Dissolved organic matter is a key compartment for biogeochemical cycles in the Arctic and Subarctic terrestrial environments. With changing vegetation ecosystems, the chemical composition of organic matter is expected to shift and thus, the most labile part of it, namely the extractable fraction. To this date, few studies have focused on the fingerprinting of DOM fraction from different primary sources, and even less on its potential repercussions on the environment. In this study, we jointly characterized the chemical composition of bulk and water-extractable organic matter (WEOM) from different vegetation species typical of Subarctic ecosystems. Through a multi-analyses approach, including elementary analysis, solid state ¹³C nuclear magnetic resonance, UV and 3D fluorescence spectroscopy, and high-resolution mass spectrometry, our results highlighted that the quantity and composition of produced WEOM significantly differed between vegetation sources and specifically between plant functional types (PFT, e.g., lichens, graminoids, and trees and shrubs). The relevance of optical indices was questioned, and the use of several of them was discarded for unprocessed WEOM study. However, the DOM proxies (optical indices, molecular composition, and stoichiometry) enabled to conclude that the lichen WEOM was likely less degradable than vascular plants WEOM, and among the latter group, graminoids produced more degradable WEOM than trees and shrubs. This work reported specific organic fingerprints for the different PFT. Consequently, the ongoing changes of vegetation in Arctic and Subarctic regions may greatly affect the composition of DOM that enters the soil and the hydrosystems, as well as the biogeochemical processes it is involved in.

溶解有机物是北极和亚北极陆地环境中生物地球化学循环的关键部分。随着植被生态系统的变化，有机物的化学成分预计会发生变化，因此，其中最不稳定的部分，即可提取部分。迄今为止，很少有研究关注来自不同主要来源的 DOM 分数的指纹识别，甚至更少关注其对环境的潜在影响。在这项研究中，我们共同表征了来自亚北极生态系统典型的不同植被物种的大量和水可提取有机物 (WEOM) 的化学成分。通过多种分析方法，包括元素分析，固态¹³C 核磁共振、紫外和 3D 荧光光谱以及高分辨率质谱，我们的结果强调了产生的 WEOM 的数量和组成在植被来源之间存在显着差异，特别是在植物功能类型（PFT，例如地衣、禾本科植物和树木和灌木）。光学指数的相关性受到质疑，其中几个被丢弃用于未处理的 WEOM 研究。然而，DOM 代理（光学指数、分子组成和化学计量）能够得出结论，地衣 WEOM 可能不如维管植物 WEOM 可降解，并且在后一组中，禾本科植物比树木和灌木产生更多可降解的 WEOM。这项工作报告了不同 PFT 的特定有机指纹。最后，