尾叶桉与马占相思人工复层林生物量及生产力研究

应用相对生长法和样方收获法，于2006年对广西国营高峰林场3年生尾叶桉与马占相思不同混交模式人工林群落生物量及生产力进行研究，结果表明:尾叶桉与马占相思不同混交模式各器官生物量与测树因子（D2H）存在紧密相关关系。在相同混交比例下，群落生物量、乔木层生物量及净生产力水平随林分密度的增加而上升。当尾叶桉与马占相思混交比例为1∶1时，林分密度为1 050和1 320株/hm2的群落生物量分别为28.556和47.853 t/hm2，平均净生产力分别为9.51和15.95 t/(hm2·a)，其中乔木层生物量分别为22.100和42.182 t/hm2，占总生物量的77.39%和88.15%；当尾叶桉与马占相思混交比例为2∶1时，林分密度810和1 170株/hm2的群落生物量分别为49.482和76.556 t/hm2，平均净生产力分别为16.49和25.51 t/(hm2·a)，乔木层生物量分别为44.340和72.733 t/hm2，占总生物量的89.60%和95.01%；当林分密度同为1 727株/hm2时，尾叶桉纯林、尾叶桉与马占相思以1∶1.6比例混交林的群落生物量分别为84.586和106.904 t/hm2，平均净生产力为28.20和35.63 t/(hm2·a)，其中乔木层生物量分别为73.942和101.480 t/hm2，占总生物量的87.42%和94.93%，混交林群落生物量比纯林群落生物量高出26.38%。在相同混交比例下，灌木层、草本层、枯枝落叶层生物量随林分密度的增加而下降；在相同密度下，尾叶桉纯林灌木层、草本层、枯枝落叶层生物量均比混交林高。在6个林分更新处理中，当尾叶桉与马占相思的混交比例为1∶1.6时，混交林的成层性最明显，林分总生物量、净生产力水平也最高，且与其他各处理间的差异达到极显著水平，是较佳的一种混交模式。 

Biomass and productivity of stratified mixed stands of Eucalyptus urophylla and Acacia mangium

The biomass and productivity of stratified mixed stands of Eucalyptus urophylla and Acacia mangium with different mixed proportions were studied by sample plot harvesting method and allometric dimension analysis in Gaofen State-owned Forest Farm of Guangxi Zhuang Autonomous Region. The results show that the biomasses of E. urophylla and A. mangiumare closely related with the measuring factors (D²H) in different mixed patterns. With the forest density increasing，community biomass，arbor layer biomass and net productivity increase at the same mixed proportion in the stratified mixed stands of E. urophylla and A. mangium. In the two kinds of stands with density of 1 050 and 1 320 trees/hm² at the mixed proportion of 1∶1 with E. urophylla to A. mangium, the community biomasses are 28.556 and 47.853 t/ hm²，average net productivity are 9.51 and 15.95 t/(hm²·year)，in which the arbor biomasses are 22.100 and 42.182 t/hm2 and make up 77.39% and 88.15% of the total biomass, respectively. In the two kinds of stands with density of 810 and 1 170 trees/hm2 at the mixed proportion of 2∶1 with E. urophylla to A. mangium, the community biomasses are 49482 and 76.556 t/hm²，net productivity are 16.49 and 25.51 t/(hm²·year)，in which the arbor biomasses are 44.340 and 72.733 t/hm²，and make up 89.60% and 95.01% of the total biomass, respectively. When the stand density is 1 727 trees/hm2 in the pure stand and the mixed stand with proportion of 1∶1.6 with E. urophylla to A. mangium，the community biomasses are 84.586 and 106.904 t/ hm²，average net productivity are 28.20 and 35.63 t/(hm2·year)，in which the arbor biomasses are 73.942 and 101.480 t/hm²，and make up 87.42% and 94.93% of the total biomass, respectively. The community biomass of mixed stand is 26.38% higher than that of the pure stand. In addition，the biomasses of shrub layer，herb layer and litter layer decrease with the stand density increasing at the same mixed proportion and these terms in the pure stand are higher than that in the mixed stand. So in the six stand regeneration patterns，the mixed proportion of 1∶1.6 with obvious layers is the more rational pattern of E. urophylla×A. mangium for the highest total biomass and net productivity which reach the extreme significance to the other treatments.