马尾松与红锥混交异龄林生物量分配格局

Distribution pattern of biomass in the mixed uneven-aged stands of Pinus massoniana and Castanopsis hystrix

在经过三次抚育间伐的24 a生马尾松林下套种红锥,经过26 a的培育后形成了针阔混交异龄林。于2009年12月按相邻网格样方法设立固定样地(以50 a生马尾松纯林作对照),按径阶平均木法分别测定马尾松与红锥的林木生物量。结果表明:马尾松-红锥混交异龄林乔木层的生物量为220.072 t/hm2,比同龄马尾松纯林(241.618 t/hm2)的低8.92%;其净生产量为5.341 t/(hm2.a),比同龄马尾松纯林的高10.53%;其林分平均单株生物量比同龄马尾松纯林的低54.72%,且差异达到显著水平(P<0.05)。两种林分乔木层的生物量、净生产量和平均单株生物量的差异是由于林木年龄、林木保存密度及其分布不均匀性的共同影响结果。马尾松-红锥混交异龄林的地上部分生物量空间结构与马尾松纯林相比存在明显差异,混交林在树干高度6～8 m段开始出现枝叶,8～20 m段出现了枯枝,其枝叶生物量有两个峰值(14～16 m和20～22 m);纯林则在树干高度为8～10 m段开始出现枝叶,在10～20 m段出现了枯枝,其枝叶生物量只有一个峰值(20～22 m)。

After three times thinning, Castanopsis hystrix were separately planted under the canopy of the 24 years old Piuns massoniana plantation, and developed into closed mixed stands of different ages after 26 years of management. In December 2009, the fixed sample plots were set up in the mixed unevened-aged stands by the adjacent grid-like method of fixed sample（with 50 years old pure Pinus massoniana plantation as control group）, according to the average diameter determination method the biomasses of the two kinds of plantations were investigated. The results show that the mixed stands of different ages total biomass was 220. 072 t/hm2 , was lower 8. 92% than pure Pinus massoniana plantation （241. 618 t/hm2） ; the net production capacity was 5. 341 t/（hm2 · a）, higher than that of the same aged pure sand by 10.53%; but the average biomass per plant was lower than that of the pure stand by 54. 72%, and the difference was significant （P〈0. 05）. The differences in two forests tree layer biomass, net production and average biomass resulted in the cooperative effects of the inhomogeneity of stand age, tree density and distribution. There existed an obvious difference in ground biomass spatial structure between the unevened-aged mixed stand and the P. massoniana pure stand; the trees in the mixed stand developed branches and foliages when the tree stem height reached 6-8 meters, and appeared dead branches when 8-20 meters; and the biomass of branches and foliages in the fixed stand had two peak values（14-16 meters, 20-22 meters） ; the pure P. massoniana stand developed branches of foliages when the tree beam height reached 8 - 10 meters, appeared dead branches and foliages at 10-20 meters; and only had one peak value of branches and foliages biomass.