杉木、观光木混交林群落细根能量动态变化

应用连续土芯法和热值测定对福建三明地区中亚热带杉木观光木混交林和杉木纯林群落细根的能量动态进行了系统研究,以揭示杉阔混交林和杉木纯林维持地力机制差异.结果表明,混交林群落细根的能量现存量达10.371MJ/m2,是纯林群落的1.17倍,其中杉木、观光木、林下植被细根分别占72.12%,14.88%和13.00%;而不同树种<0.5mm径级的细根是细根能量现存量组成中最重要的部分.混交林杉木、观光木、纯林杉木的活细根能量现存量月变化动态呈双峰型,在3月和9月较高,而死细根能量现存量月变化动态呈单谷型,在3月或5月最低.林下植被活细根能量现存量月变化呈单峰型,在5月最高,而死细根能量现存量月变化呈单谷型,在5月最低.混交林细根的年能量归还量达4.001MJ/m2,是杉木纯林的1.12倍,占地上部分年凋落物能量归还量的31.6%,不同树种的<0.5?mm径级细根的年能量归还量均占60%以上.混交林细根的年能量分解量和净生产量分别达2.009MJ/m2和7.833MJ/m2,是纯林的1.23倍和1.17倍,而混交林细根枯落物的太阳能转化效率(0.178%)亦高于纯林细根的(0.159%).

Dynamics of energy for fine roots in mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum.

To better understand the differences in the mechanism of soil fertility maintenance between mixed Chinese fir (\%Cunninghamia lanceolata\%)\|broadleaved forest and pure forest,the energy dynamics of fine roots in the pure Chinese fir forest and mixed forest of \%Tsoongiodendron odorum\% and Chinese fir in Sanming,Fujian Province,were studied.The combination of sequential root coring and caloric determination was employed.The standing crop of energy for fine roots in the mixed forest was 10 355?MJ/m 2,being 1 17 times as much as that in pure stand,of which 72 12%,14 88% and 13 00% were occupied by fine roots of Chinese fir,\%Tsoongiodendron odorum\% and undergrowth,respectively.For fine roots of tree stratum,a largest proportion of standing crop of energy was accounted for by roots of <0 5 mm in diameter.For \%Tsoongiodendron odorum\% and Chinese fir both in mixed and pure stand,seasonal dynamics of standing crop of energy for living roots showed a double\|apices line peaked in March and September,and for dead roots showed a line with single vale being lowest in March or May.For undergrowth,changes of standing crop of energy for living and dead roots showed a line with single apex and single vale,respectively,both being highest and lowest in May.Annual return of energy for fine roots in mixed stand amounted to 4 001?MJ/m 2,being 31 6% of that for litterfall above\|ground,which was 1.12 times as much as in pure stand.Roots of <0.5mm in diameter occupied over 60% of the amount of energy return for fine roots of trees.Annual release and net production of energy for fine roots in mixed forest were up to 2.009?MJ/m 2 and 7.883?MJ/m 2,respectively,which were 1.23 and 1.17 times as much as those in pure stand.The transformation effiency of radiation to fine roots was higher in mixed forest (0.178%) than in pure stand (0.159%).