【目的】探究东北地区生态习性各异的山杨(Populus davidiana)、水曲柳(Fraxinus mandshurica)和东北红豆杉(Taxus cuspidata)地上地下器官氮(N)、磷(P)养分分配模式,为深入揭示树种间养分分配策略与权衡关系提供理论参考。【方法】以野外山杨、水曲柳和东北红豆杉成年植株为研究对象,对比分析3个树种地上器官叶片枝条和地下器官粗根细根N、P含量以及叶与枝、根N、P分配比例,采用标准主轴回归斜率检验3个树种地上、地下器官N与P元素之间及地上与地下器官养分双向运输N、P同一元素的增长关系。【结果】①山杨与水曲柳叶片N、P含量接近,山杨与水曲柳叶片N、P含量分别显著高于、低于东北红豆杉针叶相应数值(P<0.05);东北红豆杉枝条N、P含量最高;3个树种粗根N含量接近,水曲柳粗根P含量及细根N、P含量均最高。②水曲柳叶片与枝条、山杨叶片与粗根N、P含量比均最高,水曲柳叶片与细根N、P含量比最低。③山杨和东北红豆杉地上器官、地下器官N与P含量分别为异速、等速关系,且地下器官N与P元素间的变化斜率仅为地上部分的1/2;而水曲柳地上器官、地下器官两元素之间的变化斜率相似,均为显著大于1的异速增长关系。山杨地上与地下双向P、东北红豆杉上行方向P含量斜率均为相应N含量的一半,东北红豆杉下行方向N、P关系均不显著,水曲柳上行方向N、P含量斜率相似,下行方向P含量斜率是N的2/3左右。【结论】与山杨和东北红豆杉相比,水曲柳倾向于将N和P养分分配到代谢活跃的叶片和细根,且其地上(地下)器官N与P含量、地上与地下N、P含量变化速率具有协调一致性。

【Objective】The objective of this study is to investigate the nitrogen (N) and phosphorus (P) allocation patterns in the above- and below-ground organs of three different tree species in northeast China, namely Populus davidiana, Fraxinus mandshurica and Taxus cuspidata, and to provide theoretical insights into the trade-offs and allocation strategies of nutrient distribution among tree species.【Method】Mature individuals of P. davidiana, F. mandshurica and T. cuspidata were selected as research subjects. The N and P contents in aboveground organs, i.e., leaves, twigs and belowground organs, i.e., coarse roots, fine roots, were analyzed and the allocation ratios of N and P contents in the leaves, twigs and roots were calculated. Standardized major axis regressions were employed to examine the relationships of N and P elements between aboveground (belowground) organs of three tree species and the bidirectional nutrient transport of the same elements between aboveground and belowground organs.【Result】(1)The N and P contents in the leaves of P. davidiana and F. mandshurica were similar. However, the N and P contents in the leaves of these two species were significantly higher and lower, respectively, compared to T. cuspidata (P<0.05). The twigs of T. cuspidata exhibited the highest N and P contents, while F. mandshurica had the highest P content in coarse roots and N and P contents in fine roots. The N content in coarse roots was similar among the three species. (2)The ratios of N and P contents in leaves to twigs and leaves to coarse roots were the highest in F. mandshurica and P. davidiana, respectively, while the ratios of leaves to fine roots were the lowest in F. mandshurica. (3)For P. davidiana and T. cuspidata, the aboveground and belowground organs showed an allometric and isometric relationship respectively between N and P contents, with the scaling exponent in belowground being approximately half of that in aboveground. In contrast, F. mandshurica exhibited similar scaling exponents aboveground and belowground, both exhibiting significantly greater than 1 allometric relationship. For P. davidiana, the slopes of both aboveground and belowground P in both directions are half of the corresponding N values. For T. cuspidata, the slopes of P content in the upward direction were also half of the corresponding N values, and the downward N and P relationships were not significant. For F. mandshurica, the slopes of N and P content in the upward direction were similar, whereas in the downward direction, the P content slope was approximately 2/3 of N.【Conclusion】In contrast to P. davidiana and T. cuspidata, F. mandshurica tended to allocate N and P to metabolically active organs such as leaves and fine roots. The relationships between N and P in aboveground (or belowground) organs and N and P between above- and below-ground showed distinct coordinations for F. mandshurica compared to P. davidiana and T. cuspidata.