Stable Isotope Pot Experiment Data

In this study we pulse-labelled <i>F. japonica </i>and <i>U. dioica</i> with ¹³CO₂ and either ¹⁵NO₃ or ¹⁵NH₄ to investigate key aspects of their biogeochemical traits, carbon allocation and nitrogen uptake. These tracers allow us to differentiate between nitrate and ammonium, analyse how freshly taken up carbon and nitrogen are distributed between above-ground and below-ground plant parts, and compare the proportion of labelled nitrogen incorporated into plant biomass to determine the efficiency with which each species converts nitrogen into growth [10]. Specifically, we used these isotopes to: (a) resolve the question of whether <i>F. japonica</i> has a greater preference for ammonium than for nitrate when compared to <i>U. dioica</i> and how it compares to the manner in which <i>U. dioica</i> takes up ammonium and nitrate, (b) further explore the NUE of <i>F. japonica</i> compared to <i>U. dioica</i>, and (c) test if it invests more in its below-ground biomass during their early stages of development.

本研究采用¹³CO₂与¹⁵N标记硝酸根（¹⁵NO₃⁻）或¹⁵N标记铵根（¹⁵NH₄⁺）对日本虎杖（*Fallopia japonica*, F. japonica）与异株荨麻（*Urtica dioica*, U. dioica）进行脉冲标记，以探究二者的生物地球化学性状、碳分配模式与氮吸收特征。上述同位素示踪剂可帮助我们区分硝态氮与铵态氮，分析新近吸收的碳、氮在植物地上与地下器官间的分配规律，并通过比较掺入植物生物量的标记氮占比，解析各物种将氮转化为生物量增长的效率[10]。具体而言，本研究借助这些同位素开展以下三项研究：(a) 解答相较于异株荨麻，日本虎杖是否对铵态氮具有更高的偏好性，并对比二者对硝态氮与铵态氮的吸收模式；(b) 进一步探究日本虎杖相较于异株荨麻的氮利用效率（Nitrogen Use Efficiency, NUE）；(c) 验证日本虎杖是否在发育早期向地下生物量分配更多资源。