Data from: How the litter-feeding bioturbator Orchestia gammarellus promotes late successional salt marsh vegetation

1.Traditionally, studies on vegetation succession have focused either on plant-plant interactions, or on interactions between plants and their physical environment, e.g. through organic matter build-up and increased nutrient cycling. These interactions can change conditions for macrodetritivores that feed on plant litter, but their role in vegetation succession is rarely studied. In this paper we explore whether the bioturbating crustacean macrodetritivore Orchestia gammarellus alters soil conditions in a salt marsh ecosystem in such a way that it promotes late successional, less stress-tolerant plant species at the expense of early successional species. 2.To answer this, we performed a field and a laboratory experiment in which we manipulated abundances of O. gammarellus, and studied the consequences for soil physical and chemical parameters and for vegetation community composition. 3.Our field experiment showed that O. gammarellus stimulated nitrogen mineralization, likely resulting from the positive effect of this macrodetritivore on soil aeration and litter decomposition. Moreover, results from the laboratory experiment showed that O. gammarellus negatively affected dicot seedling survival of mainly early successional plant species, likely through grazing, thus affecting plant community composition. 4.The experiments together provided evidence that O. gammarellus promotes late successional plant species in multiple ways: by alleviation of anoxic conditions, by promoting nutrient cycling and by selective herbivory on early successional species. 5.Synthesis: By demonstrating that a species traditionally considered as part of the detrital (‘brown’) food web is thus an important accelerator of vegetation succession, this study documents an important but often overlooked link in food web and ecosystem ecology.

1. 传统上，植被演替（vegetation succession）相关研究要么聚焦于植物间相互作用，要么关注植物与其物理环境之间的互作，例如通过有机质积累与养分循环强化的途径。这类互作会改变以植物凋落物为食的大型食碎屑动物（macrodetritivores）的生存环境，但这类动物在植被演替中的作用却鲜有研究。本文旨在探究：具有生物扰动功能的甲壳类大型食碎屑动物钩虾（Orchestia gammarellus）是否会改变盐沼生态系统的土壤环境，进而以牺牲早期演替物种为代价，促进后期演替、抗胁迫能力较弱的植物物种的生长。
2. 为解答这一科学问题，本研究开展了野外与室内受控实验：通过调控钩虾（O. gammarellus）的种群密度，探究其对土壤理化参数以及植被群落组成的影响。
3. 野外实验结果显示，钩虾可促进氮矿化过程，这一效应大概率源于该大型食碎屑动物对土壤通气性与凋落物分解的正向作用。此外，室内实验结果表明，钩虾主要通过啃食对早期演替植物的双子叶幼苗存活率产生负面影响，进而改变植物群落组成。
4. 两项实验共同证实：钩虾可通过多种途径促进后期演替植物物种的生长：一是缓解土壤缺氧环境，二是强化养分循环，三是对早期演替物种实施选择性植食。
5. 研究总结：本研究证实，一类传统上被归为碎屑（“褐色”）食物网成员的物种，实则是植被演替的重要推动者；该研究揭示了食物网与生态系统生态学中一个长期被忽视的关键关联。