33 a生福建柏人工林群落能量的研究

在福建三明对33 a生福建柏和杉木群落能量的研究结果表明福建柏群落和杉木群落干重热值和去灰分热值均以树叶最高,最低的为草本叶和茎或草本根;两个群落不同层次干重热值和去灰分热值的大小均为乔木层>林褥层>灌木层>草本层;两个群落乔木层干重热值和去灰分热值均以干皮最低. 两个群落不同组分灰分含量差异悬殊,最高的均为草本叶和茎,最低的均为干材. 福建柏的干重热值、去灰分热值、灰分含量均高于杉木,表明福建柏生成单位重量生物量的能量耗费比杉木多. 福建柏群落的能量现存量、年净增量、年归还量(通过凋落物)、年净固定量分别是杉木群落的0.97倍、1.65倍、1.15倍和1.36倍. 福建柏群落的太阳能转化效率为1.42%,而杉木群落为1.04%. 林下植被虽然能量现存量仅占群落的很小一部分,但在能量流动中占有重要地位,林下植被的能量流动速率比乔木层大得多,这对维持和提高地力较为有利. 33 a生福建柏群落仍然具有较大的能量年净增量,轮伐期应比杉木长;具有较高的能量流动速率,地力维护的能力也较强,是优良的造林树种. 福建柏经营密度应适当降低,发育群落林下植被以改良地力. 表5 参12

ENERGY OF A 33-YEAR-OLD FOKIENIA HODGINSII PLANTATION COMMUNITY

Energy of 33-year-old Fokienia hodginsii and Cunninghamia lanceolata plantation communities was studied in Sanming,Fujian,China. The results showed that gross caloric value (GCV) and ash-free caloric value (AFCV) of tree leaves were both highest,while those of herb leaves and stems or herb roots were lowest in the two communities. GCV and AFCV in both of the two communities were in the order: tree layer>forest floor>shrub layer>herb layer. GCV and AFCV of stem bark were both lowest in the tree layer of the two communities. Ash content differed significantly among different components,highest in herb leaves and stems and lowest in stem wood,in the two communities. GCV,AFCV and ash content of F. hodginsii were all higher than those of C. lanceolata,indicating F. hodginsii required higher energy than C. lanceolata . The standing crop,annual net accumulation,return (by litter) and net production of energy of F. hodginsii community were 0.97,1.65,1.15 and 1.36 times,respectively,as much as those of C. lanceolata community. The energy conversing efficiency was 1.42% for F. hodginsii and 1.04 % for C. lanceolata community. The undergrowth played an important role in energy process,though it accounted for only a slight proportion in community. A much higher rate of energy flow in undergrowth than in tree layer were favourable for maintaining and promoting soil fertility. The 33-year-old F. hodginsii plantation community still had a higher annual net increment of energy,thus should had a longer rotation period,and it had a higher rate of energy flow,indicating a higher capacity for maintaining soil fertility than that of C. lanceolata . F. hodginsii appeared to be a good tree species for forestation. The F. hodginsii plantation should had lower density to develop undergrowth for improving soil fertility. Tab 5,Ref 12