Vertical distribution of the fine root of the natural Pinus tabulaeformis f. shekannesis forest in Ziwuling Loess Plateau

Chinese. 为揭示柴松林的生理生态适应机制，采用土钻法对黄土高原子午岭林区天然柴松林细根垂直分布特征和土壤物理性质进行了研究。结果表明，柴松细根生物量、根长密度、根表面积和比根长都集中分布于0~20 cm土层，总体上均随土壤深度增加而减少。柴松林地最大细根生物量分布在10~20 cm土层，最大的根长密度、比根长和根表面积均分布在0~10 cm土层；最小比根长分布在20~30 cm土层，最小细根生物量、根长密度和根表面积均分布在60~70 cm土层。土壤含水量与柴松细根生物量、根长密度和根表面积相关性达显著水平，细根生物量与5 mm和0.25 mm的水稳性团聚体呈显著正相关关系。说明天然柴松细根分布特征受土壤环境因子的影响，同时也反映了细根功能的转变。

English. In order to reveal the physiological adaptation mechanism of the Pinus tabulaeformis f. shekannesi in Ziwuling Loess Plateau, soil coring was used to investigate the vertical distribution of the fine root (2 mm) of Pinus tabulaeformis f. shekannesis and the soil physical characters in Ziwuling Loess Plateau. The study revealed that the fine root biomass, fine root length density, fine root surface area and specific root length all concentrated on the 0-20 cm soil layer, and then all of them decreased with the increasing of soil depth. The maximum fine root biomass distributed in the 10-20 cm soil layer, and the fine root length density, fine root surface area and specific root length peaked in the uppermost (0-10 cm) soil. In contrast to the distribution of the maximum root parameters, the distribution of the minimum root parameters was different. The minimum specific root length distributed in the 20-30 cm soil layer, the minimum fine root biomass, fine root length density and fine root surface were observed in 60-70 cm soil layer. Fine root biomass was positively correlated with soil water content and had no correlation with soil bulk density; 5 mm and 0.25 mm water stable aggregates were positively correlated with fine root biomass. The results indicated that the change of the soil environment and the function of the fine root could be predicted through the vertical distribution of the fine root of Pinus tabulaeformis and there was relationship between soil water content and soil bulk density.