塔里木盆地北缘典型荒漠植物根系化学计量特征及其与土壤理化因子的关系

荒漠植物根系直接与高度盐渍化、严重缺水的土壤环境接触,是执行物质吸h收的重要营养器官,对其化学计量的研究有助于深入了解旱生植物功能特征和生存策略。以塔里木盆地北缘6种典型荒漠植物:甘草、芦苇、花花柴、骆驼刺、柽柳、盐爪爪为研究对象,分析植物根系化学计量特征,结合冗余分析探索其与土壤理化因子的相关关系。结果表明,研究区植物根系C、N、P含量分别为(443.62±70.84)mg/g,(7.44±3.59)mg/g,(0.46±1.92)mg/g;其中P的变异系数最大,C的最小;C/N、C/P、N/P的值分别为63.37、964.39、15.22,C、N、P含量及N/P值低于全球平均水平,C/N高于全球平均水平。通过冗余分析得出土壤理化因子对植物根系化学计量特征影响的重要性排序为:土壤含水量土壤电导率土壤P含量土壤C含量土壤N含量,即研究区土壤含水量与电导率是影响植物根系化学计量的重要因子。

Root stoichiometric characteristics of desert plants and their correlation with soil physicochemical factors in the northern Tarim Basin

Stoichiometry is becoming increasingly used as a method to understand ecological processes. Owing to their direct contact with saline and arid environments, the roots of desert plants play an important role in nutrient absorption from barren soil. The stoichiometric characteristics of roots are affected by several soil factors, and are effective indicators of the functional characteristics and survival strategies of xerophytes. In the present study, to understand the influence of soil factors on root stoichiometrics, we analyzed Glycyrrhiza, Phragmites australis, Karelinia caspica, Alhagi sparsifolia, Tamarix chinensis, Kalidium foliatum, and Populus euphratica Oliv from the northern Tarim Basin, and used previously collected data to investigate the stoichiometry of plant roots by experimental methods and analyzed factors, such as element content, using classic statistics, and multiple comparisons between different plant types and the stoichiometric characteristics of root carbon (C), nitrogen (N), and phosphorus (P). We studied the relationships between plant ecological stoichiometry and soil factors using redundancy analysis (RDA). Classic statistical analyses indicated that the concentrations of plant C (average:(443.62 ±70.84) mg/g), N (average:(7.44 ±3.59) mg/g), and P (average:(0.46 ±1.92) mg/g) were lower in the Tarim Basin than global averages, because the sterile soil could not provide sufficient nutrients. P had the highest and C had the lowest coefficient of variation; the ratio of C/N, C/P, and N/P were 63.37, 964.39, and 15.22, respectively. RDA revealed that soil moisture and EC ware the key soil physicochemical factors influencing root stoichiometrics. Both soil moisture and EC were significantly correlated to root stoichiometrics; however, soil stoichiometrics did not show a significant correlation to root stoichiometrics in this study, and these results differed from those of other studies. The hierarchy of importance of soil factors to root stoichiometrics could be arranged as soil moisture > EC > soil P > soil C > soil N. However, these results verified that water salinity has a greater effect on root stoichiometrics than nutrient element content, because the shortage of water made soil moisture a limiting factor, and desert plants have changed their physical characteristics to accommodate high-salinity environments. The results also indicated that water availability and salinity are the limiting factors in arid areas. Our study also confirmed that RDA could effectively be used in research to determine the relationship between stoichiometric and soil physicochemical factors. During this analysis, we studied the factors separately and ignored the interaction among them, which may have led to inaccuracies; therefore, this should be improved in future studies.