.42%,乔木层枯死细根在群落细根年枯死量中占80%以上,在杉木或观光木各径级细根枯死量组成中,<0.5mm的细根枯死量均达60%以上。混交林群落的年净生产力达18.003t·hm-2a-1,是纯林群落的1.09倍,其中乔木层的净生产力是纯林的1.19倍,而纯林林下植被层的则是混交林的1.44倍,表明合理的群落结构是提高群落净生产力的关键。
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.
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