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.,DATA weight decrease in litter bags with and without Orchestia gammarellusFile presents data from litter bag experiment to investigate the effect of Orchestia gammarellus on litter decomposition. Litter bags were in Orchestia gammarellus addition and removal treatments, in two different vegetation types: late and early successional vegetation. Litter weight decrease (of original 10 grams) was determined in presence and absence of Orchestia gammarellus.DAT_Litter bags weight decrease.xlsxDATA vegetation biomass after 2-year field experimentFile presents data vegetation biomass data from 2-year manipulation experiment with Orchestia gammarellus was addition, removed and control treatments in early (Limonium vulgare) and late successional (Elytrigia atherica) vegetationtypes. Vegetation biomass was determined in a 50x50 cm square, in July 2010. As a result of a mistake during the sample collection, two data points are missing.DAT Veg biomass field experiment.xlsxDAT Nmin, moistureFile presents data from 2-year manipulation experiment with Orchestia gammarellus addition, removed and control treatments in two different vegetation types. During this experiment, nutrient mineralization in the various treaments was monitored. This file contains data on total N mineralization, NH4 and NO3 as well as the availability of these. It also contains data on soil moisture.DATA Orchestia numbers and environmental variables along successional gradientFile contains information on Orchestia gammarellus abundances and a number of environmental parameters along a chronosequence gradient on the salt marsh of Schiermonnikoog.DAT Nr Orchestia vs environmental variables.xlsxDAT soil redox potentials Orchestia Lab experimentIn a lab experiment we added Orchestia gammarellus to compacted salt marsh soils to investigate its effect on soil aeration and facilitation of a successional plant species, Elytrigia atherica. During the experiment we measured the redox potentials every 2 weeks.DAT Lab_Redox.xlsData on other variables in the lab experimentIn a lab experiment we added Orchestia gammarellus to compacted salt marsh soils to investigate its effect on soil aeration and facilitation of a successional plant species, Elytrigia atherica. File contains data on plant performance of Elytrigia atherica, seedling germination, and survival of Orchestia gammarellus.DAT_Lab_other_variables.xls,