光皮桦木-扁穗牛鞭草复合模式细根草根生物量及空间分布

通过研究四川洪雅县光皮桦木与扁穗牛鞭草复合模式细根、草根生物量,探讨该模式地下部分空间分布格局。结果表明,水平分布上各径级的细根与草根差异较小,0～1mm活细根生物量与草根水平分布增长曲线有一定重合,表现为:100cm>150cm>50cm;直径1～2mm活细根在水平分布上呈"V"型分布规律,水平分布变化为:50cm>100cm>150cm。在垂直分布上则差异显著,0～1mm活细根在上层(0～10cm)生物量占总根量的63.73%左右,细根生物量在整个上层(0～10cm)占比例达40.02%,中、下层占59.98%;扁穗牛鞭草草根有81.27%分布于上层,即草根上层对草根总生物量贡献最大。0～1和1～2mm细根、草根的年动态增长曲线变化规律一致,显示为同步增长和同步减少;从空间分布变化显示,光皮桦木与穗牛鞭草在0～10cm的土层存在一定生长竞争,在中、下层则竞争较小。因此,光皮桦木与扁穗牛鞭草复合模式地下部分空间分布及养分种间利用表现物种间的互利现象,存在明显的共生关系。

Biomass and Spatial Distribution of the Fine Root of the Betula luminifera-Hemarthria compressa Composite Mode

On the basis of the research of the fine root of the Betula luminifera-Hemarthria compressa compound mode and grass root biomass in Hongya county,Sichuan province,we discuss the underground spatial distribution pattern of this mode.The result shows:on horizontal distribution,the difference between the fine root and grass root in every diameter is small,the curve of the biomass of the living fine root is coincident with that of the grass root growth on horizontal distribution in a way,which shows:100 cm>150 cm>50 cm;the living fine root(diameter 1～2 mm) on horizontal distribution takes on the shape "V",with horizontal distribution change of 50 cm>100 cm>150 cm,while on vertical distribution the difference is notable.The biomass of the living fine root on upper layer(diameter 0～1 mm) takes 63.73% percentage of the whole root,the biomass of the fine root on the whole upper layer takes 40.02% and that on the lower layer takes 59.98%;and at the same time the upper layer biomass of the grass root takes 81.27% percentage of the grass root,which means that the gross of the grass root makes the greatest contribution to the total biomass.The curve of annual dynamic growth change of the fine root of diameter 0～1 mm and diameter 0～1 mm and gross root is consistent,showing a single-apex line.The changes of the spatial distribution show that in the 0～10 cm layer,there is competition between the Betula luminifera and Hemarthria compressa to some degree,while under 10 cm,there is no competition at all.So Betula luminifera has been collocated with Hemarthria compressa and the competition on biomass accumulating underground is symbiont.