杉木观光木混交林群落的能量生态

对杉木观光木混交林群落能量的研究结果表明：混交林中观光木地上部分灰分含量以皮最高，而杉则以叶最高，两者GCV（干重热值）和AFCV（去灰分热值）均以叶为最高；观光木、杉木地下各部分的灰分含量均随径级的减小而增加，GCV均以粗根最高，细根最低；观光木的平均灰分含量高于杉木，但GCV和AFCV均低于杉木；从乔木层、灌木层到草本层，灰分含量依次增加，GCV和AFCV则依次降低，混交林群落的能量现存量公占群落的很小一部分，而其能量年净增量、归还量和净固定量却占有一定比重，混交林群落的太阳能转化率为1.57%，而纯林为1.44%，表明杉观混交林是一种能量生产力较高和维持地力能力较强的杉阔混交类型。同时，混交林的能量累积比大于纯林，能量流动速率则低于纯林；乔木层的能量累积比高于林下植被，能量流动速率则低于林下植被，从能量的角度看，构建合理的群落结构必须选择高能量累积比的乔木层树种，同时须促进能量流动速率快的林下植被的发育以维持和提高地力。

ENERGY FOR MIXED FOREST OF CUNNINGHAMIA LANCEOLATA AND TSOONGIODENDRON ODORUM

Based on the measurement of biomass and productivity, the caloric value of plant samples, the standing crop of energy, net energy production and energy conversing efficiency of mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum were determined. Among the aboveground fractions, ash content was highest in barks of Tsoongiodendron odorum and in leaves of Cunninghamia lanceolata , and GCV and AFCV were both highest in leaves of the two species. For underground fractions, ash content increased with the increase of root diameter size, and GCV was highest in coarse roots and lowest in fine roots. The mean ash content was higher, and the mean of GCV and AFCV of Tsoongiodendron odorum were lower than those of Cunninghamia lanceolata . The mean ash content increased in an order from tree layer, shrub layer to herb layer, while those of GCV and AFCV decreased. The standing crop, net accumulation, production and returning of energy of mixed forest were 1.26, 1.15, 1.09 and 1.02 times as much as that of pure forest, respectively. The undergrowth played an important role in energy process, though it accounted for only a slight proportion in community. The energy conversing efficiency was 1.57% for mixed forest and 1.44% for pure forest. The ratio of energy accumulation was higher, and the rate of energy flow was lower in mixed forest than in pure forest. The tree layer had a higher ratio of energy accumulation and a lower rate of energy flow than undergrowth did. In view of energy efficiency, trees with high accumulated rate of energy should be introduced and growth of undergrowth should be promoted in a managed forest community. Tab 4, Ref 22