Ecosystem functions provided by aquatic plants are context dependent and mediated by environmental conditions and plant growth form. This impedes our ability to predict the carbon (i.e., C) sink potential of multispecies coastal meadows characterized by marked seasonal succession of environmental conditions, causing a clear need to explore the distinct patterns of both C capture and release associated with seasonal succession of macrophyte growth forms and life-history strategies in aquatic plant communities. We conducted four field surveys throughout 2022–2023 (i.e., October, March, June, and August), where we sampled six soft bottom locations dominated by aquatic vascular plants in the northern Baltic Sea. Temporal differences in biomass-bound C stocks (i.e., structural elements and non-structural carbohydrates) were linked to the plant production-decomposition cycle and peaked when environmental conditions became increasingly permissive for growth and development (i.e., summer). Species identity influenced seasonal patterns of non-structural carbohydrate concentrations in both leaf and rhizome tissue by shaping the timing of short-term accumulation (i.e., photosynthesis) of C in plant tissue or release through respiration. Overall, our study illustrates that biomass-bound C stocks were shaped by both seasonality and the variation of functional structure and life history strategies found within the vegetated seascapes. This highlights the importance of addressing both biodiversity and short-term C dynamics and suggests that estimations of C budgets or stock assessments should be based on data incorporating the intra-annual variation in C dynamics to fully comprehend the C sink potential of vegetated seascapes.

中文翻译：

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季节性强烈影响沿海大型植物群落的短期碳储存

水生植物提供的生态系统功能取决于环境并受到环境条件和植物生长形式的调节。这阻碍了我们预测多物种沿海草甸的碳（即 C）汇潜力的能力，这些草甸的特点是环境条件的季节性演替，因此明确需要探索与大型植物生长的季节性演替相关的 C 捕获和释放的不同模式水生植物群落的形态和生活史策略。我们在 2022 年至 2023 年期间（即 10 月、3 月、6 月和 8 月）进行了四次实地调查，在波罗的海北部以水生维管植物为主的六个软底位置进行了采样。生物量结合碳库（即结构元素和非结构碳水化合物）的时间差异与植物生产-分解周期有关，并在环境条件变得越来越有利于生长和发育时（即夏季）达到峰值。物种身份通过影响植物组织中碳的短期积累（即光合作用）或通过呼吸释放的时间，影响叶和根茎组织中非结构碳水化合物浓度的季节模式。总体而言，我们的研究表明，生物量结合的碳库是由季节性以及植被海景中发现的功能结构和生活史策略的变化决定的。这凸显了解决生物多样性和短期碳动态的重要性，并表明碳预算或库评估的估计应基于包含碳动态的年内变化的数据，以充分理解植被海景的碳汇潜力。