阿拉善高原2种荒漠植物根系构型及生态适应性特征

Abstract

根系构型决定了植物对资源的吸收方式，根系构型的变化是植物对环境的生态适应和有效生存策略。在阿拉善高原西南缘红砂（Reaumuria soongarica）-珍珠猪毛菜（Salsola passerina）混生群落采用传统挖掘法收集两种植物根系，基于量化的根系形态指标，利用几何拓扑学及分形理论分析了根系构型特征，探讨了该地区2种植物对干旱生境的生态适应策略。结果表明：红砂和珍珠猪毛菜根系均以水平分布占优，根系浅层化分布明显，混生的两种植物占据不同的生态位；2种荒漠植物均具有较大的比根长（SRL）和比表面积（SRA），红砂SRL=21.3 cm/g，SRA=7.6 cm²/g，珍珠SRL=22.4 cm/g，SRA=6.5 cm²/g，有利于水分和养分的获取；红砂根系拓扑指数（TI）、修正拓扑参数（q_a和q_b）分别为0.86、0.52、0.49，珍珠猪毛菜对应参数分别为0.93、0.76、0.73，表明2种植物根系均趋向于鱼尾形分支结构；根系分形维数值（FD_红=1.488、FD_珍=1.422）较小，而分形丰度值（lgK_红=1.855、lgK_珍=1.774）较大，表明2种植物分支相对简单，但空间拓展能力强，有利于对营养空间的占有。上述特征可能是阿拉善西南缘红砂-珍珠猪毛菜群落2种荒漠植物植物对干旱贫瘠生境的重要生态适应策略。;The change of root architecture is an effective means for plants to adapt to environment. In this study, the root of Reaumuria soongorica and Salsola passerina were harvested by destructive sampling in the Alxa Plateau. The root architecture characteristics and adaptive strategy to arid environment were analyzed by root morphological, topology and fractal indexes. The results showed that the roots of the two desert plants were dominated by horizontal distribution and occupied different ecological niches. Large specific root length (SRL) and specific root area (SRA) values of R. soongorica (SRL =21.3 cm/g, SRA =7.6 cm²/g) and S. passerine (SRL=22.4 cm/g, SRA=6.5 cm²/g) were beneficial to obtain water and nutrients. Both R. soongarica and S. passerine roots were herringbone-like (TI, q_a, q_b being 0.86, 0.52 and 0.49 for R. soongorica, while 0.93, 0.76, and 0.73 for S. passerine) and had obvious fractal characteristics (FD and logK being 1.488 and 1.855 for R. soongorica, while 1.422 and 1.774 for for R. soongorica), which indicated that they had simple root architecture and high ability to expand living space. Above root characteristics may be the important adaptive strategies to arid environment for R. soongorica and S. passerina in Alxa Plateau.