Table1_Fertile Island Effect by Three Typical Woody Plants on Wetlands of Ebinur Lake, northwestern China.DOCX

Desertification poses a permanent threat to the security of arid ecosystems. Perennial arid vegetation plays a crucial role in maintaining the structure and function of arid ecosystems and slowing the process of desertification by forming “fertile islands” under the tree canopy. However, the process of formation and development of these fertile islands remains uncertain. Here, we explored how three typical woody plants (i.e., Populus euphratica, Haloxylon ammodendron, and Nitraria tangutorum) in the Ebinur Lake Basin of northwestern China differed in their soil nitrogen and phosphorus. 1) Significant differences of organic carbon and total and available nitrogen/phosphorus were observed in the soil among the three typical woody plant-dominated ecosystems. Populus euphratica had significant differences of N and P contents between the canopy and bare soils, except for ammonium nitrogen. 2) Our RDA analysis revealed that the major factors that influenced the soil nutrient differences among the three vegetations were plant crown width, soil water content, salinity, and pH. 3) The organic carbon content of bare soil was significantly correlated with N and P in all the three vegetations. This study contributes to our understanding of the factors that influence the fertile island effect in arid ecosystems, which may contribute to soil conservation in arid areas.

荒漠化对干旱生态系统的安全构成持续性威胁。多年生干旱植被在维持干旱生态系统的结构与功能方面发挥着关键作用，其通过在树冠下形成“肥沃岛（fertile islands）”来延缓荒漠化进程。然而，这类肥沃岛的形成与发育过程仍尚不明确。本研究以中国西北艾比湖流域的3种典型木本植物——胡杨（Populus euphratica）、梭梭（Haloxylon ammodendron）和白刺（Nitraria tangutorum）为研究对象，探究了三者的土壤氮、磷含量差异。1）在这3种典型木本植物主导的生态系统中，土壤有机碳、全量氮磷与速效氮磷含量均存在显著差异。2）通过冗余分析（Redundancy Analysis, RDA）可知，影响3种植被间土壤养分差异的核心因素为植物冠幅、土壤含水量、盐度及pH值。3）在3种植被的样地中，裸地土壤有机碳含量均与氮、磷含量呈显著相关关系。本研究有助于加深对干旱生态系统中肥沃岛效应影响因素的认知，可为干旱地区的土壤保育工作提供理论参考。