大汶河流域杨树根系的生物量组成和空间分布

Composition and spatial distribution of Populus root biomass in the Dawenhe Watershed

根系生物量在不同直径根系中的分配是根系重要的结构特征,采用分层挖掘法,研究大汶河流域杨树不同径级根系的生物量组成和空间分布.结果表明：1）不同直径根系的生物量差异显著,其中根系直径d为10mm＜d＜20 mm的根系生物量最大,其次是d＜2mm的根系,d＞20 mm根系的生物量最小.2）不同直径根系生物量的空间分布规律基本一致,在水平方向上各土层间分布的根系生物量差异性极显著,距离树干愈远,土层中的根系生物量愈小.垂直方向上杨树根系生物量集中于0～60 cm土层中,各土层间根系生物量差异性显著,但其空间分布无明显规律.3）土壤有机质及有效氮、磷、钾等养分质量分数总体上随着土层的加深递减,细根生物量的空间分布与土壤养分呈弱正相关性.

Distribution of root biomass in different diameter classes of root system is an important structural feature of root.By using digging method,composition and spatial distribution of Populus root biomass were studied in the Dawenhe Watershed.The results showed that：1） there was a significant difference in the biomass among varied root diameters.Among them,the biomass of 10-20 mm roots was the biggest,followed by that of roots less than 2 mm,and the biomass of roots ＞ 20 mm was the smallest.2） Biomass spatial distribution pattern of the roots with different diameters were basically identical.On horizontal direction,the root biomass was significantly different among all layers.The farther from the trunk,the smaller the root biomass.The difference in distribution of root biomass along vertical direction was also very remarkable,but without evident order.3） With soil depth increasing,soil bulk density,soil organic matter and available N,P,K contents decreased in an insignificant manner.The spatial distribution of Populus roots had a weakly positive correlation with soil nutrient.