华北落叶松人工幼林林分密度与生物量的关系

华北落叶松（larix principis—rupprechtii Mayr．）是燕山山地的主要树种，生态和经济效益显著。以河北木兰林管局境内13a生华北落叶松人工幼林为研究对象，用样方调查的方法对立地条件相同密度分别为1800、2400和3000株／hm^2的3种林分生物量进行研究，结果表明：林分总生物量随密度的增大而增大，低、中、高3种密度林分总生物量分别为21180．6、26724．6和31352．4kg/hm^2；乔木层生物量最大，占总生物量的98．9％，草本层次之，占0．7％，灌木层最少，仅占0．4％；林木平均木生物量随密度的增大略微减少，密度由低到高其平均木生物量依次为11537．5、11077．3和10357．8g/株；各密度林分乔木层各器官生物量均存在W干〉W枝〉W根〉W叶〉W皮的分布规律；3种密度的林分生物量结构特征基本相同，3000株／hm^2的林分结构合理，更能达到丰产的目的。

Relations of stand density and the biomass of the artificial young Larix principis- rupprechtii forest

Larix principis-rupprechtii Mayr. is the main species in the Yanshan Mountain area,and it has prominent effect in ecology and economy. The paper used the 13 year-old young plantations of Prince Rupprecht' s Larch in the area of Mulan Forestry Bureau of Hebei. The method of sampling was used for the stand biomass research among the three densities as 1 800,2 400,3 000 trees/hm2 ,but in the same conditions.The result indicated: The total stand biomass increased with the increasing density.The stand total biomass with the three densities of low, middle,high,are 21 180.6,26 724.6,31 352.4 kg/hm2 .The tree layer biomass is the largest, 98.9% on the total biomass, then Herb layer, just 0.7%, while the shrub layer is the lowest, only 0.4%. The average wood biomass of stands decreased slightly with the increasing density. The average wood biomass of stands are 11 537.5,11 077.3 and 10 357.8 g/tree in turn with the density from low to high. The organ biomasses of tree layer with every densities, has the distributing rule of Wtrunk > Wbranch > Wroot > Wieave > Wskin.The stands biomass of the three densities has the same structure character basically. The stands structure of 3 000 trees/hm2 is reasonable, and it also can meet the purpose of fertility.